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     _________________________________________________________________
   
                                                     W3C PR-CSS2-19980324
                                                                         
                      Cascading Style Sheets, level 2
                                      
                  W3C Proposed Recommendation 24-Mar-1998
                                      
   This version:
          http://www.w3.org/TR/1998/PR-CSS2-19980324
          
   Latest version:
          http://www.w3.org/TR/PR-CSS2
          
   Previous version:
          http://www.w3.org/TR/1998/WD-css2-19980128
          
   Editors:
          Bert Bos <bbos@w3.org>
          Håkon Wium Lie <howcome@w3.org>
          Chris Lilley <chris@w3.org>
          Ian Jacobs <ij@w3.org>
          
Abstract

   This specification defines Cascading Style Sheets, level 2 (CSS2).
   CSS2 is a style sheet language that allows authors and users to attach
   style (e.g., fonts, spacing, and aural cues) to structured documents
   (e.g., HTML documents and XML applications). By separating the
   presentation style of documents from the content of documents, CSS2
   simplifies Web authoring and site maintenance.
   
   CSS2 builds on CSS1 (see [CSS1]) and all valid CSS1 style sheets are
   valid CSS2 style sheets. CSS2 supports media-specific style sheets so
   that authors may tailor the presentation of their documents to visual
   browsers, aural devices, printers, braille devices, handheld devices,
   etc. This specification also supports content positioning,
   downloadable fonts, table layout, features for internationalization,
   automatic counters and numbering, and some properties related to user
   interface.
   
Status of this document

   This document is currently undergoing review by the members of the
   World Wide Web Consortium. It is a stable document derived from a
   series of working drafts produced over the last year as deliverables
   of the Style Sheets activity. Details of this review have been
   distributed to Member's representatives. Comments by non-Members
   should be sent to www-style@w3.org.
   
   The review period will end on 21 April, 1998 at 24:00 GMT. Within 14
   days from that time, the document's disposition will be announced: it
   may become a W3C Recommendation (possibly with minor changes), or it
   may revert to Working Draft status, or it may be dropped as a W3C work
   item.
   
   As a Proposed Recommendation, this document does not imply any
   endorsement by the Consortium's staff or Member organizations.
   
Available formats

   The CSS2 specification is available in the following formats:
   
   HTML:
          http://www.w3.org/TR/1998/PR-CSS2-19980324
          
   a plain text file:
          http://www.w3.org/TR/1998/PR-CSS2-19980324/css2.txt,
          
   HTML as a gzip'ed tar file:
          http://www.w3.org/TR/1998/PR-CSS2-19980324/css2.tgz,
          
   HTML as a zip file (this is a '.zip' file not an '.exe'):
          http://www.w3.org/TR/1998/PR-CSS2-19980324/css2.zip,
          
   as well as a gzip'ed PostScript file:
          http://www.w3.org/TR/1998/PR-CSS2-19980324/css2.ps.gz,
          
   and a PDF file:
          http://www.w3.org/TR/1998/PR-CSS2-19980324/css2.pdf.
          
   In case of a discrepancy between the various forms of the
   specification, the HTML version is considered the definitive version.
   
  Available languages
  
   The English version of this specification is the only normative
   version. However, for translations in other languages see
   http://www.w3.org/TR/1998/PR-CSS2-19980324/translations.html.
   
Quick Table of Contents

     * 1 About the CSS2 Specification
     * 2 Introduction to CSS2
     * 3 Conformance: Requirements and Recommendations
     * 4 CSS2 syntax and basic data types
     * 5 Selectors
     * 6 Assigning property values, Cascading, and Inheritance
     * 7 Media types
     * 8 Box model
     * 9 Visual rendering model
     * 10 Visual rendering model details
     * 11 Visual effects
     * 12 Generated content and automatic numbering
     * 13 Paged media
     * 14 Colors and Backgrounds
     * 15 Fonts
     * 16 Text
     * 17 Lists
     * 18 Tables
     * 19 User interface
     * 20 Aural style sheets
     * Appendix A. A sample style sheet for HTML 4.0
     * Appendix B. Changes from CSS1
     * Appendix C. Implementation and performance notes
     * Appendix D. The grammar of CSS2
     * Appendix E. References
     * Appendix F. Property index
     * Appendix G. Descriptor index
     * Appendix H. Index
       
Full Table of Contents

     * 1 About the CSS2 Specification
          + 1.1 Reading the specification
          + 1.2 How the specification is organized
          + 1.3 Conventions
               o 1.3.1 Document language elements and attributes
               o 1.3.2 CSS property definitions
                    # Value
                    # Initial
                    # Applies to
                    # Inherited
                    # Percentage values
                    # Media groups
               o 1.3.3 Shorthand properties
               o 1.3.4 Notes and examples
          + 1.4 Acknowledgments
          + 1.5 Copyright Notice
     * 2 Introduction to CSS2
          + 2.1 A brief CSS2 tutorial for HTML
          + 2.2 A brief CSS2 tutorial for XML
          + 2.3 The CSS2 processing model
               o 2.3.1 The canvas
               o 2.3.2 CSS2 addressing model
          + 2.4 CSS design principles
     * 3 Conformance: Requirements and Recommendations
          + 3.1 Definitions
          + 3.2 Conformance
          + 3.3 Error conditions
          + 3.4 The text/css content type
     * 4 CSS2 syntax and basic data types
          + 4.1 Syntax
               o 4.1.1 Tokenization
               o 4.1.2 Keywords
               o 4.1.3 Characters and case
               o 4.1.4 Statements
               o 4.1.5 At-rules
               o 4.1.6 Blocks
               o 4.1.7 Rule sets, declaration blocks, and selectors
               o 4.1.8 Declarations and properties
               o 4.1.9 Comments
          + 4.2 Rules for handling parsing errors
          + 4.3 Values
               o 4.3.1 Integers and real numbers
               o 4.3.2 Lengths
               o 4.3.3 Percentages
               o 4.3.4 URL + URN = URI
               o 4.3.5 Counters
               o 4.3.6 Colors
               o 4.3.7 Angles
               o 4.3.8 Times
               o 4.3.9 Frequencies
               o 4.3.10 Strings
          + 4.4 CSS document representation
               o 4.4.1 Referring to characters not represented in a
                 character encoding
     * 5 Selectors
          + 5.1 Pattern matching
          + 5.2 Selector syntax
               o 5.2.1 Grouping
          + 5.3 Universal selector
          + 5.4 Type selectors
          + 5.5 Descendant selectors
          + 5.6 Child selectors
          + 5.7 Adjacent selectors
          + 5.8 Attribute selectors
               o 5.8.1 Matching attributes and attribute values
               o 5.8.2 Default attribute values in DTDs
               o 5.8.3 Class selectors
          + 5.9 ID selectors
          + 5.10 Pseudo-elements and pseudo-classes
          + 5.11 Pseudo-classes
               o 5.11.1 :first-child pseudo-class
               o 5.11.2 The link pseudo-classes: :link and :visited
               o 5.11.3 The dynamic pseudo-classes: :hover, :active, and
                 :focus
               o 5.11.4 The language pseudo-class: :lang
          + 5.12 Pseudo-elements
               o 5.12.1 The :first-line pseudo-element
               o 5.12.2 The :first-letter pseudo-element
               o 5.12.3 The :before and :after pseudo-elements
     * 6 Assigning property values, Cascading, and Inheritance
          + 6.1 Specified, computed, and actual values
               o 6.1.1 Specified values
               o 6.1.2 Computed values 
               o 6.1.3 Actual values
          + 6.2 Inheritance
               o 6.2.1 The 'inherit' value
          + 6.3 The @import rule
          + 6.4 The cascade
               o 6.4.1 Cascading order
               o 6.4.2 !important rules
               o 6.4.3 Calculating a selector's specificity
               o 6.4.4 Precedence of non-CSS presentational hints
     * 7 Media types
          + 7.1 Introduction to media types
          + 7.2 Specifying media-dependent style sheets
               o 7.2.1 The @media rule
          + 7.3 Recognized media types
               o 7.3.1 Media groups
     * 8 Box model
          + 8.1 Box dimensions
          + 8.2 Example of margins, padding, and borders
          + 8.3 Margin properties: 'margin-top', 'margin-right',
            'margin-bottom', 'margin-left', and 'margin'
               o 8.3.1 Collapsing margins
          + 8.4 Padding properties: 'padding-top', 'padding-right',
            'padding-bottom', 'padding-left', and 'padding'
          + 8.5 Border properties
               o 8.5.1 Border width: 'border-top-width',
                 'border-right-width', 'border-bottom-width',
                 'border-left-width', and 'border-width'
               o 8.5.2 Border color: 'border-top-color',
                 'border-right-color', 'border-bottom-color',
                 'border-left-color', and 'border-color'
               o 8.5.3 Border style: 'border-top-style',
                 'border-right-style', 'border-bottom-style',
                 'border-left-style', and 'border-style'
               o 8.5.4 Border shorthand properties: 'border-top',
                 'border-bottom', 'border-right', 'border-left', and
                 'border'
     * 9 Visual rendering model
          + 9.1 Introduction to the visual rendering model
               o 9.1.1 The viewport
               o 9.1.2 Containing blocks
          + 9.2 Controlling box generation
               o 9.2.1 Block-level elements and block boxes
                    # Anonymous block boxes
               o 9.2.2 Inline-level elements and inline boxes
                    # Anonymous inline boxes
               o 9.2.3 Compact boxes
               o 9.2.4 Run-in boxes
               o 9.2.5 The 'display' property
          + 9.3 Positioning schemes
               o 9.3.1 Choosing a positioning scheme: 'position' property
               o 9.3.2 Box offsets: 'top', 'right', 'bottom', 'left'
          + 9.4 Normal flow
               o 9.4.1 Block formatting context
               o 9.4.2 Inline formatting context
               o 9.4.3 Relative positioning
          + 9.5 Floats
               o 9.5.1 Positioning the float: the 'float' property
               o 9.5.2 Controlling flow next to floats: the 'clear'
                 property
          + 9.6 Absolute positioning
               o 9.6.1 Fixed positioning
          + 9.7 Relationships between 'display', 'position', and 'float'
          + 9.8 Comparison of normal flow, floats, and absolute
            positioning
               o 9.8.1 Normal flow
               o 9.8.2 Relative positioning
               o 9.8.3 Floating a box
               o 9.8.4 Absolute positioning
          + 9.9 Layered presentation
               o 9.9.1 Specifying the stack level: the 'z-index' property
          + 9.10 Text direction: the 'direction' and 'unicode-bidi'
            properties
               o 9.10.1 Interaction between inline flow and text
                 direction
               o 9.10.2 Bidirectionality in HTML 4.0
     * 10 Visual rendering model details
          + 10.1 Details of containing block calculation
          + 10.2 Calculation of box and line box widths
          + 10.3 Box width calculations
               o 10.3.1 Content width: the 'width' property
               o 10.3.2 Width of boxes in the normal flow and floated
                 boxes
                    # Determining the content width
                    # Computing margin widths
               o 10.3.3 Width of absolutely positioned boxes
               o 10.3.4 Minimum and maximum widths: 'min-width' and
                 'max-width'
          + 10.4 Box height calculations
               o 10.4.1 Content height: the 'height' property
               o 10.4.2 Determining the content height
               o 10.4.3 Height of absolutely positioned boxes
               o 10.4.4 Minimum and maximum heights: 'min-height' and
                 'max-height'
          + 10.5 Line height calculations: the 'line-height' and
            'vertical-align' properties
               o 10.5.1 Leading and half-leading
     * 11 Visual effects
          + 11.1 Overflow and clipping
               o 11.1.1 Overflow: the 'overflow' property
               o 11.1.2 Clipping: the 'clip' property
          + 11.2 Visibility: the 'visibility' property
     * 12 Generated content and automatic numbering
          + 12.1 The :before and :after pseudo-elements
          + 12.2 The 'content' property
          + 12.3 Interaction of :before and :after with 'compact' and
            'run-in' elements
          + 12.4 Quotation marks
               o 12.4.1 Specifying quotes with the 'quotes' property
               o 12.4.2 Inserting quotes with the 'content' property
          + 12.5 Automatic counters and numbering
               o 12.5.1 Nested counters and scope
               o 12.5.2 Counter styles
               o 12.5.3 Counters in elements with 'display: none'
          + 12.6 Markers
     * 13 Paged media
          + 13.1 Introduction to paged media
          + 13.2 Page boxes: the @page rule
               o 13.2.1 Page margins
               o 13.2.2 Page size: the 'size' property
                    # Rendering page boxes that do not fit a target sheet
                    # Positioning the page box on the sheet
               o 13.2.3 Crop marks: the 'marks' property
               o 13.2.4 Left, right, and first pages
               o 13.2.5 Content outside the page box
          + 13.3 Page breaks
               o 13.3.1 Break before/after elements: 'page-break-before',
                 'page-break-after', 'page-break-inside'
               o 13.3.2 Using named pages: 'page'
               o 13.3.3 Breaks inside elements: 'orphans', 'widows', and
                 'page-break-inside'
               o 13.3.4 Allowed page breaks
               o 13.3.5 Forced page breaks
               o 13.3.6 "Best" page breaks
          + 13.4 Cascading in the page context
     * 14 Colors and Backgrounds
          + 14.1 Foreground color: the 'color' property
          + 14.2 The background
               o 14.2.1 Background properties: 'background-color',
                 'background-image', 'background-repeat',
                 'background-attachment', 'background-position', and
                 'background'
          + 14.3 Gamma correction
     * 15 Fonts
          + 15.1 Introduction
          + 15.2 Font specification
               o 15.2.1 Font specification properties
               o 15.2.2 Font family: the 'font-family' property
               o 15.2.3 Font styling: the 'font-style', 'font-variant',
                 'font-weight' and 'font-stretch' properties
               o 15.2.4 Font size: the 'font-size' and 'font-size-adjust'
                 properties
               o 15.2.5 Shorthand font property: the 'font' property
               o 15.2.6 Generic font families
                    # serif
                    # sans-serif
                    # cursive
                    # fantasy
                    # monospace
          + 15.3 Font selection
               o 15.3.1 Font Descriptions and @font-face
               o 15.3.2 Descriptors for Selecting a Font: 'font-family',
                 'font-style', 'font-variant', 'font-weight',
                 'font-stretch' and 'font-size'
               o 15.3.3 Descriptors for Font Data Qualification:
                 'unicode-range'
               o 15.3.4 Descriptor for Numeric Values: 'units-per-em'
               o 15.3.5 Descriptor for Referencing: 'src'
               o 15.3.6 Descriptors for Matching: 'panose-1', 'stemv',
                 'stemh', 'slope', 'cap-height', 'x-height', 'ascent',
                 and 'descent'
               o 15.3.7 Descriptors for Synthesis: 'widths', 'bbox' and
                 'definition-src'
               o 15.3.8 Descriptors for Alignment: 'baseline',
                 'centerline', 'mathline', and 'topline'
               o 15.3.9 Examples
          + 15.4 Font Characteristics
               o 15.4.1 Introducing Font Characteristics
               o 15.4.2 Full font name
               o 15.4.3 Coordinate units on the em square
               o 15.4.4 Central Baseline
               o 15.4.5 Font Encoding
               o 15.4.6 Font family name
               o 15.4.7 Glyph widths
               o 15.4.8 Horizontal stem width
               o 15.4.9 Height of uppercase glyphs
               o 15.4.10 Height of lowercase glyphs
               o 15.4.11 Lower Baseline
               o 15.4.12 Mathematical Baseline
               o 15.4.13 Maximal bounding box
               o 15.4.14 Maximum unaccented height
               o 15.4.15 Maximum unaccented depth
               o 15.4.16 Panose-1 number
               o 15.4.17 Range of ISO 10646 characters
               o 15.4.18 Top Baseline
               o 15.4.19 Vertical stem width
               o 15.4.20 Vertical stroke angle
          + 15.5 Font matching algorithm
               o 15.5.1 Mapping font weight values to font names
               o 15.5.2 Examples of font matching
     * 16 Text
          + 16.1 Indentation: the 'text-indent' property
          + 16.2 Alignment: the 'text-align' property
          + 16.3 Decoration
               o 16.3.1 Underlining, overlining, striking, and blinking:
                 the 'text-decoration' property
               o 16.3.2 Text shadows: the 'text-shadow' property
          + 16.4 Letter and word spacing: the 'letter-spacing' and
            'word-spacing' properties
          + 16.5 Case
               o 16.5.1 Capitalization: the 'text-transform' property
               o 16.5.2 Special first letter/first line
          + 16.6 White space: the 'white-space' property
               o 16.6.1 Line breaks
     * 17 Lists
          + 17.1 Visual formatting of lists
               o 17.1.1 List properties: 'list-style-type',
                 'list-style-image', 'list-style-position', and
                 'list-style'
     * 18 Tables
          + 18.1 Introduction to tables
          + 18.2 The CSS table model
               o 18.2.1 Anonymous table boxes
          + 18.3 Column selectors
          + 18.4 Tables in the visual rendering model
               o 18.4.1 Caption position and alignment
          + 18.5 Visual layout of table contents
               o 18.5.1 Row and column spans: 'column-span', and
                 'row-span'
               o 18.5.2 Table layers and transparency
               o 18.5.3 Table size algorithms: the 'table-layout'
                 property
                    # Fixed table layout
                    # Automatic table layout
               o 18.5.4 Alignment of cell boxes
                    # Vertical alignment in a row
                    # Horizontal alignment in a column
               o 18.5.5 Dynamic row and column effects
          + 18.6 Borders
               o 18.6.1 The separated borders model
                    # Borders around empty cells: the 'empty-cells'
                      property
               o 18.6.2 The collapsing border model
                    # Border conflict resolution
               o 18.6.3 Border styles
          + 18.7 Audio rendering of tables
               o 18.7.1 Speaking headers: the 'speak-header' property
     * 19 User interface
          + 19.1 Cursors: the 'cursor' property
          + 19.2 User preferences for colors
          + 19.3 User preferences for fonts
          + 19.4 Dynamic outlines: the 'outline' property
               o 19.4.1 Outlines and the focus
          + 19.5 Magnification
     * 20 Aural style sheets
          + 20.1 Introduction to aural style sheets
          + 20.2 Volume properties: 'volume'
          + 20.3 Speaking properties: 'speak'
          + 20.4 Pause properties: 'pause-before', 'pause-after', and
            'pause'
          + 20.5 Cue properties: 'cue-before', 'cue-after', and 'cue'
          + 20.6 Mixing properties: 'play-during'
          + 20.7 Spatial properties: 'azimuth' and 'elevation'
          + 20.8 Voice characteristic properties: 'speech-rate',
            'voice-family', 'pitch', 'pitch-range', 'stress', and
            'richness'
          + 20.9 Speech properties: 'speak-punctuation' and
            'speak-numeral'
     * Appendix A. A sample style sheet for HTML 4.0
     * Appendix B. Changes from CSS1
          + B.1 New functionality
          + B.2 Updated descriptions
          + B.3 Semantic changes from CSS1
     * Appendix C. Implementation and performance notes
          + C.1 Fonts
               o C.1.1 Glossary of font terms
               o C.1.2 Font retrieval
               o C.1.3 Meaning of the Panose Digits
               o C.1.4 Deducing Unicode Ranges for TrueType
               o C.1.5 Automatic descriptor generation
     * Appendix D. The grammar of CSS2
          + D.1 Grammar
          + D.2 Lexical scanner
          + D.3 Comparison of tokenization in CSS2 and CSS1
     * Appendix E. References
          + E.1 Normative references
          + E.2 Informative references
     * Appendix F. Property index
     * Appendix G. Descriptor index
     * Appendix H. Index
       
      Copyright  ©  1997 W3C (MIT, INRIA, Keio ), All Rights Reserved.
     _________________________________________________________________
     _________________________________________________________________
   
                       1 About the CSS2 Specification
                                      
   Contents
     * 1.1 Reading the specification
     * 1.2 How the specification is organized
     * 1.3 Conventions
          + 1.3.1 Document language elements and attributes
          + 1.3.2 CSS property definitions
               o Value
               o Initial
               o Applies to
               o Inherited
               o Percentage values
               o Media groups
          + 1.3.3 Shorthand properties
          + 1.3.4 Notes and examples
     * 1.4 Acknowledgments
     * 1.5 Copyright Notice
       
1.1 Reading the specification

   This specification has been written with two types of readers in mind:
   CSS authors and CSS implementors. We hope the specification will
   provide authors with the tools they need to write efficient,
   attractive, and accessible documents, without overexposing them to
   CSS's implementation details. Implementors, however, should find all
   they need to build conforming user agents. The specification begins
   with a general presentation of CSS and becomes more and more technical
   and specific towards the end. For quick access to information, a
   general table of contents, specific tables of contents at the
   beginning of each section, and an index provide easy navigation, in
   both the electronic and printed versions.
   
   The specification has been written with two modes of presentation in
   mind: electronic and printed. Although the two presentations will no
   doubt be similar, readers will find some differences. For example,
   links will not work in the printed version (obviously), and page
   numbers will not appear in the electronic version. In case of a
   discrepancy, the electronic version is considered the authoritative
   version of the document.
   
1.2 How the specification is organized

   The specification is organized into the following sections:
   
   Section 2: An introduction to CSS2
          The introduction includes a brief tutorial on CSS2 and a
          discussion of design principles behind CSS2.
          
   Sections 3 - 20: CSS2 reference manual.
          The bulk of the reference manual consists of the CSS2 language
          reference. This reference defines what may go into a CSS2 style
          sheet (syntax, properties, property values) and how user agents
          must interpret these style sheets in order to claim
          conformance.
          
   Appendixes:
          Appendixes contain information about a sample style sheet for
          HTML 4.0, changes from CSS1 , implementation and performance
          notes, and the grammar of CSS2, a list of normative and
          informative references, and three indexes: one for properties,
          one for descriptors, and one general index.
          
1.3 Conventions

  1.3.1 Document language elements and attributes
  
     * CSS property, descriptor, and pseudo-class names are delimited by
       single quotes.
     * CSS values are delimited by single quotes.
     * Document language element names are in uppercase letters.
     * Document language attribute names are in lowercase letters and
       delimited by double quotes.
       
  1.3.2 CSS property definitions
  
   Each CSS property definition begins with a summary of key information
   that resembles the following:
   
   'property-name'
          Value:   legal values & syntax
          Initial:   initial value
          Applies to:   elements this property applies to
          Inherited:   whether the property is inherited
          Percentages:   how percentage values are interpreted
          Media:   which media groups the property applies to
          
    Value
    
   This part specifies the set of valid values for the property. Value
   types may be designated in several ways:
    1. keyword values (e.g., auto, disc, etc.)
    2. basic data types, which appear between "<" and ">" (e.g.,
       <length>, <percentage>, etc.). In the electronic version of the
       document, each instance of a basic data type links to its
       definition.
    3. types that have the same range of values as a property bearing the
       same name (e.g., <'border-width'> <'background-attachment'>,
       etc.). In this case, the type name is the property name (complete
       with quotes) between "<" and ">" (e.g., <'border-width'>). In the
       electronic version of the document, each instance of this type of
       non-terminal links to the corresponding property definition.
    4. non-terminals that do not share the same name as a property. In
       this case, the non-terminal name appears between "<" and ">", as
       in <border-width>. Notice the distinction between <border-width>
       and <'border-width'>; the latter is defined in terms of the
       former. The definition of a non-terminal is located near its first
       appearance in the specification. In the electronic version of the
       document, each instance of this type of value links to the
       corresponding value definition.
       
   Other words in these definitions are keywords that must appear
   literally, without quotes (e.g., red). The slash (/) and the comma (,)
   must also appear literally.
   
   Values may be arranged as follows:
   
     * Several juxtaposed words mean that all of them must occur, in the
       given order.
     * A bar (|) separates two or more alternatives: exactly one of them
       must occur.
     * A double bar (||) separates two or more options: one or more of
       them must occur, in any order.
     * Brackets ([ ]) are for grouping.
       
   Juxtaposition is stronger than the double bar, and the double bar is
   stronger than the bar. Thus, the following lines are equivalent:

    a b   |   c || d e
  [ a b ] | [ c || [ d e ]]

   Every type, keyword, or bracketed group may be followed by one of the
   following modifiers:
   
     * An asterisk (*) indicates that the preceding type, word or group
       occurs zero or more times.
     * A plus (+) indicates that the preceding type, word or group occurs
       one or more times.
     * A question mark (?) indicates that the preceding type, word or
       group is optional.
     * A pair of numbers in curly braces ({A,B}) indicates that the
       preceding type, word or group occurs at least A and at most B
       times.
       
   The following examples illustrate different value types:
   
     Value: N | NW | NE
     Value: [ <length> | thick | thin ]{1,4}
     Value: [<family-name> , ]* <family-name>
     Value: <uri>? <color> [ / <color> ]?
     Value: <uri> || <color>
     
    Initial
    
   This part specifies the property's initial value. If the property is
   inherited, this is the value that is given to the root element of the
   document tree. Please consult the section on the cascade for
   information about the interaction between style sheet-specified,
   inherited, and initial values.
   
    Applies to
    
   This part lists the elements to which the property applies. All
   elements are considered to have all properties, but some properties
   have no rendering effect on some types of elements. For example,
   'white-space' only affects block-level elements.
   
    Inherited
    
   This part indicates whether the value of the property is inherited
   from an ancestor element. Please consult the section on the cascade
   for information about the interaction between style sheet-specified,
   inherited, and initial values.
   
    Percentage values
    
   This part indicates how percentages should be interpreted, if they
   occur in the value of the property. If "N/A" appears here, it means
   that the property does not accept percentages as values.
   
    Media groups
    
   This part indicates the media groups to which the property applies.
   The conformance conditions state that user agents must support this
   property if they support rendering to the media types included in
   these media groups.
   
  1.3.3 Shorthand properties
  
   Some properties are shorthand rules that allow authors to specify the
   values of several properties with a single property.
   
   For instance, the 'font' property is a shorthand property for setting
   'font-style', 'font-variant', 'font-weight', 'font-size',
   'line-height', and 'font-family' all at once.
   
   When values are omitted from a shorthand form, each "missing" property
   is assigned its initial value (see the section on the cascade).
   
   The multiple style rules of this example:
   
H1 {
  font-weight: bold;
  font-size: 12pt;
  line-height: 14pt;
  font-family: Helvetica;
  font-variant: normal;
  font-style: normal;
  font-stretch: normal;
  font-size-adjust: none
}

   may be rewritten with a single shorthand property:
   
H1 { font: bold 12pt/14pt Helvetica }

   In this example, 'font-variant', 'font-stretch', 'font-size-adjust',
   and 'font-style' could be omitted from the shorthand form, since they
   have their initial value ('normal').
   
  1.3.4 Notes and examples
  
   All examples that illustrate illegal usage are clearly marked as
   "ILLEGAL EXAMPLE".
   
   All HTML examples conform to the strict DTD (defined in [HTML40])
   unless otherwise indicated by a document type declaration.
   
   All notes are informative only.
   
   Examples and notes are marked within the source HTML for the
   specification and CSS1 user agents will render them specially.
   
1.4 Acknowledgments

   This specification is the product of the W3C Working Group on
   Cascading Style Sheets and Formatting Properties. In addition to the
   editors of this specification, the members of the Working Group are:
   Brad Chase (Bitstream), Chris Wilson (Microsoft), Daniel Glazman
   (Electricité de France), Dave Raggett (W3C/HP), Ed Tecot (Microsoft),
   Jared Sorensen (Novell), Lauren Wood (SoftQuad), Laurie Anna Kaplan
   (Microsoft), Mike Wexler (Adobe), Murray Maloney (Grif), Powell Smith
   (IBM), Robert Stevahn (HP), Steve Byrne (JavaSoft), Steven Pemberton
   (CWI), Thom Phillabaum (Netscape), Douglas Rand (Silicon Graphics),
   Robert Pernett (Lotus), Dwayne Dicks (SoftQuad), and Sho Kuwamoto
   (Macromedia). We thank them for their continued efforts.
   
   A number of invited experts to the Working Group have contributed:
   George Kersher, Glenn Rippel (Bitstream), Jeff Veen (HotWired), Markku
   T. Hakkinen (The Productivity Works), Martin Dürst (W3C, formerly
   Universität Zürich), Roy Platon (RAL), Todd Fahrner (Verso), Frederick
   Boland (NIST), Eric Meyer (Case Western Reserve University), and
   Vincent Quint (W3C).
   
   The section on Web Fonts was strongly shaped by Brad Chase (Bitstream)
   David Meltzer (Microsoft Typography) and Steve Zilles (Adobe). The
   following people have also contributed in various ways to the section
   pertaining to fonts: Alex Beamon (Apple), Ashok Saxena (Adobe), Ben
   Bauermeister (HP), Dave Raggett (W3C/HP), David Opstad (Apple), David
   Goldsmith (Apple), Ed Tecot (Microsoft), Erik van Blokland
   (LettError), François Yergeau (Alis), Gavin Nicol (Inso), Herbert van
   Zijl (Elsevier), Liam Quin, Misha Wolf (Reuters), Paul Haeberli (SGI),
   and the late Phil Karlton (Netscape).
   
   The section on Paged Media was in large parts authored by Robert
   Stevahn (HP) and Stephen Waters (Microsoft).
   
   Robert Stevahn (HP), Scott Furman (Netscape), and Scott Isaacs
   (Microsoft) were key contributors to CSS Positioning.
   
   Mike Wexler (Adobe) was the editor of the interim Working Draft which
   described many of the new features of CSS2.
   
   T.V. Raman (Adobe) made pivotal contributions towards Aural Cascading
   Style Sheets (ACSS) and the concepts of aural presentation based on
   his work on AsTeR (Audio System For Technical Readings). He
   contributed an initial draft of the ACSS specification that shaped the
   current specification. Values for aural properties in the HTML 4.0
   sample style sheet are of his devising; he currently uses them on a
   daily basis on his audio desktop in conjunction with Emacspeak and the
   Emacs W3 browser (authored by William Perry, who also implemented the
   aural extensions on the W3 side of the fence).
   
   Todd Fahrner (Verso) researched contemporary and historical browsers
   to develop the sample style sheet in the appendix.
   
   Thanks to Jan Kärrman, author of html2ps for helping so much in
   creating the PostScript version of the specification.
   
   Through electronic and physical encounters, the following people have
   contributed to the development of CSS2: Robert Cailliau, Liz Castro,
   James Clark, Dan Connolly, Donna Converse, Daniel Dardailler, Scott
   Isaacs, Geir Ivarsøy, Lou Montulli, Henrik Frystyk Nielsen, Jacob
   Nielsen, Vincent Mallet, Eva von Pepel, William Perry, David Siegel,
   Al Gilman, and Jason White.
   
   The discussions on www-style@w3.org have been influential in many key
   issues for CSS. Especially, we would like to thank Bjorn Backlund,
   Todd Fahrner, Lars Marius Garshol, Ian Hickson, Susan Lesch, Andrew
   Marshall, MegaZone, Eric Meyer, Russell O'Connor, David Perrell, Liam
   Quinn, Neil St.Laurent, Taylor, Brian Wilson, and Chris Wilson for
   their participation.
   
   Many thanks to Philippe Le Hégaret, whose CSS validator helped ensure
   correct examples and a sensible grammar.
   
   Special thanks to Arnaud Le Hors, whose engineering contributions made
   this document work.
   
   Adam Costello improved this specification by performing a detailed
   review.
   
   Lastly, thanks to Tim Berners-Lee without whom none of this would have
   been possible.
   
1.5 Copyright Notice

   Copyright © 1997 World Wide Web Consortium, (Massachusetts Institute
   of Technology, Institut National de Recherche en Informatique et en
   Automatique, Keio University). All Rights Reserved.
   
   Documents on the W3C site are provided by the copyright holders under
   the following license. By obtaining, using and/or copying this
   document, or the W3C document from which this statement is linked, you
   agree that you have read, understood, and will comply with the
   following terms and conditions:
   
   Permission to use, copy, and distribute the contents of this document,
   or the W3C document from which this statement is linked, in any medium
   for any purpose and without fee or royalty is hereby granted, provided
   that you include the following on ALL copies of the document, or
   portions thereof, that you use:
    1. A link or URI to the original W3C document.
    2. The pre-existing copyright notice of the original author, if it
       doesn't exist, a notice of the form: "Copyright © World Wide Web
       Consortium, (Massachusetts Institute of Technology, Institut
       National de Recherche en Informatique et en Automatique, Keio
       University). All Rights Reserved."
    3. If it exists, the STATUS of the W3C document.
       
   When space permits, inclusion of the full text of this NOTICE should
   be provided. In addition, credit shall be attributed to the copyright
   holders for any software, documents, or other items or products that
   you create pursuant to the implementation of the contents of this
   document, or any portion thereof.
   
   No right to create modifications or derivatives is granted pursuant to
   this license.
   
   THIS DOCUMENT IS PROVIDED "AS IS," AND COPYRIGHT HOLDERS MAKE NO
   REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, INCLUDING, BUT NOT
   LIMITED TO, WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR
   PURPOSE, NON-INFRINGEMENT, OR TITLE; THAT THE CONTENTS OF THE DOCUMENT
   ARE SUITABLE FOR ANY PURPOSE; NOR THAT THE IMPLEMENTATION OF SUCH
   CONTENTS WILL NOT INFRINGE ANY THIRD PARTY PATENTS, COPYRIGHTS,
   TRADEMARKS OR OTHER RIGHTS.
   
   COPYRIGHT HOLDERS WILL NOT BE LIABLE FOR ANY DIRECT, INDIRECT, SPECIAL
   OR CONSEQUENTIAL DAMAGES ARISING OUT OF ANY USE OF THE DOCUMENT OR THE
   PERFORMANCE OR IMPLEMENTATION OF THE CONTENTS THEREOF.
   
   The name and trademarks of copyright holders may NOT be used in
   advertising or publicity pertaining to this document or its contents
   without specific, written prior permission. Title to copyright in this
   document will at all times remain with copyright holders.
     _________________________________________________________________
     _________________________________________________________________
   
                           2 Introduction to CSS2
                                      
   Contents
     * 2.1 A brief CSS2 tutorial for HTML
     * 2.2 A brief CSS2 tutorial for XML
     * 2.3 The CSS2 processing model
          + 2.3.1 The canvas
          + 2.3.2 CSS2 addressing model
     * 2.4 CSS design principles
       
2.1 A brief CSS2 tutorial for HTML

   In this tutorial, we show how easy it can be to design simple style
   sheets. For this tutorial, you will need to know a little HTML (see
   [HTML40]) and some basic desktop publishing terminology.
   
   We begin with a small HTML document:
   
<HTML>
  <TITLE>Bach's home page</TITLE>
  <BODY>
    <H1>Bach's home page</H1>
    <P>Johann Sebastian Bach was a prolific composer.
  </BODY>
</HTML>

   To set the text color of the H1 elements to blue, you can write the
   following CSS rule:
   
  H1 { color: blue }

   A CSS rule consists of two main parts: selector ('H1') and declaration
   ('color: blue'). The declaration has two parts: property ('color') and
   value ('blue'). While the example above tries to influence only one of
   the properties needed for rendering an HTML document, it qualifies as
   a style sheet on its own. Combined with other style sheets (one
   fundamental feature of CSS is that style sheets are combined) it will
   determine the final presentation of the document.
   
   The HTML 4.0 specification defines how style sheet rules may be
   specified for HTML documents: either within the HTML document, or via
   an external style sheet. To put the style sheet into the document, use
   the STYLE element:
   
<HTML>
  <TITLE>Bach's home page</TITLE>
  <STYLE type="text/css">
    H1 { color: blue }
  </STYLE>
  <BODY>
    <H1>Bach's home page</H1>
    <P>Johann Sebastian Bach was a prolific composer.
  </BODY>
</HTML>

   For maximum flexibility, we recommend that authors specify external
   style sheets; they may be changed without modifying the source HTML
   document, and they may be shared among several documents. To link to
   an external style sheet, you can use the LINK element:
   
<HTML>
  <TITLE>Bach's home page</TITLE>
  <LINK rel="stylesheet" href="bach.css" type="text/css">
  <BODY>
    <H1>Bach's home page</H1>
    <P>Johann Sebastian Bach was a prolific composer.
  </BODY>
</HTML>

   The LINK element specifies:
   
     * the type of link: to a "stylesheet".
     * the location of the style sheet via the href attribute.
     * the type of style sheet being linked: "text/css".
       
   To show the close relationship between a style sheet and the
   structured markup, we continue to use the STYLE element in this
   tutorial. Let's add more colors:

<HTML>
  <TITLE>Bach's home page</TITLE>
  <STYLE type="text/css">
    BODY { color: red }
    H1 { color: blue }
  </STYLE>
  <BODY>
    <H1>Bach's home page</H1>
    <P>Johann Sebastian Bach was a prolific composer.
  </BODY>
</HTML>

   The style sheet now contains two rules: the first one sets the color
   of the BODY element to 'red', while the second one sets the color of
   the H1 element to 'blue'. Since no color value has been specified for
   the P element, it will inherit the color from its parent element,
   namely BODY. The H1 element is also a child element of BODY but the
   second rule overrides the inherited value. In CSS there are often such
   conflicts between different values, and this specification describes
   how to resolve them.
   
   CSS2 has more than 100 different properties and 'color' is one of
   them. Let's look at some of the others:

<HTML>
  <TITLE>Bach's home page</TITLE>
  <STYLE type="text/css">
    BODY {
      font-family: "Gill Sans", sans-serif;
      font-size: 12pt;
      margin: 3em;
    }
  </STYLE>
  <BODY>
    <H1>Bach's home page</H1>
    <P>Johann Sebastian Bach was a prolific composer.
  </BODY>
</HTML>

   The first thing to notice is that several declarations are grouped
   within a block enclosed by curly braces ({...}), and separated by
   semicolons, though the last declaration may also be followed by a
   semicolon.
   
   The first declaration on the BODY element sets the font family to
   "Gill Sans". If that font isn't available, the user agent (often
   referred to as a "browser") will use the 'sans-serif' font family
   which is one of five generic font families which all users agents
   know. Child elements of BODY will inherit the value of the
   'font-family' property.
   
   The second declaration sets the font size of the BODY element to 12
   points. The "point" unit is commonly used in print-based typography to
   indicate font sizes and other length values. It's an example of an
   absolute unit which does not scale relative to the environment.
   
   The third declaration uses a relative unit which scales with regard to
   its surroundings. The "em" unit refers to the font size of the
   element. In this case the result is that the margins around the BODY
   element are three times wider than the font size.
   
2.2 A brief CSS2 tutorial for XML

   CSS can be used with any structured document format, for example with
   applications of the eXtensible Markup Language [XML10]. In fact, XML
   depends more on style sheets than HTML, since authors can make up
   their own elements that user agents don't know how to display.
   
   Here is a simple XML fragment:
<ARTICLE>
  <HEADLINE>Fredrick the Great meets Bach</HEADLINE>
  <AUTHOR>Johann Nikolaus Forkel</AUTHOR>
  <PARA>
    One evening, just as he was getting his
    <INSTRUMENT>flute</INSTRUMENT> ready and his
    musicians were assembled, an officer brought him a list of
    the strangers who had arrived.
  </PARA>
</ARTICLE>

   To display this fragment in a document-like fashion, we must first
   declare which elements are inline-level (i.e., do not cause line
   breaks) and which are block-level (i.e., cause line breaks).

INSTRUMENT { display: inline }
ARTICLE, HEADLINE, AUTHOR, PARA { display: block }

   The first rule declares INSTRUMENT to be inline and the second rule,
   with its comma-separated list of selectors, declares all the other
   elements to be block-level.
   
   One proposal for linking a style sheet to an XML document is to use a
   processing instruction:

<?XML:stylesheet type="text/css" href="bach.css"?>
<ARTICLE>
  <HEADLINE>Fredrick the Great meets Bach</HEADLINE>
  <AUTHOR>Johann Nikolaus Forkel</AUTHOR>
  <PARA>
    One evening, just as he was getting his
    <INSTRUMENT>flute</INSTRUMENT> ready and his
    musicians were assembled, an officer brought him a list of
    the strangers who had arrived.
  </PARA>
</ARTICLE>

   A visual user agent could format the above example as:
   
   Example rendering
   
   Notice that the word "flute" remains within the paragraph since it is
   the content of the inline element INSTRUMENT.
   
   Still, the text isn't formatted the way you would expect. For example,
   the headline font size should be larger than then rest of the text,
   and you may want to display the author's name in italic:
   
INSTRUMENT { display: inline }
ARTICLE, HEADLINE, AUTHOR, PARA { display: block }
HEADLINE { font-size: 1.3em }
AUTHOR { font-style: italic }
ARTICLE, HEADLINE, AUTHOR, PARA { margin: 0.5em }

   Example rendering
   
   Adding more rules to the style sheet will allow you to further improve
   the presentation of the document.
   
2.3 The CSS2 processing model

   This section presents one possible model of how user agents that
   support CSS work. This is only a conceptual model; real
   implementations may vary.
   
   In this model, a user agent processes a source by going through the
   following steps:
   
    1. Parse the source document and create a document tree from the
       source document.
    2. Identify the target media type.
    3. Retrieve all style sheets associated with the document that are
       specified for the target media type.
    4. Annotate every element of the document tree by assigning a single
       value to every property that is applicable to the target media
       type. Properties are assigned values according to the mechanisms
       described in the section on cascading and inheritance.
       Part of the calculation of values depends on the formatting
       algorithm appropriate for the target media type. For example, if
       the target medium is the screen, user agents apply the visual
       rendering model. If the destination medium is the printed page,
       user agents apply the page model. If the destination medium is an
       aural rendering device (e.g., speech synthesizer), user agents
       apply the aural rendering model.
    5. From the annotated document tree, generate a rendering structure.
       Often, the rendering structure closely resembles the document
       tree, but it may also differ significantly, notably when authors
       make use of pseudo-elements and generated content. First, the
       rendering structure need not be "tree-shaped" at all -- the nature
       of the structure depends on the implementation. Second, the
       rendering structure may contain more or less information than the
       document tree. For instance, if an element in the document tree
       has a value of 'none' for the 'display' property, that element
       will generate nothing in the rendering structure. A list element,
       on the other hand, may generate more information in the rendering
       structure: the list element's content and list style information
       (e.g., a bullet image).
       Note that the CSS user agent does not alter the document tree
       during this phase. In particular, content generated due to style
       sheets is not fed back to the document language processor (e.g.,
       for reparsing).
    6. Transfer the rendering structure to the target medium (e.g., print
       the results, display them on the screen, render them as speech,
       etc.).
       
   Step 1 lies outside the scope of this specification (see, for example,
   [DOM]).
   
   Steps 2-5 are addressed by the bulk of this specification.
   
   Step 6 lies outside the scope of this specification.
   
  2.3.1 The canvas
  
   For all media, the term canvas describes "the space where the
   rendering structure is rendered." The canvas is infinite for each
   dimension of the space, but rendering generally occurs within a finite
   region of the canvas, established by the user agent according to the
   target medium. For instance, user agents rendering to a screen
   generally impose a minimum width and choose an initial width based on
   the dimensions of the viewport. User agents rendering to a page
   generally impose width and height constraints. Aural user agents may
   impose limits in audio space, but not in time.
   
  2.3.2 CSS2 addressing model
  
   CSS2 selectors and properties allow style sheets to refer to the
   following characteristics of a document:
   
     * Elements in the document tree and certain relationships between
       them (see the section on selectors).
     * Attributes of elements in the document tree, and values of those
       attributes (see the section on attribute selectors).
     * Some parts of element content (see the :first-line and
       :first-letter pseudo-elements.
     * Elements of the document tree when they are in a certain state
       (see the section on pseudo-classes).
     * Some aspects of the canvas where the document will be rendered.
     * Some system information (see the section on user interface).
       
2.4 CSS design principles

   CSS2, as CSS1 before it, is based on a set of design principles:
   
     * Forward and backward compatibility. CSS2 user agents will be able
       to understand CSS1 style sheets. CSS1 user agents will be able to
       read CSS2 style sheets and discard parts they don't understand.
       Also, user agents with no CSS support will be able to display
       style-enhanced documents. Of course, the stylistic enhancements
       made possible by CSS will not be rendered, but all content will be
       presented.
     * Complementary to structured documents. Style sheets complement
       structured documents (e.g., HTML and XML applications), providing
       stylistic information for the marked-up text. It should be easy to
       change the style sheet with little or no impact on the markup.
     * Vendor, platform, and device independence. Style sheets enable
       documents to remain vendor, platform, and device independent.
       Style sheets themselves are also vendor and platform independent,
       but CSS2 allows you to target a style sheet for a group of devices
       (e.g., printers).
     * Maintainability. By pointing to style sheets from documents,
       webmasters can simplify site maintenance and retain consistent
       look and feel throughout the site. For example, if the
       organization's background color changes, only one file needs to be
       changed.
     * Simplicity. CSS2 is more complex than CSS1, but it remains a
       simple style language which is human readable and writable. The
       CSS properties are kept independent of each other to the largest
       extent possible and there is generally only one way to achieve a
       certain effect.
     * Network performance. CSS provides for compact encodings of how to
       present content. Compared to images or audio files, which are
       often used by authors to achieve certain rendering effects, style
       sheets most often decrease the content size. Also, fewer network
       connections have to be opened which further increases network
       performance.
     * Flexibility. CSS can be applied to content in several ways. The
       key feature is the ability to cascade style information specified
       in the default (user agent) style sheet, user style sheets, linked
       style sheets, the document head, and in attributes for the
       elements forming the document body.
     * Richness. Providing authors with a rich set of rendering effects
       increases the richness of the Web as a medium of expression.
       Designers have been longing for functionality commonly found e.g.,
       in desktop publishing and slide-show applications. Some of the
       requested rendering effects conflict with device independence, but
       CSS2 goes a long way toward granting designers their requests.
     * Alternative language bindings. The set of CSS properties described
       in this specification form a consistent formatting model for
       visual and aural presentations. This formatting model can be
       accessed through the CSS language, but bindings to other languages
       are also possible. For example, a JavaScript program may
       dynamically change the value of a certain element's 'color'
       property.
     * Accessibility. Last, but not least, CSS will increase
       accessibility to Web documents, not just for people with
       handicaps, but for everybody, and even for robots. By retaining
       textual information in text form, robots and human users alike
       will have more options for digesting the content. Users can
       provide their personal style sheets if author-suggested style
       sheets hinder accessibility. The cascading mechanism combines and
       selects from different style sheets.
     _________________________________________________________________
     _________________________________________________________________
   
              3 Conformance: Requirements and Recommendations
                                      
   Contents
     * 3.1 Definitions
     * 3.2 Conformance
     * 3.3 Error conditions
     * 3.4 The text/css content type
       
3.1 Definitions

   In this section, we begin the formal specification of CSS2, starting
   with the contract between authors, users, and implementers.
   
   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 (see
   [RFC2119]). However, for readability, these words do not appear in all
   uppercase letters in this specification.
   
   At times, this specification recommends good practice for authors and
   user agents. These recommendations are not normative and conformance
   with this specification does not depend on their realization. These
   recommendations contain the expression "We recommend ...", "This
   specification recommends ...", or some similar wording.
   
   Style sheet
          A set of statements that specify presentation of a document.
          
          Style sheets may have three different origins: author, user,
          and user agent. The interaction of these sources is described
          in the section on cascading and inheritance.
          
   Valid style sheet
          The validity of a style sheet depends on the level of CSS used
          for the style sheet. All valid CSS1 style sheets are valid CSS2
          style sheets. However, some changes from CSS1 mean that a few
          CSS1 style sheets will have slightly different semantics in
          CSS2.
          
          A valid CSS2 style sheet must be written according to the
          grammar of CSS2. Furthermore, it must contain only at-rules,
          property names, and property values defined in this
          specification. An illegal or invalid at-rule, property name, or
          property value is one that is not valid.
          
   Source document
          The document to which one or more style sheets refer. This is
          encoded in some language that represents the document as a tree
          of elements. Each element consists of a name that identifies
          the type of element, optionally a number of attributes, and a
          (possibly empty) content.
          
   Document language
          The encoding language of the source document (e.g., HTML or an
          XML application).
          
   Element
          (An SGML term, see [ISO8879].) The primary syntactic constructs
          of the document language. Most CSS style sheet rules use the
          names of these elements (such as "P", "TABLE", and "OL" for
          HTML) to specify rendering information for them.
          
   Attribute
          A value associated with an element, consisting of a name, and
          an associated (textual) value.
          
   Content
          The content associated with an element in the source document;
          not all elements have content in which case they are called
          empty. The content of an element may include text, and it may
          include a number of sub-elements, in which case the element is
          called the parent of those sub-elements.
          
   Rendered content
          The content of an element after the rendering that applies to
          it according to the relevant style sheets has been applied. The
          rendered content of a replaced element (one that causes
          external content to be inserted in the document) may come from
          outside the source document (e.g., HTML's IMG element).
          Rendered content may also be alternate text for an element
          (e.g., the value of the HTML "alt" attribute), and may include
          items inserted implicitly or explicitly by the style sheet,
          such as bullets, numbering, etc.
          
   Document tree
          The tree of elements encoded in the source document. Each
          element in this tree has exactly one parent, with the exception
          of the root element, which has none.
          
   Child
          An element A is called the child of element B if an only if B
          is the parent of A.
          
   Descendant
          An element A is called a descendant of an element B, if either
          (1) A is a child of B, or (2) A is the child of some element C
          that is a descendant of B.
          
   Ancestor
          An element A is called an ancestor of an element B, if and only
          if B is a descendant of A.
          
   Sibling
          An element A is called a sibling of an element B, if and only
          if B and A share the same parent element. Element A is a
          preceding sibling if it comes before B in the document tree.
          Element B is a following sibling if it comes after B in the
          document tree.
          
   Preceding element
          An element A is called a preceding element of an element B, if
          and only if (1) A is an ancestor of B or (2) A is a preceding
          sibling of B.
          
   Following element
          An element A is called a following element of an element B, if
          and only if B is a preceding element of A.
          
   Author
          An author is a person who writes documents and associated style
          sheets. An authoring tool generates documents and associated
          style sheets.
          
   User
          A user is a person who interacts with a user agent to view,
          hear, or otherwise use a document and its associated style
          sheet. The user may provide a personal style sheet that encodes
          personal preferences.
          
   User agent (UA)
          A user agent is any program that interprets a document written
          in the document language and applies associated style sheets
          according to the terms of this specification. A user agent may
          display a document, read it aloud, cause it to be printed,
          convert it to another format, etc.
          
   Here is an example of a source document encoded in HTML:
<HTML>
  <TITLE>My home page</TITLE>
  <BODY>
    <H1>My home page</H1>
    <P>Welcome to my home page! Let me tell you about my favorite
                composers:
    <UL>
      <LI> Elvis Costello
      <LI> Johannes Brahms
      <LI> Georges Brassens
    </UL>
  </BODY>
</HTML>

   This results in the following tree:
   
   Sample document tree
   
   According to the definition of HTML, HEAD elements will be inferred
   during parsing and become part of the document tree even if the HEAD
   tags are not in the document source. Similarly, the parser knows where
   the P and LIs end, even though there are no </P> and </LI> tags in the
   source.
   
3.2 Conformance

   This section defines conformance with the CSS2 specification only.
   There may be other levels of CSS in the future that may require a user
   agent to implement a different set of features in order to conform.
   
   In general, the following points must be observed by a user agent
   claiming conformance to this specification:
   
    1. It must support one or more of the CSS2 media types.
    2. For each source document, it must attempt to retrieve all
       associated style sheets that are appropriate for the supported
       media types. If it cannot retrieve all associated style sheets
       (for instance, because of network errors), it must display the
       document using those it can retrieve.
    3. It must parse the style sheets according to this specification. In
       particular, it must recognize all at-rules, blocks, declarations,
       and selectors (see the grammar of CSS2). If a user agent
       encounters a property that applies for a supported media type, the
       user agent must parse the value according to the property
       definition. This means that the user agent must accept all valid
       values and must ignore declarations with invalid values. User
       agents must ignore rules that apply to unsupported media types.
    4. Given a document tree, it must assign a value for every supported
       property according to the rules of cascading and inheritance.
    5. If the source document comes with alternate style sheets (such as
       with the "alternate" keyword in HTML 4.0 [HTML40]), the UA must
       allow the user to select one from among these style sheets and
       apply the selected one.
       
   Not every user agent must observe every point, however:
   
     * A user agent that inputs style sheets must respect points 1 - 3.
     * An authoring tool is only required to output valid style sheets
     * A user agent that renders a document with associated style sheets
       must respect points 1 - 5 and render the document according to the
       media-specific requirements set forth in this specification.
       Values may be approximated when required by the user agent.
       
   The inability of a user agent to implement part of this specification
   due to the limitations of a particular device (e.g., a user agent
   cannot render colors on a monochrome monitor or page) does not imply
   non-conformance.
   
   This specification recommends that a user agent allow the user to
   specify user style sheets.
   
3.3 Error conditions

   In general, this document does not specify error handling behavior for
   user agents (e.g., how they behave when they cannot find a resource
   designated by a URI).
   
   However, user agents must observe the rules for handling parsing
   errors.
   
   Since user agents may vary in how they handle error conditions,
   authors and users must not rely on specific error recovery behavior.
   
3.4 The text/css content type

   CSS style sheets that exist in separate files are sent over the
   Internet as a sequence of bytes accompanied by encoding information
   (see [HTML40], chapter 5). The structure of the transmission, termed a
   message entity, is defined by RFC 2045 and RFC 2068 (see [RFC2045] and
   [RFC2068]). A message entity with a content type of "text/css"
   represents an independent CSS document.
   
   Note. The "text/css" content type is currently being registered
   through IETF.
     _________________________________________________________________
     _________________________________________________________________
   
                     4 CSS2 syntax and basic data types
                                      
   Contents
     * 4.1 Syntax
          + 4.1.1 Tokenization
          + 4.1.2 Keywords
          + 4.1.3 Characters and case
          + 4.1.4 Statements
          + 4.1.5 At-rules
          + 4.1.6 Blocks
          + 4.1.7 Rule sets, declaration blocks, and selectors
          + 4.1.8 Declarations and properties
          + 4.1.9 Comments
     * 4.2 Rules for handling parsing errors
     * 4.3 Values
          + 4.3.1 Integers and real numbers
          + 4.3.2 Lengths
          + 4.3.3 Percentages
          + 4.3.4 URL + URN = URI
          + 4.3.5 Counters
          + 4.3.6 Colors
          + 4.3.7 Angles
          + 4.3.8 Times
          + 4.3.9 Frequencies
          + 4.3.10 Strings
     * 4.4 CSS document representation
          + 4.4.1 Referring to characters not represented in a character
            encoding
       
4.1 Syntax

   This section describes a grammar common to any version of CSS
   (including CSS2). Future versions of CSS will adhere to this core
   syntax, although they may add additional syntactic constraints.
   
   These descriptions are normative. They are also complemented by the
   normative grammar rules presented in Appendix D.
   
  4.1.1 Tokenization
  
   All levels of CSS -- level 1, level 2, and any future levels -- use
   the same core syntax. This allows UAs to parse (though not completely
   understand) style sheets written in levels of CSS that didn't exist at
   the time the UAs were created. Designers can use this feature to
   create style sheets that work with older user agents, while also
   exercising the possibilities of the latest levels of CSS.
   
   At the lexical level, CSS style sheets consist of a sequence of
   tokens. The list of tokens for CSS2 is as follows. The definitions use
   Lex-style regular expressions. Octal codes refer to ISO 10646
   ([ISO10646]). As in Lex, in case of multiple matches, the longest
   match determines the token.
   Token Definition
     _________________________________________________________________
   
   IDENT {ident}
   ATKEYWORD @{ident}
   STRING {string}
   HASH #{name}
   NUMBER {num}
   PERCENTAGE {num}%
   DIMENSION {num}{ident}
   URI url\({w}{string}{w}\)
   |url\({w}([!#$%&*-~]|{nonascii}|{escape})*{w}\)
   UNICODE-RANGE U\+[0-9A-F?]{1,6}(-[0-9A-F]{1,6})?
   CDO <!--
   CDC -->
   ; ;
   { \{
   } \}
   ( \(
   ) \)
   [ \[
   ] \]
   S [ \t\r\n\f]+
   COMMENT \/\*[^*]*\*+([^/][^*]*\*+)*\/
   FUNCTION {ident}\(
   INCLUDES ~=
   DASHMATCH |=
   DELIM any other character not matched by the above rules
   
   The macros in curly braces ({}) above are defined as follows:
   Macro Definition
     _________________________________________________________________
   
   ident {nmstart}{nmchar}*
   nmstart [a-zA-Z]|{nonascii}|{escape}
   nonascii [^\0-\177]
   unicode \\[0-9a-f]{1,6}[ \n\r\t\f]?
   escape {unicode}|\\[ -~\200-\4177777]
   nmchar [a-z0-9-]|{nonascii}|{escape}
   num [0-9]+|[0-9]*\.[0-9]+
   string {string1}|{string2}
   string1 \"([\t !#$%&(-~]|\\\n|\'|{nonascii}|{escape})*\"
   string2 \'([\t !#$%&(-~]|\\\n|\"|{nonascii}|{escape})*\'
   w [ \t\r\n\f]*
   
   Below is the core syntax for CSS. The sections that follow describe
   how to use it. Appendix D describes a more restrictive grammar that is
   closer to the CSS level 2 language.

stylesheet  : [ CDO | CDC | S | statement ]*;
statement   : ruleset | at-rule;
at-rule     : ATKEYWORD S* any* [ block | ';' S* ];
block       : '{' S* [ any | block | ATKEYWORD S* | ';' ]* '}' S*;
ruleset     : selector? '{' S* declaration? [ ';' S* declaration? ]* '}' S*;
selector    : any+;
declaration : property ':' S* value;
property    : IDENT S*;
value       : [ any | block | ATKEYWORD S* ]+;
any         : [ IDENT | NUMBER | PERCENTAGE | DIMENSION | STRING
              | DELIM | URI | HASH | UNICODE-RANGE | INCLUDES
              | FUNCTION | DASHMATCH | '(' any* ')' | '[' any* ']' ] S*;

   COMMENT tokens do not occur in the grammar (to keep it readable), but
   any number of these tokens may appear anywhere between other tokens.
   
   The token S in the grammar above stands for whitespace. Only the
   characters "space" (Unicode code 32), "tab" (9), "line feed" (10),
   "carriage return" (13), and "form feed" (12) can occur in whitespace.
   Other space-like characters, such as "em-space" (8195) and
   "ideographic space" (12288), are never part of whitespace.
   
  4.1.2 Keywords
  
   Keywords have the form of identifiers. Keywords must not be placed
   between quotes ("..." or '...'). Thus,

red

   is a keyword, but
"red"

   is not. (It is a string.) Other illegal examples:
   
width: "auto";
border: "none";
font-family: "serif";
background: "red";

  4.1.3 Characters and case
  
   The following rules always hold:
   
     * All CSS style sheets are case-insensitive, except for parts that
       are not under the control of CSS. For example, the
       case-sensitivity of values of the HTML attributes 'id' and
       'class', of font names, and of URIs lies outside the scope of this
       specification. Note in particular that element names are
       case-insensitive in HTML, but case-sensitive in XML.
     * In CSS2, identifiers (including element names, classes and IDs in
       selectors) can contain only the characters [A-Za-z0-9] and ISO
       10646 characters 161 and higher, plus the hyphen (-); they cannot
       start with a hyphen or a digit. They can also contain escaped
       characters and any ISO 10646 character as a numeric code (see next
       item). For instance, the identifier "B&W?" may be written as
       "B\&W\?" or "B\26 W\3F".
       Note that Unicode is code-by-code equivalent to ISO 10646 (see
       [UNICODE] and [ISO10646]).
     * In CSS2, a backslash (\) character indicates three types of
       character escape.
       First, inside a string, a backslash followed by a newline is
       ignored (i.e., the string is deemed not to contain either the
       backslash or the newline).
       Second, it cancels the meaning of special CSS characters. Any
       character (except a hexadecimal digit) can be escaped with a
       backslash to remove its special meaning. For example, "\"" is a
       string consisting of one double quote. Style sheet preprocessors
       must not remove these backslashes from a style sheet since that
       would change the style sheet's meaning.
       Third, backslash escapes allow authors to refer to characters they
       can't easily put in a document. In this case, the backslash is
       followed by at most six hexadecimal digits (0..9A..F), which stand
       for the ISO 10646 ([ISO10646]) character with that number. If a
       digit or letter follows the hexadecimal number, the end of the
       number needs to be made clear. There are two ways to do that:
         1. with a space (or other whitespace character): "\26 B" ("&B")
         2. by providing exactly 6 hexadecimal digits: "\000026B" ("&B")
       In fact, these two methods may be combined. Only one whitespace
       character is ignored after a hexadecimal escape. Note that this
       means that a "real" space after the escape sequence must itself
       either be escaped or doubled.
     * Backslash escapes are always considered to be part of an
       identifier or a string (i.e., "\7B" is not punctuation, even
       though "{" is, and "\32" is allowed at the start of a class name,
       even though "2" is not).
       
  4.1.4 Statements
  
   A CSS style sheet, for any version of CSS, consists of a list of
   statements (see the grammar above). There are two kinds of statements:
   at-rules and rule sets. There may be whitespace around the statements.
   
   In this specification, the expressions "immediately before" or
   "immediately after" mean with no intervening white space or comments.
   
  4.1.5 At-rules
  
   At-rules start with an at-keyword, an '@' character followed by an
   identifier (for example, '@import', '@page').
   
   An at-rule consists of everything up to and including the next
   semicolon (;) or the next block, whichever comes first. A CSS user
   agent that encounters an unrecognized at-rule must ignore the whole of
   the @-rule and continue parsing after it.
   
   CSS2 user agents must ignore any '@import' rule that occurs inside a
   block or that doesn't precede all rule sets.
   
   Here is an example. Assume a CSS2 parser encounters this style sheet:
@import "subs.css";
H1 { color: blue }
@import "list.css";

   The second '@import' is illegal according to CSS2. The CSS2 parser
   ignores the whole at-rule, effectively reducing the style sheet to:

@import "subs.css";
H1 { color: blue }

   In the following example, the second '@import' rule is invalid, since
   it occurs inside a '@media' block.

@import "subs.css";
@media print {
  @import "print-main.css";
  BODY { font-size: 10pt }
}
H1 {color: blue }

  4.1.6 Blocks
  
   A block starts with a left curly brace ({) and ends with the matching
   right curly brace (}). In between there may be any characters, except
   that parentheses (( )), brackets ([ ]) and braces ({ }) must always
   occur in matching pairs and may be nested. Single (') and double
   quotes (") must also occur in matching pairs, and characters between
   them are parsed as a string. See Tokenization above for the definition
   of a string.
   
   Here is an example of a block. Note that the right brace between the
   double quotes does not match the opening brace of the block, and that
   the second single quote is an escaped character, and thus doesn't
   match the first single quote:

{ causta: "}" + ({7} * '\'') }

   Note that the above rule is not valid CSS2, but it is still a block as
   defined above.
   
  4.1.7 Rule sets, declaration blocks, and selectors
  
   A rule set (also called "rule") consists of a selector followed by a
   declaration block.
   
   A declaration-block (also called a {}-block in the following text)
   starts with a left curly brace ({) and ends with the matching right
   curly brace (}). In between there must be a list of zero or more
   semicolon-separated (;) declarations.
   
   The selector (see also the section on selectors) consists of
   everything up to (but not including) the first left curly brace ({). A
   selector always goes together with a {}-block. When a user agent can't
   parse the selector (i.e., it is not valid CSS2), it must ignore the
   {}-block as well.
   
   CSS2 gives a special meaning to the comma (,) in selectors. However,
   since it is not known if the comma may acquire other meanings in
   future versions of CSS, the whole statement should be ignored if there
   is an error anywhere in the selector, even though the rest of the
   selector may look reasonable in CSS2.
   
   For example, since the "&" is not a valid token in a CSS2 selector, a
   CSS2 user agent must ignore the whole second line, and not set the
   color of H3 to red:

H1, H2 {color: green }
H3, H4 & H5 {color: red }
H6 {color: black }

   Here is a more complex example. The first two pairs of curly braces
   are inside a string, and do not mark the end of the selector. This is
   a valid CSS2 statement.

P[example="public class foo\
{\
    private int x;\
\
    foo(int x) {\
        this.x = x;\
    }\
\
}"] { color: red }

  4.1.8 Declarations and properties
  
   A declaration is either empty or consists of a property, followed by a
   colon (:), followed by a value. Around each of these there may be
   whitespace.
   
   Because of the way selectors work, multiple declarations for the same
   selector may be organized into semicolon (;) separated groups.
   
   Thus, the following rules:
   
H1 { font-weight: bold }
H1 { font-size: 12pt }
H1 { line-height: 14pt }
H1 { font-family: Helvetica }
H1 { font-variant: normal }
H1 { font-style: normal }

   are equivalent to:
   
H1 {
  font-weight: bold;
  font-size: 12pt;
  line-height: 14pt;
  font-family: Helvetica;
  font-variant: normal;
  font-style: normal
}

   A property is an identifier. Any character may occur in the value, but
   parentheses ("( )"), brackets ("[ ]"), braces ("{ }"), single quotes
   (') and double quotes (") must come in matching pairs, and semicolons
   not in strings must be escaped. Parentheses, brackets, and braces may
   be nested. Inside the quotes, characters are parsed as a string.
   
   The syntax of values is specified separately for each property, but in
   any case, values are built from identifiers, strings, numbers,
   lengths, percentages, URIs, colors, angles, times, and frequencies.
   
   A user agent must ignore a declaration with an invalid property name
   or an invalid value. Every CSS2 property has its own syntactic and
   semantic restrictions on the values it accepts.
   
   For example, assume a CSS2 parser encounters this style sheet:
H1 { color: red; font-style: 12pt }  /* Invalid value: 12pt */
P { color: blue;  font-vendor: any;  /* Invalid prop.: font-vendor */
    font-variant: small-caps }
EM EM { font-style: normal }

   The second declaration on the first line has an invalid value '12pt'.
   The second declaration on the second line contains an undefined
   property 'font-vendor'. The CSS2 parser will ignore these
   declarations, effectively reducing the style sheet to:

H1 { color: red; }
P { color: blue;  font-variant: small-caps }
EM EM { font-style: normal }

  4.1.9 Comments
  
   Comments begin with the characters "/*" and end with the characters
   "*/". They may occur anywhere between tokens, and their contents have
   no influence on the rendering. Comments may not be nested.
   
   CSS also allows the SGML comment delimiters ("<!--" and "-->") in
   certain places, but they do not delimit CSS comments. They are
   permitted so that style rules appearing in an HTML source document (in
   the STYLE element) may be hidden from pre-HTML 3.2 user agents. See
   the HTML 4.0 specification ([HTML40]) for more information.
   
4.2 Rules for handling parsing errors

   In some cases, user agents must ignore part of an illegal style sheet.
   This specification defines ignore to mean that the user agent parses
   the illegal part (in order to find its beginning and end), but
   otherwise acts as if it had not been there.
   
   To ensure that new properties and new values for existing properties
   can be added in the future, user agents are required to obey the
   following rules when they encounter these parsing errors:
   
     * Unknown properties. User agents must ignore a declaration with an
       unknown property. For example, if the style sheet is:

H1 { color: red; rotation: 70minutes }
       the user agent will treat this as if the style sheet had been

H1 { color: red }
     * Illegal values. User agents must ignore a declaration with an
       illegal value. For example:

IMG { float: left }       /* correct CSS2 */
IMG { float: left here }  /* "here" is not a value of 'float' */
IMG { background: "red" } /* keywords cannot be quoted in CSS2 */
IMG { border-width: 3 }   /* a unit must be specified for length values */
   A CSS2 parser would honor the first rule and ignore the rest, as if
       the style sheet had been:

IMG { float: left }
IMG { }
IMG { }
IMG { }
       A user agent conforming to a future CSS specification may accept
       one or more of the other rules as well.
     * Invalid at-keywords. User agents must ignore an invalid at-keyword
       together with everything following it, up to and including the
       next semicolon (;) or block ({...}), whichever comes first. For
       example, consider the following:

@three-dee {
  @background-lighting {
    azimuth: 30deg;
    elevation: 190deg;
  }
  H1 { color: red }
}
H1 { color: blue }
       The '@three-dee' at-rule is not part of CSS2. Therefore, the whole
       at-rule (up to, and including, the third right curly brace) is
       ignored. A CSS2 user agent ignores it, effectively reducing the
       style sheet to:

H1 { color: blue }

4.3 Values

  4.3.1 Integers and real numbers
  
   Some value types may have integer values (denoted by <integer>) or
   real number values (denoted by <number>). Real numbers and integers
   are specified in decimal notation only. An <integer> consists of one
   or more digits "0" to "9". A <number> can either be an <integer>, or
   it can be zero or more digits followed by a dot (.) followed by one or
   more digits. Both integers and real numbers may be preceded by a "-"
   or "+" to indicate the sign.
   
   Note that many properties that allow an integer or real number as a
   value actually restrict the value to some range, often to a
   non-negative value.
   
  4.3.2 Lengths
  
   Lengths refer to horizontal or vertical measurements.
   
   The format of a length value (denoted by <length> in this
   specification) is an optional sign character ('+' or '-', with '+'
   being the default) immediately followed by a <number> (with or without
   a decimal point) immediately followed by a unit identifier (e.g., px,
   deg, etc.). After the '0' length, the unit identifier is optional.
   
   Some properties allow negative length values, but this may complicate
   the formatting model and there may be implementation-specific limits.
   If a negative length value cannot be supported, it should be converted
   to the nearest value that can be supported.
   
   There are two types of length units: relative and absolute. Relative
   length units specify a length relative to another length property.
   Style sheets that use relative units will more easily scale from one
   medium to another (e.g., from a computer display to a laser printer).
   
   Relative units are:
     * em: the 'font-size' of the relevant font
     * ex: the 'x-height' of the relevant font
     * px: pixels, relative to the viewing device
       
H1 { margin: 0.5em }      /* em */
H1 { margin: 1ex }        /* ex */
P  { font-size: 12px }    /* px */

   The 'em' unit is equal to the computed value of the 'font-size'
   property of the element on which it is used. The exception is when
   'em' occurs in the value of the 'font-size' property itself, in which
   case it refers to the font size of the parent element. It may be used
   for vertical or horizontal measurement. (This unit is also sometimes
   called the quad-width in typographic texts.)
   
   The 'ex' unit is defined by the font's 'x-height'. The x-height is so
   called because it is often equal to the height of the lowercase "x".
   However, an 'ex' is be defined even for fonts that don't contain an
   "x".
   
   The rule:
H1 { line-height: 1.2em }

   means that the line height of H1 elements will be 20% greater than the
   font size of the H1 elements. On the other hand:

H1 { font-size: 1.2em }

   means that the font-size of H1 elements will be 20% greater than the
   font size inherited by H1 elements.
   
   When specified for the root of the document tree (e.g., "HTML" in
   HTML), 'em' and 'ex' refer to the property's initial value.
   
   Pixel units are relative to the resolution of the viewing device,
   i.e., most often a computer display. If the pixel density of the
   output device is very different from that of a typical computer
   display, the user agent should rescale pixel values. It is recommended
   that the reference pixel be the visual angle of one pixel on a device
   with a pixel density of 90dpi and a distance from the reader of an
   arm's length. For a nominal arm's length of 28 inches, the visual
   angle is therefore about 0.0227 degrees.
   
   For reading at arm's length, 1px thus corresponds to about 0.28 mm
   (1/90 inch). When printed on a laser printer, meant for reading at a
   little less than arm's length (55 cm, 21 inch), 1px is about 0.21 mm.
   On a 300 dots-per-inch (dpi) printer, that may be rounded up to 3 dots
   (0.25 mm); on a 600 dpi printer, it can be rounded to 5 dots.
   
   The two images below illustrate the effect of viewing distance on the
   size of a pixel and the effect of a device's resolution. In the first
   image, a reading distance of 71 cm (28 inch) results in a px of
   0.28 mm, while a reading distance of 3.5 m (12 feet) requires a px of
   1.4 mm.
   
   Showing that pixels must become larger if the viewing distance
   increases
   
   In the second image, an area of 1px by 1px is covered by a single dot
   in a low-resolution device (a computer screen), while the same area is
   covered by 16 dots in a higher resolution device (such as a 400 dpi
   laser printer).
   
   Showing that more device pixels (dots) are needed to cover a 1px by
   1px area on a high-resolution device than on a low-res one
   
   Child elements do not inherit the relative values specified for their
   parent; they inherit the actual values. For example:
   
BODY {
  font-size: 12pt;
  text-indent: 3em;  /* i.e., 36pt */
}
H1 { font-size: 15pt }

   In these rules, the 'text-indent' value of H1 elements will be 36pt,
   not 45pt, if H1 is a child of the BODY element (assuming the actual
   font size is the same as the specified one: 12pt).
   
   Absolute length units are only useful when the physical properties of
   the output medium are known. The absolute units are:
     * in: inches -- 1 inch is equal to 2.54 centimeters.
     * cm: centimeters
     * mm: millimeters
     * pt: points -- the points used by CSS2 are equal to 1/72th of an
       inch.
     * pc: picas -- 1 pica is equal to 12 points.
       
   For example:
H1 { margin: 0.5in }      /* inches  */
H2 { line-height: 3cm }   /* centimeters */
H3 { word-spacing: 4mm }  /* millimeters */
H4 { font-size: 12pt }    /* points */
H4 { font-size: 1pc }     /* picas */

   In cases where the specified length cannot be supported, user agents
   must approximate it. For all CSS2 properties, further computations and
   inheritance is be based on the approximated value.
   
  4.3.3 Percentages
  
   The format of a percentage value (denoted by <percentage> in this
   specification) is an optional sign character ('+' or '-', with '+'
   being the default) immediately followed by a number immediately
   followed by '%'.
   
   Percentage values are always relative to another value, for example a
   length. Each property that allows percentages also defines the value
   to which the percentage refers. The value may be that of another
   property for the same element, a property for an ancestor element, or
   a value of the rendering context (e.g., the width of a containing
   block). When a percentage value is set for a property of the root
   element and the percentage is defined as referring to the inherited
   value of some property, the resultant value is the percentage times
   the initial value of that property.
   
   Since child elements inherit the actual values of their parent, in the
   following example, the children of the P element will inherit a value
   of 12pt for 'line-height', not the percentage value (120%):

P { font-size: 10pt }
P { line-height: 120% }  /* relative to 'font-size', i.e., 12pt */

  4.3.4 URL + URN = URI
  
   URLs (Uniform Resource Locators, see [RFC1738] and [RFC1808]) provide
   the address of a resource on the Web. An expected new way of
   identifying resources is called URN (Uniform Resource Name). Together
   they are called URIs (Uniform Resource Identifiers, see [URI]). This
   specification uses the term URI throughout.
   
   URI values in this specification are denoted by <uri>. The functional
   notation used to designate URIs in property values is "url()".
   
   For example:
BODY { background: url(http://www.bg.com/pinkish.gif) }

   The format of a URI value is 'url(' followed by optional whitespace
   followed by an optional single quote (') or double quote (") character
   followed by the URI itself, followed by an optional single quote (')
   or double quote (") character followed by optional whitespace followed
   by ')'. Quote characters must be balanced.
   
   Parentheses, commas, whitespace characters, single quotes (') and
   double quotes (") appearing in a URI must be escaped with a backslash:
   '\(', '\)', '\,'.
   
   Depending on the type of URI, it might also be possible to write the
   above characters as URI-escapes (where "(" = %28, ")" = %29, etc.) as
   described in [URI].
   
   In order to create modular style sheets that are not dependent on the
   absolute location of a resource, authors may use relative URIs.
   Relative URIs (as defined in [RFC1808]) are resolved to full URIs
   using a base URI. RFC 1808, section 3, defines the normative algorithm
   for this process. For CSS style sheets, the base URI is that of the
   style sheet, not that of the source document.
   
   For example, suppose the following rule is located in a style sheet
   designated by the URI http://www.myorg.org/style/basic.css:

BODY { background: url(yellow) }

   The background of the source document's BODY will be tiled with
   whatever image is described by the resource designated by the URI
   http://www.myorg.org/style/yellow.
   
   User agents may vary in how they handle URIs that designate
   unavailable or inapplicable resources.
   
  4.3.5 Counters
  
   Counters are denoted by identifiers (see the 'counter-increment' and
   'counter-reset' properties). To refer to the value of a counter, the
   notation 'counter(<identifier>)' or 'counter(<identifier>,
   <list-style-type>)' is used. The default style is 'decimal'.
   
   To refer to a sequence of nested counters of the same name the
   notation is 'counters(<identifier>, <string>)' or
   'counters(<identifier>, <string>, <list-style-type>)'. See "Nested
   counters and scope" in the chapter on generated content.
   
   In CSS2, the values of counters can only be referred to from the
   'content' property. Note that 'none' is a possible style; 'counter(x,
   none)' yields an empty string.
   
   Here is a style sheet that numbers paragraphs (P) for each chapter
   (H1). The paragraphs are numbered with roman numerals, followed by a
   period and a space:

P {counter-increment: par-num}
H1 {counter-reset: par-num}
P:before {content: counter(par-num, upper-roman) ". "}

   Counters that are not in the scope of any 'counter-reset', are assumed
   to have been reset to 0 by a 'counter-reset' on the root element.
   
  4.3.6 Colors
  
   A <color> is either a keyword or a numerical RGB specification.
   
   The list of keyword color names is: aqua, black, blue, fuchsia, gray,
   green, lime, maroon, navy, olive, purple, red, silver, teal, white,
   and yellow. These 16 colors are defined in HTML 4.0 ([HTML40]).

BODY {color: black; background: white }
H1 { color: maroon }
H2 { color: olive }

   The RGB color model is used in numerical color specifications. These
   examples all specify the same color:

EM { color: #f00 }              /* #rgb */
EM { color: #ff0000 }           /* #rrggbb */
EM { color: rgb(255,0,0) }      /* integer range 0 - 255 */
EM { color: rgb(100%, 0%, 0%) } /* float range 0.0% - 100.0% */

   In addition to these color keywords, users may specify keywords that
   correspond to the colors used by certain objects in the user's
   environment. Please consult the section on system colors for more
   information.
   
   The format of an RGB value in hexadecimal notation is a '#'
   immediately followed by either three or six hexadecimal characters.
   The three-digit RGB notation (#rgb) is converted into six-digit form
   (#rrggbb) by replicating digits, not by adding zeros. For example,
   #fb0 expands to #ffbb00. This makes sure that white (#ffffff) can be
   specified with the short notation (#fff) and removes any dependencies
   on the color depth of the display.
   
   The format of an RGB value in the functional notation is 'rgb('
   followed by a comma-separated list of three numerical values (either
   three integer values, or three percentage values) followed by ')'. The
   integer value 255 corresponds to 100%, and to F or FF in the
   hexadecimal notation: rgb(255,255,255) = rgb(100%,100%,100%) = #FFF.
   Whitespace characters are allowed around the numerical values.
   
   Values outside the device gamut should be clipped: the red, green and
   blue values must be changed to fall within the range supported by the
   device. For a device whose gamut is exactly 0-255 in each of red,
   green, and blue (typical for CRT monitors), the three rules below are
   equivalent:

EM { color: rgb(255,0,0) }       /* integer range 0 - 255 */
EM { color: rgb(300,0,0) }       /* clipped to rgb(255,0,0) */
EM { color: rgb(255,-10,0) }     /* clipped to rgb(255,0,0) */
EM { color: rgb(110%, 0%, 0%) }  /* clipped to rgb(100%,0%,0%) */

   All RGB colors are specified in the sRGB color space (see [SRGB]).
   User agents may vary in the fidelity with which they represent these
   colors, but using sRGB provides an unambiguous and objectively
   measurable definition of what the color should be, which can be
   related to international standards (see [COLORIMETRY]).
   
   Conforming user agents may limit their color-displaying efforts to
   performing a gamma-correction on them. sRGB specifies a display gamma
   of 2.2 under specified viewing conditions. User agents should adjust
   the colors given in CSS such that, in combination with an output
   device's "natural" display gamma, an effective display gamma of 2.2 is
   produced. See the section on gamma correction for further details.
   Note that only colors specified in CSS are affected; e.g., images are
   expected to carry their own color information.
   
  4.3.7 Angles
  
   Angle values (denoted by <angle> in the text) are used with aural
   style sheets.
   
   Their format is an optional sign character ('+' or '-', with '+' being
   the default) immediately followed by a <number> immediately followed
   by an angle unit identifier.
   
   The following are valid angle unit identifiers:
   
     * deg: degrees
     * grad: grads
     * rad: radians
       
   Angle values may be negative. They should be normalized to the range
   0-360deg by the user agent. For example, -10deg and 350deg are
   equivalent.
   
   For example, a right angle is '90deg' or '100grad' or
   '1.570796326794897rad'.
   
  4.3.8 Times
  
   Time values (denoted by <time> in the text) are used with aural style
   sheets.
   
   Their format is a <number> immediately followed by a time unit
   identifier.
   
   The following are valid time unit identifiers:
   
     * ms: milliseconds
     * s: seconds
       
   Time values may not be negative.
   
  4.3.9 Frequencies
  
   Frequency values (denoted by <frequency> in the text) are used with
   aural cascading style sheets.
   
   Their format is a <number> immediately followed by a frequency unit
   identifier.
   
   There are two valid frequency unit identifiers:
   
     * Hz: Hertz
     * kHz: kilo Hertz
       
   For example, 200Hz (or 200hz) is a bass sound, and 6kHz (or 6khz) is a
   treble sound.
   
  4.3.10 Strings
  
   Strings can either be written with double quotes or with single
   quotes. Double quotes cannot occur inside double quotes, unless
   escaped (as '\"' or as '\22'). Analogously for single quotes ("\'" or
   "\27"). Examples:

"this is a 'string'"
"this is a \"string\""
'this is a "string"'
'this is a \'string\''

   A string cannot directly contain a newline. To include a newline in a
   string, use the escape "\A" (hexadecimal A is the line feed character
   in Unicode, but represents the generic notion of "newline" in CSS).
   
   It is possible to break strings over several lines, for aesthetic or
   other reasons, but in such a case the newline itself has to be escaped
   with a backslash (\). For instance, the following two selectors are
   exactly the same:

A[TITLE="a not s\
o very long title"] {/*...*/}
A[TITLE="a not so very long title"] {/*...*/}

4.4 CSS document representation

   A CSS style sheet is a sequence of characters from the Universal
   Character Set (see [ISO10646]). For transmission and storage, these
   characters must be encoded by a character encoding that supports the
   set of characters available in US-ASCII (e.g., ISO 8859-x, SHIFT JIS,
   etc.). For a good introduction to character sets and character
   encodings, please consult the HTML 4.0 specification ([HTML40],
   chapter 5), See also the XML 1.0 specification ([XML10], sections 2.2
   and 4.3.3, and Appendix F.
   
   When a style sheet is embedded in another document, such as in the
   STYLE element or STYLE attribute of HTML, the style sheet shares the
   character encoding of the whole document.
   
   When a style sheet resides in a separate file, user agents must
   observe the following priorities when determining a document's
   character encoding (from highest priority to lowest):
   
    1. An HTTP "charset" parameter in a "Content-Type" field.
    2. The @charset at-rule.
    3. Mechanisms of the language of the referencing document (e.g., in
       HTML, the "charset" attribute of the LINK element).
       
   At most one @charset rule may appear in an external style sheet -- it
   must not appear in an embedded style sheet -- and it must appear at
   the very start of the document, not preceded by any characters. After
   "@charset", authors specify the name of a character encoding. The name
   must be a charset name as described in the IANA registry (See [IANA].
   Also, see [CHARSETS] for a complete list of charsets). For example:
   
   @charset "ISO-8859-1";
   
   This specification does not mandate which character encodings a user
   agent must support.
   
   Note that reliance on the @charset construct theoretically poses a
   problem since there is no a priori information on how it is encoded.
   In practice, however, the encodings in wide use on the Internet are
   either based on ASCII, UTF-16, UCS-4, or (rarely) on EBCDIC. This
   means that in general, the initial byte values of a document enable a
   user agent to detect the encoding family reliably, which provides
   enough information to decode the @charset rule, which in turn
   determines the exact character encoding.
   
  4.4.1 Referring to characters not represented in a character encoding
  
   A style sheet may have to refer to characters that cannot be
   represented in the current character encoding. These characters must
   be written as escaped references to ISO 10646 characters. These
   escapes serve the same purpose as numeric character references in HTML
   or XML documents (see [HTML40], Chapters 5 and 25).
   
   The character escape mechanism should be used when only a few
   characters must be represented this way. If most of a document
   requires escaping, authors should encode it with a more appropriate
   encoding (e.g., if the document contains a lot of Greek characters,
   authors might use "ISO-8859-7" or "UTF-8").
   
   Intermediate processors using a different character encoding may
   translate these escaped sequences into byte sequences of that
   encoding. Intermediate processors must not, on the other hand, alter
   escape sequences that cancel the special meaning of an ASCII
   character.
   
   Conforming user agents must correctly map to Unicode all characters in
   any character encodings that they recognize (or they must behave as if
   they did).
   
   For example, a document transmitted as ISO-8859-1 (Latin-1) cannot
   contain Greek letters directly: "&#954;&#959;&#965;&#961;&#959;&#962;"
   (Greek: "kouros") has to be written as "\3BA\3BF\3C5\3C1\3BF\3C2".
   
   Note. In HTML 4.0, numeric character references are interpreted in
   "style" attribute values but not in the content of the STYLE element.
   Because of this asymmetry, we recommend that authors use the CSS
   character escape mechanism rather than numeric character references
   for both the "style" attribute and the STYLE element. For example, we
   recommend:
   
<SPAN style="voice-family: D\FC rst">...</SPAN>

   rather than:
   
<SPAN style="voice-family: D&#252;rst">...</SPAN>
     _________________________________________________________________
     _________________________________________________________________
   
                                5 Selectors
                                      
   Contents
     * 5.1 Pattern matching
     * 5.2 Selector syntax
          + 5.2.1 Grouping
     * 5.3 Universal selector
     * 5.4 Type selectors
     * 5.5 Descendant selectors
     * 5.6 Child selectors
     * 5.7 Adjacent selectors
     * 5.8 Attribute selectors
          + 5.8.1 Matching attributes and attribute values
          + 5.8.2 Default attribute values in DTDs
          + 5.8.3 Class selectors
     * 5.9 ID selectors
     * 5.10 Pseudo-elements and pseudo-classes
     * 5.11 Pseudo-classes
          + 5.11.1 :first-child pseudo-class
          + 5.11.2 The link pseudo-classes: :link and :visited
          + 5.11.3 The dynamic pseudo-classes: :hover, :active, and
            :focus
          + 5.11.4 The language pseudo-class: :lang
     * 5.12 Pseudo-elements
          + 5.12.1 The :first-line pseudo-element
          + 5.12.2 The :first-letter pseudo-element
          + 5.12.3 The :before and :after pseudo-elements
       
5.1 Pattern matching

   In CSS, pattern matching rules determine which style rules apply to
   elements in the document tree. These patterns, called selectors, may
   range from simple element names to rich contextual patterns. If all
   conditions in the pattern are true for a certain element, the selector
   matches the element.
   
   The case-sensitivity of document language element names in selectors
   depends on the document language. For example, in HTML, element names
   are case-insensitive, but in XML they are case-sensitive.
   
   The following table summarizes CSS2 selector syntax:
   
   Pattern Meaning Described in section
   * Matches any element. Universal selector
   E Matches any E element (i.e., an element of type E). Type selectors
   E F Matches any E element that is a descendant of an F element.
   Descendant selectors
   E > F Matches any F element that is a child of an element E. Child
   selectors
   E:first-child Matches element E when E is the first child of some
   other element The :first-child pseudo-class
   E:link
   E:visited Matches element E if E is the source anchor of a hyperlink
   of which the target is not yet visited (:link) or already visited
   (:visited) The link pseudo-classes
   E:active
   E:hover
   E:focus Matches E during certain user actions The dynamic
   pseudo-classes
   E:lang(c) Matches element of type E if it is in (human) language c
   (the document language specifies how language is determined) The
   :lang() pseudo-class
   E + F Matches any F element immediately preceded by an element E.
   Adjacent selectors
   E[foo] Matches any E element with the "foo" attribute set (whatever
   the value). Attribute selectors
   E[foo="warning"] Matches any E element whose "foo" attribute value is
   exactly equal to "warning". Attribute selectors
   E[foo~="warning"] Matches any E element whose "foo" attribute value is
   a list of space-separated values, one of which is exactly equal to
   "warning". Attribute selectors
   E[lang|="en"] Matches any E element whose "lang" attribute has a
   hyphen-separated list of values beginning (from the left) with "en".
   Attribute selectors
   DIV.warning HTML only. The same as DIV[class~="warning"]. Class
   selectors
   E#myid Matches any E element ID equal to "myid". ID selectors
   
5.2 Selector syntax

   A simple selector is either a type selector or universal selector
   followed immediately by zero or more attribute selectors, ID selectors
   or pseudo-classes, in any order. The simple selector matches if all of
   its components match.
   
   A selector is a chain of one or more simple selectors separated by
   combinators. Combinators are: whitespace, ">", and "+". Whitespace may
   appear between a combinator and the simple selectors around it.
   
   The elements of the document tree that match a selector are called
   subjects of the selector. A selector consisting of a single simple
   selector matches any element satisfying its requirements. Prepending a
   simple selector and combinator to a chain imposes additional matching
   constraints, so the subjects of a selector are always a subset of the
   elements matching the rightmost simple selector.
   
   One pseudo-element may be appended to the last simple selector in a
   chain, in which case the style information applies to a subpart of
   each subject.
   
  5.2.1 Grouping
  
   When several selectors share the same declarations, they may be
   grouped into a comma-separated list.
   
   In this example, we condense three rules with identical declarations
   into one. Thus,

H1 { font-family: sans-serif }
H2 { font-family: sans-serif }
H3 { font-family: sans-serif }

   is equivalent to:
   
H1, H2, H3 { font-family: sans-serif }

   CSS offers other "shorthand" mechanisms as well, including multiple
   declarations and shorthand properties.
   
5.3 Universal selector

   The universal selector, written "*", matches the name of any element
   type. It matches any single element in the document tree.
   
   If the universal selector is not the only component of a simple
   selector, the '*' may be omitted. For example:
   
     * *[LANG=fr] and [LANG=fr] are equivalent.
     * *.warning and .warning are equivalent.
     * *#myid and #myid are equivalent.
       
5.4 Type selectors

   A type selector matches the name of a document language element type.
   A type selector matches every instance of the element type in the
   document tree.
   
   The following rule matches all H1 elements in the document tree:
   
H1 { font-family: sans-serif }

5.5 Descendant selectors

   At times, authors may want selectors to match an element that is the
   descendant of another element in the document tree (e.g., "Match those
   EM elements that are contained by an H1 element"). Descendant
   selectors express such a relationship in a pattern. A descendant
   selector is made up of two or more selectors separated by whitespace.
   A descendant selector of the form "A B" matches when an element B is
   an arbitrary descendant of some ancestor element A.
   
   For example, consider the following rules:
   
H1 { color: red }
EM { color: red }

   Although the intention of these rules is to add emphasis to text by
   changing its color, the effect will be lost in a case such as:
   
<H1>This headline is <EM>very</EM> important</H1>

   We address this case by supplementing the previous rules with a rule
   that sets the text color to blue whenever an EM occurs anywhere within
   an H1:
   
H1 { color: red }
EM { color: red }
H1 EM { color: blue }

   The third rule will match the EM in the following fragment:
   
<H1>This <SPAN class="myclass">headline
is <EM>very</EM> important</SPAN></H1>

   The following selector:
   
DIV * P

   matches a P element that is a grandchild or later descendant of a DIV
   element.
   
   The selector in the following rule, which combines descendant and
   attribute selectors, matches any element with an "href" attribute
   inside a P that is itself inside a DIV:
   
DIV P *[href]

5.6 Child selectors

   A child selector matches when an element is the child of some element.
   A child selector is made up of two or more selectors separated by ">".
   
   The following rule sets the style of all P elements that are children
   of BODY:
   
BODY > P { line-height: 1.3 }

   The following example combines descendant selectors and child
   selectors:
   
DIV OL > LI P

   matches a P element that is a descendant of an LI; the LI element must
   be the child of an OL element; the OL element must be a descendant of
   a DIV.
   
   For information on selecting the first child of an element, please see
   the section on the :first-child pseudo-class below.
   
5.7 Adjacent selectors

   Often, special formatting rules apply when two types of elements
   appear next to each other in a document. For example, when block-level
   elements are laid out, the vertical space between them collapses. In
   this case, the special formatting is handled by the rules for
   collapsing margins, but in other cases of adjacent selectors, authors
   may want to specify their own special formatting rules.
   
   Adjacent selectors have the following syntax: E1 + E2, where E2 is the
   subject of the selector. The selector matches if E1 and E2 share the
   same parent in the document tree and E1 immediately precedes E2.
   
   Thus, the following rule states that when a P element immediately
   follows a MATH element, it should not be indented:
   
MATH + P { text-indent: 0 }

   The next example reduces the vertical space separating an H1 and an H2
   that immediately follows it:
   
H1 + H2 { margin-top: -5mm }

   The following rule is similar to the one in the previous example,
   except that it adds an attribute selector. Thus, special formatting
   only occurs when H1 has class="opener":
   
H1.opener + H2 { margin-top: -5mm }

5.8 Attribute selectors

   CSS2 allows authors to specify rules that match attributes defined in
   the source document.
   
  5.8.1 Matching attributes and attribute values
  
   Attribute selectors may match in four ways:
   
   [att]
          Match when the element sets the "att" attribute, whatever the
          value of the attribute.
          
   [att=val]
          Match when the element's "att" attribute value is exactly
          "val".
          
   [att~=val]
          Match when the element's "att" attribute value is a
          space-separated list of "words", one of which is exactly "val".
          If this selector is used, the words in the value must not
          contain spaces (since they are separated by spaces).
          
   [att|=val]
          Match when the element's "att" attribute value is a
          hyphen-separated list of "words", beginning with "val". The
          match always starts at the beginning of the attribute value.
          This is primarily intended to allow language subcode matches
          (e.g., the "lang" attribute in HTML) as described in RFC 1766
          ([RFC1766]).
          
   Attribute values must be identifiers or strings. The case-sensitivity
   of attribute names and values in selectors depends on the document
   language.
   
   For example, the following attribute selector matches all H1 elements
   that specify the "title" attribute, whatever its value:
   
H1[title] { color: blue; }

   In the following example, the selector matches all SPAN elements whose
   "class" attribute has exactly the value "example":
   
SPAN[class=example] { color: blue; }

   Multiple attribute selectors can be used to refer to several
   attributes of an element, or even several times the same attribute.
   
   Here, the selector matches all SPAN elements whose "hello" attribute
   has exactly the value "Cleveland" and whose "goodbye" attribute has
   exactly the value "Columbus":
   
SPAN[hello="Cleveland"][goodbye="Columbus"] { color: blue; }

   The following selectors illustrate the differences between "=" and
   "~=". The first selector will match, for example, the value "copyright
   copyleft copyeditor" for the "rel" attribute. The second selector will
   only match when the "colspan" attribute has the value "2".
   
A[rel~="copyright"]
TD[colspan="2"]

   The following rule hides all elements for which the value of the
   "lang" attribute is "fr" (i.e., the language is French).

*[LANG=fr] { display : none }

   The following rule will match for values of the "lang" attribute that
   begin with "en", including "en", "en-US", and "en-cockney":
   
*[LANG|="en"] { color : red }

   Similarly, the following aural style sheet rules allow a script to be
   read aloud in different voices for each role:
   
DIALOGUE[character=romeo]
     { voice-family: "Lawrence Olivier", charles, male }

DIALOGUE[character=juliet]
     { voice-family: "Vivien Leigh", victoria, female }

  5.8.2 Default attribute values in DTDs
  
   Matching takes place on attribute values in the document tree. For
   document languages other than HTML, default attribute values may be
   defined in a DTD or elsewhere. Style sheets should be designed so that
   they work even if the default values are not included in the document
   tree.
   
   For example, consider an element EXAMPLE with an attribute "notation"
   that has a default value of "decimal". The DTD fragment might be

<!ATTLIST EXAMPLE notation (decimal,octal) "decimal">

   If the style sheet contains the rules
EXAMPLE[notation=decimal] { /*... default property settings ...*/ }
EXAMPLE[notation=octal] { /*... other settings...*/ }

   then to catch the cases where this attribute is set by default, and
   not explicitly, the following rule might be added:

EXAMPLE { /*... default property settings ...*/ }

   Because this selector is less specific than an attribute selector, it
   will only be used for the default case. Care has to be taken that all
   other attribute values that don't get the same style as the default
   are explicitly covered.
   
  5.8.3 Class selectors
  
   For style sheets used with HTML, authors may use the dot (.) notation
   as an alternative to the "~=" notation when matching on the "class"
   attribute. Thus, for HTML, "DIV.value" and "DIV[class~=value]" have
   the same meaning. The attribute value must immediately follow the ".".
   
   For example, we can assign style information to all elements with
   class~="pastoral" as follows:
   
*.pastoral { color: green }  /* all elements with class~=pastoral */

   or just
.pastoral { color: green }  /* all elements with class~=pastoral */

   The following assigns style only to H1 elements with
   class~="pastoral":
   
H1.pastoral { color: green }  /* H1 elements with class~=pastoral */

   Given these rules, the first H1 instance below would not have green
   text, while the second would:
   
<H1>Not green</H1>
<H1 class="pastoral">Very green</H1>

   To match a subset of "class" values, each value must be preceded by a
   ".", in any order.
   
   For example, the following rule matches any P element whose "class"
   attribute has been assigned a list of space-separated values that
   includes "pastoral" and "marine":
   

P.pastoral.marine { color: green }

   This rule matches when class="pastoral blue aqua marine" but does not
   match for class="pastoral blue".
   
   Note. CSS gives so much power to the "class" attribute, that authors
   could conceivably design their own "document language" based on
   elements with almost no associated presentation (such as DIV and SPAN
   in HTML) and assigning style information through the "class"
   attribute. Authors should avoid this practice since the structural
   elements of a document language have recognized and accepted meanings
   and author-defined classes may not.
   
5.9 ID selectors

   Document languages may contain attributes that are declared to be of
   type ID. What makes attributes of type ID special is that no two such
   attributes can have the same value; whatever the document language, an
   ID attribute can be used to uniquely identify its element. In HTML all
   ID attributes are named "id"; XML applications may name ID attributes
   differently, but the same restriction applies.
   
   The ID attribute of a document language allows authors to assign an
   identifier to one element instance in the document tree. CSS ID
   selectors match an element instance based on its identifier. A CSS ID
   selector contains a "#" immediately followed by the ID value.
   
   The following ID selector matches the H1 element whose ID attribute
   has the value "chapter1":
   
H1#chapter1 { text-align: center }

   In the following example, the style rule matches the element that has
   the ID value "z98y". The rule will thus match for the P element:
   
<HEAD>
  <TITLE>Match P</TITLE>
  <STYLE type="text/css">
    *#z98y { letter-spacing: 0.3em }
  </STYLE>
</HEAD>
<BODY>
   <P id=z98y>Wide text</P>
</BODY>

   In the next example, however, the style rule will only match an H1
   element that has an ID value of "z98y". The rule will not match the P
   element in this example:
   
<HEAD>
  <TITLE>Match H1 only</TITLE>
  <STYLE type="text/css">
    H1#z98y { letter-spacing: 0.5em }
  </STYLE>
</HEAD>
<BODY>
   <P id=z98y>Wide text</P>
</BODY>

   ID selectors have a higher precedence than attribute selectors. For
   example, in HTML, the selector #p123 is more specific than [ID=p123]
   in terms of the cascade.
   
   Note: In XML, the information about which attribute contains an
   element's IDs is contained in a DTD. When parsing XML, UAs do not
   always read the DTD, and thus may not know what the ID of an element
   is. If a style sheet designer knows or suspects that this will be the
   case, he should use normal attribute selectors instead: [name=p371]
   instead of #p371. However, the cascading order of normal attribute
   selectors is different from ID selectors. It may be necessary to add
   an "!important" priority to the declarations: [name=p371] {color: red
   ! important}. Of course, elements in XML documents without a DTD do
   not have IDs at all.
   
5.10 Pseudo-elements and pseudo-classes

   In CSS2, style is normally attached to an element based on its
   position in the document tree. This simple model is sufficient for
   many cases, but some common publishing scenarios may not be possible
   due to the structure of the document tree. For instance, in HTML 4.0
   (see [HTML40]), no element refers to the first line of a paragraph,
   and therefore no simple CSS selector may refer to it.
   
   CSS introduces the concepts of pseudo-elements and pseudo-classes to
   permit formatting based on information that lies outside the document
   tree.
   
     * Pseudo-elements create abstractions about the document tree beyond
       those specified by the document language. For instance, document
       languages do not offer mechanisms to access the first letter or
       first line of an element's content. CSS pseudo-elements allow
       style sheet designers to refer to this otherwise inaccessible
       information. Pseudo-elements may also provide style sheet
       designers a way to assign style to content that does not exist in
       the source document (e.g., the :before and :after pseudo-elements
       give access to generated content).
     * Pseudo-classes classify elements on characteristics other than
       their name, attributes or content; in principle characteristics
       that cannot be deduced from the document tree. Pseudo-classes may
       be dynamic, in the sense that an element may acquire or lose a
       pseudo-class while a user interacts with the document. The
       exception is ':first-child', which can be deduced from the
       document tree.
       
   Neither pseudo-elements nor pseudo-classes appear in the document
   source or document tree.
   
   Pseudo-classes are allowed anywhere in selectors while pseudo-elements
   may only appear after the subject of the selector.
   
   Pseudo-elements and pseudo-class names are case-insensitive.
   
   Some pseudo-classes are mutually exclusive, while others can be
   applied simultaneously to the same element. In case of conflicting
   rules, the normal cascading order determines the outcome.
   
   Conforming HTML user agents may ignore all rules with :first-line or
   :first-letter in the selector, or, alternatively, may only support a
   subset of the properties on these pseudo-elements.
   
5.11 Pseudo-classes

  5.11.1 :first-child pseudo-class
  
   The :first-child pseudo-class matches an element that is the first
   child of some other element.
   
   In the following example, the selector matches any P element that is
   the first child of a DIV element. The rule suppresses indentation for
   the first paragraph of a DIV:
   
DIV > P:first-child { text-indent: 0 }

   This selector would match the P inside the DIV of the following
   fragment:

<P> The last P before the note.
<DIV class="note">
   <P> The first P inside the note.
</DIV>

   but would not match the second P in the following fragment:
<P> The last P before the note.
<DIV class="note">
   <H2>Note</H2>
   <P> The first P inside the note.
</DIV>

   The following rule sets the font weight to "bold" for any EM element
   that is some descendant of a P element that is a first child:
   
P:first-child EM { font-weight : bold }

   Note that since anonymous boxes are not part of the document tree,
   they are not counted when calculating the first child.
   
   For example, the EM in:
   
<P>abc <EM>default</EM>

   is the first child of the P.
   
   The following two selectors are equivalent:
   
* > A:first-child   /* A is first child of any element */
A:first-child       /* Same */

  5.11.2 The link pseudo-classes: :link and :visited
  
   User agents commonly display unvisited links differently from
   previously visited ones. CSS provides the pseudo-classes ':link' and
   ':visited' to distinguish them:
   
     * The :link pseudo-class applies for links that have not yet been
       visited.
     * The :visited pseudo-class applies once the link has been visited
       by the user.
       
   Note. After a certain amount of time, user agents may choose to return
   a visited link to the (unvisited) ':link' state.
   
   The two states are mutually exclusive.
   
   The document language determines which elements are hyperlink source
   anchors. For example, In HTML 4.0, the link pseudo-classes only apply
   to A elements with an "href" attribute. Thus, the following two CSS2
   declarations are equivalent:
   
A:link { color: red }
:link  { color: red }

   If the following link:
   
<A class="external" href="http://out.side/">external link</A>

   has been visited, this rule:
A.external:visited { color: blue }

   will cause it to be blue.
   
  5.11.3 The dynamic pseudo-classes: :hover, :active, and :focus
  
   Interactive user agents sometimes change the rendering in response to
   user actions. CSS provides three pseudo-classes for common cases:
   
     * The :hover pseudo-class applies while the user designates an
       element (with some pointing device), but does not activate it. For
       example, a visual user agent could apply this pseudo-class when
       the cursor (mouse pointer) hovers over a box generated by the
       element. User agents not supporting interactive media do not have
       to support this pseudo-class. Some conforming user agents
       supporting interactive media may not be able to support this
       pseudo-class (e.g., a pen device).
     * The :active pseudo-class applies while an element is being
       activated by the user. For example, between the times the user
       presses the mouse button and releases it.
     * The :focus pseudo-class applies while an element has the focus
       (accepts keyboard events, or other forms of text input).
       
   These pseudo-classes are not mutually exclusive. An element may match
   several of them at the same time.
   
   CSS doesn't define which elements may be in the above states, or how
   the states are entered and left. Scripting may change whether elements
   react to user events or not, and different devices and UAs may have
   different ways of pointing to, or activating elements.
   
   User agents are not required to reflow a currently displayed document
   due to pseudo-class transitions. For instance, a style sheet may
   specify that the 'font-size' of an :active link should be larger than
   that of an inactive link, but since this may cause letters to change
   position when the reader selects the link, a UA may ignore the
   corresponding style rule.
   
   Example:
   
A:link    { color: red }    /* unvisited links */
A:visited { color: blue }   /* visited links   */
A:hover   { color: yellow } /* user hovers     */
A:active  { color: lime }   /* active links    */

   Note that the A:hover must be placed after the A:link and A:visited
   rules, since otherwise the cascading rules will hide the 'color'
   property of the A:hover rule. Similarly, because A:active is placed
   after A:hover, the active color (lime) will apply when the user both
   activates and hovers over the A element.
   
   An example of combining dynamic pseudo classes:
A:focus { background: yellow }
A:focus:hover { background: white }

   The last selector matches A elements which are in pseudo-class :focus
   and in pseudo-class :hover.
   
   For information about the presentation of focus outlines, please
   consult the section on dynamic focus outlines.
   
   Note. In CSS1, the ':active' pseudo-class was mutually exclusive with
   ':link' and ':visited'. That is no longer the case. An element can be
   both ':visited' and ':active' (or ':link' and ':active') and the
   normal cascading rules determine which properties apply. 
   
  5.11.4 The language pseudo-class: :lang
  
   If the document language specifies how the human language of an
   element is determined, it is possible to write selectors in CSS that
   match an element based on its language. For example, in HTML [HTML40],
   the language is determined by a combination of the LANG attribute, the
   META element, and possibly by information from the protocol (such as
   HTTP headers). XML uses an attribute called XML:LANG, and there may be
   other document language-specific methods for determining the language.
   
   The pseudo-class ':lang(C)' matches if the element is in language C.
   Here C is a language code as specified in HTML 4.0 [HTML40] and
   RFC 1766 [RFC1766]. It is matched the same way as for the '|='
   operator.
   
   The following rules set the quotation marks for an HTML document that
   is either in French or German:
   
HTML:lang(fr) { quotes: '« ' ' »' }
HTML:lang(de) { quotes: '»' '«' '\2039' '\203A' }
:lang(fr) > Q { quotes: '« ' ' »' }
:lang(de) > Q { quotes: '»' '«' '\2039' '\203A' }

   The second pair of rules actually set the 'quotes' property on Q
   elements according to the language of its parent. This is done because
   the choice of quote marks is typically based on the language of the
   element around the quote, not the quote itself: like this piece of
   French &#8220;à l'improviste&#8221; in the middle of an English text
   uses the English quotation marks.
   
5.12 Pseudo-elements

  5.12.1 The :first-line pseudo-element
  
   The :first-line pseudo-element applies special styles to the first
   formatted line of a paragraph. For instance:
   
P:first-line { text-transform: uppercase }

   The above rule means "change the letters of the first line of every
   paragraph to uppercase". However, the selector "P:first-line" does not
   match any real HTML element. It does match a pseudo-element that
   conforming user agents will insert at the beginning of every
   paragraph.
   
   Note that the length of the first line depends on a number of factors,
   including the width of the page, the font size, etc. Thus, an ordinary
   HTML paragraph such as:
   
<P>This is a
somewhat long HTML
paragraph that will be
broken into several
lines. The first line will be identified
by a fictional tag sequence. The other lines will
be treated as ordinary lines in the paragraph.</P>

   the lines of which happen to be broken as follows:
THIS IS A SOMEWHAT LONG HTML PARAGRAPH THAT WILL
be broken  into  several  lines. The  first line
will   be    identified  by    a fictional   tag
sequence. The  other  lines  will be treated  as
ordinary lines in the paragraph.

   might be "rewritten" by user agents to include the fictional tag
   sequence for :first-line. This fictional tag sequence helps to show
   how properties are inherited.

<P><P:first-line> This is a
somewhat long HTML
paragraph that will</P:first-line> be
broken into several
lines. The first line will be identified
by a fictional tag sequence. The other lines will
be treated as ordinary lines in the paragraph.</P>

   If a pseudo-element breaks up a real element, the desired effect can
   often be described by a fictional tag sequence that closes and then
   re-opens the element. Thus, if we mark up the previous paragraph with
   a SPAN element:
   
<P><SPAN class="test"> This is a
somewhat long HTML
paragraph that will be
broken into several
lines.</SPAN> The first line will be identified
by a fictional tag sequence. The other lines will
be treated as ordinary lines in the paragraph.</P>

   the user agent could generate the appropriate start and end tags for
   SPAN when inserting the fictional tag sequence for :first-line.

<P><P:first-line><SPAN class="test"> This is a
somewhat long HTML
paragraph that will </SPAN></P:first-line><SPAN class="test"> be
broken into several
lines.</SPAN> The first line will be identified
by a fictional tag sequence. The other lines will
be treated as ordinary lines in the paragraph.</P>

   The :first-line pseudo-element can only be attached to a block-level
   element.
   
   The :first-line pseudo-element is similar to an inline-level element,
   but with certain restrictions. Only the following properties apply to
   a :first-line element: font properties, color properties, background
   properties, 'word-spacing', 'letter-spacing', 'text-decoration',
   'vertical-align', 'text-transform', 'line-height', 'text-shadow', and
   'clear'.
   
  5.12.2 The :first-letter pseudo-element
  
   The :first-letter pseudo-element may be used for "initial caps" and
   "drop caps", which are common typographical effects. This type of
   initial letter is similar to an inline-level element if its 'float'
   property is 'none', otherwise it is similar to a floating element.
   
   These are the properties that apply to :first-letter pseudo-elements:
   font properties, color properties, background properties,
   'text-decoration', 'vertical-align' (only if 'float' is 'none'),
   'text-transform', 'line-height', margin properties, padding
   properties, border properties, 'float', 'text-shadow', and 'clear'.
   
   The following CSS2 will make a dropcap initial letter span two lines:
   
<HTML>
 <HEAD>
  <TITLE>Dropcap initial letter</TITLE>
  <STYLE type="text/css">
   P              { font-size: 12pt; line-height: 12pt }
   P:first-letter { font-size: 200%; font-style: italic;
                    font-weight: bold; float: left }
   SPAN           { text-transform: uppercase }
  </STYLE>
 </HEAD>
 <BODY>
  <P><SPAN>The first</SPAN> few words of an article
    in The Economist.</P>
 </BODY>
</HTML>

   This example might be formatted as follows:
   
   Image illustrating the combined effect of the :first-letter and
   :first-line pseudo-elements
   
   The fictional tag sequence is:
   
<P>
<SPAN>
<P:first-letter>
T
</P:first-letter>he first
</SPAN>
few words of an article in the Economist.
</P>

   Note that the :first-letter pseudo-element tags abut the content
   (i.e., the initial character), while the :first-line pseudo-element
   start tag is inserted right after the start tag of the element to
   which it is attached.
   
   In order to achieve traditional drop caps formatting, user agents may
   approximate font sizes, for example to align baselines. Also, the
   glyph outline may be taken into account when formatting.
   
   Punctuation (i.e, characters defined in Unicode [UNICODE] in the
   "open" (Ps), "close" (Pe), and "other" (Po) punctuation classes), that
   precedes the first letter should be included, as in:
   
   Quotes that precede the first letter should be included.
   
   The :first-letter pseudo-element matches parts of block-level elements
   only.
   
   Some languages may have specific rules about how to treat certain
   letter combinations. In Dutch, for example, if the letter combination
   "ij" appears at the beginning of a word, they should both be
   considered within the :first-letter pseudo-element.
   
   The following example illustrates how overlapping pseudo-elements may
   interact. The first letter of each P element will be green with a font
   size of '24pt'. The rest of the first formatted line will be 'blue'
   while the rest of the paragraph will be 'red'.
   
P { color: red; font-size: 12pt }
P:first-letter { color: green; font-size: 200% }
P:first-line { color: blue }

<P>Some text that ends up on two lines</P>

   Assuming that a line break will occur before the word "ends", the
   fictional tag sequence for this fragment might be:
   
<P>
<P:first-line>
<P:first-letter>
S
</P:first-letter>ome text that
</P:first-line>
ends up on two lines
</P>

   Note that the :first-letter element is inside the :first-line element.
   Properties set on :first-line are inherited by :first-letter, but are
   overridden if the same property is set on :first-letter.
   
  5.12.3 The :before and :after pseudo-elements
  
   The ':before' and ':after' pseudo-elements can be used to insert fixed
   text before or after an element. They are explained in the section on
   generated text.
   
   Example:
   
H1:before {content: counter(chapno, upper-roman) ". "}

   When the :first-letter and :first-line pseudo-elements are combined
   with :before and :after, they apply to the first letter or line of the
   element including the inserted text.
   
   Example:
P.special:before {content: "Special! "}
P.special:first-letter {color: #ffd800}

   This will render the "S" of "Special!" in gold.
     _________________________________________________________________
     _________________________________________________________________
   
          6 Assigning property values, Cascading, and Inheritance
                                      
   Contents
     * 6.1 Specified, computed, and actual values
          + 6.1.1 Specified values
          + 6.1.2 Computed values 
          + 6.1.3 Actual values
     * 6.2 Inheritance
          + 6.2.1 The 'inherit' value
     * 6.3 The @import rule
     * 6.4 The cascade
          + 6.4.1 Cascading order
          + 6.4.2 !important rules
          + 6.4.3 Calculating a selector's specificity
          + 6.4.4 Precedence of non-CSS presentational hints
       
6.1 Specified, computed, and actual values

   Once a user agent has parsed a document and constructed a document
   tree, it must assign, for every element in the tree, a value to every
   property that applies to the target media type.
   
   The final value of a property is the result of a three-step
   calculation: the value is determined through specification (the
   "specified value"), then resolved into an absolute value if necessary
   (the "computed value"), and finally transformed according to the
   limitations of the local environment (the "actual value").
   
  6.1.1 Specified values
  
   User agents must first assign a specified value to a property based on
   the following mechanisms (in order of precedence):
   
    1. If the cascade results in a value, use it.
    2. Otherwise, if the property is inherited, use the value of the
       parent element, usually the actual value.
    3. Otherwise use the property's initial value. The initial value of
       each property is indicated in the property's definition.
       
   Since it has no parent, the root of the document tree cannot use
   values from the parent element; in this case, the initial value is
   used if necessary.
   
  6.1.2 Computed values
  
   Specified values may be absolute (i.e., they are not specified
   relative to another value, as in 'red' or '2mm') or relative (i.e.,
   they are specified relative to another value, as in 'auto', '2em', and
   '12%'). For absolute values, no computation is needed to find the
   computed value.
   
   Relative values, on the other hand, must be transformed into computed
   values: percentages must be multiplied by the referenced actual value
   (each property defines which value that is), values with relative
   units (em, ex, px) must be made absolute by multiplying with the
   appropriate font or pixel size, 'auto' values must be computed by the
   formulas given with each property, certain keywords ('smaller',
   'bolder', 'inherit') must be replaced according to their definitions.
   
  6.1.3 Actual values
  
   A computed value is in principle ready to be used, but a user agent
   may not be able to make use of the value in a given environment. For
   example, a user agent may only be able to render borders with integer
   pixel widths and may therefore have to approximate the computed width.
   The actual value is the computed value after any approximations have
   been applied.
   
   In most cases, elements inherit actual values. However, there are some
   properties whose specified or computed values may be inherited (e.g.,
   the 'font-size' property and the number value for the 'line-height'
   property). The definition of a property whose actual value is not what
   other elements inherit will clearly say so.
   
6.2 Inheritance

   Some values are inherited by the children of an element in the
   document tree. Each property defines whether it is inherited or not.
   
   Suppose there is an H1 element with an emphasizing element (EM)
   inside:
   
<H1>The headline <EM>is</EM> important!</H1>

   If no color has been assigned to the EM element, the emphasized "is"
   will inherit the color of the parent element, so if H1 has the color
   blue, the EM element will likewise be in blue.
   
   To set a "default" style property for a document, authors may set the
   property on the root of the document tree. In HTML, for example, the
   HTML or BODY elements can serve this function. Note that this will
   work even if the author omits the BODY tag in the HTML source since
   the HTML parser will infer the missing tag.
   
   For example, since the 'color' property is inherited, all descendants
   of the BODY element will inherit the color 'black':

BODY { color: black; }

   The following example illustrates that specified percentage values are
   not inherited; only actual values are inherited. Consider the style
   sheet:

BODY { font-size: 10pt }
H1 { font-size: 120% }

   and the document fragment:
<BODY>
  <H1>A <EM>large</EM> heading</H1>
</BODY>

   The computed value of the 'font-size' property for the H1 element is
   12pt (120% times 10pt). If the user agent has the appropriate 12pt
   font available, 12pt will also be the property's actual value and the
   EM will inherit that value for the 'font-size' property. However, if
   the user agent does not have the 12pt font available, it may assign an
   actual value of, for example, 11pt to the 'font-size' property of the
   H1 element. In that case, the EM will inherit a value of 11pt for the
   same property.
   
  6.2.1 The 'inherit' value
  
   Each property may also have a specified value of 'inherit', which
   means that, for a given element, the property takes the same actual
   value as the property for the element's parent. The inherited value,
   which is normally only used as a fallback value, can be strengthened
   by setting 'inherit' explicitly.
   
   In the example below, the 'color' and 'background' properties are set
   on the BODY element. On all other elements, the 'color' value will be
   inherited and the background will be transparent. If these rules are
   part of the user's style sheet, black text on a white background will
   be enforced throughout the document.

BODY {
  color: black !important;
  background: white !important;
}

* {
  color: inherit !important;
  background: transparent;
}

6.3 The @import rule

   The '@import' rule allows users to import style rules from other style
   sheets. The '@import' keyword must be followed by the URI of the style
   sheet to include. (A string is also allowed: it will be interpreted as
   if it had url(...) around it.). Any @import rules must precede all
   rule sets in a style sheet.
   
   Two examples: both of these import rules are valid; the first one
   illustrates that the "url()" syntax may be replaced by a string in the
   @import rule:
   
@import "mystyle.css";
@import url(herstyle.css);

   So that user agents can avoid retrieving resources for unsupported
   media types, authors may specify media-dependent @import rules. These
   conditional imports specify comma-separated media types after the URI.
   
   The following rules have the same effect as if the imported style
   sheet were wrapped in an @media rule for the same media, but it may
   save the UA a fruitless download.

@import url(fineprint.css) print;
@import url(bluish.css) projection, tv;

   In the absence of any media types, the import is unconditional.
   Specifying 'all' for the medium has the same effect.
   
6.4 The cascade

   Style sheets may have three different origins: author, user, and user
   agent.
   
     * Author. The author specifies style sheets for a source document
       according to the conventions of the document language. For
       instance, in HTML, style sheets may be included in the document or
       linked externally.
     * User: The user may be able to specify style information for a
       particular document. For example, the user may specify a file that
       contains a style sheet or the user agent may provide an interface
       that generates a user style sheet (or behave as if it did).
     * User agent: Conforming user agents must apply a default style
       sheet (or behave as if they did) prior to all other style sheets
       for a document. A user agent's default style sheet should present
       the elements of the document language in ways that satisfy general
       presentation expectations for the document language (e.g., for
       visual browsers, the EM element in HTML is presented using an
       italic font). See "A sample style sheet for HTML 4.0" for a
       recommended default style sheet for HTML 4.0 documents.
       Note that the default style sheet may change if system settings
       are modified by the user (e.g., system colors). However, due to
       limitations in a user agent's internal implementation, it may be
       impossible to change the values in the default style sheet.
       
   Style sheets from these three origins will overlap in scope, and they
   interact according to the cascade.
   
   The CSS cascade assigns a weight to each style rule. When several
   rules apply, the one with the greatest weight takes precedence.
   
   By default, rules in a user's personal style sheets have less weight
   than rules in the author's style sheets. Thus, if there are conflicts
   between the style sheets of an incoming document and the reader's
   personal sheets, the author's rules will be used. Both reader and
   author rules override the UA's default style sheet.
   
   Imported style sheets also cascade and their weight depends on their
   import order. Rules specified in a given style sheet override rules
   imported from other style sheets. Imported style sheets can themselves
   import and override other style sheets, recursively, and the same
   precedence rules apply.
   
  6.4.1 Cascading order
  
   To find the value for an element/property combination, user agents
   must apply the following algorithm:
   
    1. Find all declarations that apply to the element and property in
       question, for the target media type. Declarations apply if the
       associated selector matches the element in question. If no
       declarations apply, terminate the algorithm.
    2. Sort the declarations by weight and origin: For normal
       declarations, author style sheets override user style sheets which
       override the default style sheet. For "!important" declarations,
       user style sheets override author style sheets which override the
       default style sheet. An imported style sheet has the same origin
       as the style sheet that imported it.
    3. Sort by specificity of selector: more specific selectors will
       override more general ones. Pseudo-elements and pseudo-classes are
       counted as normal elements and classes, respectively.
    4. Sort by order specified: if two rules have the same weight, the
       latter specified wins. Rules in imported style sheets are
       considered to be before any rules in the style sheet itself.
       
   The search for the property value must be terminated when any of the
   above steps yields a rule that has a higher weight than the other
   rules that apply to the same element/property combination.
   
   Apart from the "!important" setting on individual declarations, this
   strategy gives author's style sheets higher weight than those of the
   reader. It is therefore important that the User Agent gives the user
   the ability to turn off the influence of a certain style sheet, e.g.,
   through a pull-down menu.
   
  6.4.2 !important rules
  
   CSS attempts to create a balance of power between author and user
   style sheets. By default, rules in an author's style sheet override
   those in a user's style sheet (see cascade rule 3).
   
   However, for balance, an "!important" declaration (the keywords "!"
   and "important" follow the declaration) takes precedence over a normal
   declaration. Both author and user style sheets may contain
   "!important" declarations, and user "!important" rules override author
   "!important" rules.
   
   Note. This is a semantic change since CSS1. In CSS1, author
   "!important" rules took precedence over user "!important" rules. 
   
   Declaring a shorthand property (e.g., 'background') to be "!important"
   is equivalent to declaring all of its sub-properties to be
   "!important".
   
   The first rule in the user's style sheet in the following example
   contains an "!important" declaration, which override the corresponding
   declaration in the author's styles sheet. The second declaration will
   also win due to being marked "!important". However, the third rule in
   the user's style sheet is not "!important" and will therefore lose to
   the second rule in the author's style sheet (which happens to set
   style on a shorthand property). Also, the third author rule will lose
   to the second author rule since the second rule is "!important". This
   shows that "!important" declarations have a function also within
   author style sheets.

/* From the user's style sheet */
P { text-indent: 1em ! important }
P { font-style: italic ! important }
P { font-size: 18pt }

/* From the author's style sheet */
P { text-indent: 1.5em !important }
P { font: 12pt sans-serif !important }
P { font-size: 24pt }

  6.4.3 Calculating a selector's specificity
  
   A selector's specificity is calculated as follows:
   
     * count the number of ID attributes in the selector (= a)
     * count the number of other attributes and pseudo-classes in the
       selector (= b)
     * count the number of element names in the selector (= c)
     * ignore pseudo-elements.
       
   Concatenating the three numbers a-b-c (in a number system with a large
   base) gives the specificity.
   
   Some examples:
*             {}  /* a=0 b=0 c=0 -> specificity =   0 */
LI            {}  /* a=0 b=0 c=1 -> specificity =   1 */
UL LI         {}  /* a=0 b=0 c=2 -> specificity =   2 */
UL OL+LI      {}  /* a=0 b=0 c=3 -> specificity =   3 */
H1 + *[REL=up]{}  /* a=0 b=1 c=1 -> specificity =  11 */
UL OL LI.red  {}  /* a=0 b=1 c=3 -> specificity =  13 */
LI.red.level  {}  /* a=0 b=2 c=1 -> specificity =  21 */
#x34y         {}  /* a=1 b=0 c=0 -> specificity = 100 */

   In HTML, values of an element's "style" attribute are style sheet
   rules. These rules have no selectors, but for the purpose of step 3 of
   the cascade algorithm, they are considered to have an ID selector
   (specificity: a=1, b=0, c=0). For the purpose of step 4, they are
   considered to be after all other rules.
   
<HEAD>
<STYLE type="text/css">
  #x97z { color: blue }
</STYLE>
</HEAD>
<BODY>
<P ID=x97z style="color: red">
</BODY>

   In the above example, the color of the P element would be red.
   Although the specificity is the same for both declarations, the
   declaration in the "style" attribute will override the one in the
   STYLE element because of cascading rule 4.
   
  6.4.4 Precedence of non-CSS presentational hints
  
   The UA may choose to honor presentational hints from other sources
   than style sheets, for example the FONT element or the "align"
   attribute in HTML. If so, the non-CSS presentational hints must be
   translated to the corresponding CSS rules with specificity equal to
   zero. The rules are assumed to be at the start of the author style
   sheet and may be overridden by subsequent style sheet rules.
   
   Note. In a transition phase, this policy will make it easier for
   stylistic attributes to coexist with style sheets. 
   
   Note. In CSS1, the non-CSS presentational hints were given a
   specificity equal to 1, not 0. The change is due to the introduction
   of the universal selector which has a specificity of 0. 
     _________________________________________________________________
     _________________________________________________________________
   
                               7 Media types
                                      
   Contents
     * 7.1 Introduction to media types
     * 7.2 Specifying media-dependent style sheets
          + 7.2.1 The @media rule
     * 7.3 Recognized media types
          + 7.3.1 Media groups
       
7.1 Introduction to media types

   One of the most important features of style sheets is that they
   specify how a document is to be presented on different media: on the
   screen, on paper, with a speech synthesizer, with a braille device,
   etc.
   
   Certain CSS properties are only designed for certain media (e.g., the
   'cue-before' property for aural style sheets). On occasion, however,
   style sheets for different media types may share a property, but
   require different values for that property. For example, the
   'font-size' property is useful both for screen and print media.
   However, the two media are different enough to require different
   values for the common property; a document will typically need a
   larger font on a computer screen than on paper. Experience also shows
   that sans serif fonts are easier to read on screen, while fonts with
   serifs are easier to read on paper. For these reasons, it is necessary
   to express that a style sheet -- or a section of a style sheet --
   applies to certain media types.
   
7.2 Specifying media-dependent style sheets

   There are currently two ways to specify media dependencies for style
   sheets:
   
     * Specify the target medium from a style sheet with the @media or
       @import at-rules.
       
@import url(loudvoice.css) aural;
@media print {
  /* style sheet for print goes here */
}
     * Specify the target medium within the document language. For
       example, in HTML 4.0 ([HTML40]), the "media" attribute on the LINK
       element specifies the target medium of an external style sheet:
       
<HTML>
<HEAD>
<TITLE>Link to a target medium</TITLE>
<LINK rel="stylesheet" type="text/css"
         media="print" href="foo.css">
</HEAD>
<BODY>
<P>The body...
</BODY>
</HTML>
       
   The @import rule is defined in the chapter on the cascade.
   
  7.2.1 The @media rule
  
   An @media rule lists the media types (separated by commas) affected by
   a set of rules delimited by curly braces.
   
   The @media construct allows style sheet rules for various media in the
   same style sheet:
   
  @media print {
    BODY { font-size: 10pt }
  }
  @media screen {
    BODY { font-size: 12pt }
  }
  @media screen, print {
    BODY { line-height: 1.2 }
  }

7.3 Recognized media types

   A CSS media type names a set of CSS properties. A user agent that
   claims to support a media type by name must implement all of the
   properties that apply to that media type.
   
   The names chosen for CSS media types reflect target devices for which
   the relevant properties make sense. In the list of CSS media types,
   the parenthetical descriptions are not normative. They only give a
   sense of what device the media type is meant to refer to.
   
   Due to rapidly changing technologies, CSS2 does not specify a
   definitive list of media types that may be values for @media.
   
   all
          Suitable for all devices.
          
   aural
          Intended for speech synthesizers. See the section on aural
          style sheets for details.
          
   braille
          Intended for braille tactile feedback devices.
          
   embossed
          Intended for paged braille printers.
          
   handheld
          Intended for handheld devices (typically small screen,
          monochrome, limited bandwidth).
          
   print
          Intended for paged, opaque material and for documents viewed on
          screen in print preview mode. Please consult the section on
          paged media for information about formatting issues that are
          specific to paged media.
          
   projection
          Intended for projected presentations, for example projectors or
          print to transparencies. Please consult the section on paged
          media for information about formatting issues that are specific
          to paged media.
          
   screen
          Intended primarily for color computer screens.
          
   tty
          Intended for media using a fixed-pitch character grid, such as
          teletypes, terminals, or portable devices with limited display
          capabilities. Authors should not use pixel units with the "tty"
          media type.
          
   tv
          Intended for television-type devices (low resolution, color,
          limited-scrollability screens, sound available).
          
   Media type names are case-insensitive.
   
   Note. Future versions of CSS may extend this list. Authors should not
   rely on media type names that are not yet defined by a CSS
   specification. 
   
  7.3.1 Media groups
  
   Each CSS property definition specifies the media types for which the
   property must be implemented by a conforming user agent. Since
   properties generally apply to several media, the "Applies to media"
   section of each property definition indicates a media group rather
   than a list of media types. A property applies to all media types that
   belong to a given media group.
   
   CSS2 defines the following media groups:
   
     * continuous or paged. "Both" means that the property in question
       applies to both media groups.
     * visual, aural, or tactile.
     * grid (for character grid devices), or bitmap. "Both" means that
       the property in question applies to both media groups.
     * interactive (for devices that allow user interaction), or static
       (for those that don't). "Both" means that the property in question
       applies to both media groups.
     * all (includes all media types)
       
   The following table shows the relationships between media groups and
   media types:
   
   CAPTION: Relationship between media groups and media types
   
   Media Types Media Groups
     continuous/paged visual/aural/tactile grid/bitmap interactive/static
   aural continuous aural N/A both
   braille continuous tactile grid both
   emboss paged tactile grid both
   handheld both visual both both
   print paged visual bitmap static
   projection paged visual bitmap static
   screen continuous visual bitmap both
   tty continuous visual grid both
   tv both visual, aural bitmap both
     _________________________________________________________________
     _________________________________________________________________
   
                                8 Box model
                                      
   Contents
     * 8.1 Box dimensions
     * 8.2 Example of margins, padding, and borders
     * 8.3 Margin properties: 'margin-top', 'margin-right',
       'margin-bottom', 'margin-left', and 'margin'
          + 8.3.1 Collapsing margins
     * 8.4 Padding properties: 'padding-top', 'padding-right',
       'padding-bottom', 'padding-left', and 'padding'
     * 8.5 Border properties
          + 8.5.1 Border width: 'border-top-width', 'border-right-width',
            'border-bottom-width', 'border-left-width', and
            'border-width'
          + 8.5.2 Border color: 'border-top-color', 'border-right-color',
            'border-bottom-color', 'border-left-color', and
            'border-color'
          + 8.5.3 Border style: 'border-top-style', 'border-right-style',
            'border-bottom-style', 'border-left-style', and
            'border-style'
          + 8.5.4 Border shorthand properties: 'border-top',
            'border-bottom', 'border-right', 'border-left', and 'border'
       
   The CSS box model describes the rectangular boxes that are generated
   for elements in the document tree and formatted by the visual
   rendering model. The page box is a special kind of box that is
   described in detail in the section on paged media.
   
8.1 Box dimensions

   Each box has a content area (e.g., text, an image, etc.) and optional
   surrounding padding, border, and margin areas; the size of each area
   is specified by properties defined below. The following diagram shows
   how these areas relate and the terminology used to refer to pieces of
   margin, border, and padding:
   
   Image illustrating the relationship between content, padding, borders,
   and margins.
   
   The margin, border, and padding can be broken down into left, right,
   top, and bottom segments (e.g., in the diagram, "LM" for left margin,
   "RP" for right padding, "TB" for top border, etc.
   
   The perimeter of each of the four areas (content, padding, border, and
   margin) is called an "edge", so each box has four edges:
   
   content edge or inner edge
          The content edge surrounds the element's rendered content.
          
   padding edge
          The padding edge surrounds the box padding. If the padding has
          0 width, the padding edge is the same as the content edge. The
          padding edge of a box defines the edges of the containing block
          established by the box.
          
   border edge
          The border edge surrounds the box's border. If the border has 0
          width, the border edge is the same as the padding edge.
          
   margin edge or outer edge
          The margin edge surrounds the box margin. If the margin has 0
          width, the margin edge is the same as the border edge.
          
   Each edge may be broken down into a left, right, top, and bottom edge.
   
   The dimensions of the content area of a box -- the content width and
   content height -- depend on several factors: whether the element
   generating the box has the 'width' or 'height' property set, whether
   the box contains text or other boxes, whether the box is a table, etc.
   Box widths and heights are discussed in the chapter on visual
   rendering model details.
   
   The box width (height) is given by the sum of the content width
   (height), the padding, the border, and the margin.
   
   Note that there are no properties to set the color of margins and
   padding; margins are always transparent and padding areas always use
   the background of the element itself. The background of an element
   extends to the padding edge of the box it generates.
   
8.2 Example of margins, padding, and borders

   This example illustrates how margins, padding, and borders interact.
   The example HTML document:

<HTML>
  <HEAD>
    <STYLE type="text/css">
      UL {
        background: orange;
        margin: 12px 12px 12px 12px;
        padding: 3px 3px 3px 3px;
                                     /* No borders set */
      }
      LI {
        color: white;                /* text color is white */
        background: blue;            /* Content, padding will be blue */
        margin: 12px 12px 12px 12px;
        padding: 12px 0px 12px 12px; /* Note 0px padding right */
        list-style: none             /* no glyphs before a list item */
                                     /* No borders set */
      }
      LI.withborder {
        border-style: dashed;
        border-width: medium;        /* sets border width on all sides */
        border-color: green;
      }
    </STYLE>
  </HEAD>
  <BODY>
    <UL>
      <LI>First element of list
      <LI class="withborder">Second element of list is longer
           to illustrate wrapping.
    </UL>
  </BODY>
</HTML>

   results in a document tree with (among other relationships) a UL
   element that has two LI children.
   
   The first of the following diagrams illustrates what this example
   would produce. The second illustrates the relationship between the
   margins, padding, and borders of the UL elements and those of its
   children LI elements.
   
   Image illustrating how parent and child margins, borders, and padding
   relate.
   
   Note that:
   
     * The content width for each LI box is calculated top-down; the
       containing block for each LI box is the box generated by the UL
       element.
     * The height of each LI box is given by its content height, plus
       padding, borders, and margins. Note that vertical margins between
       the LI boxes collapse.
     * The right padding of the LI boxes has been set to zero width (the
       'padding' property). The effect is apparent in the second
       illustration.
     * The foreground color of the LI boxes has been set to white for
       legibility against a blue background (the 'color' property).
     * The margins of the LI boxes are transparent -- margins are always
       transparent -- so the background color of the UL boxes (orange)
       shines through them. However, the (blue) background of the LI
       boxes is also used for the LI padding.
     * The second LI element specifies a dashed border (the
       'border-style' property).
       
8.3 Margin properties: 'margin-top', 'margin-right', 'margin-bottom',
'margin-left', and 'margin'

   Margin properties specify the width of the margin area of a box. The
   'margin' shorthand property sets the margin for all four sides while
   the other margin properties only set their respective side. These
   properties apply to all elements generating block boxes and also if
   'display' is set to 'caption'.
   
   The properties defined in this section refer to the <margin-width>
   value type, which may take one of the following values:
   
   <length>
          Specifies a fixed width.
          
   <percentage>
          Specifies a percentage width. The percentage is calculated with
          respect to the generated box's containing block.
          
   auto
          See the section on box width calculations for behavior.
          
   Negative values for margin properties are allowed, but there may be
   implementation-specific limits.
   
   'margin-top', 'margin-right', 'margin-bottom', 'margin-left'
          Value:   <margin-width> | inherit
          Initial:   0
          Applies to:   all elements
          Inherited:   no
          Percentages:   refer to width of containing block
          Media:   visual
          
   These properties set the top, right, bottom, resp. left margin of a
   box.
   
H1 { margin-top: 2em }

   'margin'
          Value:   <margin-width>{1,4} | inherit
          Initial:   not defined for shorthand properties
          Applies to:   all elements
          Inherited:   no
          Percentages:   refer to width of containing block
          Media:   visual
          
   The 'margin' property is a shorthand property for setting
   'margin-top', 'margin-right' 'margin-bottom' and 'margin-left' at the
   same place in the style sheet.
   
   Note that percentages, even for 'margin-top' and 'margin-bottom', are
   relative to the 'width' property, not the 'height' property. If they
   were dependent on the height, they might result in a mutual
   dependency, and they would also make progressive rendering impossible.
   
   If there is only one value, it applies to all sides. If there are two
   values, the top and bottom margins are set to the first value and the
   right and left margins are set to the second. If there are three
   values, the top is set to the first value, the left and right are set
   to the second, and the bottom is set to the third. If there are four
   values, they apply to the top, right, bottom, and left, respectively.
   
BODY { margin: 2em } /* all margins set to 2em */
BODY { margin: 1em 2em } /* top & bottom = 1em, right & left = 2em */
BODY { margin: 1em 2em 3em } /* top=1em, right=2em, bottom=3em, left=2em */

   The last rule of the example above is equivalent to the example below:

BODY {
  margin-top: 1em;
  margin-right: 2em;
  margin-bottom: 3em;
  margin-left: 2em;        /* copied from opposite side (right) */
}

  8.3.1 Collapsing margins
  
   In this specification, the expression collapsing margins means that
   adjoining margins (no padding or border areas separate them) of two or
   more boxes (which may be next to one another or nested) combine to
   form a single margin.
   
   In CSS2, horizontal margins never collapse.
   
   Vertical margins may collapse between certain boxes:
   
     * Two or more adjoining vertical margins of block boxes in the
       normal flow collapse. The resulting margin width is the maximum of
       the adjoining margin widths. In the case of negative margins, the
       absolute maximum of the negative adjoining margins is deducted
       from the maximum of the positive adjoining margins. If there are
       no positive margins, the absolute maximum of the negative
       adjoining margins is deducted from zero.
     * Vertical margins between a floating box and any other box do not
       collapse.
     * Margins of absolutely positioned boxes do not collapse.
       
   Please consult the examples of margin, padding, and borders for an
   illustration of collapsed margins.
   
8.4 Padding properties: 'padding-top', 'padding-right', 'padding-bottom',
'padding-left', and 'padding'

   The padding properties specify the width of the padding area of a box.
   The 'padding' shorthand property sets the padding for all four sides
   while the other padding properties only set their respective side.
   These properties apply to all elements.
   
   The properties defined in this section refer to the <padding-width>
   value type, which may take one of the following values:
   
   <length>
          Specifies a fixed width.
          
   <percentage>
          Specifies a percentage width. The percentage is calculated with
          respect to the generated box's containing block.
          
   Unlike margin properties, values for padding values cannot be
   negative. Like margin properties, percentage values for padding
   properties refer to the width of the generated box's containing block.
   
   'padding-top', 'padding-right', 'padding-bottom', 'padding-left'
          Value:   <padding-width> | inherit
          Initial:   0
          Applies to:   all elements
          Inherited:   no
          Percentages:   refer to width of containing block
          Media:   visual
          
   These properties set the top, right, bottom, resp. left padding of a
   box.
   
BLOCKQUOTE { padding-top: 0.3em }

   'padding'
          Value:   <padding-width>{1,4} | inherit
          Initial:   not defined for shorthand properties
          Applies to:   all elements
          Inherited:   no
          Percentages:   refer to width of containing block
          Media:   visual
          
   The 'padding' property is a shorthand property for setting
   'padding-top', 'padding-right', 'padding-bottom', and 'padding-left'
   at the same place in the style sheet.
   
   If there is only one value, it applies to all sides. If there are two
   values, the top and bottom paddings are set to the first value and the
   right and left paddings are set to the second. If there are three
   values, the top is set to the first value, the left and right are set
   to the second, and the bottom is set to the third. If there are four
   values, they apply to the top, right, bottom, and left, respectively.
   
   The surface color or image of the padding area is specified via the
   'background' property:
   
H1 {
  background: white;
  padding: 1em 2em;
}

   The example above specifies a '1em' vertical padding ('padding-top'
   and 'padding-bottom') and a '2em' horizontal padding ('padding-right'
   and 'padding-left'). The 'em' unit is relative to the element's font
   size: '1em' is equal to the size of the font in use.
   
8.5 Border properties

   The border properties specify the width, color, and style of the
   border area of a box. These properties apply to all elements.
   
  8.5.1 Border width: 'border-top-width', 'border-right-width',
  'border-bottom-width', 'border-left-width', and 'border-width'
  
   The border width properties specify the width of the border area. The
   properties defined in this section refer to the <border-width> value
   type, which may take one of the following values:
   
   thin
          A thin border.
          
   medium
          A medium border.
          
   thick
          A thick border.
          
   <length>
          The border's thickness has an explicit value. Explicit border
          widths cannot be negative.
          
   The interpretation of the first three values depends on the user
   agent. The following relationships must hold, however:
   
   'thin' <='medium' <= 'thick'.
   
   Furthermore, these widths must be constant throughout a document.
   
   'border-top-width', 'border-right-width', 'border-bottom-width',
          'border-left-width'
          Value:   <border-width> | inherit
          Initial:   medium
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   These properties set the width of the top, right, bottom, resp. left
   border of a box.
   
   'border-width'
          Value:   <border-width>{1,4} | inherit
          Initial:   see individual properties
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   This property is a shorthand property for setting 'border-top-width',
   'border-right-width', 'border-bottom-width', and 'border-left-width'
   at the same place in the style sheet.
   
   If there is only one value, it applies to all sides. If there are two
   values, the top and bottom borders are set to the first value and the
   right and left are set to the second. If there are three values, the
   top is set to the first value, the left and right are set to the
   second, and the bottom is set to the third. If there are four values,
   they apply to the top, right, bottom, and left, respectively.
   
   In the examples below, the comments indicate the resulting widths of
   the top, right, bottom and left borders:

H1 { border-width: thin }                   /* thin thin thin thin */
H1 { border-width: thin thick }             /* thin thick thin thick */
H1 { border-width: thin thick medium }      /* thin thick medium thick */

  8.5.2 Border color: 'border-top-color', 'border-right-color',
  'border-bottom-color', 'border-left-color', and 'border-color'
  
   The border color properties specify the color of a box's border.
   
   'border-top-color', 'border-right-color', 'border-bottom-color',
          'border-left-color'
          Value:   <color> | inherit
          Initial:   the value of the 'color' property
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   'border-color'
          Value:   <color>{1,4} | transparent | inherit
          Initial:   see individual properties
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   The 'border-color' property sets the color of the four borders. Values
   have the following meanings:
   
   <color>
          Specifies a color value.
          
   transparent
          The border is transparent (though it may have width).
          
   The 'border-color' property can have from one to four values, and the
   values are set on the different sides as for 'border-width'.
   
   If an element's border color is not specified with a border property,
   user agents must use the value of the element's 'color' property as
   the computed value for the border color.
   
   In this example, the border will be a solid black line.
P {
  color: black;
  background: white;
  border: solid;
}

  8.5.3 Border style: 'border-top-style', 'border-right-style',
  'border-bottom-style', 'border-left-style', and 'border-style'
  
   The border style properties specify the line style of a box's border
   (solid, double, dashed, etc.). The properties defined in this section
   refer to the <border-style> value type, which make take one of the
   following:
   
   none
          No border. This value forces the computed value of
          'border-width' to be '0'.
          
   hidden
          Same as 'none', except in terms of border conflict resolution
          for table elements.
          
   dotted
          The border is a series of dots.
          
   dashed
          The border is a series of short line segments.
          
   solid
          The border is a single line segment.
          
   double
          The border is two solid lines. The sum of the two lines and the
          space between them equals the value of 'border-width'.
          
   groove
          The border looks as though it were carved into the canvas.
          
   ridge
          The opposite of 'grove': the border looks as though it were
          coming out of the canvas.
          
   inset
          The border makes the entire box look as though it were embedded
          in the canvas.
          
   outset
          The opposite of 'inset': the order makes the entire box look as
          though it were coming out of the canvas.
          
   All borders are drawn on top of the box's background. The color of
   borders drawn for values of 'groove', 'ridge', 'inset', and 'outset'
   depends on the element's 'color' property.
   
   Conforming HTML user agents may interpret 'dotted', 'dashed',
   'double', 'groove', 'ridge', 'inset', and 'outset' to be 'solid'.
   
   'border-top-style', 'border-right-style', 'border-bottom-style',
          'border-left-style'
          Value:   <border-style> | inherit
          Initial:   none
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   'border-style'
          Value:   <border-style>{1,4} | inherit
          Initial:   see individual properties
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   The 'border-style' property sets the style of the four borders. It can
   have from one to four values, and the values are set on the different
   sides as for 'border-width' above.
   
#xy34 { border-style: solid dotted }

   In the above example, the horizontal borders will be 'solid' and the
   vertical borders will be 'dotted'.
   
   Since the initial value of the border styles is 'none', no borders
   will be visible unless the border style is set.
   
  8.5.4 Border shorthand properties: 'border-top', 'border-bottom',
  'border-right', 'border-left', and 'border'
  
   'border-top', 'border-right', 'border-bottom', 'border-left'
          Value:   [ <'border-top-width'> || <'border-style'> || <color>
          ] | inherit
          Initial:   see individual properties
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   This is a shorthand property for setting the width, style, and color
   of the top, right, bottom, resp. left border of a box.
   
H1 { border-bottom: thick solid red }

   The above rule will set the width, style, and color of the border
   below the H1 element. Omitted values will be set to their initial
   values:

H1 { border-bottom: thick solid }

   Since the color value is omitted in the above example, the border
   color will be the same as the 'color' value of the element itself.
   
   Note that while the 'border-style' property accepts up to four values,
   this property only accepts one style value.
   
   'border'
          Value:   [ <'border-width'> || <'border-style'> || <color> ] |
          inherit
          Initial:   see individual properties
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   The 'border' property is a shorthand property for setting the same
   width, color, and style for all four borders of a box. Unlike the
   shorthand 'margin' and 'padding' properties, the 'border' property
   cannot set different values on the four borders. To do so, one or more
   of the other border properties must be used.
   
   For example, the first rule below is equivalent to the set of four
   rules shown after it:

P { border: solid red }
P {
  border-top: solid red;
  border-right: solid red;
  border-bottom: solid red;
  border-left: solid red
}

   Since, to some extent, the properties have overlapping functionality,
   the order in which the rules are specified is important.
   
   Consider this example:
BLOCKQUOTE {
  border-color: red;
  border-left: double;
  color: black
}

   In the above example, the color of the left border is black, while the
   other borders are red. This is due to 'border-left' setting the width,
   style, and color. Since the color value is not given by the
   'border-left' property, it will be taken from the 'color' property.
   The fact that the 'color' property is set after the 'border-left'
   property is not relevant.
     _________________________________________________________________
     _________________________________________________________________
   
                          9 Visual rendering model
                                      
   Contents
     * 9.1 Introduction to the visual rendering model
          + 9.1.1 The viewport
          + 9.1.2 Containing blocks
     * 9.2 Controlling box generation
          + 9.2.1 Block-level elements and block boxes
               o Anonymous block boxes
          + 9.2.2 Inline-level elements and inline boxes
               o Anonymous inline boxes
          + 9.2.3 Compact boxes
          + 9.2.4 Run-in boxes
          + 9.2.5 The 'display' property
     * 9.3 Positioning schemes
          + 9.3.1 Choosing a positioning scheme: 'position' property
          + 9.3.2 Box offsets: 'top', 'right', 'bottom', 'left'
     * 9.4 Normal flow
          + 9.4.1 Block formatting context
          + 9.4.2 Inline formatting context
          + 9.4.3 Relative positioning
     * 9.5 Floats
          + 9.5.1 Positioning the float: the 'float' property
          + 9.5.2 Controlling flow next to floats: the 'clear' property
     * 9.6 Absolute positioning
          + 9.6.1 Fixed positioning
     * 9.7 Relationships between 'display', 'position', and 'float'
     * 9.8 Comparison of normal flow, floats, and absolute positioning
          + 9.8.1 Normal flow
          + 9.8.2 Relative positioning
          + 9.8.3 Floating a box
          + 9.8.4 Absolute positioning
     * 9.9 Layered presentation
          + 9.9.1 Specifying the stack level: the 'z-index' property
     * 9.10 Text direction: the 'direction' and 'unicode-bidi' properties
          + 9.10.1 Interaction between inline flow and text direction
          + 9.10.2 Bidirectionality in HTML 4.0
       
9.1 Introduction to the visual rendering model

   This chapter and the next describe the visual rendering model: how
   user agents process the document tree for visual media.
   
   In the visual rendering model, each element in the document tree
   generates zero or more boxes according to the box model. The layout of
   these boxes is governed by:
   
     * box dimensions and type.
     * positioning scheme (normal flow, float, and absolute positioning
       models).
     * relationships between elements in the document tree.
     * external information (e.g., viewport size, intrinsic dimensions of
       images, etc.).
       
   The properties defined in this chapter and the next apply to both
   continuous media and paged media. However, the meanings of the margin
   properties vary when applied to paged media (see the page model for
   details).
   
   The visual rendering model does not specify all aspects of formatting
   (e.g., it does not specify a letter-spacing algorithm). Conforming
   user agents may behave differently for those formatting issues not
   covered by this specification.
   
  9.1.1 The viewport
  
   User agents for continuous media generally offer users a viewport (a
   window or other viewing area on the screen) through which users
   consult a document. User agents may change the document's layout when
   the viewport is resized (see the initial containing block). When the
   viewport is smaller than the document's initial containing block, the
   user agent should offer a scrolling mechanism. There is at most one
   viewport per canvas, but user agents may offer users several views of
   a document.
   
  9.1.2 Containing blocks
  
   In CSS2, all box positions are calculated with respect to the edges of
   a rectangular box called a containing block. A box establishes
   reference edges for its descendants and is itself positioned with
   respect to its containing block. The phrase "a box's containing block"
   means "the containing block in which the box lives", not the one it
   generates.
   
   Each box is positioned with respect to its containing block, but it is
   not confined by this containing block (it may overflow)
   
   The root of the document tree generates a box that serves as the
   initial containing block for subsequent layout. If the 'width'
   property for the root element has the value 'auto', the user agent
   supplies an initial width (e.g., the user agent uses the current width
   of the viewport). The initial containing block cannot be positioned or
   floated (i.e., user agents ignore the 'position' 'float' properties
   for the root element).
   
   The details of how a containing block's dimensions are calculated are
   described in the next chapter.
   
9.2 Controlling box generation

   The following sections describe the types of boxes that may be
   generated in CSS2. A box's type affects, in part, its behavior in the
   visual rendering model. The 'display' property, described below,
   specifies a box's type.
   
  9.2.1 Block-level elements and block boxes
  
   Block-level elements are those elements of the source document
   language that are formatted visually as blocks (e.g., paragraphs).
   Several values of the 'display' property make an element block-level:
   'block', 'list-item', 'compact' and 'run-in' (part of the time; see
   compact and run-in boxes), and 'table'.
   
   Block-level elements generate a principal block box that contains
   block boxes. The principal block box establishes the containing block
   for descendant boxes and is also the box involved in any positioning
   scheme. Sibling block boxes participate in a block formatting context.
   
   Some block-level elements generate additional boxes outside of the
   principal box: 'list-item' elements and those with markers. These
   additional boxes follow the principal box when it is positioned.
   
    Anonymous block boxes
    
   In a document like this:
<DIV>
  Some text
  <P>Some more text
</DIV>

   (and assuming the DIV and the P both have 'display: block'), the DIV
   appears to have both inline content and block content. To make it
   easier to define the formatting, we assume that there is an anonymous
   block box around "Some text".
   
   diagram showing the three boxes for the example above
   
   Diagram showing the three boxes, of which one is anonymous, for the
   example above
   
   In other words: if a block box (such as that generated for the DIV
   above) has another block box inside it (such as the P above), then we
   force it to have only block boxes inside it, by wrapping any inline
   boxes in an anonymous block box.
   
   The properties of these anonymous boxes are inherited from the
   enclosing non-anonymous box (in the example: the one for DIV).
   Non-inherited properties have their initial value. For example, the
   font of the anonymous box is inherited from the DIV, but the margins
   will be 0.
   
  9.2.2 Inline-level elements and inline boxes
  
   Inline-level elements are those elements of the source document that
   do not form new blocks of content; the content is distributed in lines
   (e.g., emphasized pieces of text within a paragraph, inline images,
   etc.). Several values of the 'display' property make an element
   inline: 'inline', 'inline-table', 'compact' and 'run-in' (part of the
   time; see compact and run-in boxes). Inline-level elements generate
   inline boxes.
   
   An inline box participates in an inline formatting context with its
   siblings and children.
   
    Anonymous inline boxes
    
   In a document like this:
<P>Some <EM>emphasized</em> text

   The P generates a block box, with several inline boxes inside it. The
   box for "emphasized" is an inline box generated by an inline element
   (EM), but the other boxes ("Some" and "text") are inline boxes
   generated by a block-level element (P). The latter are called
   anonymous inline boxes, because they don't have an associated
   inline-level element.
   
   Such anonymous inline boxes inherit inheritable properties from their
   block parent box. Non-inherited properties have their initial value.
   
   In the example, the color of the anonymous initial boxes is inherited
   from the P, but the background is transparent.
   
   If it is clear from the context which type of anonymous box is meant,
   both anonymous inline boxes and anonymous block boxes are simply
   called anonymous boxes in his specification.
   
   There are more types of anonymous boxes in the table context.
   
  9.2.3 Compact boxes
  
   A compact box behaves as follows:
   
     * If a block box (that does not float and is not absolutely
       positioned) follows the compact box, the compact box is formatted
       like a one-line inline box. The resulting box width is compared to
       one of the side margins of the block box. The choice of left or
       right margin is determined by the 'direction' specified for the
       element producing the containing block for the compact box and
       following box. If the inline box width is less than or equal to
       the margin, the inline box is positioned in the margin as
       described immediately below.
     * Otherwise, the compact box behaves like a block box.
       
   The compact box is positioned in the margin as follows: it is outside
   (to the left or right) of the first line box of the block, but it
   affects the calculation of that line box's height. The
   'vertical-align' property of the compact box determines the vertical
   position of the compact box relative to that line box. The horizontal
   position of the compact box is always in the margin of the block box.
   
   An element that cannot be rendered on one line cannot be placed in the
   margin of the following block. For example, a 'compact' element in
   HTML that contains a <BR> element will always be rendered as a block
   box (assuming the default style for BR, which inserts a newline). For
   placing multi-line texts in the margin, the 'float' property is often
   more adequate.
   
   The following example illustrates a compact box.
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
  <HEAD>
    <TITLE>A compact box example</TITLE>
    <STYLE type="text/css">
      DT { display: compact }
      DD { margin-left: 4em }
    </STYLE>
  </HEAD>
  <BODY>
    <DL>
      <DT>Short
        <DD><P>Description goes here.
      <DT>too long for the margin
        <DD><P>Description goes here.
    </DL>
  </BODY>
</HTML>

   This example might be rendered as:
short    Description goes here

too long for the margin
         Description goes here

   The 'text-align' property can be used to align the compact element
   inside the margin: against the left edge of the margin ('left'),
   against the right edge ('right'), or centered in the margin
   ('center'). The value 'justify' doesn't apply, and is handled as
   either 'left' or 'right', depending on the 'direction' of the
   block-level element in whose margin the compact element is rendered.
   ('left' if the direction is 'ltr', 'right' if it is 'rtl'.)
   
   Please consult the section on generated content for information about
   how compact boxes interact with generated content.
   
  9.2.4 Run-in boxes
  
   A run-in box behaves as follows:
   
     * If a block box (that does not float and is not absolutely
       positioned) follows the run-in box, the run-in box behaves like an
       inline child of the block box.
     * Otherwise, the run-in box behaves like a block box.
       
   A 'run-in' box is useful for run-in headers, as in this example:
   
<HTML>
  <HEAD>
    <TITLE>A run-in box example</TITLE>
    <STYLE type="text/css">
      H3 { display: run-in }
    </STYLE>
  </HEAD>
  <BODY>
    <H3>A run-in heading.</H3>
    <P>And a paragraph of text that
       follows it.
  </BODY>
</HTML>

   This example might be rendered as:
  A run-in heading. And a
  paragraph of text that
  follows it.

   The properties of the run-in element are inherited from its parent in
   the source tree, not from the block box it visually becomes part of.
   
   Please consult the section on generated content for information about
   how run-in boxes interact with generated content.
   
  9.2.5 The 'display' property
  
   'display'
          Value:   inline | block | list-item | run-in | compact | marker
          | table | inline-table | table-row-group | table-column-group |
          table-header-group | table-footer-group | table-row |
          table-cell | table-caption | none | inherit
          Initial:   inline
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   all
          
   The values of this property have the following meanings:
   
   block
          This value causes an element to generate a principal block box.
          
   inline
          This value causes an element to generate one or more inline
          boxes.
          
   list-item
          This value causes an element to generate a principal block box
          and a list-item marker box. For example, in HTML, the LI
          element will typically have this 'display' value. For
          information about lists and examples of list formatting, please
          consult the section on lists.
          
   marker
          This value declares generated content before or after a box to
          be a marker. This value is only useful with the :before and
          :after pseudo-elements, on other elements is interpreted as
          'inline'. Please consult the section on markers for more
          information.
          
   none
          This value causes an element to generate no boxes in the
          rendering structure (i.e., the element has no effect on
          layout). Descendant elements do not generate any boxes either;
          this behavior cannot be overridden by setting the 'display'
          property on the descendants.
          
          Please note that a display of 'none' does not create an
          invisible box; it creates no box at all. CSS includes
          mechanisms that enable an element to generate boxes in the
          rendering structure that affect formatting but are not visible
          themselves. Please consult the section on visibility for
          details.
          
   run-in and compact
          These values create either block or inline boxes, depending on
          context. Properties apply to run-in and compact boxes based on
          their final status (inline-level or block-level). For example,
          the 'white-space' property only applies if the box behaves like
          a block box.
          
   table, inline-table, table-row-group, table-column-group,
          table-header-group, table-footer-group, table-row, table-cell,
          and table-caption
          These values cause an element to behave like a table element
          (subject to restrictions described in the chapter on tables).
          
   Note that although the initial value of 'display' is 'inline', rules
   in the user agent's default style sheet may override this value. See
   the sample style sheet for HTML 4.0 in the appendix.
   
   Here are some examples of the 'display' property:
P   { display: block }
EM  { display: inline }
LI  { display: list-item }
IMG { display: none }      /* Don't display images */

   Conforming HTML user agents may ignore the 'display' property when
   specified in author and user style sheets but must specify a value for
   it in the default style sheet.
   
9.3 Positioning schemes

   In CSS2, a box may be laid out according to three positioning schemes
   
    1. Normal flow. In CSS2, normal flow includes block formatting of
       block boxes, inline formatting of inline boxes, relative
       positioning of block or inline boxes, and positioning of compact
       and run-in boxes.
    2. Floats. In the float model, a box is first positioned in the
       normal flow, then taken out of the flow and shifted to the left or
       right as far as possible. Content may flow along the side of a
       float.
    3. Absolute positioning. In the absolute positioning model, a box is
       removed from the normal flow entirely (it has no impact on later
       siblings) and assigned coordinates with respect to a containing
       block.
       
  9.3.1 Choosing a positioning scheme: 'position' property
  
   The 'position' and 'float' properties determine which CSS2 positioning
   algorithms are used to calculate the coordinates of a box.
   
   'position'
          Value:   static | relative | absolute | fixed | inherit
          Initial:   static
          Applies to:   all elements (except generated content)
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   The values of this property have the following meanings:
   
   static
          The box is a normal box, positioned according to the normal
          flow. The 'left' and 'top' properties do not apply. (The word
          "static" may seem confusing--&#8212
          static than 'static'-&#8212
          expectation is that it will most often be used in scripts that
          "animate" elements by modifying 'top', 'left', 'bottom', and/or
          'right'.)
          
   relative
          The box coordinates are calculated according to the normal
          flow, then the box is offset relative to its normal position.
          When a box B is relatively positioned, the position of the
          following box is calculated as though B were not offset.
          
   absolute
          The box coordinates (and possibly size) are assigned with the
          'left' 'right', 'top', and 'bottom' properties. These
          properties specify offsets with respect to the box's containing
          block. Absolutely positioned boxes are taken out of the normal
          flow. This means they have no impact on the layout of later
          siblings. Also, though absolutely positioned boxes have
          margins, they do not collapse with any other margins.
          
   fixed
          The box coordinates are calculated according to the 'absolute'
          model, but in addition, the box is fixed with respect to some
          reference. In the case of continuous media, the box is fixed
          with respect to the viewport (and doesn't move when scrolled).
          In the case of paged media, the box is fixed with respect to
          the page, even if that page is seen through a viewport (in the
          case of a print-preview, for example). Authors may wish to
          specify 'fixed' in a media-dependent way. For instance, an
          author may want a box to remain at the top of the viewport on
          the screen, but not at the top of each printed page. The two
          specifications may be separated by using an @media rule, as in:
          

@media screen {
  H1#first { position: fixed }
}
@media print {
  H1#first { position: static }
}

  9.3.2 Box offsets: 'top', 'right', 'bottom', 'left'
  
   The position of a relatively or absolutely (including fixed)
   positioned box is established by four properties:
   
   'top'
          Value:   <length> | <percentage> | auto | inherit
          Initial:   auto
          Applies to:   all elements
          Inherited:   no
          Percentages:   refer to height of containing block
          Media:   visual
          
   This property specifies how far a box's top content edge is offset
   below the top edge of the box's containing block.
   
   'right'
          Value:   <length> | <percentage> | auto | inherit
          Initial:   auto
          Applies to:   all elements
          Inherited:   no
          Percentages:   refer to width of containing block
          Media:   visual
          
   This property specifies how far a box's right content edge is offset
   to the left of the right edge of the box's containing block.
   
   'bottom'
          Value:   <length> | <percentage> | auto | inherit
          Initial:   auto
          Applies to:   all elements
          Inherited:   no
          Percentages:   refer to height of containing block
          Media:   visual
          
   This property specifies how far a box's bottom content edge is offset
   above the bottom of the box's containing block.
   
   'left'
          Value:   <length> | <percentage> | auto | inherit
          Initial:   auto
          Applies to:   all elements
          Inherited:   no
          Percentages:   refer to width of containing block
          Media:   visual
          
   This property specifies how far a box's left content edge is offset to
   the right of the left edge of the box's containing block.
   
   The values for the four properties have the following meanings:
   
   <length>
          The offset is a fixed distance from the reference edge.
          
   <percentage>
          The offset is a percentage of the containing block's width (for
          'left' or 'right') or height (for 'top' and 'bottom').
          
   auto
          The value depends on which of the other properties are 'auto'
          as well. See "Width of absolutely positioned boxes".
          
   For absolutely positioned boxes, the offsets are with respect to the
   box's containing block. For relatively positioned boxes, the offsets
   are with respect to the outer edges of the box itself (i.e., the box
   is normally positioned, then offset from that position according to
   these properties).
   
9.4 Normal flow

   Boxes in the normal flow belong to a formatting context, which may be
   block or inline, but not both simultaneously. Block boxes participate
   in a block formatting context. Inline boxes participate in an inline
   formatting context.
   
  9.4.1 Block formatting context
  
   In a block formatting context, boxes are laid out one after the other,
   vertically, beginning at the top of a containing block. The vertical
   distance between two sibling boxes is determined by the 'margin'
   properties. Vertical margins between adjacent block boxes in a block
   formatting context collapse.
   
   In a block formatting context, each box's left outer edge touches the
   left edge of the containing block (for right-to-left formatting, right
   edges touch).
   
   For information about page breaks in paged media, please consult the
   section on allowed page breaks.
   
  9.4.2 Inline formatting context
  
   In an inline formatting context, boxes are laid out horizontally, one
   after the other, beginning at the top of a containing block.
   Horizontal margins, borders, and padding are respected between these
   boxes. They may be aligned vertically in different ways: their bottoms
   or tops may be aligned, or the baselines of text within them may be
   aligned. The rectangular area that contains the boxes that form a line
   is called a line box. The margin between the first inline box in a
   line box and the near line box edge is respected; the same holds for
   the last inline box and the opposite line box edge.
   
   The width of a line box is determined by a containing block. The
   height of a line box is determined by the rules given in the section
   on line height calculations. A line box is always tall enough for all
   of the boxes it contains. However, it may be taller than the tallest
   box it contains (if, for example, boxes are aligned so that baselines
   line up). When the height of a box B is less than the height of the
   line box containing it, the vertical alignment of B within the line
   box is determined by the 'vertical-align' property.
   
   When several inline boxes cannot fit within a single line box, they
   are distributed among two or more vertically-stacked line boxes. Thus,
   a paragraph is a vertical stack of line boxes. Line boxes are stacked
   with no vertical separation and they never overlap.
   
   In left-to-right formatting, the left edge of a line box generally
   touches the left edge of its containing block (right edges touch in
   right-to-left formatting). However, floating boxes may come between
   the containing block edge and the line box edge. Thus, although line
   boxes in the same inline formatting context generally have the same
   width (that of the containing block), they may vary in width if
   available horizontal space is reduced due to floats. Line boxes in the
   same inline formatting context generally vary in height (e.g., one
   line might contain a tall image while the others contain only text).
   
   When the total width of the boxes on a line is less than the width of
   the line box containing them, their horizontal distribution within the
   line box is determined by the 'text-align' property. If that property
   has the value 'justify', the user agent may stretch the inline boxes
   as well.
   
   Since an inline box may not exceed the width of a line box, long
   inline boxes are split into several boxes and these boxes distributed
   across several line boxes. When an inline box is split, margins,
   borders, and padding have no visual effect where the split occurs.
   Rendering of margins, borders, and padding may not be fully defined if
   the split occurs within a bidirectional embedding.
   
   Inline boxes may also be split into several boxes within the same line
   box due to bidirectional text processing.
   
   Here is an example of inline box construction. The following paragraph
   (created by the HTML block-level element P) contains anonymous text
   interspersed with the elements EM and STRONG:

<P>Several <EM>emphasized words</EM> appear
<STRONG>in this</STRONG> sentence, dear.</P>

   The P element generates a block box that contains five inline boxes,
   three of which are anonymous:
   
     * Anonymous: "Several"
     * EM: "emphasized words"
     * Anonymous: "appear"
     * STRONG: "in this"
     * Anonymous: "sentence, dear."
       
   To format the paragraph, the user agent flows the five boxes into line
   boxes. Since the parent box in normal flow acts as the containing
   block for an inline box, the width of the P box determines the width
   of these line boxes. If the width of P is sufficient, all the inline
   boxes will fit into a single line box:

 Several emphasized words appear in this sentence, dear.

   If the boxes do not fit within a single line box, they will be split
   up and distributed across several line boxes. The previous paragraph
   might be split as follows:

Several emphasized words appear
in this sentence, dear.

   or like this:
Several emphasized
words appear in this
sentence, dear.

   In the previous example, the EM box was split into two EM boxes (call
   them "split1" and "split2"). Margins, borders, padding, or text
   decorations have no visible effect after split1 or before split2.
   
   Consider the following example:
<HTML>
  <HEAD>
    <TITLE>Example of inline flow on several lines</TITLE>
    <STYLE type="text/css">
      EM {
        padding: 2px;
        margin: 1em;
        border-width: medium;
        border-style: dashed;
        line-height: 2.4em;
      }
    </STYLE>
  </HEAD>
  <BODY>
    <P>Several <EM>emphasized words</EM> appear here.</P>
  </BODY>
</HTML>

   Depending on the width of the P, the boxes may be distributed as
   follows:
   
   Image illustrating the effect of line breaking on the display of
   margins, borders, and padding.
   
     * The margin is inserted before "emphasized" and after "words".
     * The padding is inserted before, above, and below "emphasized" and
       after, above, and below "words". A dashed border is rendered on
       three sides in each case.
       
   Note that with a small line height, the padding and borders around
   text in different lines may overlap.
   
  9.4.3 Relative positioning
  
   Once a box has been assigned a position according to the normal flow,
   it may be shifted relative to this position. This is called relative
   positioning. Offsetting a box in this way has no effect on the
   following box: it is positioned as if the preceding box were not
   offset and it is not repositioned after the offset is applied. This
   implies that relative positioning may cause boxes to overlap.
   
   Relatively positioned boxes keep their normal flow size, including
   line breaks and the space originally reserved for them. A relatively
   positioned box establishes a new containing block for descendant
   boxes.
   
   A relatively positioned box is generated when the 'position' property
   for an element has the value 'relative'. The offset is specified by
   the 'top', 'bottom', 'left', and 'right' properties.
   
   Dynamic movement of relatively positioned boxes can produce animation
   effects in scripting environments (see also the 'visibility'
   property). Relative positioning may also be used as a general form of
   superscripting and subscripting except that line height is not
   automatically adjusted to take the positioning into consideration. See
   the description of line height calculations for more information.
   
   Examples of relative positioning are provided in the section comparing
   normal, relative, floating, and absolute positioning.
   
9.5 Floats

   A float is a box that is shifted to the left or right on the current
   line. The most interesting characteristic of a floated box is that
   content may flow along its side (or be prohibited from doing so by the
   'clear' property). Content flows down the right side of a left-floated
   box and down the left side of a right-floated box. The following is an
   introduction to float positioning and content flow; the exact rules
   governing float behavior are given in the description of the 'float'
   property.
   
   A floated box must have an explicit width (assigned via the 'width'
   property, or its intrinsic width in the case of replaced elements). A
   floated box becomes a block box that is shifted to the left or right
   until its outer edge touches the containing block edge or the outer
   edge of another float. The top of the floated box is aligned with the
   top of the current line box (or bottom of the preceding block box if
   no line box exists). If there isn't enough horizontal room on the
   current line for the float, it is shifted downward, line by line,
   until a line has room for it.
   
   Since a float is not in the flow, non-positioned block boxes created
   before and after the float box flow vertically as if the float didn't
   exist. However, line boxes created next to the float are shortened to
   make room for the float. Any content in the current line before a
   floated box is reflowed in the first available line on the other side
   of the float.
   
   Several floats may be adjacent, and this model also applies to
   adjacent floats in the same line.
   
   The following rule floats all IMG boxes with class="icon" to the left
   (and sets the left margin to '0'):
   
IMG.icon {
  float: left;
  margin-left: 0;
}

   Consider the following HTML source and style sheet:
   

<HTML>
  <HEAD>
    <STYLE type="text/css">
      IMG { float: left }
      BODY, P, IMG { margin: 2em }
    </STYLE>
  </HEAD>
  <BODY>
    <P><IMG src=img.gif alt="This image will illustrate floats">
       Some sample text that has no other...
  </BODY>
</HTML>

   The IMG box is floated to the left. The content that follows is
   rendered to the right of the float, starting on the same line as the
   float. The line boxes to the right of the float are shortened due to
   the float's presence, but resume their "normal" width (that of the
   containing block established by the P element) after the float. This
   document might be formatted as:
   
   Image illustrating how floating boxes interact with margins.
   
   Rendering would have been exactly the same if the document had been:
  <BODY>
    <P>Some sample text
    <IMG src=img.gif alt="This image will illustrate floats">
             that has no other...
  </BODY>

   because the content to the left of the float is displaced by the float
   and reflowed down its right side.
   
   The margins of floating boxes never collapse with margins of adjacent
   boxes. Thus, in the previous example, vertical margins do not collapse
   between the P box and the floated IMG box.
   
   A float can overlap other boxes in the normal flow (e.g., when a
   normal flow box next to a float has negative margins). When an inline
   box overlaps with a float, it is rendered in front of the float. When
   a block box overlaps, the background and borders of the block box are
   "clipped" by the non-transparent parts of the float, but the content
   is rendered in front of the float.
   
   Here is another illustration, showing what happens when a float
   overlaps borders of elements in the normal flow.
   
   Image showing a floating image that overlaps the borders of two
   paragraphs: the borders are interrupted by the image.
   
   The floating image is larger than the block that it is a child of, so
   it interrupts the border of the block, and also the border of the next
   block. Borders are "clipped" by floats".
   
   The following example illustrates the use of the 'clear' property to
   prevent content from flowing next to a float.
   
   This style rule means that no H1 element may have a floating element
   to its left; this means that H1 elements will be positioned below any
   left floating box.

H1 { clear: left }

   Here is an example illustrating the effect of 'clear: left' on two
   paragraphs. Assuming a rule such as this:

P {clear: left }

   a rendering might look like this:
   
   Image showing a floating image and the effect of 'clear: left' on the
   two paragraphs.
   
   Both paragraphs have set 'clear: left', which causes the second
   paragraph to be "pushed down" to a position below the float.
   
  9.5.1 Positioning the float: the 'float' property
  
   'float'
          Value:   left | right | none | inherit
          Initial:   none
          Applies to:   elements that are not positioned absolutely
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   This property specifies whether a box should float to the left, right,
   or not at all. It may be set for elements that generate boxes that are
   not positioned absolutely (i.e., not 'absolute' or 'fixed'). The
   values of this property have the following meanings:
   
   left
          The element generates a block box that is floated to the left.
          Content flows on the right side of the box, starting at the top
          (subject to the 'clear' property). The 'display' is ignored,
          unless it has the value 'none'.
          
   right
          Same as 'left', but content flows on the left side of the box,
          starting at the top.
          
   none
          Has no effect on the generated box.
          
   Here are the precise rules that govern the behavior of floats:
   
    1. The left outer edge of a left-floating box may not be to the left
       of the left edge of its containing block. An analogous rule holds
       for right-floating elements.
    2. If the current box is left-floating, and there are any left
       floating boxes generated by elements earlier in the source
       document, then for each such earlier box, either the left outer
       edge of the current box must be to the right of the right outer
       edge of the earlier box, or its top must be lower than the bottom
       of the earlier box. Analogous rules hold for right-floating boxes.
    3. The right outer edge of a left-floating box may not be to the
       right of the left outer edge of any right-floating box that is to
       the right of it. Analogous rules hold for right-floating elements.
    4. A floating box's outer top may not be higher than the top of its
       containing block.
    5. The outer top of a floating box may not be higher than the outer
       top of any block or floated box generated by an element earlier in
       the source document.
    6. The outer top of an element's floating box may not be higher than
       the top of any line-box containing a box generated by an element
       earlier in the source document.
    7. A floating box must be placed as high as possible.
    8. A left-floating box must be put as far to the left as possible, a
       right-floating box as far to the right as possible. A higher
       position is preferred over one that is further to the left/right.
       
  9.5.2 Controlling flow next to floats: the 'clear' property
  
   'clear'
          Value:   none | left | right | both | inherit
          Initial:   none
          Applies to:   block-level elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   This property indicates which sides of an element's box(es) may not be
   adjacent to an earlier floating box. (It may be that the element
   itself has floating descendants; the 'clear' property has no effect on
   those.)
   
   This property may only be specified for block-level elements
   (including floats). For compact and run-in boxes, this property
   applies to the final block box to which the compact or run-in box
   belongs.
   
   Values have the following meanings when applied to non-floating block
   boxes:
   
   left
          The top margin of the generated box is increased enough that
          the top border edge is below the bottom outer edge of any left
          floating boxes that resulted from elements earlier in the
          source document.
          
   right
          Same as left, but with respect to right floating boxes.
          
   both
          The generated box is moved below all floating boxes of earlier
          elements in the source document..
          
   none
          No constraint on the box's position with respect to floats.
          
   When the property is set on floating elements, it results in a
   modification of the rules for positioning the float. An extra
   constraint (#9) is added:
     * The top outer edge of the float must be below the bottom outer
       edge of all earlier left floating boxes (in the case of 'clear:
       left'), or all earlier right floating boxes (in the case of
       'clear: right'), or both ('clear: both').
       
9.6 Absolute positioning

   In the absolute positioning model, a box is assigned explicit
   coordinates with respect to its containing block. It is removed from
   the normal flow entirely (it has no impact on later siblings). Like
   other boxes, an absolutely positioned box establishes a new containing
   block for descendant boxes. However, the contents of an absolutely
   positioned element do not flow around any other boxes. They may or may
   not obscure the contents of another box, depending on the stack levels
   of the overlapping boxes.
   
  9.6.1 Fixed positioning
  
   Fixed positioning is a variant of absolute positioning. The only
   difference is that for a fixed positioned box, the containing block is
   established by the viewport. For continuous media, fixed boxes do not
   move when the document is scrolled. In this respect, they are similar
   to fixed background images. For paged media, boxes with fixed
   positions are repeated on every page. This is useful for placing, for
   instance, a signature at the bottom of each page.
   
   Authors may use fixed positioning to create frame-like presentations.
   Consider the following frame layout:
   
   Image illustrating a frame-like layout with position='fixed'.
   
   This might be achieved with the following HTML document and style
   rules:
   
<HTML>
  <HEAD>
    <TITLE>A frame document with CSS2</TITLE>
    <STYLE type="text/css">
      #header {
        position: fixed;
        width: 100%;
        height: 15%;
        top: 0;
        right: 0;
        bottom: auto;
        left: 0;
      }
      #sidebar {
        position: fixed;
        width: 10em;
        height: auto;
        top: 15%;
        right: auto;
        bottom: 100px;
        left: 0;
      }
      #main {
        position: fixed;
        width: auto;
        height: auto;
        top: 15%;
        right: 0;
        bottom: 100px;
        left: 10em;
      }
      #footer {
        position: fixed;
        width: 100%;
        height: 100px;
        top: auto;
        right: 0;
        bottom: 0;
        left: 0;
      }
    </STYLE>
  </HEAD>
  <BODY>
    <DIV id="header"> ...  </DIV>
    <DIV id="sidebar"> ...  </DIV>
    <DIV id="main"> ...  </DIV>
    <DIV id="footer"> ...  </DIV>
  </BODY>
</HTML>

9.7 Relationships between 'display', 'position', and 'float'

   When specified for the same elements, the three properties that affect
   box generation and layout -- 'display', 'position', and 'float' --
   interact according to the following precedences (highest to lowest):
   
    1. If 'display' has the value 'none', user agents must ignore
       'position' and 'float'. In this case, the element generates no
       box.
    2. Otherwise, if 'position' has the value 'absolute' or 'fixed', the
       generated box will be non-floating and block. The position of the
       box will be determined by the 'top', 'right', 'bottom' and 'left'
       properties and the box's containing block.
    3. Otherwise, if 'float' has a value other than 'none', the generated
       box is a block box and is floated.
    4. Otherwise, the remaining 'display' properties apply as specified.
       
   Note. CSS2 does not specify layout behavior when values for these
   properties are changed by scripts. For example, what happens when an
   element having 'width: auto' is repositioned? Do the contents reflow,
   or do they maintain their original formatting? The answer is outside
   the scope of this document, and such behavior is likely to differ in
   initial implementations of CSS2. 
   
9.8 Comparison of normal flow, floats, and absolute positioning

   To illustrate the relationship between normal flow, relative
   positioning, floats, and absolute positioning, we provide a series of
   examples based on the following HTML fragment:

<HTML>
  <HEAD>
    <TITLE>Comparison of positioning schemes</TITLE>
  </HEAD>
  <BODY>
    <P>Beginning of body contents.
      <SPAN id="outer"> Start of outer contents.
      <SPAN id="inner"> Inner contents.</SPAN>
      End of outer contents.</SPAN>
      End of body contents.
    </P>
  </BODY>
</HTML>

   The final positions of boxes generated by the outer and inner elements
   vary in each example. In each illustration, the numbers to the left of
   the illustration indicate the normal flow position of the
   double-spaced (for clarity) lines. (Note: the illustrations use
   different horizontal and vertical scales.)
   
  9.8.1 Normal flow
  
   Consider the following CSS declarations for outer and inner that don't
   alter the normal flow of boxes:
   
#outer { color: red }
#inner { color: blue }

   This results in something like the following:
   
   Image illustrating the normal flow of text between parent and sibling
   boxes.
   
  9.8.2 Relative positioning
  
   To see the effect of relative positioning, consider the following CSS
   rules:

BODY { line-height: 200% }
#outer { position: relative; top: -12px; color: red }
#inner { position: relative; top: 12px; color: blue }

   First, the outer text is flowed into its normal flow position and
   dimensions at the end of line 1. Then, the inline boxes containing the
   text (distributed over three lines) are shifted as a unit upwards by
   12px.
   
   The contents of inner, as a child of outer, would normally flow
   immediately after the words "of outer contents" (on line 1.5).
   However, the inner contents are themselves offset relative to the
   outer contents by 12px downwards, back to their original position on
   line 2.
   
   Note that the content following outer is not affected by the relative
   positioning of outer.
   
   Image illustrating the effects of relative positioning on a box's
   content.
   
   Note also that if the relative positioning of outer were -24px, the
   text of outer and the body text would have overlapped.
   
  9.8.3 Floating a box
  
   Now consider the effect of floating the inner element's text to the
   right by means of the following rules:

#outer { color: red }
#inner { float: right; width: 130px; text-align: top; color: blue }

   First, the inner box (whose width has been set explicitly) is floated
   to the right margin. Then, the text of the outer element that follows
   the inner element text flows in the space vacated by the inner box.
   This flow respects the new right margin established by the left border
   of the inner box.
   
   Image illustrating the effects of floating a box.
   
   To show the effect of the 'clear' property, we add a sibling element
   to the example:

<HTML>
  <HEAD>
    <TITLE>Comparison of positioning schemes II</TITLE>
  </HEAD>
  <BODY>
    <P>Beginning of body contents.
      <SPAN id=outer> Start of outer contents.
      <SPAN id=inner> Inner contents.</SPAN>
      <SPAN id=sibling> Sibling contents.</SPAN>
      End of outer contents.</SPAN>
      End of body contents.
    </P>
  </BODY>
</HTML>

   The following rules:
  #inner { float: right; width: 130px;
           text-align: top; color: blue }
  #sibling { color: red }

   cause the inner box to float to the right and the text of the sibling
   element to flow in the vacated space:
   
   Image illustrating the effects of floating a box without setting the
   clear property to control the flow of text around the box.
   
   However, if the 'clear' property on the sibling element is set to
   'right' (i.e., the generated sibling box will not accept being
   positioned next to floating boxes to its right), the sibling box is
   moved below the float:

  #inner { float: right; width: 130px;
           text-align: top; color: blue }
  #sibling { clear: right; color: red }

   Image illustrating the effects of floating an element with setting the
   clear property to control the flow of text around the element.
   
  9.8.4 Absolute positioning
  
   Finally, we consider the effect of absolute positioning. Consider the
   following CSS declarations for outer and inner:
   
  #outer {
    position: absolute;
    top: 200px;
    left: 200px;
    width: 200px;
    color: red;
  }
  #inner { color: blue }

   which cause the top of the outer box to be positioned with respect to
   the containing block (which we suppose is established by the initial
   containing block). The top side of the outer box is 200px from the top
   of the containing block and the left side is 200px from the left side.
   The child box of outer is flowed normally with respect to its parent.
   
   Image illustrating the effects of absolutely positioning a box.
   
   Note that because outer has been absolutely positioned, it establishes
   a new containing block for descendant boxes.
   
   The following example shows an absolutely positioned box that is a
   child of a relatively positioned box. Although the parent outer box is
   not actually offset, setting its 'position' property to 'relative'
   causes its box to serve as the containing block for any descendant
   boxes. Since the outer box is an inline box that is split across
   several lines, only the first box (whose upper left-hand corner is
   designated by a "@" in the illustration below) establishes the
   containing block for the descendants.

  #outer {
    position: relative;
    color: red
  }
  #inner {
    position: absolute;
    top: 200px;
    left: -100px;
    height: 130px;
    width: 130px;
    color: blue;
  }

   This results in something like the following:
   
   Image illustrating the effects of absolutely positioning a box with
   respect to a containing block.
   
   The following rules don't establish a new positioning context for
   inner:

  #outer { color: red }
  #inner {
    position: absolute;
    top: 200px;
    left: -100px;
    height: 130px;
    width: 130px;
    color: blue;
  }

   but cause the inner box to be positioned with respect to the
   containing block (which we assume here is initial containing block).
   
   Image illustrating the effects of absolutely positioning a box with
   respect to a coordinate system established by a normally positioned
   parent.
   
   Relative and absolute positioning may be used to implement change
   bars, as shown in the following example. We use a value of 'auto' for
   the 'top' property, which results in the box being placed at the
   "current" location, just as if the box were being flowed into that
   space. The following HTML text:
   
<P style="position: relative; margin-right: 10px; left: 10px;">
I used two red hyphens to serve as a change bar. They
will "float" to the left of the line containing THIS
<SPAN style="position: absolute; top: auto; left: 0px; color: red;">--</SPAN>
word.</P>

   might result in something like:
   
   Image illustrating the use of floats to create a changebar effect.
   
9.9 Layered presentation

   In the following sections, the expression "in front of" means closer
   to the user as the user faces the screen.
   
   In CSS2, each box has a position in three dimensions. In addition to
   their horizontal and vertical positions, boxes lie along a "z-axis"
   and are rendered one on top of the other. Z-axis positions are
   particularly relevant when boxes overlap visually. This section
   discusses how boxes may be positioned along the z-axis.
   
   Each box belongs to one stacking context. Each box in a given stacking
   context has an integer stack level, which is its position on the
   z-axis relative to other boxes in the same stacking context. Boxes
   with greater stack levels are always rendered in front of boxes with
   lower stack levels. Boxes may have negative stack levels. Boxes with
   the same stack level in a stacking context are stacked bottom-to-top
   according to document tree order.
   
   The root element creates a root stacking context, but other elements
   may establish local stacking contexts. Stacking contexts are
   inherited. A local stacking context is atomic; boxes in other stacking
   contexts may not come between any of its boxes.
   
   An element that establishes a local stacking context generates a box
   that has two stack levels: one for the stacking context it creates
   (always '0') and one for the stacking context to which it belongs
   (given by the 'z-index' property).
   
   An element's box has the same stack level as its parent's box unless
   given a different stack level with the 'z-index' property.
   
  9.9.1 Specifying the stack level: the 'z-index' property
  
   'z-index'
          Value:   auto | <integer> | inherit
          Initial:   auto
          Applies to:   elements that generate absolutely and relatively
          positioned boxes
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   For an absolutely or relatively positioned box, the 'z-index' property
   specifies:
    1. The stack level of the box in the current stacking context.
    2. Whether the box establishes a local stacking context.
       
   Values have the following meanings:
   
   <integer>
          This integer is the stack level of the generated box in the
          current stacking context. The box also establishes a local
          stacking context in which its stack level is '0'.
          
   auto
          The stack level of the generated box in the current stacking
          context is the same as its parent's box. The box does not
          establish a new local stacking context.
          
   In the following example, the stack levels of the boxes (named with
   their "id" attributes) are: "text2"=0, "image"=1, "text3"=2, and
   "text1"=3. The "text2" stack level is inherited from the root box. The
   others are specified with the 'z-index' property.

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<HTML>
  <HEAD>
    <TITLE>Z-order positioning</TITLE>
    <STYLE type="text/css">
      .pile {
        position: absolute;
        left: 2in;
        top: 2in;
        width: 3in;
        height: 3in;
      }
    </STYLE>
  </HEAD>
  <BODY>
    <P>
      <IMG id="image" class="pile"
           src="butterfly.gif" alt="A butterfly image"
           style="z-index: 1">

    <DIV id="text1" class="pile"
         style="z-index: 3">
      This text will overlay the butterfly image.
    </DIV>

    <DIV id="text2">
      This text will be beneath everything.
    </DIV>

    <DIV id="text3" class="pile"
         style="z-index: 2">
      This text will underlay text1, but overlay the butterfly image
    </DIV>
  </BODY>
</HTML>

   This example demonstrates the notion of transparency. The default
   behavior of a box is to allow boxes behind it to be visible through
   transparent areas in its content. In the example, each box
   transparently overlays the boxes below it. This behavior can be
   overridden by using one of the existing background properties.
   
9.10 Text direction: the 'direction' and 'unicode-bidi' properties

   The characters in certain scripts are written from right to left. In
   some languages, in particular those written with the Arabic or Hebrew
   script, and in some mixed-language contexts, text in a single
   (visually displayed) block can therefore appear with mixed
   directionality. This phenomenon is called bidirectionality, or "bidi"
   for short. For an introduction to bidirectionality issues, please
   consult the HTML 4.0 specification ([HTML40], section 8.2).
   
   The Unicode ([UNICODE]) specification assigns directionality to
   characters and defines a complex algorithm for determining the proper
   directionality of text. The 'direction' and 'unicode-bidi' properties
   allow authors to specify how the elements and attributes of a document
   language correspond to units of the Unicode bidi algorithm.
   
   Because the directionality of a text depends on the structure and
   semantics of the document language, these properties should in most
   cases be used only by designers of document type descriptions (DTDs),
   or authors of special documents. A typical exception would be to
   override bidi behavior in a user agent if that user agent
   transliterates Yiddish (usually written with Hebrew letters) to Latin
   letters at the user's request.
   
   If a document contains right-to-left characters, and if the user agent
   displays these characters (with appropriate glyphs, not arbitrary
   substitutes such as a question mark, a hex code, a black box, etc.),
   the user agent must apply the bidirectional algorithm. This seemingly
   one-sided requirement reflects the fact that, although not every
   Hebrew or Arabic document contains mixed-directionality text, such
   documents are much more likely to contain left-to-right text (e.g.,
   numbers, text from other languages) than are documents written in
   left-to-right languages.
   
   Conforming HTML user agents may ignore the 'direction' and
   'unicode-bidi' properties in author and user style sheets but must
   behave as if they used the style sheet fragment given below.
   
   'direction'
          Value:   ltr | rtl | inherit
          Initial:   ltr
          Applies to:   all elements, but see prose
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property specifies the direction of inline box flow, embedded
   text direction (see 'unicode-bidi'), table column layout, and content
   overflow.
   
   Values for this property have the following meanings:
   
   ltr
          Left-to-right direction.
          
   rtl
          Right-to-left direction.
          
   'unicode-bidi'
          Value:   normal | embed | bidi-override | inherit
          Initial:   normal
          Applies to:   all elements, but see prose
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   The writing direction of text within an inline box depends on two
   factors:
   
    1. The directionality of the characters, as specified in the Unicode
       specification ([UNICODE]).
    2. The value of the 'unicode-bidi' property (in conjunction with the
       value of the 'direction' property).
       
   User agents following the bidirectional algorithm will display
   characters in the correct writing direction automatically, except when
   elements with reversed writing direction are embedded more than one
   level deep. In such cases, authors must assist the user agent by
   signaling that an element opens a new level of embedding with respect
   to the bidirectional algorithm.
   
   Thus, values for 'unicode-bidi' have the following meanings:
   
   normal
          The element does not open an additional level of embedding with
          respect to the bidirectional algorithm. For inline-level
          elements, implicit reordering works across element boundaries.
          
   embed
          The element opens an additional level of embedding with respect
          to the bidirectional algorithm. The direction of this embedding
          level is given by the 'direction' property. Inside the element,
          reordering is done implicitly.
          
   bidi-override
          Like 'embed', the element opens an additional level of
          embedding with respect to the bidirectional algorithm and the
          direction of this embedding level is given by the 'direction'
          property. However, inside the element, reordering is strictly
          in sequence according to the 'direction' property; this value
          overrides the implicit bidirectional algorithm.
          
   For the 'direction' property to have any effect on inline-level
   elements, the 'unicode-bidi' property must have as value either
   'embed' or 'override'.
   
   If a default style sheet specifies values for 'unicode-bidi', authors
   and users should not specify rules to override them.
   
   The following example shows an XML document with bidirectional text.
   It illustrates an important design principle: DTD designers should
   take bidi into account both in the language proper (elements and
   attributes) and in any accompanying style sheets. The style sheets
   should be designed so that bidi rules are separate from other style
   rules. The bidi rules should not be overridden by other style sheets
   so that the document language's or DTD's bidi behavior is preserved.
   
   In this example, lowercase letters stand for inherently left-to-right
   characters and uppercase letters represent inherently right-to-left
   characters:

<HEBREW>
  <PAR>HEBREW1 HEBREW2 english3 HEBREW4 HEBREW5</PAR>
  <PAR>HEBREW6 <EMPH>HEBREW7</EMPH> HEBREW8</PAR>
</HEBREW>
<ENGLISH>
  <PAR>english9 english10 english11 HEBREW12 HEBREW13</PAR>
  <PAR>english14 english15 english16</PAR>
  <PAR>english17 <HE-QUO>HEBREW18 english19 HEBREW20</HE-QUO></PAR>
</ENGLISH>

   Since this is XML, the style sheet is responsible for setting the
   writing direction. This is the style sheet:
   
/* Rules for bidi */
HEBREW, HE-QUO  {direction: rtl; unicode-bidi: embed}
ENGLISH         {direction: ltr; unicode-bidi: embed}

/* Rules for presentation */
HEBREW, ENGLISH, PAR  {display: block}
EMPH                  {font-weight: bold}

   The HEBREW element is a block with a right-to-left base direction, the
   ENGLISH element is a block with a left-to-right base direction. The
   PARs are blocks that inherit the base direction from their parents.
   Thus, the first two PARs are read starting at the top right, the final
   three are read starting at the top left.
   
   The EMPH element is inline-level, and since its value for
   'unicode-bidi' is 'normal' (the initial value), it has no effect on
   the ordering of the text. The HE-QUO element, on the other hand,
   creates an embedding.
   
   The rendering of this text might look like this if the line length is
   long:

               5WERBEH 4WERBEH english3 2WERBEH 1WERBEH

                                8WERBEH 7WERBEH 6WERBEH

english9 english10 english11 13WERBEH 12WERBEH

english14 english15 english16

english17 20WERBEH english19 18WERBEH

   Note that the HE-QUO embedding causes HEBREW18 to be to the right of
   english19.
   
   If lines have to be broken, it might be more like this:
       2WERBEH 1WERBEH
  -EH 4WERBEH english3
                 5WERB

   -EH 7WERBEH 6WERBEH
                 8WERB

english9 english10 en-
glish11 12WERBEH
13WERBEH

english14 english15
english16

english17 18WERBEH
20WERBEH english19

   Because HEBREW18 must be read before english19, it is on the line
   above english19. Just breaking the long line from the earlier
   rendering would not have worked. Note also that the first syllable
   from english19 might have fit on the previous line, but hyphenation of
   left-to-right words in a right-to-left context, and vice versa, is
   usually suppressed to avoid having to display a hyphen in the middle
   of a line.
   
   Note that the default style sheet "states" that the HEBREW, HE-QUO,
   and ENGLISH elements all create embeddings. This bidi behavior should
   be preserved even if a user decides to change 'display: inline' for
   these elements. The rules that specify 'unicode-bidi: embed' achieve
   this as long as they are not overridden by user rules.
   
  9.10.1 Interaction between inline flow and text direction
  
   The 'direction' property determines the direction of several types of
   flow:
   
    1. When set for a block-level element, it specifies the base writing
       direction of inline text generated by the element. It also
       determines the position of an incomplete last line in a block in
       case of 'text-align: justify'.
    2. When set for an inline-level element, in coordination with a value
       of 'embed' or 'bidi-override' for the 'unicode-bidi' property, it
       specifies an additional embedding level.
    3. When set for a table element, it specifies the direction of table
       column layout. Note. The 'direction', when specified for table
       column elements, is not inherited by cells in the column since
       columns don't exist in the document tree. Thus, CSS cannot easily
       capture the "dir" attribute inheritance rules described in
       [HTML40], section 11.3.2.1.
    4. It specifies the direction of horizontal overflow.
       
   In order to ensure the proper application of the bidirectional
   algorithm, inline boxes (including anonymous inline boxes) must be
   constructed, split up if necessary, and flowed so that the final order
   of the characters on each line conforms to the Unicode bidirectional
   algorithm. This means that left-to-right character sequences and
   right-to-left character sequences can occur within an element's
   content, but inline boxes are constructed so that flow remains in one
   direction. Non-textual entities such as images are treated as neutral
   characters, unless their 'unicode-bidi' property has a value other
   than 'normal', in which case they are treated as strong characters in
   the 'direction' specified for the element.
   
   For instance, suppose that in the middle of a paragraph of Hebrew
   (right-to-left) text, we embed an English quotation:
   
<P lang="he">WERBEH WERBEH WERBEH WERBEH WERBEH
WERBEH WERBEH WERBEH WERBEH WERBEH
WERBEH WERBEH WERBEH <SPAN lang="en">English
quote here</SPAN> WERBEH WERBEH</>

   The right-to-left flow of Hebrew text stops at the asterisk (*) in the
   following diagram:
   

WERBEH WERBEH WERBEH WERBEH WERBEH
WERBEH WERBEH WERBEH WERBEH WERBEH
             *WERBEH WERBEH WERBEH

   While inline flow continues right-to-left after the asterisk, the
   English text is laid out left-to-right. Thus, successive letters will
   fill in the available space as follows:
   
            E *WERBEH WERBEH WERBEH
           En *WERBEH WERBEH WERBEH
          Eng *WERBEH WERBEH WERBEH
         Engl *WERBEH WERBEH WERBEH
        Engli *WERBEH WERBEH WERBEH
       Englis *WERBEH WERBEH WERBEH

   Etc., onto the following line:
   
English quote *WERBEH WERBEH WERBEH
                                  h

English quote *WERBEH WERBEH WERBEH
                                 he

English quote *WERBEH WERBEH WERBEH
                                her

English quote *WERBEH WERBEH WERBEH
                               here

   Hebrew text continues to flow right-to-left at the end of the English
   text.
   
  9.10.2 Bidirectionality in HTML 4.0
  
   In order to preserve the expected behavior of HTML 4.0 elements, their
   bidirectionality must be preserved however they are rendered. For
   example, people expect paragraphs to behave like a block with respect
   to bidirectionality, so even if a paragraph is displayed as an
   'inline' element, it must introduce a new level of bidi embedding.
   
   The following rules capture the remaining bidi semantics of HTML 4.0:
   
  BDO[DIR="ltr"]  { direction: ltr; unicode-bidi: bidi-override }
  BDO[DIR="rtl"]  { direction: rtl; unicode-bidi: bidi-override }

  *[DIR="ltr"]    { direction: ltr; unicode-bidi: embed }
  *[DIR="rtl"]    { direction: rtl; unicode-bidi: embed }

  /* Block-level elements */
  ADDRESS, BLOCKQUOTE, BODY, DD, DIV, DL, DT, FIELDSET,
  FORM, FRAME, FRAMESET, H1, H2, H3, H4, H5, H6, IFRAME,
  NOSCRIPT, NOFRAMES, OBJECT, OL, P, UL, APPLET, CENTER,
  DIR, HR, MENU, PRE, LI, TABLE, TR, THEAD, TBODY, TFOOT,
  COL, COLGROUP, TD, TH, CAPTION
                  { unicode-bidi: embed }
     _________________________________________________________________
     _________________________________________________________________
   
                     10 Visual rendering model details
                                      
   Contents
     * 10.1 Details of containing block calculation
     * 10.2 Calculation of box and line box widths
     * 10.3 Box width calculations
          + 10.3.1 Content width: the 'width' property
          + 10.3.2 Width of boxes in the normal flow and floated boxes
               o Determining the content width
               o Computing margin widths
          + 10.3.3 Width of absolutely positioned boxes
          + 10.3.4 Minimum and maximum widths: 'min-width' and
            'max-width'
     * 10.4 Box height calculations
          + 10.4.1 Content height: the 'height' property
          + 10.4.2 Determining the content height
          + 10.4.3 Height of absolutely positioned boxes
          + 10.4.4 Minimum and maximum heights: 'min-height' and
            'max-height'
     * 10.5 Line height calculations: the 'line-height' and
       'vertical-align' properties
          + 10.5.1 Leading and half-leading
       
10.1 Details of containing block calculation

   The containing block for a box other than the root box is determined
   as follows:
   
     * If the value of the 'position' property for the parent element is
       anything but 'static' then the containing block is established by
       the parent box.
     * Otherwise, if the value of the 'display' property for the parent
       element is anything but 'inline' then the containing block is
       established by the parent box.
     * Otherwise, the containing block is the parent's containing block.
       
   When a containing block is established by a block box, it has the same
   width, height, and position as the box's padding edge. The edges are
   called the top, bottom, left, and right of the containing block.
   
   When a containing block is established by an inline-level element, it
   has the same width, height, and position as the padding edge of the
   first (in the source tree) inline box generated by the inline-level
   element.
   
   Relatively positioned inline boxes must be considered specially since
   (1) the rendered content of an inline-level element may not be
   rectangular in shape but (2) a relatively positioned box establishes a
   new containing block and containing blocks must be rectangular. The
   reference edges for descendants are the following:
   
     * For left-to-right scripts, the left and top edges are those of the
       first inline box. The bottom and right edges are those of the last
       inline box.
     * For right-to-left scripts, the right and top edges are those of
       the first inline box. The bottom and left edges are those of the
       last inline box.
       
10.2 Calculation of box and line box widths

   Box and line box widths and heights may be established in one of
   several ways:
   
   Width and height properties set explicitly
          If 'width' or 'height' is set explicitly (i.e., not 'auto'),
          the box will have the specified width or height, except in
          tables, where a 'width' or 'height' is interpreted as a minimum
          size, or even ignored, depending on the table layout algorithm.
          The 'width' and 'height' properties do not apply to
          non-replaced inline elements.
          
   Block box widths are calculated top-down
          The width of a block box is given by the width of its
          containing block minus the box's margins, borders, and padding.
          
   Inline box widths are calculated bottom-up
          The width of an inline box is given by its rendered content.
          
   Block box heights are calculated bottom-up
          Block level boxes grow to the size of the boxes they contain
          (unless the 'height' property is set). Please consult the
          section on box height calculations for details.
          
   Inline box heights are given by the 'line-height' property
          Please consult the section on box height calculations for
          details.
          
   Line heights depend on inline box heights and alignment
          Please consult the section on line height calculations for
          details.
          
   Intrinsic dimension of replaced content
          The rendered content of a replaced element may have "intrinsic
          dimensions" that user agents use as the computed content width
          and height (e.g., the unscaled width and height of an included
          image). If the intrinsic dimensions are overridden, the
          replaced content is scaled by the user agent. When scaling an
          element with intrinsic dimensions, the aspect ratio is
          preserved if values for the 'width' and 'height' properties are
          set to 'auto'.
          
   Hybrid calculations
          The dimension of a table cell is determined by both the cell's
          contents and the surrounding available space.
          
   The sections below describe these calculations in detail.
   
10.3 Box width calculations

   As discussed in the section on box dimensions, the content width of a
   box is assigned explicitly (via the 'width' property), given
   "intrinsically" (for replaced elements), or calculated "top-down"
   (based on the width of the box's containing block).
   
   The following sections explain the exact computation of a box's
   width-related properties.
   
  10.3.1 Content width: the 'width' property
  
   'width'
          Value:   <length> | <percentage> | auto | inherit
          Initial:   auto
          Applies to:   all elements but non-replaced inline elements,
          table rows and row groups
          Inherited:   no
          Percentages:   refer to width of containing block
          Media:   visual
          
   This property specifies the content width of a block box. Values have
   the following meanings:
   
   <length>
          Specifies a fixed width.
          
   <percentage>
          Specifies a percentage width. The percentage is calculated with
          respect to width of the generated box's containing block.
          
   auto
          See the section on widths of boxes in the normal flow and
          floated boxes.
          
   Negative values for 'width' are illegal. User agents must ignore this
   property for elements with 'display' set to 'row' or 'row-span'.
   
   For example, the following rule fixes the width of paragraphs to 100
   pixels:
   
P { width: 100px }

  10.3.2 Width of boxes in the normal flow and floated boxes
  
   The 'width' property does not apply to non-replaced inline-level
   elements. These elements generate boxes that flow into line boxes. The
   width of line boxes is given by the their containing block, but may be
   shorted by the presence of floats.
   
   For other types of boxes in the normal flow and for floats, a box's
   margin, padding, border, and content width must equal the width of its
   containing block. These widths are specified with the following seven
   properties: 'margin-left', 'border-left', 'padding-left', 'width',
   'padding-right', 'border-right', and 'margin-right'. However, if the
   'border-style' for an element has the value 'none', the corresponding
   border widths will be '0'.
   
   Three of these properties ('margin-left', 'width', and 'margin-right')
   may take the value 'auto'. Their computed values are determined as
   follows.
   
    Determining the content width
    
   When the 'width' property has the value 'auto', user agents should
   assign it a computed value based on computed margin widths. In
   addition:
   
    1. For inline-level elements and those that generate floating boxes,
       the computed value of 'width' is '0'.
    2. For replaced elements, user agents should use the intrinsic width
       of the element's rendered content as the box's computed width.
       (Note that for other values of 'width', the replaced contents may
       be scaled).
    3. Minimum and maximum computed values for the 'width' property may
       be assigned with the 'min-width' and 'max-width' properties.
       
    Computing margin widths
    
   User agents should assign computed values for 'margin-left', 'width',
   and 'margin-right' as follows:
   
    1. If exactly one of 'margin-left', 'width' or 'margin-right' has the
       value 'auto', the computed value of that property is assigned so
       that the seven width properties add up to the width of the
       containing block.
    2. If none of the properties has the value 'auto', 'margin-right' is
       assigned a computed value so that the seven width properties add
       up to the width of the containing block.
    3. If more than one of the three has the value 'auto', and one of
       them is 'width', than the other two ('margin-left' and/or
       'margin-right') will be assigned the computed value '0' and
       'width' will be assigned a computed value so that the seven width
       properties add up to the width of the containing block.
    4. Otherwise, if both 'margin-left' and 'margin-right' have the value
       'auto', they will each be assigned a computed value that is half
       of the available horizontal space (this centers the box within its
       containing block).
       
  10.3.3 Width of absolutely positioned boxes
  
   The width of an absolutely positioned box may be computed in three
   ways:
    1. The element generating the box has a value other than 'auto' for
       the 'width' property.
    2. The element is a replaced element with an intrinsic width and
       'width' has the value 'auto'.
    3. The width is given by the difference between the 'left' and
       'right' offsets (minus padding, borders, and margins). When
       padding, border, and margin properties have the specified value
       'auto', the computed value is '0'.
       
   In cases one and two, for left-to-right formatting, values of 'left'
   and 'right' are computed as follows:
   
     * If both 'left' and 'right' have the value 'auto', 'left' is the
       offset between the left containing block edge and the box's left
       side as though it were in normal flow. Then 'right' is computed
       based on the known left offset and width.
     * If one property has a value other than 'auto', this known offset
       and the width are used to calculate the offset of the opposite
       side.
     * If both properties have a value other than 'auto', 'right' is
       treated as though it were 'auto'.
       
   In case three, for left-to-right formatting, values of 'left',
   'right', and 'width' are computed as follows:
   
     * If 'right' has the value 'auto', it is assigned the value '0'. The
       width is the (absolute) distance between the right containing
       block edge and the box's left edge. A value of 'auto' for 'left'
       means the left offset is calculated as though the box were in
       normal flow.
     * For other values of 'right', the width is the (absolute) distance
       between the right offset and the position of the box's left edge,
       calculated as before.
       
   For all of the above cases, analogous rules hold for right-to-left
   formatting, switching right and left.
   
  10.3.4 Minimum and maximum widths: 'min-width' and 'max-width'
  
   'min-width'
          Value:   <length> | <percentage> | inherit
          Initial:   0
          Applies to:   all
          Inherited:   no
          Percentages:   refer to width of containing block
          Media:   visual
          
   'max-width'
          Value:   <length> | <percentage> | inherit
          Initial:   100%
          Applies to:   all
          Inherited:   no
          Percentages:   refer to width of containing block
          Media:   visual
          
   These two properties allow authors to constrain box widths to a
   certain range. Values have the following meanings:
   
   <length>
          Specifies a fixed minimum or maximum computed width.
          
   <percentage>
          Specifies a percentage for determining the computed value. The
          percentage is calculated with respect to the width of the
          generated box's containing block.
          
   The following algorithm describes how the two properties influence the
   computed value of the 'width' property:
   
    1. the normal width is computed (without 'min-width' and
       'max-width').
    2. if the computed value of 'min-width' is greater than the value of
       'max-width', 'max-width' is set to the value of 'min-width'.
    3. if the computed width is greater than 'max-width', the computed
       value of 'width' is set to the value of 'max-width'.
    4. if the computed width is smaller than 'min-width', the computed
       value of 'width' is set to the value of 'min-width'.
       
   The user agent may define a non-negative minimum value for the 'width'
   property, which may vary from element to element and even depend on
   other properties. If 'width' goes below this limit, either because it
   was set explicitly, or because it was 'auto' and the rules below would
   make it too small, the user agent may use the minimum value as the
   computed value.
   
10.4 Box height calculations

   As discussed in the section on box dimensions, the content height of a
   box is assigned explicitly (via the 'height' property), given
   "intrinsically" (for replaced elements), or calculated as the minimal
   height necessary to include the vertical content of the element and
   that of all its flowed children. This is the height necessary before
   any relative offset of children.
   
   The following sections explain the exact computation of a box's
   height-related properties.
   
  10.4.1 Content height: the 'height' property
  
   'height'
          Value:   <length> | <percentage> | auto | inherit
          Initial:   auto
          Applies to:   all elements but non-replaced inline elements,
          table columns and column groups
          Inherited:   no
          Percentages:   see prose
          Media:   visual
          
   This property specifies a box's content height. Values have the
   following meanings:
   
   <length>
          Specifies a fixed height.
          
   <percentage>
          Specifies a percentage height. The percentage is calculated
          with respect to the width of the generated box's containing
          block.
          
   auto
          See the section on heights of boxes in the normal flow and
          floated boxes.
          
   Negative values for 'height' are illegal. User agents must ignore this
   property for elements with 'display' set to 'col' or 'column-span'.
   
   For example, the following rule fixes the height of paragraphs to 100
   pixels:
   
P { height: 100px }

   Paragraphs that require more than 100 pixels of height will overflow
   according to the 'overflow' property.
   
   The height may be enforced by the user interface (e.g., a scrollbar).
   
  10.4.2 Determining the content height
  
   When the 'height' property has the value 'auto', user agents should
   assign it a computed value based on the space required by the
   element's rendered content. In addition:
   
    1. For replaced elements, user agents should use the intrinsic height
       of the element's rendered content as the box's computed height.
       (Note that for other values of 'height', the replaced contents may
       be scaled).
    2. Minimum and maximum computed values for the 'height' property may
       be assigned with the 'min-height' and 'max-height' properties.
       
  10.4.3 Height of absolutely positioned boxes
  
   The height of an absolutely positioned box may be computed in three
   ways:
    1. The element generating the box has a value other than 'auto' for
       the 'height' property.
    2. The element is a replaced element with an intrinsic height and
       'height' has the value 'auto'.
    3. The height is given by the different between the 'top' and
       'bottom' offsets (minus padding, borders, and margins). When
       padding, border, and margin properties have the specified value
       'auto', the computed value is '0'. In this case, the height of the
       box's containing block must be known, otherwise the 'bottom' of
       the box cannot be specified and the height is undefined.
       
   In cases one and two, values of 'top' and 'bottom' are computed as
   follows:
   
     * If both 'top' and 'bottom' have the value 'auto', 'top' is the
       offset between the top containing block edge and the box's top
       side as though it were in normal flow. Then 'bottom' is computed
       based on the known top offset and height.
     * If one property has a value other than 'auto', this known offset
       and the height are used to calculate the offset of the opposite
       side.
     * If both properties have a value other than 'auto', 'bottom' is
       treated as though it were 'auto'.
       
   In case three, the values of 'top', 'bottom', and 'height' are
   computed as follows:
   
     * If 'bottom' has the value 'auto', it is assigned the value '0'.
       The height is the (absolute) distance between the bottom
       containing block edge and the box's top edge. A value of 'auto'
       for 'top' means the top offset is calculated as though the box
       were in normal flow.
     * For other values of 'bottom', the width is the (absolute) distance
       between the bottom offset and the position of the box's top edge,
       calculated as before.
       
  10.4.4 Minimum and maximum heights: 'min-height' and 'max-height'
  
   It is sometimes useful to constrain the height of elements to a
   certain range. Two properties offer this functionality:
   
   'min-height'
          Value:   <length> | <percentage> | inherit
          Initial:   0
          Applies to:   all
          Inherited:   no
          Percentages:   refer to height of containing block
          Media:   visual
          
   'max-height'
          Value:   <length> | <percentage> | inherit
          Initial:   100%
          Applies to:   all
          Inherited:   no
          Percentages:   refer to height of containing block
          Media:   visual
          
   These two properties allow authors to constrain box heights to a
   certain range. Values have the following meanings:
   
   <length>
          Specifies a fixed minimum or maximum computed height.
          
   <percentage>
          Specifies a percentage for determining the computed value. The
          percentage is calculated with respect to the generated box's
          containing block.
          
   The following algorithm describes how the two properties influence the
   computed value of the 'height' property:
   
    1. the normal height is computed (without 'min-height' and
       'max-height').
    2. if the value of 'min-height' is greater than the value of
       'max-height', 'max-height' is set to the value of 'min-height'
    3. if the calculated height is greater than 'max-height', the value
       of 'height' is set to 'max-height'.
    4. if the calculated height is smaller than 'min-height', the value
       of 'height' is set to 'min-height'.
       
10.5 Line height calculations: the 'line-height' and 'vertical-align'
properties

   As described in the section on inline formatting contexts, user agents
   flow inline boxes into a vertical stack of line boxes. The height of a
   line box is determined as follows:
   
    1. The height of each inline box in the line box is calculated. The
       height of an inline box is given by its 'line-height' property,
       unless it is generated by a replaced element, in which case the
       'height' property gives the height of the inline box.
    2. The inline boxes are aligned vertically according to their
       'vertical-align' property. If an element has the values 'top' or
       'bottom' for this property, only the height of the generated boxes
       affects the line box height calculation; the boxes cannot be
       aligned until the line box has been fully constructed.
    3. The line box height is the distance between the uppermost box top
       and the lowermost box bottom.
       
   Empty inline elements generate empty inline boxes, but these boxes
   still have margins, padding, borders and a line height, and thus
   influence these calculations just like elements with content.
   
   Note that if all the boxes in the line box are aligned along their
   bottoms, the line box will be exactly the height of the tallest box.
   If, however, the boxes are aligned along a common baseline, the line
   box top and bottom may not touch the top and bottom of the tallest
   box.
   
   Note that top and bottom margins, borders, and padding specified for
   inline-level elements do not enter into the calculation of line box
   heights but are visible (inside and outside line boxes).
   
  10.5.1 Leading and half-leading
  
   Since the height of an inline box may be different from the font size
   of text in the box (e.g., 'line-height' > 1em), there may be space
   above and below rendered glyphs. The difference between the font size
   and the (actual) value of 'line-height' is called the leading. Half
   the leading is called the half-leading.
   
   User agents center the glyph vertically in the box, adding
   half-leading on the top and bottom. For example, if a piece of text is
   '12pt' high and the 'line-height' value is '14pt', 2pts of extra space
   should be added: 1pt above and 1pt below the letters. (This applies to
   empty boxes as well, as if the empty box contained an infinitely
   narrow letter.)
   
   When the 'line-height' value is less than the font size, the final
   line box height will be less than the font size and the rendered
   glyphs will "bleed" outside the box. If such a box touches the edge of
   a line box, the rendered glyphs will also "bleed" into the adjacent
   line box.
   
   Although margins, borders, and padding do not enter into the line box
   height calculation, they are still rendered around inline boxes
   (except where boxes are split across lines). This means that if the
   height of a line box is shorter than the outer edges of the boxes it
   contains, backgrounds and colors may "bleed" into adjacent line boxes.
   However, in this case, some user agents may use the line box to "clip"
   the border and padding areas (i.e., not render them).
   
   'line-height'
          Value:   normal | <number> | <length> | <percentage> | inherit
          Initial:   normal
          Applies to:   all elements
          Inherited:   yes
          Percentages:   relative to the font size of the element itself
          Media:   visual
          
   If the property is set on a block-level element whose content is
   composed of inline-level elements, it specifies the minimal height of
   each inline box.
   
   If the property is set on an inline-level element, it specifies the
   exact height of each box generated by the element. (Except for inline
   replaced elements, where the height of the box is given by the
   'height' property.)
   
   Values for this property have the following meanings:
   
   normal
          Tells user agents to set the computed value to a "reasonable"
          value based on the font size of the element. The value has the
          same meaning as <number> We recommend a number between 1.0 to
          1.2.
          
   <length>
          The box height is set to this length. Negative values are
          illegal.
          
   <number>
          The computed value of the property is this number multiplied by
          the element's font size. Negative values are illegal. However,
          the number, not the actual value, is inherited.
          
   <percentage>
          The actual value of the property is this percentage multiplied
          by the element's font size. Negative values are illegal.
          
   Note that replaced elements have a 'font-size' and a 'line-height'
   property, even if they are not used directly to determine the height
   of the box. The 'font-size' is, however, used to define the 'em' and
   'ex' units, and the 'line-height' has a role in the 'vertical-align'
   property.
   
   The three rules in the example below have the same resultant line
   height:

DIV { line-height: 1.2; font-size: 10pt }     /* number */
DIV { line-height: 1.2em; font-size: 10pt }   /* length */
DIV { line-height: 120%; font-size: 10pt }    /* percentage */

   When an element contains text that is rendered in more than one font,
   user agents should determine the 'line-height' value according to the
   largest font size.
   
   Generally, when there is only one value of 'line-height' for all
   inline boxes in a paragraph (and no tall images), the above will
   ensure that baselines of successive lines are exactly 'line-height'
   apart. This is important when columns of text in different fonts have
   to be aligned, for example in a table.
   
   'vertical-align'
          Value:   baseline | sub | super | top | text-top | middle |
          bottom | text-bottom | <percentage> | <length> | inherit
          Initial:   baseline
          Applies to:   inline-level and table cell elements
          Inherited:   no
          Percentages:   refer to the 'line-height' of the element itself
          Media:   visual
          
   This property affects the vertical positioning inside a line box of
   the boxes generated by an inline-level element. The following values
   only have meaning with respect to a parent inline-level element, or to
   a parent block-level element, if that element generates anonymous
   inline boxes; they have no effect if no such parent exists
   
   Note. Values of this property have slightly different meanings in the
   context of tables. Please consult the section on vertical alignment of
   table context for details. 
   
   baseline
          Align the baseline of the box with the baseline of the parent
          box. If the box doesn't have a baseline, align the bottom of
          the box with the parent's baseline.
          
   middle
          Align the vertical midpoint of the box with the baseline of the
          parent box plus half the x-height of the parent.
          
   sub
          Lower the baseline of the box to the proper position for
          subscripts of the parent's box. (This value has no effect on
          the font size of the element's text.)
          
   super
          Raise the baseline of the box to the proper position for
          superscripts of the parent's box. (This value has no effect on
          the font size of the element's text.)
          
   text-top
          Align the top of the box with the top of the parent element's
          font.
          
   text-bottom
          Align the bottom of the box with the bottom of the parent
          element's font.
          
   <percentage> 
          Raise (positive value) or lower (negative value) the box by
          this distance (a percentage of the 'line-height' value). The
          value '0%' means the same as 'baseline'.
          
   <length> 
          Raise (positive value) or lower (negative value) the box by
          this distance. The value '0cm' means the same as 'baseline'.
          
   The remaining values refer to the line box in which the generated box
   appears:
   
   top
          Align the top of the box with the top of the line box.
          
   bottom
          Align the bottom of the box with the bottom of the line box.
     _________________________________________________________________
     _________________________________________________________________
   
                             11 Visual effects
                                      
   Contents
     * 11.1 Overflow and clipping
          + 11.1.1 Overflow: the 'overflow' property
          + 11.1.2 Clipping: the 'clip' property
     * 11.2 Visibility: the 'visibility' property
       
   The visual effects discussed in these sections do not alter layout,
   only presentation.
   
11.1 Overflow and clipping

   Generally, the contents of a block box are confined within the content
   edges of the box. In certain cases, a box may overflow, meaning its
   content lies partly or entirely outside of the block:
   
     * Content is too wide for the containing block. This may happen when
       an element's 'width' property has a value that causes the
       generated box (or inline boxes) to spill over sides of the
       containing block. An inline replaced element (e.g., an image) that
       has a large intrinsic width may also overflow.
     * An element's height exceeds an explicit height assigned to the
       containing block (i.e., the containing block's height is
       determined by the 'height' property, not by content height).
     * It is positioned absolutely.
     * It has negative margins.
       
   Whenever overflow occurs, the 'overflow' property specifies how a box
   is clipped. The 'clip' property specifies the size and shape of the
   clipping region. Specifying a small clipping region may cause clipping
   of otherwise visible contents.
   
  11.1.1 Overflow: the 'overflow' property
  
   'overflow'
          Value:   visible | hidden | scroll | auto | inherit
          Initial:   visible
          Applies to:   block-level and replaced elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   This property specifies whether the contents of a block-level element
   are clipped when they overflow the element's box. Values have the
   following meanings:
   
   visible
          This value indicates that nested boxes are not clipped, i.e.,
          they may be rendered outside the block box.
          
   hidden
          This value indicates that the boxes are clipped and that no
          scrolling mechanism should be provided to view the content
          outside the clipping region; users will not have access to
          clipped content. The size and shape of the clipping region is
          specified by the 'clip' property.
          
   scroll
          This value indicates that if the user agent supports a visible
          scrolling mechanism, that mechanism should be displayed for a
          box whether or not any of its content is clipped. This avoids
          any problem with scrollbars appearing and disappearing in a
          dynamic environment. When this value is specified and the
          target medium is 'print' or 'projection', overflowing content
          should be printed.
          
   auto
          The behavior of the 'auto' value is user agent-dependent, but
          should cause a scrolling mechanism to appear for overflowing
          boxes.
          
   Even if 'overflow' is set to 'visible', contents may be clipped to a
   UA's document window by the native operating environment.
   
   Consider the following example, of a block quotation (BLOCKQUOTE) that
   is too big for its containing block (established by a DIV). Here is
   the source document:
   
<DIV>
<BLOCKQUOTE>
I didn't like the play, but then I saw
it under adverse conditions - the curtain was up.
<DIV class="attributed-to">- Groucho Marx</DIV>
</BLOCKQUOTE>
</DIV>

   Here is the style sheet controlling the sizes and style of the
   generated boxes:

DIV { width : 100px; height: 100px;
      border: thin solid red
      }

BLOCKQUOTE   { width : 125px; height : 100px;
      position: absolute;
      top: 50px; left: 50px;
      border: thin dashed black
      }

DIV.attributed-to { text-align : right; }

   The initial value of 'overflow' is 'visible', so the BLOCKQUOTE would
   be formatted without clipping, something like this:
   
   Rendered overflow
   
   Setting 'overflow' to 'hidden' for the DIV element, on the other hand,
   causes the BLOCKQUOTE to be clipped by the containing block:
   
   Clipped overflow
   
   A value of 'scroll' would tell UAs that support a visible scrolling
   mechanism to display one so that users could access the clipped
   content.
   
  11.1.2 Clipping: the 'clip' property
  
   A clipping region defines what portion of an element's rendered
   content is visible. By default, the clipping region for an element has
   the dimensions of the containing block of its generated boxes.
   However, the clipping region may be modified by the 'clip' property.
   
   'clip'
          Value:   <shape> | auto | inherit
          Initial:   auto
          Applies to:   block-level and replaced elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   Values have the following meanings:
   
   auto
          The clipping region for boxes generated by this element is the
          same size as the boxes themselves.
          
   <shape>
          In CSS2, the only valid <shape> value is: rect (<top> <right>
          <bottom> <left>) where <top>, <bottom> <right>, and <left>
          specify offsets from the respective sides of the box.
          
          <top>, <right>, <bottom>, and <left> may either have a <length>
          value or 'auto'. Negative lengths are permitted. The value
          'auto' means that a given edge of the clipping region will be
          the same as the edge of the element's generated box. (I.e.,
          'auto' is the same as '0'.)
          
          When converted to pixel coordinates, the bottom-right corner is
          excluded from the clipping rectangle. This rule is necessary to
          permit the definition of zero-width or zero-height rectangles.
          
   If the clipping region exceeds the bounds of the UA's document window,
   contents may be clipped to that window by the native operating
   environment.
   
   The following two rules:
   
P { clip: rect(5px, 10px, 10px, 5px); }
P { clip: rect(5px, -5px, 10px, 5px); }

   will create the rectangular clipping regions delimited by the dotted
   line in the following illustrations:
   
   Two clipping regions
   
   Note. In CSS2, all clipping regions are rectangular. We anticipate
   future extensions to permit non-rectangular clipping. 
   
11.2 Visibility: the 'visibility' property

   'visibility'
          Value:   visible | hidden | collapse | inherit
          Initial:   inherit
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   The 'visibility' property specifies whether the boxes generated by an
   element are rendered. Invisible boxes still affect layout (set the
   'display' property to 'none' to suppress box generation altogether).
   Values have the following meanings:
   
   visible
          The generated box is visible.
          
   hidden
          The generated box is invisible, but still affects layout.
          
   collapse
          Please consult the section on dynamic row and column effects in
          tables. If used on elements other than rows or columns,
          'collapse' has the same meaning as 'hidden'.
          
   This property may be used in conjunction with scripts to create
   dynamic effects.
   
   In the following example, pressing either form button invokes a
   user-defined script function that causes the corresponding box to
   become visible and the other to be hidden. Since these boxes have the
   same size and position, the effect is that one replaces the other.

<HTML>
<HEAD>
<STYLE type="text/css">
<!--
   #container1 { position: absolute; top: 2in; left: 2in; width: 2in}
   #container2 { position: absolute; top: 2in; left: 2in; width: 2in;
                 visibility: hidden; }
-->
</STYLE>
</HEAD>
<BODY>
<P>Choose a suspect:</P>
<DIV id="container1">
   <IMG alt="Al Capone" width="100" height="100" src="suspect1.jpg">
   <P>Name: Al Capone</P>
   <P>Residence: Chicago</P>
</DIV>

<DIV id="container2">
   <IMG alt="Lucky Luciano" width="100" height="100" src="suspect2.jpg">
   <P>Name: Lucky Luciano</P>
   <P>Residence: New York</P>
</DIV>

<FORM method="post" action="http://www.suspect.org/process-bums">
   <P>
   <INPUT name="Capone" type="button" value="Capone" onclick='show("container1"
);hide("container2")'>
   <INPUT name="Luciano" type="button" value="Luciano" onclick='show("container
2");hide("container1")'>
</FORM>
</BODY>
</HTML>

   Note that the 'position' property of each DIV element has the value
   'relative'. A more visually appealing version of the above might be
   designed using overlapping absolutely positioned boxes.
     _________________________________________________________________
     _________________________________________________________________
   
                12 Generated content and automatic numbering
                                      
   Contents
     * 12.1 The :before and :after pseudo-elements
     * 12.2 The 'content' property
     * 12.3 Interaction of :before and :after with 'compact' and 'run-in'
       elements
     * 12.4 Quotation marks
          + 12.4.1 Specifying quotes with the 'quotes' property
          + 12.4.2 Inserting quotes with the 'content' property
     * 12.5 Automatic counters and numbering
          + 12.5.1 Nested counters and scope
          + 12.5.2 Counter styles
          + 12.5.3 Counters in elements with 'display: none'
     * 12.6 Markers
       
   In some cases, authors may want user agents to render content that
   does not come from the document tree. One familiar example of this is
   a numbered list; the author does not want to list the numbers
   explicitly, he or she wants the user agent to generate them
   automatically. Similarly, authors may want the user agent to insert
   the word "Figure" before the caption of a figure, or "Chapter 7"
   before the seventh chapter title. For audio or braille in particular,
   user agents should be able to insert these strings.
   
   In CSS2, content may be generated by several mechanisms:
   
     * The 'content' property, in conjunction with the :before and :after
       pseudo-elements.
     * The 'cue-before', 'cue-after' aural properties. When the aural
       properties are specified as well as the the 'content' property,
       content is rendered in the following order: :before, 'cue-before',
       ('pause-before'), the element's content, ('pause-after'),
       'cue-after', and :after.
     * Elements with a value of 'list-item' for the 'display' property.
       
   Below we describe the mechanisms associated with the 'content'
   property.
   
12.1 The :before and :after pseudo-elements

   Authors specify the style and location of generated content with the
   :before and :after pseudo-elements. The 'content' property, in
   conjunction with these pseudo-elements, specifies what is inserted. As
   their names indicate, the :before and :after pseudo-elements specify
   content before and after an element's document tree content.
   
   For example, the following rules insert the keyword "Note: " before
   the content of every P element whose "class" attribute has the value
   "note":
   
P.note:before { content: "Note: " }

   The rendering objects (e.g., boxes) generated by an element include
   generated content. So, for example, changing the above style sheet to:
   
P.note:before { content: "Note: ";
                border: solid green}

   would cause a solid green border to be rendered around the entire
   paragraph, including the initial string.
   
   The :before and :after pseudo-elements inherit any inheritable
   properties from the element in the document tree to which they are
   attached.
   
   For example, the following rules insert an open quote mark before
   every Q element. The color of the quote mark will be red, but the font
   will be the same as the font of the rest of the Q element:
   
Q:before {
  content: open-quote;
  color: red
}

   In a :before or :after pseudo-element declaration, non-inherited
   properties take their initial values.
   
   So, for example, because the initial value of the 'display' property
   is 'inline', the quote in the previous example is inserted as an
   inline box (i.e., on the same line as the element's initial text
   content). The next example explicitly sets the 'display' property to
   'block', so that the inserted text becomes a block:
   
BODY:after {
    content: "The End";
    display: block;
    margin-top: 2em;
    text-align: center;
}

   Note that an audio user agent would speak the words "The End" after
   rendering the rest of the BODY content.
   
   User agents must ignore the following properties with :before and
   :after pseudo-elements: 'position', 'float', list properties, and
   table properties.
   
   The :before and :after pseudo-elements elements allow values of the
   'display' property as follows:
     * If the subject of the selector is a block-level element, allowed
       values are 'none', 'inline', 'block', and 'marker'. If the value
       of the 'display' has any other value, the pseudo-element will
       behave as if the value were 'block'.
     * If the subject of the selector is an inline-level element, allowed
       values are 'none' and 'inline'. If the value of the 'display' has
       any other value, the pseudo-element will behave as if the value
       were 'inline'.
       
   Note. Other values may be permitted in future levels of CSS.
   
12.2 The 'content' property

   'content'
          Value:   [ <string> | <uri> | <counter> | attr(X) | open-quote
          | close-quote | no-open-quote | no-close-quote ]+ | inherit
          Initial:   empty string
          Applies to:   :before and :after pseudo-elements
          Inherited:   no
          Percentages:   N/A
          Media:   all
          
   This property is used with the :before and :after pseudo-elements to
   generate content in a document. The 'display' property controls
   whether the content is placed in an inline or block box.
   
   The values have the following meanings:
   
   <string>
          Text content.
          
   <uri>
          The value is a URI that designates an external resource. If a
          user agent cannot support the resource because of the media
          types it supports, it must ignore the resource. Note. CSS2
          offers no mechanism to change the size of the embedded object,
          or to provide a textual description, like the "alt" or
          "longdesc" attributes do for images in HTML. This may change in
          future levels of CSS.
          
   <counter>
          Counters may be specified with two different functions:
          'counter()' or 'counters()'. The former has two forms:
          'counter(name)' or 'counter(name, style)'. The generated text
          is the value of the named counter at this point in the
          rendering structure, in the indicated style ('decimal' by
          default). The latter also has two forms: 'counter(name,
          string)' or 'counter(name, string, style)'. The generated text
          is the value of all counters with the given name at this point
          in the rendering structure, separated by the specified string.
          The counters are rendered in the indicated style ('decimal' by
          default).
          
   open-quote and 'close-quote'
          Both of these values are replaced by the appropriate string
          from the 'quotes' property.
          
   no-open-quote and no-close-quote
          Inserts nothing (the empty string), but increments, resp.
          decrements the level of nesting for quotes.
          
   attr(X)
          This function returns the value of attribute X as a string. The
          string is not parsed by the CSS processor. If the current
          element doesn't have an attribute X, an empty string is
          returned. The case-sensitivity of attribute names depends on
          the document language.
          
   Authors should put 'content' declarations in @media rules when the
   content requires media consideration. For instance, literal text may
   be used for any media group, but images only apply to the visual,
   bitmap media groups, and sound files only apply to the aural media
   group.
   
   The following rule causes a sound file to be played at the end of a
   quotation (see the section on aural style sheets for additional
   mechanisms):
   
@media aural {
   BLOCKQUOTE:after {content: url(beautiful-music.wav)}
   }

   The next rule inserts the text of the HTML "alt" attribute before the
   image. If the image is not displayed, the reader will still see the
   "alt" text.

IMG:before {content: attr(alt)}

   Authors may include newlines in the generated content by writing the
   "\A" escape sequence in one of the strings after the 'content'
   property. This inserts a forced line break, similar to the BR element
   in HTML. See "Strings" and "Characters and case" for more information
   on the "\A" escape sequence.
   
   Example:
H1:before {
    display: block;
    text-align: center;
    content: "chapter\A hoofdstuk\A chapitre"
}

   Generated content does not alter the document tree. In particular, it
   is not fed back to the document language processor (e.g., for
   reparsing).
   
   Note. In future levels of CSS, the 'content' property may accept
   additional values, allowing it to vary the style of pieces of the
   generated content, but in CSS2, the content of the :before or :after
   pseudo-element all has the same style. 
   
12.3 Interaction of :before and :after with 'compact' and 'run-in' elements

   The following cases can occur:
   
    1. A 'run-in' or 'compact' element has a :before pseudo-element of
       type 'inline': the pseudo-element is taken into account when the
       size of the element is computed (for 'compact') and is rendered
       inside the same block box as the element.
    2. A 'run-in' or 'compact' element has an :after pseudo-element of
       type 'inline': ditto.
    3. A 'run-in' or 'compact' element has a :before pseudo-element of
       type 'block': the pseudo-element is rendered as a block above the
       element, and does not take part in the computation of the
       element's size (for 'compact').
    4. A 'run-in' or 'compact' element has an :after pseudo-element of
       type 'block': both the element and its :after pseudo-element are
       rendered as block boxes. The element is not rendered as an inline
       box in its own :after pseudo-element.
    5. The element following a 'run-in' or 'compact' element has a
       :before of type 'block': the decision how to render the
       'run-in'/'compact' element is made with respect to the block box
       resulting from the :before pseudo-element.
    6. The element following a 'run-in' or 'compact' element has an
       :before of type 'inline': the decision how to render the
       'run-in'/'compact' element depends on the type of the element to
       which the :before is attached.
       
   Here is an example of a 'run-in' header with an :after pseudo-element,
   followed by a paragraph with a :before pseudo-element. All
   pseudo-elements are inline (the default) in this example. When the
   style sheet:
   
H3 { display: run-in }
H3:after { content: ": " }
P:before { content: "... " }

   is applied to this source document:
   
<H3>Centaurs</H3>
<P>have hoofs
<P>have a tail

   The visual rendering will resemble:
   
Centaurs: ... have hoofs
... have a tail

12.4 Quotation marks

   In CSS2, authors may specify how user agents should render quotation
   marks in a style-sensitive and context-dependent manner. The 'quotes'
   property specifies pairs of quotation marks for each level of embedded
   quotation. The 'content' property gives access to those quotation
   marks and causes them to be inserted before and after a quotation.
   
  12.4.1 Specifying quotes with the 'quotes' property
  
   'quotes'
          Value:   [<string> <string>]+ | none | inherit
          Initial:   depends on user agent
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property specifies quotation marks for any number embedded
   quotations. Values have the following meanings:
   
   none
          The 'open-quote' and 'close-quote' values of the 'content'
          property produce no quotations marks.
          
   [<string>  <string>]+
          Values for the 'open-quote' and 'close-quote' values of the
          'content' property are taken from this list of pairs of
          quotation marks (opening and closing). The first (leftmost)
          pair represents the outermost level of quotation, the second
          pair the first level of embedding, etc. The user agent must
          apply the appropriate pair of quotation marks according to the
          level of embedding.
          
   For example, applying the following style sheet:
   
/* Specify pairs of quotes for two levels in two languages */
Q:lang(en) { quotes: '"' '"' "'" "'" }
Q:lang(no) { quotes: "«" "»" "'" "'" }

/* Insert quotes before and after Q element content */
Q :before { content : open-quote }
Q :after  { content : close-quote }

   to the following HTML fragment:
   
<HTML lang="en">
  <BODY>
    <P><Q>Quote me!</Q>
  </BODY>
</HTML>

   would allow a user agent to render:
   
"Quote me!"

   while this HTML fragment:
   
<HTML lang="no">
  <BODY>
    <P><Q>Han sa <Q>vet ikke</Q>!</Q>
  </BODY>
</HTML>

   would produce:
   
«Han sa 'vet ikke'!»

   Note. While the quotation marks specified by 'quotes' in the previous
   examples are conveniently located on computer keyboards, high quality
   typesetting would require different ISO 10646 characters. The
   following informative table lists some of the ISO 10646 quotation mark
   characters:
   
   Ascii approximation ISO 10646 code (hex) Description
   " 0022 QUOTATION MARK [the ASCII double quotation mark]
   ' 0027 APOSTROPHE [the ASCII single quotation mark]
   [2039 SINGLE LEFT-POINTING ANGLE QUOTATION MARK
   [>] 203A SINGLE RIGHT-POINTING ANGLE QUOTATION MARK
   « 00AB LEFT-POINTING DOUBLE ANGLE QUOTATION MARK
   » 00BB RIGHT-POINTING DOUBLE ANGLE QUOTATION MARK
   [`] 2018 LEFT SINGLE QUOTATION MARK [single high-6]
   ['] 2019 RIGHT SINGLE QUOTATION MARK [single high-9]
   [``] 201C LEFT DOUBLE QUOTATION MARK [double high-6]
   [''] 201D RIGHT DOUBLE QUOTATION MARK [double high-9]
   [,,] 201E DOUBLE LOW-9 QUOTATION MARK [double low-9]
   
  12.4.2 Inserting quotes with the 'content' property
  
   Quotation marks are inserted in appropriate places in a document with
   the 'open-quote' and 'close-quote' values of the 'content' property.
   Each occurrence of 'open-quote' or 'close-quote' is replaced by one of
   the strings from the value of 'quotes', based on the depth of nesting.
   
   'Open-quote' refers to the first of a pair of quotes, 'close-quote'
   refers to the second. Which pair of quotes is used depend on the
   nesting level of quotes: the number of occurrences of 'open-quote' in
   all generated text before the current occurrence, minus the number of
   occurrences of 'close-quote'. If the depth is 0, the first pair is
   used, if the depth is 1, the second pair is used, etc. If the depth is
   greater than the number of pairs, the last pair is repeated.
   
   Note that this quoting depth is independent of the nesting of the
   source document or the rendering structure.
   
   Some typographic styles require open quotation marks to be repeated
   before every paragraph of a quote spanning several paragraphs, but
   only the last paragraph ends with a closing quotation mark. In CSS,
   this can be achieved by inserting "phantom" closing quotes. The
   keyword 'no-close-quote' decrements the quoting level, but does not
   insert a quotation mark.
   
   The following style sheet puts opening quotation marks on every
   paragraph in a BLOCKQUOTE, and inserts a single closing quote at the
   end:

BLOCKQUOTE P:before { content: open-quote }
BLOCKQUOTE P:after { content: no-close-quote }
BLOCKQUOTE P.last:after { content: close-quote }

   This relies on the last paragraph being marked with a class "last",
   since there are no selectors that can match the last child of an
   element.
   
   For symmetry, there is also a 'no-open-quote' keyword, which inserts
   nothing, but increments the quotation depth by one.
   
   Note. If a quotation is in a different language than the surrounding
   text, it is customary to quote the text with the quote marks of the
   language of the surrounding text, not the language of the quotation
   itself. For example, French inside English:
   
     The device of the order of the garter is &#8220;Honi soit qui mal y
     pense.&#8221;
     
   English inside French:
   
     Il disait: « Il faut mettre l'action en &#8249; fast
     forward &#8250;.»
     
   A style sheet like the following will set the 'quotes' property so
   that 'open-quote' and 'close-quote' will work correctly on all
   elements. These rules are for documents that contain only English,
   French, or both. One rule is needed for every additional language.
   Note the use of the child combinator (">") to set quotes on elements
   based on the language of the surrounding text:
   
[LANG|=fr] > *  {quotes: "«" "»" "\2039" "\203A"}
[LANG|=en] > *  {quotes: "\201C" "\201D" "\2018" "\2019"}

   The quotation marks for English are shown here in a form that most
   people will be able to type. If you can type them directly, they will
   look like this:

[LANG|=fr] > * {quotes: "«" "»" "&#8249;" "&#8250;"}
[LANG|=en] > * {quotes: "&#8220;" "&#8221;" "&#8216;" "&#8217;"}

12.5 Automatic counters and numbering

   Automatic numbering in CSS2 is controlled with two properties,
   'counter-increment' and 'counter-reset'. The counters defined by these
   properties can be used to generate text for the 'content' property
   (see the counter() function).
   
   'counter-reset'
          Value:   [ <identifier> <integer>? ]+ | none | inherit
          Initial:   none
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   all
          
   'counter-increment'
          Value:   [ <identifier> <integer>? ]+ | none | inherit
          Initial:   none
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   all
          
   The 'counter-increment' property accepts one or more names of counters
   (identifiers), each one optionally followed by an integer. The integer
   indicates by how much the counter is incremented for every occurrence
   of the element. The default increment is 1. Zero and negative integers
   are allowed.
   
   The 'counter-reset' property also contains a list of one or more names
   of counters, each one optionally followed by an integer. The integer
   gives the value that the counter is set to on each occurrence of the
   element. The default is 0.
   
   If 'counter-increment' refers to a counter that is not in the scope
   (see below) of any 'counter-reset', the counter is assumed to have
   been reset to 0 by the root element.
   
   This example shows a way to number chapters and sections with "Chapter
   1", "1.1", "1.2", etc.

H1:before {
    content: "Chapter " counter(chapter) ". ";
    counter-increment: chapter;  /* Add 1 to chapter */
    counter-reset: section;      /* Set section to 0 */
}
H2:before {
    content: counter(chapter) "." counter(section) " ";
    counter-increment: section;
}

   If an element increments/resets a counter and also uses it (in the
   'content' property of its :before or :after pseudo-element), the
   counter is used after being incremented/reset.
   
   If an element both resets and increments a counter, the counter is
   reset first and then incremented.
   
   The 'counter-reset' property follows the cascading rules. Thus, due to
   cascading, the following stylesheet:
   
H1 {counter-reset: section -1}
H1 {counter-reset: imagenum 99}

   will only reset 'imagenum'. To reset both counters, they have to be
   specified together:
   
H1 {counter-reset: section -1 imagenum 99}

  12.5.1 Nested counters and scope
  
   Counters are "self-nesting", in the sense that re-using a counter in a
   child element automatically creates a new instance of the counter.
   This is important for situations like lists in HTML, where elements
   can be nested inside themselves to arbitrary depth. It would be
   impossible to define uniquely named counters for each level.
   
   Thus the following suffices to number nested list items. The result is
   very similar to that of setting 'display:list-item' and 'list-style:
   inside' on the LI element:

OL {counter-reset: item}
LI {display: block}
LI:before {content: counter(item) ". "; counter-increment: item}

   The self-nesting is based on the principle that every element that has
   a 'counter-reset' for a counter X, creates a fresh counter X, the
   scope of which is the element, its younger siblings, and all the
   descendants of the element and its younger siblings.
   
   In the example above, an OL will create a counter, and all children of
   the OL will refer to that counter.
   
   If we denote by item[n] the nth counter, and by "(" and ")" the
   beginning and end of a scope, then the following HTML fragment will
   use the indicated counters. (We assume the style sheet as given in the
   example above).

<OL>               <!-- (set item[0] to 0          -->
  <LI>item         <!--  increment item[0] (= 1)   -->
  <LI>item         <!--  increment item[0] (= 2)   -->
    <OL>           <!--  (set item[1] to 0         -->
      <LI>item     <!--   increment item[1] (= 1)  -->
      <LI>item     <!--   increment item[1] (= 2)  -->
      <LI>item     <!--   increment item[1] (= 3)  -->
        <OL>       <!--   (set item[2] to 0        -->
          <LI>item <!--    increment item[2] (= 1) -->
        </OL>      <!--   )                        -->
        <OL>       <!--   (set item[3] to 0        -->
          <LI>     <!--    increment item[3] (= 1) -->
        </OL>      <!--   )                        -->
      <LI>item     <!--   increment item[1] (= 4)  -->
    </OL>          <!--  )                         -->
  <LI>item         <!--  increment item[0] (= 3)   -->
  <LI>item         <!--  increment item[0] (= 4)   -->
</OL>              <!-- )                          -->
<OL>               <!-- (reset item[4] to 0        -->
  <LI>item         <!--  increment item[4] (= 1)   -->
  <LI>item         <!--  increment item[4] (= 2)   -->
</OL>              <!-- )                          -->

   The 'counters()' function generates a string composed of all counters
   with the same name, separated by a given string.
   
   The following style sheet numbers nested list items as "1", "1.1",
   "1.1.1", etc.

OL {counter-reset: item}
LI {display: block}
LI:before {content: counters(item, "."); counter-increment: item}

  12.5.2 Counter styles
  
   By default, counters are rendered with decimal numbers, but all the
   styles available for the 'list-style-type' property are also available
   for counters. The notation is:
   
counter(name)

   for the default, decimal style, or:
   
counter(name, 'list-style-type')

   All the styles are allowed, including 'disc', 'circle', 'square', and
   'none'.
   
   Examples:
H1:before { content: counter(chno, upper-latin) ". " }
H2:before { content: counter(section, upper-roman) " - " }
BLOCKQUOTE:after { content: " [" counter(bq, hebrew) "]" }
DIV.note:before { content: counter(notecntr, disc) " " }
P:before { content: counter(p, none) }

  12.5.3 Counters in elements with 'display: none'
  
   An element that is not displayed ('display' set to 'none') cannot
   increment or reset a counter.
   
   For example, with the following style sheet, H2s with class "secret"
   do not increment 'count2'.

H2.secret {counter-increment: count2; display: none}

   Elements with 'visibility' set to 'hidden', on the other hand, do
   increment counters.
   
12.6 Markers

   There are very few situations in CSS2 where an element causes the
   generation of more than one box. The most common case occurs for
   elements with 'display: list-item' (see the section on lists). The two
   generated boxes are the principal box (the list item content) and the
   list item marker (to the side of the principal box). Authors have very
   limited control of the style or position of the list item marker
   through the list style properties.
   
   Markers are used together with the :before and :after pseudo-elements
   to offer similar functionality, but give authors more control over the
   position of the generated content. Markers may be used with automatic
   counters to create a wider variety of list styles than available with
   the list properties. They may also be used to create numbered margin
   notes, etc.
   
   An element may generate two marker boxes: one for :before content and
   one for :after content, in addition to one principal box (that of the
   element's content). Marker boxes must only contain one line of content
   (i.e., one line box), so they are not as flexible as floats, which may
   be used to align entire blocks horizontally.
   
   Marker boxes have padding and borders, but no margins.
   
   To create a marker box for :before or :after content, the 'display'
   property must be given the value 'marker'. The marker box is only
   created if the 'content' property for the pseudo-element actually
   generates content. The content will be formatted as a single line.
   
   For the :before pseudo-element, the baseline of text in the marker box
   will be vertically aligned with the baseline of text in the first line
   of content in the principal box. If the principal box contains no
   text, the top outer edge of the marker box will be aligned with the
   top outer edge of the principal box. For the :after pseudo-element,
   the baseline of text in the marker box will be vertically aligned with
   the baseline of text in the last line of content in the principal box.
   If the principal box contains no text, the bottom outer edge of the
   marker box will be aligned with the bottom outer edge of the principal
   box.
   
   The vertical alignment of content within the marker box may be
   specified with the 'vertical-align' property.
   
   The height of the :before marker and of the first line box of the
   principal box is computed as if they were a single line box.
   Analogously for the :after marker and the last line box. The
   'line-height' property sets the height of the marker box.
   
   The width of a marker box defaults to the natural width of its
   content, but may be specified with the 'width' property. If the width
   of a marker box's content is greater than the specified width, the
   'overflow' property specifies overflow behavior. Marker boxes may
   overlap principal boxes.
   
   If the 'width' is not 'auto', and is larger than the natural width,
   the 'text-align' property determines the horizontal alignment of the
   content in the marker box.
   
   The 'marker-offset' property specifies the horizontal offset between a
   marker box and the associated principal box. The distance is measured
   between their nearest border edges.
   
   When the 'display' property has the value 'marker' for content
   generated by an element with 'display: list-item', a marker box
   generated for ':before' replaces the normal list item marker.
   
   The following example illustrates how markers may be used to add
   periods after each numbered list item. This HTML program and style
   sheet:
   
<HTML>
   <HEAD>
     <STYLE type="text/css">
          LI:before {
              display: marker;
              content: counter(mycounter, lower-roman) ".";
              counter-increment: mycounter;
          }
     </STYLE>
  </HEAD>
  <BODY>
    <OL>
      <LI> This is the first item.
      <LI> This is the second item.
      <LI> This is the third item.
    </OL>
  </BODY>
</HTML>

   should produce something like this:
   
   i. This is the first item.
  ii. This is the second item.
 iii. This is the third item.

   This next example shows a different horizontal alignment: the content
   is centered within a box of a fixed width. This document:
   
 <HTML>
    <HEAD>
      <STYLE type="text/css">
           LI:before {
               display: marker;
               content: "(" numeric(counter) ")";
               width: 6em;
               text-align: center;
           }
      </STYLE>
   </HEAD>
   <BODY>
     <OL>
       <LI> This is the first item.
       <LI> This is the second item.
       <LI> This is the third item.
     </OL>
   </BODY>
 </HTML>

   should produce something like this:
   
  (1)    This is the
         first item.
  (2)    This is the
         second item.
  (3)    This is the
         third item.

   The next example creates markers before and after list items. This
   document:
   
<HTML>
  <HEAD>
    <STYLE type="text/css">
      @media screen, print {
         LI:before {
              display: marker;
              content: url(smiley.gif);
         LI:after {
              display: marker;
              content: url(sad.gif);
         }
      }
    </STYLE>
  </HEAD>
  <BODY>
    <UL>
      <LI>first list item comes first
      <LI>second list item comes second
    </UL>
  </BODY>
</HTML>

   should produce something like this (ascii art is used instead of
   smiley gif images here):
   
  :-) first list item
      comes first      :-(
  :-) second list item
      comes second     :-(

   The next example uses markers to number notes (paragraphs). The
   following document:
   
<HTML>
  <HEAD>
    <STYLE type="text/css">
      P { margin-left: 12 em; }
      @media screen, print {
         P.Note:before         {
              display: marker;
              content: url(note.gif)
                       "Note " numeric(note-counter) ":";
              counter-increment: note-counter;
              text-align: left;
              width: 10em;
         }
     }
    </STYLE>
  </HEAD>
  <BODY>
    <P>This is the first paragraph in this document.</P>
    <P CLASS="Note">This is a very short document.</P>
    <P>This is the end.</P>
  </BODY>
</HTML>

   should produce something like:
   
            This is the first paragraph
            in this document.

  Note 1:   This is a very short
            document.

            This is the end.

   'marker-offset'
          Value:   <length> | auto | inherit
          Initial:   auto
          Applies to:   elements with 'display' set to 'marker'
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   This property specifies the distance between the nearest border edges
   of a marker box and its associated principal box. The offset may
   either be a user-specified (<length>) or chosen by the UA ('auto').
   Lengths may be negative, but there may be implementation-specific
   limits.
   
   The following example illustrates how markers may be used to add
   periods after each numbered list item. This HTML program and style
   sheet:
   
 <HTML>
    <HEAD>
      <STYLE type="text/css">
           LI:before {
               display: marker;
               marker-offset: 3em;
               content: counter(mycounter, lower-roman) ".";
               counter-increment: mycounter;
           }
      </STYLE>
   </HEAD>
   <BODY>
     <P> This is a long preceding paragraph ...
     <OL>
       <LI> This is the first item.
       <LI> This is the second item.
       <LI> This is the third item.
     </OL>
     <P> This is a long following paragraph ...
   </BODY>
 </HTML>

   should produce something like this:
   
        This is a long preceding
        paragraph ...

   i.   This is the first item.
  ii.   This is the second item.
 iii.   This is the third item.

        This is a long following
        paragraph ...
     _________________________________________________________________
     _________________________________________________________________
   
                               13 Paged media
                                      
   Contents
     * 13.1 Introduction to paged media
     * 13.2 Page boxes: the @page rule
          + 13.2.1 Page margins
          + 13.2.2 Page size: the 'size' property
               o Rendering page boxes that do not fit a target sheet
               o Positioning the page box on the sheet
          + 13.2.3 Crop marks: the 'marks' property
          + 13.2.4 Left, right, and first pages
          + 13.2.5 Content outside the page box
     * 13.3 Page breaks
          + 13.3.1 Break before/after elements: 'page-break-before',
            'page-break-after', 'page-break-inside'
          + 13.3.2 Using named pages: 'page'
          + 13.3.3 Breaks inside elements: 'orphans', 'widows', and
            'page-break-inside'
          + 13.3.4 Allowed page breaks
          + 13.3.5 Forced page breaks
          + 13.3.6 "Best" page breaks
     * 13.4 Cascading in the page context
       
13.1 Introduction to paged media

   Paged media (e.g., paper, transparencies, pages that are displayed on
   computer screens, etc.) differ from continuous media in that the
   content of the document is split into one or more discrete pages. To
   handle page breaks, CSS2 extends the visual rendering model as
   follows:
   
    1. The page box extends the box model to allow authors to specify the
       size of a page, its margins, etc.
    2. The page model extends the visual rendering layout model to
       account for page breaks.
       
   The CSS2 page model specifies how a document is formatted within a
   rectangular area -- the page box -- that has a finite width and
   height. The page box does not necessarily correspond to the real sheet
   where the document will ultimately be rendered (paper, transparency,
   screen, etc.). The CSS page model specifies formatting in the page
   box, but it is the user agent's responsibility to transfer the page
   box to the sheet. Some transfer possibilities include:
   
     * Transferring one page box to one sheet (e.g., single-sided
       printing).
     * Transferring two page boxes to both sides of the same sheet (e.g.,
       double-sided printing).
     * Transferring N (small) page boxes to one sheet (called "n-up").
     * Transferring one (large) page box to N x M sheets (called
       "tiling").
     * Creating signatures. A signature is a group of pages printed on a
       sheet, which, when folded and trimmed like a book, appear in their
       proper sequence.
     * Printing one document to several output trays.
     * Outputting to a file.
       
   Although CSS2 does not specify how user agents transfer page boxes to
   sheets, it does include certain mechanisms for telling user agents
   about the target sheet size and orientation.
   
13.2 Page boxes: the @page rule

   The page box is a rectangular region that contains two embedded areas:
   
     * The page area. The page area includes the boxes laid out on that
       page. The edges of the page area act as a containing block for
       layout that occurs between page breaks. It also acts as the
       initial containing block.
     * The margin area.
       
   Note. In CSS2, the border properties and padding properties do not
   apply to pages; they may in the future. 
   
   Authors specify the dimensions, orientation, margins, etc. of a page
   box within an @page rule. An @page rule consists of the keyword
   "@page", a page selector, and a block of declarations (said to be in
   the page context).
   
   The page selector specifies for which pages the declarations apply. In
   CSS2, page selectors may designate the first page, all left pages, all
   right pages, or a page with a specific name.
   
   The dimensions of the page box are set with the 'size' property. The
   'marks' property specifies crop and cross marks.
   
   For example, the following @page rule sets the margins of the page to
   2cm.

@page { margin: 2cm }

  13.2.1 Page margins
  
   The margin properties ('margin-top', 'margin-right', 'margin-bottom',
   'margin-left', and 'margin') apply within the page context. The
   following diagram shows the relationships between the sheet, page box,
   and page margins:
   
   Illustration of sheet, page box, and margin.
   
   The actual value of element margins that fall at the top or bottom of
   a page is set to 0.
   
   The page context has no notion of fonts, so 'em' and 'ex' units are
   not allowed. Percentage values on the margin properties are relative
   to the dimensions of the page box. All other units associated with the
   respective CSS2 properties are allowed.
   
   Due to negative margin values (either on the page box or on elements)
   or absolute positioning content may end up outside the page box, but
   this content may be "cut" -- by the user agent, the printer, or
   ultimately, the paper cutter.
   
  13.2.2 Page size: the 'size' property
  
   'size'
          Value:   <length>{1,2} | auto | portrait | landscape | inherit
          Initial:   auto
          Applies to:   page context
          Inherited:   N/A
          Percentages:   N/A
          Media:   visual, paged
          
   This property specifies the size and orientation of a page box.
   
   The size of a page box may either be "absolute" (fixed size) or
   "relative" (scalable, i.e., fitting available sheet sizes). Relative
   page boxes allow user agents to scale a document and make optimal use
   of the target size.
   
   Three values for the 'size' property create a relative page box:
   
   auto
          The page box will be set to the size and orientation of the
          target sheet.
          
   landscape
          Overrides the target's orientation. The page box is the same
          size as the target, and the longer sides are horizontal.
          
   portrait
          Overrides the target's orientation. The page box is the same
          size as the target, and the shorter sides are horizontal.
          
   In the following example, the outer edges of the page box will align
   with the target. The percentage value on the 'margin' property is
   relative to the target size so if the target sheet dimensions are
   21.0cm x 29.7cm (i.e., A4), the margins are 2.10cm and 2.97cm.

@page {
  size: auto;   /* auto is the initial value */
  margin: 10%;
}

   Length values for the 'size' property create an absolute page box. If
   only one length value is specified, it sets both the width and height
   of the page box (i.e., the box is a square). Since the page box is the
   initial containing block, percentage values are not allowed for the
   'size' property.
   
   For example:
@page {
  size: 8.5in 11in;  /* width height */
}

   The above example set the width of the page box to be 8.5in and the
   height to be 11in. The page box in this example requires a target
   sheet size of 8.5"x11" or larger.
   
   User agents may allow users to control the transfer of the page box to
   the sheet (e.g., rotating an absolute page box that's being printed).
   
    Rendering page boxes that do not fit a target sheet
    
   If the page box does not fit the target sheet dimensions, the user
   agent may choose to:
   
     * Rotate the page box 90° if this will make the page box fit.
     * Scale the page to fit the target.
       
   The user agent should consult the user before performing these
   operations.
   
    Positioning the page box on the sheet
    
   When the page box is smaller than the target size, the user agent is
   free to place the page box anywhere on the sheet. However, it is
   recommended that the page box be centered on the sheet since this will
   align double-sided pages and avoid accidental loss of information that
   is printed near the edge of the sheet.
   
  13.2.3 Crop marks: the 'marks' property
  
   'marks'
          Value:   [ crop || cross ] | none | inherit
          Initial:   none
          Applies to:   page context
          Inherited:   N/A
          Percentages:   N/A
          Media:   visual, paged
          
   In high-quality printing, marks are often added outside the page box.
   This property specifies whether cross marks or crop marks or both
   should be rendered just outside the page box edge.
   
   Crop marks indicate where the page should be cut. Cross marks (also
   known as register marks or registration marks) are used to align
   sheets.
   
   Marks are visible only on absolute page boxes (see the 'size'
   property). In relative page boxes, the page box will be aligned with
   the target and the marks will be outside the printable area.
   
   The size, style, and position of cross marks depend on the user agent.
   
  13.2.4 Left, right, and first pages
  
   When printing double-sided documents, the page boxes on left and right
   pages should be different. This can be expressed through two CSS
   pseudo-classes that may be defined in the page context.
   
   All pages are automatically classified by user agents into either the
   :left or :right pseudo-class.
   
@page :left {
  margin-left: 4cm;
  margin-right: 3cm;
}

@page :right {
  margin-left: 3cm;
  margin-right: 4cm;
}

   If different declarations have been given for left and right pages,
   the user agent must honor these declarations even if the user agent
   does not transfer the page boxes to left and right sheets (e.g., a
   printer that only prints single-sided).
   
   Authors may also specify style for the first page of a document with
   the :first pseudo-class:
   
@page { margin: 2cm } /* All margins set to 2cm */

@page :first {
  margin-top: 10cm    /* Top margin on first page 10cm */
}

   Whether the first page of a document is :left or :right depends on the
   major writing direction of the document and is outside the scope of
   this document. However, to force a :left or :right first page, authors
   may insert a page break before the first generated box (e.g., in HTML,
   specify this for the BODY element).
   
   Properties specified in a :left (or :right) @page rule override those
   specified in an @page rule that has no pseudo-class specified.
   Properties specified in a :first @page rule override those specified
   in :left (or :right) @page rules.
   
   Note. Adding declarations to the :left or :right pseudo-class does not
   influence whether the document comes out of the printer double- or
   single-sided (which is outside the scope of this specification). 
   
   Note. Future versions of CSS may include other page pseudo-classes. 
   
  13.2.5 Content outside the page box
  
   When formatting content in the page model, some content may end up
   outside the page box. For example, an element whose 'white-space'
   property has the value 'pre' may generate a box that is wider than the
   page box. Also, when boxes are positioned absolutely, they may end up
   in "inconvenient" locations. For example, images may be placed on the
   edge of the page box or 100,000 inches below the page box.
   
   A specification for the exact formatting of such elements lies outside
   the scope of this document. However, we recommend that authors and
   user agents observe the following general principles concerning
   content outside the page box:
   
     * Content should be allowed slightly beyond the page box to allow
       pages to "bleed".
     * User agents should avoid generating a large number of empty page
       boxes to honor the positioning of elements (e.g., you don't want
       to print 100 blank pages). Note, however, that generating a small
       number of empty page boxes may be necessary to honor the 'left'
       and 'right' values for 'page-break-before' and 'page-break-after'.
     * Authors should not position elements in inconvenient locations
       just to avoid rendering them. Instead:
          + To suppress box generation entirely, set the 'display'
            property to 'none'.
          + To render a box invisible, use the 'visibility' property.
     * User agents may handle boxes positioned outside the page box in
       several ways, including discarding them or creating page boxes for
       them at the end of the document.
       
13.3 Page breaks

   The following sections explain page formatting in CSS2. Five
   properties indicate where the user agent may or should break pages,
   and on what page (left or right) the subsequent content should resume.
   Each page break ends layout in the current page box and causes
   remaining pieces of the document tree to be laid out in a new page
   box.
   
  13.3.1 Break before/after elements: 'page-break-before', 'page-break-after',
  'page-break-inside'
  
   'page-break-before'
          Value:   auto | always | avoid | left | right | inherit
          Initial:   auto
          Applies to:   block-level elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual, paged
          
   'page-break-after'
          Value:   auto | always | avoid | left | right | inherit
          Initial:   auto
          Applies to:   block-level elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual, paged
          
   'page-break-inside'
          Value:   avoid | auto | inherit
          Initial:   auto
          Applies to:   block-level elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual, paged
          
   Values for these properties have the following meanings:
   
   auto
          Neither force nor forbid a page break before (after, inside)
          the generated box.
          
   always
          Always force a page break before (after) the generated box.
          
   avoid
          Avoid a page break before (after, inside) the generated box.
          
   left
          Force one or two page breaks before (after) the generated box
          so that the next page is formatted as a left page.
          
   right
          Force one or two page breaks before (after) the generated box
          so that the next page is formatted as a right page.
          
   A potential page break location is typically under the influence of
   the parent element's 'page-break-inside' property, the
   'page-break-after' property of the preceding element, and the
   'page-break-before' property of the following element. When these
   properties have values other than 'auto', the values 'always', 'left',
   and 'right' take precedence over 'avoid'. See the section on allowed
   page breaks for the exact rules on how these properties may force or
   suppress a page break.
   
  13.3.2 Using named pages: 'page'
  
   'page'
          Value:   <identifier> [ :left | :right ]? | auto
          Initial:   auto
          Applies to:   block-level elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual, paged
          
   The 'page' property can be used to specify a particular type of page
   where an element should be displayed.
   
   By adding ':left' or ':right' the element can be forced to fall on a
   left or right page as well.
   
   This example will put all tables on a right-hand side landscape page
   (named "rotated"):
   
@page rotated {size: landscape}
TABLE {page: rotated:right}

   The 'page' property works as follows: If a block box with inline
   content has a 'page' property that is different from the preceding
   block box with inline content, then one or two page breaks are
   inserted between them, and the boxes after the break are rendered onto
   a page box of the named type. See "Forced page breaks" below.
   
   In this example, the two tables are rendered on landscape pages
   (indeed, on the same page, if they fit), and the page type "narrow" is
   not used at all, despite having been set on the DIV:
   
@page narrow {size: 9cm 18cm}
@page rotated {size: landscape}
DIV {page: narrow}
TABLE {page: rotated}

   with this document::
<DIV>
<TABLE>...</TABLE>
<TABLE>...</TABLE>
</DIV>

  13.3.3 Breaks inside elements: 'orphans', 'widows', and 'page-break-inside'
  
   'orphans'
          Value:   <integer> | inherit
          Initial:   2
          Applies to:   block-level elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual, paged
          
   'widows'
          Value:   <integer> | inherit
          Initial:   2
          Applies to:   block-level elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual, paged
          
   The 'orphans' property specifies the minimum number of lines of a
   paragraph that must be left at the bottom of a page. The 'widows'
   property specifies the minimum number of lines of a paragraph that
   must be left at the top of a page. Examples of how they are used to
   control page breaks are given below.
   
   The 'page-break-inside' property can be used to turn off page breaking
   inside an element completely, i.e., keep the whole element on one
   page. The 'widows' and 'orphans' properties are not used if
   'page-break-inside' is 'avoid'. However, if the element is larger than
   the page, so that it has to be broken, then the 'page-break-inside'
   property is ignored (treated as if it were 'auto') and page breaks are
   determined using the 'widows' and 'orphans' properties.
   
   For information about paragraph formatting, please consult the section
   on line boxes.
   
  13.3.4 Allowed page breaks
  
   In the normal flow, page breaks can occur at the following places:
   
    1. In the vertical margin between block boxes. When a page break
       occurs here, the actual values of the relevant 'margin-top' and
       'margin-bottom' properties are set to '0'.
    2. Between line boxes inside a block box.
       
   These breaks are subject to the following rules:
     * Rule A: Breaking at (1) is allowed only if the 'page-break-after'
       and 'page-break-before' properties of all the elements generating
       boxes that meet at this margin allow it, which is when at least
       one of them has the value 'always', 'left', or 'right', or when
       all of them are 'auto'.
     * Rule B: However, if all of them are 'auto' and the nearest common
       ancestor of all the elements has a 'page-break-inside' value of
       'avoid', then breaking here is not allowed.
     * Rule C: Breaking at (2) is allowed only if the number of line
       boxes between the break and the start of the enclosing block box
       is 'orphans' or more, and the number of line boxes between the
       break and the end of the box is 'widows' or more.
     * Rule D: In addition, breaking at (2) is allowed only if the
       'page-break-inside' property is 'auto'.
       
   If the above doesn't provide enough break points to keep content from
   overflowing the page boxes, then rules B and D are dropped in order to
   find additional breakpoints.
   
   If that still does not lead to sufficient break points, rules A and C
   are dropped as well, to find still more break points.
   
   Page breaks cannot occur inside boxes that are absolutely-positioned.
   
  13.3.5 Forced page breaks
  
   A page break must occur at (1) if, among the 'page-break-after' and
   'page-break-before' properties of all the elements generating boxes
   that meet at this margin, there is at least one with the value
   'always', 'left', or 'right'.
   
   A page break must also occur at (1) if the last line box above this
   margin and the first one below it do not have the same value for
   'page'.
   
  13.3.6 "Best" page breaks
  
   CSS2 does not define which of a set of allowed page breaks must be
   used; CSS2 does not forbid a user agent from breaking at every
   possible break point, or not to break at all. But CSS2 does recommend
   that user agents observe the following heuristics (while recognizing
   that they are sometimes contradictory):
   
     * Break as few times as possible.
     * Make all pages that don't end with a forced break appear to have
       about the same height.
     * Avoid breaking inside a block that has a border.
     * Avoid breaking inside a table.
     * Avoid breaking inside a floating element
       
   Suppose, for example, that the style sheet contains 'orphans : 4',
   'widows : 2', and there are 20 lines (line boxes) available at the
   bottom of the current page:
   
     * If a paragraph at the end of the current page contains 20 lines or
       fewer, it should be placed on the current page.
     * If the paragraph contains 21 or 22 lines, the second part of the
       paragraph must not violate the 'widows' constraint, and so the
       second part must contain exactly two lines
     * If the paragraph contains 23 lines or more, the first part should
       contain 20 lines and the second part the remaining lines.
       
   Now suppose that 'orphans' is '10', 'widows' is '20', and there are 8
   lines available at the bottom of the current page:
   
     * If a paragraph at the end of the current page contains 8 lines or
       fewer, it should be placed on the current page.
     * If the paragraph contains 9 lines or more, it cannot be split
       (that would violate the orphan constraint), so it should move as a
       block to the next page.
       
13.4 Cascading in the page context

   Declarations in the page context obey the cascade just like normal
   CSS2 declarations.
   
   Consider the following example:
@page {
  margin-left: 3cm;
}

@page :left {
  margin-left: 4cm;
}

   Due to the higher specificity of the pseudo-class selector, the left
   margin on left pages will be '4cm' and all other pages (i.e., the
   right pages) will have a left margin of '3cm'.
     _________________________________________________________________
     _________________________________________________________________
   
                         14 Colors and Backgrounds
                                      
   Contents
     * 14.1 Foreground color: the 'color' property
     * 14.2 The background
          + 14.2.1 Background properties: 'background-color',
            'background-image', 'background-repeat',
            'background-attachment', 'background-position', and
            'background'
     * 14.3 Gamma correction
       
   CSS properties allow authors to specify the foreground color and
   background of an element. Backgrounds may be colors or images.
   Background properties allow authors to position the image, repeat it,
   and declare whether it should be fixed with respect to the viewport or
   scrolled along with the document.
   
   See the section on color units for the syntax of valid color values.
   
14.1 Foreground color: the 'color' property

   'color'
          Value:   <color> | inherit
          Initial:   depends on user agent
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property describes the foreground color of an element's text
   content. There are different ways to specify red:
   
EM { color: red }              /* predefined color name */
EM { color: rgb(255,0,0) }     /* RGB range 0-255   */

14.2 The background

   Authors may specify the background of an element (i.e., its rendering
   surface) as either a color or an image. In terms of the box model,
   "background" refers to the background of the content and the padding
   area. Border colors and styles are set with the border properties.
   Margins are always transparent so the background of the parent box
   always shines through.
   
   Background properties are not inherited, but the parent box's
   background will shine through by default because of the initial
   'transparent' value on 'background-color'.
   
   The background of the box generated by the root element covers the
   entire canvas.
   
   For HTML documents, however, we recommend that authors specify the
   background for the BODY element rather than the HTML element. User
   agents should observe the following precedence rules to fill in the
   background: if the value of the 'background' property for the HTML
   element is different from 'transparent' then use it, else use the
   value of the 'background' property for the BODY element. If the
   resulting value is 'transparent', the rendering is undefined.
   
   According to these rules, the canvas underlying the following HTML
   document will have a "marble" background:

<HTML>
  <HEAD>
    <STYLE type="text/css">
       BODY { background: url(http://style.com/marble.png) }
    </STYLE>
    <TITLE>Setting the canvas background</TITLE>
  </HEAD>
  <BODY>
    <P>My background is marble.
  </BODY>
</HTML>

  14.2.1 Background properties: 'background-color', 'background-image',
  'background-repeat', 'background-attachment', 'background-position', and
  'background'
  
   'background-color'
          Value:   <color> | transparent | inherit
          Initial:   transparent
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   This property sets the background color of an element, either a
   <color> value or the keyword 'transparent', to make the underlying
   colors shine through.
   
H1 { background-color: #F00 }

   'background-image'
          Value:   <uri> | none | inherit
          Initial:   none
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   This property sets the background image of an element. When setting a
   background image, authors should also specify a background color that
   will be used when the image is unavailable. When the image is
   available, it is rendered on top of the background color. (Thus, the
   color is visible in the transparent parts of the image).
   
   The values are <uri>, to specify the image, or 'none', when no image
   is used.
   
   Example:
BODY { background-image: url(marble.gif) }
P { background-image: none }

   'background-repeat'
          Value:   repeat | repeat-x | repeat-y | no-repeat | inherit
          Initial:   repeat
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   If a background image is specified, this property specifies whether
   the image is repeated (tiled), and how. All tiling covers the content
   and padding areas of a box. Values have the following meanings:
   
   repeat
          The image is repeated both horizontally and vertically.
          
   repeat-x
          The image is repeated horizontally only.
          
   repeat-y
          The image is repeated vertically only.
          
   no-repeat
          The image is not repeated: only one copy of the image is drawn.
          
   Example:
BODY {
  background: red url(pendant.gif);
  background-repeat: repeat-y;
  background-position: center;
}

   A centered background image, with copies repeated up and down the
   padding and content areas.
   
   One copy of the background image is centered, and other copies are put
   above and below it to make a vertical band behind the element.
   
   'background-attachment'
          Value:   scroll | fixed | inherit
          Initial:   scroll
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   If a background image is specified, this property specifies whether it
   is fixed with regard to the viewport ('fixed') or scrolls along with
   the document ('scroll').
   
   Even if the image is fixed, it is still only visible when it is in the
   background or padding area of the element. Thus, unless the image is
   tiled ('background-repeat: repeat'), it may be invisible.
   
   This example creates an infinite vertical band that remains "glued" to
   the viewport when the element is scrolled.

BODY {
  background: red url(pendant.gif);
  background-repeat: repeat-y;
  background-attachment: fixed;
}

   User agents may treat 'fixed' as 'scroll'. However, it is recommended
   they interpret 'fixed' correctly, at least for the HTML and BODY
   elements, since there is no way for an author to provide an image only
   for those browsers that support 'fixed'. See the section on
   conformance for details.
   
   'background-position'
          Value:   [ [<percentage> | <length> ]{1,2} | [ [top | center |
          bottom] || [left | center | right] ] ] | inherit
          Initial:   0% 0%
          Applies to:   block-level and replaced elements
          Inherited:   no
          Percentages:   refer to the size of the element itself
          Media:   visual
          
   If a background image has been specified, this property specifies its
   initial position. Values have the following meanings:
   
   <percentage> <percentage>
          With a value pair of '0% 0%', the upper left corner of the
          image is aligned with the upper left corner of the box's
          padding edge. A value pair of '100% 100%' places the lower
          right corner of the image in the lower right corner of the box.
          With a value pair of '14% 84%', the point 14% across and 84%
          down the image is to be placed at the point 14% across and 84%
          down the box.
          
   <length> <length>
          With a value pair of '2cm 2cm', the upper left corner of the
          image is placed 2cm to the right and 2cm below the upper left
          corner of the box.
          
   top left and left top
          Same as '0% 0%'.
          
   top, top center, and center top
          Same as '50% 0%'.
          
   right top and top right
          Same as '100% 0%'.
          
   left, left center, and center left
          Same as '0% 50%'.
          
   center and center center
          Same as '50% 50%'.
          
   right, right center, and center right
          Same as '100% 50%'.
          
   bottom left and left bottom
          Same as '0% 100%'.
          
   bottom, bottom center, and center bottom
          Same as '50% 100%'.
          
   bottom right and right bottom
          Same as '100% 100%'.
          
   If only one percentage or length value is given, it sets the
   horizontal position only, the vertical position will be 50%. If two
   values are given, the horizontal position comes first. Combinations of
   length and percentage values are allowed, (e.g., '50% 2cm'). Negative
   positions are allowed. Keywords cannot be combined with percentage
   values or length values (all possible combinations are given above).
   
   Examples:
BODY { background: url(banner.jpeg) right top }    /* 100%   0% */
BODY { background: url(banner.jpeg) top center }   /*  50%   0% */
BODY { background: url(banner.jpeg) center }       /*  50%  50% */
BODY { background: url(banner.jpeg) bottom }       /*  50% 100% */

   If the background image is fixed within the viewport (see the
   'background-attachment' property), the image is placed relative to the
   viewport instead of the element's box. For example,
   
BODY {
  background-image: url(logo.png);
  background-attachment: fixed;
  background-position: 100% 100%;
}

   In the example above, the image is placed in the lower-right corner of
   the viewport.
   
   'background'
          Value:   [<'background-color'> || <'background-image'> ||
          <'background-repeat'> || <'background-attachment'> ||
          <'background-position'>] | inherit
          Initial:   not defined for shorthand properties
          Applies to:   all elements
          Inherited:   no
          Percentages:   allowed on 'background-position'
          Media:   visual
          
   The 'background' property is a shorthand property for setting the
   individual background properties (i.e., 'background-color',
   'background-image', 'background-repeat', 'background-attachment' and
   'background-position') at the same place in the style sheet.
   
   The 'background' property always sets all the individual background
   properties.
   
   In the first rule of the following example, only a value for
   'background-color' has been given and the other individual properties
   are set to their initial value. In the second rule, all individual
   properties have been specified.

BODY { background: red }
P { background: url(chess.png) gray 50% repeat fixed }

14.3 Gamma correction

   For information about gamma issues, please consult the the Gamma
   Tutorial in the PNG specification ([PNG10]).
   
   In the computation of gamma correction, UAs displaying on a CRT may
   assume an ideal CRT and ignore any effects on apparent gamma caused by
   dithering. That means the minimal handling they need to do on current
   platforms is:
   
   PC using MS-Windows
          none
          
   Unix using X11
          none
          
   Mac using QuickDraw
          apply gamma 1.39 [ICC32] (ColorSync-savvy applications may
          simply pass the sRGB ICC profile to ColorSync to perform
          correct color correction)
          
   SGI using X
          apply the gamma value from /etc/config/system.glGammaVal (the
          default value being 1.70; applications running on Irix 6.2 or
          above may simply pass the sRGB ICC profile to the color
          management system)
          
   NeXT using NeXTStep
          apply gamma 2.22
          
   "Applying gamma" means that each of the three R, G and B must be
   converted to R'=Rgamma, G'=Ggamma, B'=Bgamma, before handing to the
   OS.
   
   This may rapidly be done by building a 256-element lookup table once
   per browser invocation thus:

for i := 0 to 255 do
  raw := i / 255.0;
  corr := pow (raw, gamma);
  table[i] := trunc (0.5 + corr * 255.0)
end

   which then avoids any need to do transcendental math per color
   attribute, far less per pixel.
     _________________________________________________________________
     _________________________________________________________________
   
                                  15 Fonts
                                      
   Contents
     * 15.1 Introduction
     * 15.2 Font specification
          + 15.2.1 Font specification properties
          + 15.2.2 Font family: the 'font-family' property
          + 15.2.3 Font styling: the 'font-style', 'font-variant',
            'font-weight' and 'font-stretch' properties
          + 15.2.4 Font size: the 'font-size' and 'font-size-adjust'
            properties
          + 15.2.5 Shorthand font property: the 'font' property
          + 15.2.6 Generic font families
               o serif
               o sans-serif
               o cursive
               o fantasy
               o monospace
     * 15.3 Font selection
          + 15.3.1 Font Descriptions and @font-face
          + 15.3.2 Descriptors for Selecting a Font: 'font-family',
            'font-style', 'font-variant', 'font-weight', 'font-stretch'
            and 'font-size'
          + 15.3.3 Descriptors for Font Data Qualification:
            'unicode-range'
          + 15.3.4 Descriptor for Numeric Values: 'units-per-em'
          + 15.3.5 Descriptor for Referencing: 'src'
          + 15.3.6 Descriptors for Matching: 'panose-1', 'stemv',
            'stemh', 'slope', 'cap-height', 'x-height', 'ascent', and
            'descent'
          + 15.3.7 Descriptors for Synthesis: 'widths', 'bbox' and
            'definition-src'
          + 15.3.8 Descriptors for Alignment: 'baseline', 'centerline',
            'mathline', and 'topline'
          + 15.3.9 Examples
     * 15.4 Font Characteristics
          + 15.4.1 Introducing Font Characteristics
          + 15.4.2 Full font name
          + 15.4.3 Coordinate units on the em square
          + 15.4.4 Central Baseline
          + 15.4.5 Font Encoding
          + 15.4.6 Font family name
          + 15.4.7 Glyph widths
          + 15.4.8 Horizontal stem width
          + 15.4.9 Height of uppercase glyphs
          + 15.4.10 Height of lowercase glyphs
          + 15.4.11 Lower Baseline
          + 15.4.12 Mathematical Baseline
          + 15.4.13 Maximal bounding box
          + 15.4.14 Maximum unaccented height
          + 15.4.15 Maximum unaccented depth
          + 15.4.16 Panose-1 number
          + 15.4.17 Range of ISO 10646 characters
          + 15.4.18 Top Baseline
          + 15.4.19 Vertical stem width
          + 15.4.20 Vertical stroke angle
     * 15.5 Font matching algorithm
          + 15.5.1 Mapping font weight values to font names
          + 15.5.2 Examples of font matching
       
15.1 Introduction

   When a document's text is to be displayed visually, characters
   (abstract information elements) must be mapped to abstract glyphs. One
   or more characters may be depicted by one or more abstract glyphs, in
   a possibly context-dependent fashion. A glyph is the actual artistic
   representation of an abstract glyph, in some typographic style, in the
   form of outlines or bitmaps that may be drawn on the screen or paper.
   A font is a set of glyphs, all observing the same basic motif
   according to design, size, appearance, and other attributes associated
   with the entire set, and a mapping from characters to abstract glyphs.
   
   A visual user agent must address the following issues before actually
   rendering a character:
   
     * Is there, directly or by inheritance, a font specified for this
       character?
     * Does the user agent have this font available?
     * If so, what glyph(s) does this character or sequence of characters
       map to?
     * If not, what should be done? Should a different font be
       substituted? Can the font be synthesized? Can it be retrieved from
       the Web?
       
   In both CSS1 and CSS2, authors specify font characteristics via a
   series of font properties.
   
   How the user agent handles with properties, when there is no matching
   font on the client, has expanded between CSS1 and CSS2. In CSS1, all
   fonts were assumed to be present on the client system and were
   identified solely by name. Alternate fonts could be specified through
   the properties, but beyond that, user agents had no way to propose
   other fonts to the user (even stylistically similar fonts that the
   user agent had available) other than generic default fonts.
   
   CSS2 changes all that, and allows much greater liberty for:
   
     * style sheet authors, to describe the fonts they want to be used
     * user agents, in selecting a font when an author's requested font
       is not immediately available.
       
   CSS2 improves client-side font matching, enables font synthesis and
   progressive rendering, and enables fonts to be downloaded over the
   Web.
   
   In the CSS2 font model, as in CSS1, each user agent has a "font
   database" at its disposition. CSS1 referred to this database but gave
   no details about what was in it. CSS2 defines the information in that
   database and allows style sheet authors to contribute to it. When
   asked to display a character with a particular font, the user agent
   first identifies the font in the database that "best fits" the
   specified font (according to the font matching algorithm) Once it has
   identified a font, it retrieves the font data locally or from the Web,
   and may display the character using those glyphs.
   
   In light of this model, we have organized the specification into two
   sections. The first concerns the font specification mechanism, whereby
   authors specify which fonts they would like to have used. The second
   concerns the font selection mechanism, whereby the client's user agent
   identifies and loads a font that best fits the author's specification.
   
   How the user agent constructs the font database lies outside the scope
   of this specification since the database's implementation depends on
   such factors as the operating system, the windowing system, and the
   client.
   
15.2 Font specification

   The first phase of the CSS font mechanism concerns how style sheet
   authors specify which fonts should be used by a user agent. At first,
   it seem that the obvious way to specify a font is by it's name, a
   single string - which appears to be separated into distinct parts; for
   example "BT Swiss 721 Heavy Italic".
   
   Unfortunately, there exists no well-defined and universally accepted
   taxonomy for classifying fonts based on their names, and terms that
   apply to one font family name may not be appropriate for others. For
   example, the term 'italic' is commonly used to label slanted text, but
   slanted text may also be labeled Oblique, Slanted, Incline, Cursive or
   Kursiv. Similarly, font names typically contain terms that describe
   the "weight" of a font. The primary role of these names is to
   distinguish faces of differing darkness within a single font family.
   There is no accepted, universal meaning to these weight names and
   usage varies widely. For example a font that you might think of as
   being bold might be described as being Regular, Roman, Book, Medium,
   Semi- or Demi-Bold, Bold, or Black, depending on how black the
   "normal" face of the font is within the design.
   
   This lack of systematic naming makes it impossible, in the general
   case, to generate a modified font face name that differs in a
   particular way, such as being bolder.
   
   Because of this, CSS uses a different model. Fonts are requested not
   through a single font name but through setting a series of font
   properties. These property values form the basis of the user agent's
   font selection mechanism. The font properties can be individually
   modified, for example to increase the boldness, and the new set of
   font property values will then be used to select from the font
   database again. The result is an increase in regularity for style
   sheet authors and implementors, and an increase in robustness.
   
  15.2.1 Font specification properties
  
   CSS2 specifies fonts according to these characteristics:
   
   Font family
          The font family specifies which font family is to be used to
          render the text. A font family is a group of fonts,designed to
          be used in combination and exhibiting similarities in design.
          One member of the family may be italic, another bold, another
          condensed or using small caps. Font family names include
          Helvetica, "New Century Schoolbook", and "Kyokasho ICA L". Font
          family names are not restricted to Latin characters. Font
          families may be grouped into different categories: those with
          or without serifs, those whose characters are or are not
          proportionally spaced, those that resemble handwriting, those
          that are fantasy fonts, etc.
          
   Font style
          The font style specifies whether the text is to be rendered
          using a normal, italic, or oblique face. Italic is a more
          cursive companion face to the normal face, but not so cursive
          as to make it a script face. Oblique is a slanted form of the
          normal face, and is more commonly used as a companion face to
          sans-serif. This definition avoids having to label slightly
          slanted normal faces as oblique, or normal Greek faces as
          italic.
          
   Font variant
          The font variant indicates whether the text is to be rendered
          using the normal glyphs for lowercase characters or using
          small-caps glyphs for lowercase characters. A particular font
          may contain only normal, only small-caps, or both types of
          glyph; this property is used to request an appropriate font
          and, if the font contains both variants, the appropriate
          glyphs.
          
   Font weight
          The font weight refers to the boldness or lightness of the
          glyphs used to render the text, relative to other fonts in the
          same font family.
          
   Font stretch
          The font stretch indicates the desired amount of condensing or
          expansion in the glyphs used to render the text, relative to
          other fonts in the same font family.
          
   Font size
          The font size refers to the size of the font from baseline to
          baseline, when set solid (in CSS terms, this is when the
          'font-size' and 'line-height' properties have the same value).
          
   On all properties except 'font-size', 'em' and 'ex' length values
   refer to the font size of the current element. For 'font-size', these
   length units refer to the font size of the parent element. Please
   consult the section on length units for more information.
   
   These font properties in CSS are used to describe the desired
   appearance of text in the document. The font descriptors, in contrast,
   are used to describe the characteristics of fonts, so that a suitable
   font can be chosen to create the desired appearance. For information
   about the classification of fonts, please consult the section on font
   descriptors.
   
  15.2.2 Font family: the 'font-family' property
  
   'font-family'
          Value:   [[ <family-name> | <generic-family> ],]*
          [<family-name> | <generic-family>] | inherit
          Initial:   depends on user agent
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property specifies a prioritized list of font family names and/or
   generic family names. To deal with the problem that a single font may
   not contain glyphs to display all the characters in a document, or
   that not all fonts are available on all systems, this property allows
   authors to specify a list of fonts, all of the same style and size,
   that are tried in sequence to see if they contain a glyph for a
   certain character. This list is called a font set.
   
   For example, text that contains English words mixed with mathematical
   symbols may need a font set of two fonts, one containing Latin letters
   and digits, the other containing mathematical symbols. Here is an
   example of a font set suitable for a text that is expected to contain
   text with Latin characters, Japanese characters, and mathematical
   symbols:

BODY { font-family: Baskerville, "Heisi Mincho W3", Symbol, serif }

   The glyphs available in the "Baskerville" font (a font which covers
   only Latin characters) will be taken from that font, Japanese glyphs
   will be taken from "Heisi Mincho W3", and the mathematical symbol
   glyphs will come from "Symbol". Any others will come from the generic
   font family 'serif'.
   
   The generic font family will be used if one or more of the other fonts
   in a font set is unavailable. Although many fonts provide the "missing
   character" glyph, typically an open box, as its name implies this
   should not be considered a match except for the last font in a font
   set.
   
   There are two types of font family names:
   
   <family-name>
          The name of a font family of choice. In the previous example,
          "Baskerville", "Heisi Mincho W3", and "Symbol" are font
          families. Font family names containing whitespace should be
          quoted. If quoting is omitted, any whitespace characters before
          and after the font name are ignored and any sequence of
          whitespace characters inside the font name is converted to a
          single space.
          
   <generic-family>
          The following generic families are defined: 'serif',
          'sans-serif', 'cursive', 'fantasy' and 'monospace'. Please see
          the section on generic font families for descriptions of these
          families. Generic font family names are keywords and therefore
          must not be quoted.
          
          Authors are encouraged to offer a generic font family as a last
          alternative, for improved robustness.
          
   For example:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">
<HTML>
  <HEAD>
    <TITLE>Font test</TITLE>
    <STYLE type="text/css">
      BODY { font-family: "new century schoolbook", serif }
    </STYLE>
  </HEAD>
  <BODY>
   <H1 style="font-family: 'My own font', fantasy">Test</H1>
    <P>What's up, Doc?
  </BODY>
</HTML>

   The richer selector syntax of CSS2 may be used to create
   language-sensitive typography. For example, some Chinese and Japanese
   characters are unified to have the same Unicode codepoint, although
   the abstract glyphs are not the same in the two languages.

*:lang(ja-jp) { font: 900 14pt/16pt "Heisei Mincho W9", serif }
*:lang(zh-tw) { font: 800 14pt/16.5pt "Li Sung", serif }

   This selects any element which has the given language - Japanese or
   Traditional Chinese - and requests the appropriate font.
   
  15.2.3 Font styling: the 'font-style', 'font-variant', 'font-weight' and
  'font-stretch' properties
  
   'font-style'
          Value:   normal | italic | oblique | inherit
          Initial:   normal
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   The 'font-style' property requests normal (sometimes referred to as
   "roman" or "upright"), italic, and oblique faces within a font family.
   Values have the following meanings:
   
   normal
          Specifies a font that is classified as 'normal' in the UA's
          font database.
          
   oblique
          Specifies a font that is classified as 'oblique' in the UA's
          font database. Fonts with Oblique, Slanted or Incline in their
          names will typically be labeled 'oblique' in the font database.
          A font that is labeled 'oblique' in the UA's font database may
          actually have been generated by electronically slanting a
          normal font.
          
   italic
          Specifies a font that is classified as 'italic' in the UA's
          font database, or, if that is not available, one labeled
          'oblique'. Fonts with Italic, Cursive or Kursiv in their names
          will typically be labeled 'italic'.
          
   In this example, normal text in an H1, H2, or H3 element will be
   displayed with an italic font. However, emphasized text (EM) within an
   H1 will appear in a normal face.

H1, H2, H3 { font-style: italic }
H1 EM { font-style: normal }

   'font-variant'
          Value:   normal | small-caps | inherit
          Initial:   normal
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   In a small-caps font, the glyphs for lowercase letters look similar to
   the uppercase ones, but in a smaller size and with slightly different
   proportions. The 'font-variant' property requests such a font for
   bicameral (having two cases, as with Latin script). This property has
   no visible effect for scripts which are unicameral (having only one
   case, as with most of the world's writing systems). Values have the
   following meanings:
   
   normal
          Specifies a font that is not labeled as a small-caps font.
          
   small-caps
          Specifies a font that is labeled as a small-caps font. If a
          genuine small-caps font is not available, user agents should
          simulate a small-caps font, for example by taking a normal font
          and replacing the lowercase letters by scaled uppercase
          characters. As a last resort, unscaled uppercase letter glyphs
          in a normal font may replace glyphs in a small-caps font so
          that the text appears in all uppercase letters.
          
   The following example results in an H3 element in small-caps, with
   emphasized words (EM) in oblique small-caps:

H3 { font-variant: small-caps }
EM { font-style: oblique }

   Insofar as this property causes text to be transformed to uppercase,
   the same considerations as for 'text-transform' apply.
   
   'font-weight'
          Value:   normal | bold | bolder | lighter | 100 | 200 | 300 |
          400 | 500 | 600 | 700 | 800 | 900 | inherit
          Initial:   normal
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   The 'font-weight' property specifies the weight of the font. Values
   have the following meanings:
   
   100 to 900
          These values form an ordered sequence, where each number
          indicates a weight that is at least as dark as its predecessor.
          
   normal
          Same as '400'.
          
   bold
          Same as '700'.
          
   bolder
          Specifies the next weight that is assigned to a font that is
          darker than the inherited one. If there is no such weight, it
          simply results in the next darker numerical value (and the font
          remains unchanged), unless the inherited value was '900', in
          which case the resulting weight is also '900'.
          
   lighter
          Specifies the next weight that is assigned to a font that is
          lighter than the inherited one. If there is no such weight, it
          simply results in the next lighter numerical value (and the
          font remains unchanged), unless the inherited value was '100',
          in which case the resulting weight is also '100'.
          
P { font-weight: normal }   /* 400 */
H1 { font-weight: 700 }     /* bold */
BODY { font-weight: 400 }
STRONG { font-weight: bolder } /* 500 if available */

   Child elements inherit the computed value of the weight.
   
   'font-stretch'
          Value:   normal | wider | narrower | ultra-condensed |
          extra-condensed | condensed | semi-condensed | semi-expanded |
          expanded | extra-expanded | ultra-expanded | inherit
          Initial:   normal
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   The 'font-stretch' property specifies between normal, condensed and
   extended faces within a font family. Absolute keyword values have the
   following ordering, from narrowest to widest :
   
    1. ultra-condensed
    2. extra-condensed
    3. condensed
    4. semi-condensed
    5. normal
    6. semi-expanded
    7. expanded
    8. extra-expanded
    9. ultra-expanded
       
   The relative keyword 'wider' sets the value to the next more expanded
   value more than the inherited value (while not increasing it above
   ultra-expanded); the relative keyword 'narrower' sets the value to the
   next more condensed value than the inherited value (while not
   decreasing it below ultra-condensed).
   
  15.2.4 Font size: the 'font-size' and 'font-size-adjust' properties
  
   'font-size'
          Value:   <absolute-size> | <relative-size> | <length> |
          <percentage> | inherit
          Initial:   medium
          Applies to:   all elements
          Inherited:   yes, the computed value is inherited
          Percentages:   relative to parent element's font size
          Media:   visual
          
   This property describes the size of the font when set solid. Values
   have the following meanings:
   
   <absolute-size>
          An <absolute-size> keyword refers to an entry in a table of
          font sizes computed and kept by the user agent. Possible values
          are:
          
          [ xx-small | x-small | small | medium | large | x-large |
          xx-large ]
          
          On a computer screen a scaling factor of 1.2 is suggested
          between adjacent indexes; if the 'medium' font is 12pt, the
          'large' font could be 14.4pt. Different media may need
          different scaling factors. Also, the user agent should take the
          quality and availability of fonts into account when computing
          the table. The table may be different from one font family to
          another.
          
          Note: In CSS1, the suggested scaling factor between adjacent
          indexes was 1.5 which user experience proved to be too large.
          
   <relative-size>
          A <relative-size> keyword is interpreted relative to the table
          of font sizes and the font size of the parent element. Possible
          values are:
          
          [ larger | smaller ]
          
          For example, if the parent element has a font size of 'medium',
          a value of 'larger' will make the font size of the current
          element be 'large'. If the parent element's size is not close
          to a table entry, the user agent is free to interpolate between
          table entries or round off to the closest one. The user agent
          may have to extrapolate table values if the numerical value
          goes beyond the keywords.
          
   <length>
          A length value specifies an absolute font size (that is
          independent of the user agent's font table). Negative lengths
          are illegal.
          
   <percentage> 
          A percentage value specifies an absolute font size relative to
          the parent element's font size. Use of percentage values, or
          values in 'em's, leads to more robust and cascadable style
          sheets.
          
   The actual value of this property may differ from the computed value
   due a numerical value on 'font-size-adjust' and the unavailability of
   certain font sizes.
   
   Child elements inherit the computed 'font-size' value. Otherwise, the
   effect of 'font-size-adjust' would have been applied multiple times.
   
   Examples:
P { font-size: 12pt; }
BLOCKQUOTE { font-size: larger }
EM { font-size: 150% }
EM { font-size: 1.5em }

   'font-size-adjust'
          Value:   <number> | none | inherit
          Initial:   none
          Applies to:   all elements
          Inherited:   yes
          Percentages:   relative to parent element's font size
          Media:   visual
          
   In bicameral scripts, the subjective apparent size (and general
   character of a font on screen) is less dependent on its 'font-size'
   than on the value of its 'x-height', or, more usefully, on the ratio
   of these two values, called the z value (font size divided by
   x-height). The lower the z value, the more likely it is that a font at
   smaller em sizes will be legible. Inversely, faces with a higher z
   value will become illegible more rapidly below a given threshold size
   than faces with a lower z value. Straightforward font substitution
   that relies on font size alone may lead to illegible characters.
   
   For example, the popular font Verdana has a z value of 1.72; in an
   instance of Verdana with 'font-size' 100 points, the 'x-height' is 58
   pt (100/58=1.72). For comparison, Times New Roman has a z value of
   2.17. As the z value increases, a font for a bicameral script becomes
   less legible at a given point size.
   
   This property allows authors to specify a z value for an element that
   preserves the 'x-height' of the first choice substitute font. Values
   have the following meanings:
   
   none
          Do not preserve the font's x-height.
          
   <number>
          Specifies the z value. This number refers to the 'z' value of
          the "first choice" font. The scaling factor for available fonts
          is computed according to the following formula:
          

a(z'/z) = b

          where:
          
a = 'font-size' of first-choice font
z' = z of available font
b = 'font-size' to apply to available font

   For example, if 14px Verdana (with a z value of 1.72) was unavailable
   and the generic sans-serif on a particular platform had a z value of
   2.09, the size of the sans-serif would be 14 times (2.09/1.72) = 17px.
   
   Font size adjustments are based on the computed value of 'font-size'.
   
   The first image below shows several typefaces as rasterized on a
   Macintosh at 12-point, together with their z values. No matter what
   the typographical family (or nominal base size, unit, or platform),
   faces with lower z values look bigger than those with higher z values.
   Faces with very high z values are illegible at the size shown.
   
   Comparison of 12 point fonts
   
   The next image shows the results of 'font-size-adjust' with the fonts
   shown in the previous image. These fonts' em sizes range all the way
   up to 25-point, but appear subjectively to be about as large as
   12-point Verdana, whose z value served as the base for scaling. As
   adjusted, the legibility characteristics of these faces on screen are
   nearly linear across faces. Note that 'font-size-adjust' tends to
   stabilize the horizontal metrics of lines, as well.
   
   Comparison of font-adjusted fonts
   
  15.2.5 Shorthand font property: the 'font' property
  
   'font'
          Value:   [ [ <'font-style'> || <'font-variant'> ||
          <'font-weight'> ]? <'font-size'> [ / <'line-height'> ]?
          <'font-family'> ] | caption | icon | menu | message-box |
          small-caption | status-bar | inherit
          Initial:   see individual properties
          Applies to:   all elements
          Inherited:   yes
          Percentages:   allowed on 'font-size' and 'line-height'
          Media:   visual
          
   The 'font' property is, except as described below, a shorthand
   property for setting 'font-style', 'font-variant', 'font-weight',
   'font-size', 'line-height', and 'font-family', at the same place in
   the style sheet. The syntax of this property is based on a traditional
   typographical shorthand notation to set multiple properties related to
   fonts.
   
   All font related properties are first reset to their initial values,
   including those listed in the preceding paragraph plus 'font-stretch'
   and 'font-size-adjust'. Then, those properties that are given explicit
   values in the 'font' shorthand are set to those values. For a
   definition of allowed and initial values, see the previously defined
   properties. For reasons of backwards compatibility, it is not possible
   to set 'font-stretch' and 'font-size-adjust' to other than their
   initial values using the 'font' shorthand property; instead, set the
   individual properties.
   
   Examples:
P { font: 12pt/14pt sans-serif }
P { font: 80% sans-serif }
P { font: x-large/110% "new century schoolbook", serif }
P { font: bold italic large Palatino, serif }
P { font: normal small-caps 120%/120% fantasy }
P { font: oblique "Helvetica Nue", serif; font-stretch: condensed }

   In the second rule, the font size percentage value ('80%') refers to
   the font size of the parent element. In the third rule, the line
   height percentage ('110%') refers to the font size of the element
   itself.
   
   The first three rules do not specify the 'font-variant' and
   'font-weight' explicitly, so these properties receive their initial
   values ('normal'). Notice that the font family name "new century
   schoolbook", which contains spaces, is enclosed in quotes. The fourth
   rule sets the 'font-weight' to 'bold', the 'font-style' to 'italic',
   and implicitly sets 'font-variant' to 'normal'.
   
   The fifth rule sets the 'font-variant' ('small-caps'), the 'font-size'
   (120% of the parent's font size), the 'line-height' (120% of the font
   size) and the 'font-family' ('fantasy'). It follows that the keyword
   'normal' applies to the two remaining properties: 'font-style' and
   'font-weight'.
   
   The sixth rule sets the 'font-style' and 'font-family', the other font
   properties being set to their initial values; it then sets
   'font-stretch' to 'condensed' since it cannot be set to that value
   using the 'font' shorthand property.
   
   The following values refer to system fonts:
   
   caption
          The font used for captioned controls (e.g. buttons, drop-downs,
          etc.).
          
   icon
          The font used to label icons.
          
   menu
          The font used in menus (e.g., dropdown menus and menu lists).
          
   message-box
          The font used in dialog boxes.
          
   small-caption
          The font used for labeling small controls.
          
   status-bar
          The font used in window status bars.
          
   System fonts may only be set as a whole; that is, the font family,
   size, weight, style, etc. are all set at the same time.These values
   may then be altered individually if desired. If no font with the
   indicated characteristics exists on a given platform, the user agent
   should either intelligently substitute (e.g., a smaller version of the
   'caption' font might be used for the 'smallcaption' font), or
   substitute a user agent default font. As for regular fonts, if, for a
   system font, any of the individual properties are not part of the
   operating system's available user preferences, those properties should
   be set to their initial values.
   
   That is why this property is "almost" a shorthand property: system
   fonts can only be specified with this property, not with 'font-family'
   itself, so 'font' allows authors to do more than the sum of its
   subproperties. However, the individual properties such as
   'font-weight' are still given values taken from the system font, which
   can be independently varied.
   
   Example:
BUTTON { font: 300 italic 1.3em/1.7em "FB Armada", sans-serif }
BUTTON P { font: menu }
BUTTON P EM { font-weight: bolder }

   If the font used for dropdown menus on a particular system happened to
   be 9-point Charcoal, with a weight of 600, then P elements which were
   descendants of BUTTON would be displayed as if this rule were in
   effect (the values for the remaining properties being taken from the
   initial values):

BUTTON P {
  font-style: normal;
  font-variant: normal;
  font-weight: 600;
  font-size: 9pt;
  line-height: normal;
  font-family: Charcoal
}

  15.2.6 Generic font families
  
   Generic font families are a fallback mechanism, a means of preserving
   some of the style sheet writer's intent in the worst case when none of
   the specified fonts can be selected. For optimum typographic control,
   particular named fonts should be used in style sheets.
   
   All five generic font families are defined to exist in all CSS
   implementations (they need not necessarily map to five distinct actual
   fonts, in all cases). User agents should provide reasonable default
   choices for the generic font families, which express the
   characteristics of each family as well as possible within the limits
   allowed by the underlying technology.
   
   User agents are encouraged to allow users to select alternative
   choices for the generic fonts.
   
    serif
    
   Glyphs of serif fonts, as the term is used in CSS, have finishing
   strokes, flared or tapering ends, or have actual serifed endings
   (including slab serifs). Serif fonts are typically proportionately
   spaced. They often display a greater variation between thick and thin
   strokes than fonts from the 'sans-serif' generic font family. CSS uses
   the term 'serif' to apply to a font for any script, although other
   names may be more familiar for particular scripts, such as Mincho
   (Japanese), Sung or Song (Chinese), Totum or Kodig (Korean), and any
   font which is so described may be used to represent the generic
   'serif' family.
   
   Examples of fonts that fit this description include:
   
   Latin fonts Times New Roman, Bodoni, Garamond, Minion Web, ITC Stone
   Serif, MS Georgia, Bitstream Cyberbit
   Greek fonts Bitstream Cyberbit
   Cyrillic fonts Adobe Minion Cyrillic, Excelcior Cyrillic Upright,
   Monotype Albion 70, Bitstream Cyberbit, ER Bukinst
   Hebrew fonts New Peninim, Raanana, Bitstream Cyberbit
   Japanese fonts Ryumin Light-KL, Kyokasho ICA, Futo Min A101
   Arabic fonts Bitstream Cyberbit
   Cherokee fonts Lo Cicero Cherokee
   
    sans-serif
    
   Glyphs in sans-serif fonts, as the term is used in CSS, have stroke
   endings that are plain -- without any flaring, cross stroke, or other
   ornamentation. Sans-serif fonts are typically proportionately spaced.
   They often have little variation between thick and thin strokes,
   compared to fonts from the 'serif' family. CSS uses the term
   'sans-serif' to apply to a font for any script, although other names
   may be more familiar for particular scripts, such as Gothic
   (Japanese), Kai (Chinese), Pathang (Korean), and any font which is so
   described may be used to represent the generic 'sans-serif' family.
   
   Examples of fonts that fit this description include:
   
   Latin fonts MS Trebuchet, ITC Avant Garde Gothic, MS Arial, MS
   Verdana, Univers, Futura, ITC Stone Sans, Gill Sans, Akzidenz Grotesk,
   Helvetica
   Greek fonts Attika, Typiko New Era, MS Tahoma, Monotype Gill Sans 571,
   Helvetica Greek
   Cyrillic fonts Helvetica Cyrillic, ER Univers, Lucida Sans Unicode,
   Bastion
   Hebrew fonts Arial Hebrew, MS Tahoma
   Japanese fonts Shin Go, Heisei Kaku Gothic W5
   Arabic fonts MS Tahoma
   
    cursive
    
   Glyphs in cursive fonts, as the term is used in CSS, generally have
   either joining strokes or other cursive characteristics beyond those
   of italic typefaces. The glyphs are partially or completely connected,
   and the result looks more like handwritten pen or brush writing than
   printed letterwork. Fonts for some scripts, such as Arabic, are almost
   always cursive. CSS uses the term 'cursive' to apply to a font for any
   script, although other names such as Chancery, Brush, Swing and Script
   are also used in font names.
   
   Examples of fonts that fit this description include:
   
   Latin fonts Caflisch Script, Adobe Poetica, Sanvito, Ex Ponto, Snell
   Roundhand, Zapf-Chancery
   Cyrillic fonts ER Architekt
   Hebrew fonts Corsiva
   Arabic fonts DecoType Naskh, Monotype Urdu 507
   
    fantasy
    
   Fantasy fonts, as used in CSS, are primarily decorative while still
   containing representations of characters (as opposed to Pi or Picture
   fonts, which do not represent characters). Examples include:
   
   Latin fonts Alpha Geometrique, Critter, Cottonwood, FB Reactor, Studz
   
    monospace
    
   The sole criterion of a monospace font is that all glyphs have the
   same fixed width. (This can make some scripts, such as Arabic, look
   most peculiar.) The effect is similar to a manual typewriter, and is
   often used to set samples of computer code.
   
   Examples of fonts which fit this description include:
   Latin fonts Courier, MS Courier New, Prestige, Everson Mono
   Greek Fonts MS Courier New, Everson Mono
   Cyrillic fonts ER Kurier, Everson Mono
   Japanese fonts Osaka Monospaced
   Cherokee fonts Everson Mono
   
15.3 Font selection

   The second phase of the CSS2 font mechanism concerns the user agent's
   selection of a font based on author-specified font properties,
   available fonts, etc. The details of the font matching algorithm are
   provided below.
   
   There are four possible font selection actions: name matching,
   intelligent matching, synthesis, and download.
   
   font name matching
          In this case, the user agent uses an existing, accessible font
          that has the same family name as the requested font. (Note that
          the appearance and the metrics might not necessarily match, if
          the font that the document author used and the font on the
          client system are from different foundries). The matching
          information is restricted to the CSS font properties, including
          the family name. This is the only method used by CSS1.
          
   intelligent font matching
          In this case, the user agent uses an existing, accessible font
          that is the closest match in appearance to the requested font.
          (Note that the metrics might not match exactly). The matching
          information includes information about the kind of font (text
          or symbol), nature of serifs, weight, cap height, x height,
          ascent, descent, slant, etc.
          
   font synthesis
          In this case, the user agent creates a font that is not only a
          close match in appearance, but also matches the metrics of the
          requested font. The synthesizing information includes the
          matching information and typically requires more accurate
          values for the parameters than are used for some matching
          schemes. In particular, synthesis requires accurate width
          metrics and character to glyph substitution and position
          information if all the layout characteristics of the specified
          font are to be preserved.
          
   font download
          Finally, the user agent may retrieve a font over the Web. This
          is similar to the process of fetching images, sounds, or
          applets over the Web for display in the current document, and
          likewise can cause some delay before the page can be displayed.
          
   Progressive rendering is a combination of download and one of the
   other methods; it provides a temporary substitute font (using name
   matching, intelligent matching, or synthesis) to allow content to be
   read while the requested font downloads. Once the real font has been
   successfully downloaded, it replaces the temporary font, hopefully
   without the need to reflow.
   
   Note. Progressive rendering requires metric information about the font
   in order to avoid re-layout of the content when the actual font has
   been loaded and rendered. This metric information is sufficiently
   verbose that it should only be specified at most once per font in a
   document. 
   
  15.3.1 Font Descriptions and @font-face
  
   The font description provides the bridge between an author's font
   specification and the font data, which is the data needed to format
   text and to render the abstract glyphs to which the characters map -
   the actual scalable outlines or bitmaps. Fonts are referenced by style
   sheet properties.
   
   The font description is added to the font database and then used to
   select the relevant font data. The font description contains
   descriptors such as the location of the font data on the Web, and
   characterizations of that font data. The font descriptors are also
   needed to match the style sheet font properties to particular font
   data. The level of detail of a font description can vary from just the
   name of the font up to a list of glyph widths.
   
   Font descriptors may be classified into three types:
   
    1. those that provide the link between the CSS usage of the font and
       the font description (these have the same names as the
       corresponding CSS font properties),
    2. the URI for the location of the font data,
    3. those that further characterize the font, to provide a link
       between the font description and the font data.
       
   All font descriptions are specified via a @font-face at-rule. The
   general form is:
   
   @font-face { <font-description> }
   
   where the <font-description> has the form:
descriptor: value;
descriptor: value;
[...]
descriptor: value;

   Each @font-face rule specifies a value for every font descriptor,
   either implicitly or explicitly. Those not given explicit values in
   the rule take the initial value listed with each descriptor in this
   specification. These descriptors apply solely within the context of
   the @font-face rule in which they are defined, and do not apply to
   document language elements. Thus, there is no notion of which elements
   the descriptors apply to, or whether the values are inherited by child
   elements.
   
   The available font descriptors are described in later sections of this
   specification.
   
   For example, here the font 'Robson Celtic' is defined and referenced
   in a style sheet contained in an HTML document.

<HTML>
  <HEAD>
    <TITLE>Font test</TITLE>
    <STYLE TYPE="text/css" MEDIA="screen, print">
      @font-face {
        font-family: "Robson Celtic";
        src: url(http://site/fonts/rob-celt)
      }
      H1 { font-family: "Robson Celtic", serif }
    </STYLE>
  </HEAD>

  <BODY>
    <H1> This heading is displayed using Robson Celtic</H1>
  </BODY>
</HTML>

   The style sheet (in the STYLE element) contains a CSS rule that sets
   all H1 elements to use the 'Robson Celtic' font family.
   
   A CSS1 implementation will search the client for a font whose family
   name and other properties match 'Robson Celtic' and, if it fails to
   find it, will use the UA-specific fallback serif font (which is
   defined to exist).
   
   A user agent implementing CSS2 will first examine @font-face rules in
   search of a font description defining 'Robson Celtic'. This example
   contains a rule which matches. Although this rule doesn't contain much
   font data, it does have a URI where the font can be retrieved for
   rendering this document. Downloaded fonts should not be made available
   to other applications. If no matching @font-face is found, the user
   agent will attempt the same match as a user agent implementing CSS1.
   
   Note that if the font 'Robson Celtic' had been installed on the client
   system, this would cause the UA to add an entry in the font database
   for the installed copy as described in the section on the font
   matching algorithm. The installed copy would have been matched before
   the downloadable font in the example above.
   
   CSS1 implementations, which do not understand the @font-face rule,
   will encounter the opening curly brackets and will ignore forward
   until the matching closing curly brackets. This at-rule conforms with
   the forward-compatible parsing requirement of CSS. Parsers may ignore
   these rules without error.
   
   Having the font descriptors separate from the font data has a benefit
   beyond being able to do font selection and/or substitution. The data
   protection and replication restrictions on the font descriptors may be
   much weaker than on the full font data. Thus, it may be possible to
   locally install the font definition, or at least to have it in a local
   cache if it occurs in a commonly-referenced style sheet; which would
   not require accessing the full font definition over the Web more than
   once per named font.
   
   If a font descriptor is duplicated, the last occurring descriptor wins
   and the rest must be ignored.
   
   Also, any descriptors that are not recognized or useful to the user
   agent should be ignored. Future versions of CSS may allow additional
   descriptors for the purpose of better font substitution, matching, or
   synthesis.
   
  15.3.2 Descriptors for Selecting a Font: 'font-family', 'font-style',
  'font-variant', 'font-weight', 'font-stretch' and 'font-size'
  
   The following descriptors have the same names as the corresponding
   CSS2 font properties, and take a single value or comma-separated list
   of values.
   
   The values within that list are, except as explicitly noted, the same
   as those for the corresponding CSS2 property. If there is a single
   value, that is the value that must be matched. If there is a list, any
   list item constitutes a match. If the descriptor is omitted from the
   @font-face, the initial value for the descriptor is used.
   
   'font-family' (Descriptor)
          Value:   [ <family-name> | <generic-family> ] [, [<family-name>
          | <generic-family> ]]*
          Initial:   depends on user agent
          Media:   visual
          
   This is the descriptor for the font family name of a font and takes
   the same values as the 'font-family' property.
   
   'font-style' (Descriptor)
          Value:   all | [ normal | italic | oblique ] [, [normal |
          italic | oblique] ]*
          Initial:   all
          Media:   visual
          
   This is the descriptor for the style of a font and takes the same
   values as the 'font-style' property, except that a comma-separated
   list is permitted.
   
   'font-variant' (Descriptor)
          Value:   [normal | small-caps] [,[normal | small-caps]]*
          Initial:   normal
          Media:   visual
          
   This is the CSS indication of whether this face is the small-caps
   variant of a font. It takes the same values as the 'font-variant'
   property except that a comma-separated list is permitted.
   
   Note. Cyrillic pryamo&#301; faces may be labeled with a 'font-variant'
   of small-caps, which will give better consistency with Latin faces
   (and the companion kursiv face labeled with 'font-style' italic for
   the same reason). 
   
   'font-weight' (Descriptor)
          Value:   all | [normal | bold | 100 | 200 | 300 | 400 | 500 |
          600 | 700 | 800 | 900] [, [normal | bold | 100 | 200 | 300 |
          400 | 500 | 600 | 700 | 800 | 900]]*
          Initial:   all
          Media:   visual
          
   This is the descriptor for the weight of a face relative to others in
   the same font family. It takes the same values as the 'font-weight'
   property with three exceptions:
   
    1. relative keywords (bolder, lighter) are not permitted.
    2. a comma-separated list of values is permitted, for fonts which
       contain multiple weights.
    3. an additional keyword, 'all' is permitted, which means that the
       font will match for all possible weights; either because it
       contains multiple weights, or because that face only has a single
       weight.
       
   'font-stretch' (Descriptor)
          Value:   all | [ normal | ultra-condensed | extra-condensed |
          condensed | semi-condensed | semi-expanded | expanded |
          extra-expanded | ultra-expanded ] [, [ normal | ultra-condensed
          | extra-condensed | condensed | semi-condensed | semi-expanded
          | expanded | extra-expanded | ultra-expanded] ]*
          Initial:   normal
          Media:   visual
          
   This is the CSS indication of the condensed or expanded nature of the
   face relative to others in the same font family. It takes the same
   values as the 'font-stretch' property except that:
   
     * relative keywords (wider, narrower) are not permitted
     * a comma-separated list is permitted
     * The keyword 'all' is permitted
       
   'font-size' (Descriptor)
          Value:   all | [<length> [,[<length>]]* ]
          Initial:   all
          Media:   visual
          
   This is the descriptor for the sizes provided by this font. Only
   absolute length units are permitted, in contrast to the 'font-size'
   property, which allows both relative and absolute lengths and sizes. A
   comma-separated list of absolute lengths is permitted.
   
   The initial value of 'all' is suitable for most scalable fonts, so
   this descriptor is primarily for use in an @font-face for bitmap
   fonts, or scalable fonts designed to be rasterised at a restricted
   range of font sizes.
   
  15.3.3 Descriptors for Font Data Qualification: 'unicode-range'
  
   The following descriptor is optional within a font definition, but is
   used to avoid checking or downloading a font that does not have
   sufficient glyphs to render a particular character.
   
   'unicode-range' (Descriptor)
          Value:   <urange>+
          Initial:   U+0-7FFFFFFF
          Media:   visual
          
   This is the descriptor for the range of ISO 10646 characters covered
   by the font.
   
   The values of <urange> are expressed using hexadecimal numbers
   prefixed by "U+", corresponding to character code positions in ISO
   10646 ([ISO10646]).
   
   For example, U+05D1 is the ISO 10646 character 'Hebrew letter bet'.
   For values outside the Basic Multilingual Plane (BMP), additional
   leading digits corresponding to the plane number are added, also in
   hexadecimal, like this: U+A1234 which is the character on Plane 10 at
   hexadecimal code position 1234. At the time of writing no characters
   had been assigned outside the BMP. Leading zeros (for example,
   0000004D) are valid, but not required.
   
   The initial value (i.e., the value used when no value is given in the
   style sheet) covers not only the entire Basic Multilingual Plane
   (BMP), which would be expressed as U+0-FFFF, but also the whole
   repertoire of ISO 10646. Thus, the initial value says that the font
   may have glyphs for characters anywhere in ISO 10646. Specifying a
   value for 'unicode-range' provides information to make searching
   efficient, by declaring a constrained range in which the font may have
   glyphs for characters. The font need not be searched for characters
   outside this range.
   
   Values may be written with any number of digits. For single numbers,
   the character '?' is assumed to mean 'any value' which creates a range
   of character positions. Thus, using a single number:
   
   unicode-range: U+20A7
          no wild cards - it indicates a single character position (the
          Spanish peseta currency symbol)
          
   unicode-range: U+215?
          one wild card, covers the range 2150 to 215F (the fractions)
          
   unicode-range: U+00??
          two wild cards, covers the range 0000 to 00FF (Latin-1)
          
   unicode-range: U+E??
          two wild cards, covers 0E00 to 0EFF (the Lao script)
          
   A pair of numbers in this format can be combined with the dash
   character to indicate larger ranges. For example:
   
   unicode-range: U+AC00-D7FF
          the range is AC00 to D7FF (the Hangul Syllables area)
          
   Multiple, discontinuous ranges can be specified, separated by a comma.
   As with other comma-separated lists in CSS, any whitespace before or
   after the comma is ignored. For example:
   
   unicode-range: U+370-3FF, U+1F??
          This covers the range 0370 to 03FF (Modern Greek) plus 1F00 to
          1FFF (Ancient polytonic Greek).
          
   unicode-range: U+3000-303F, U+3100-312F, U+32??, U+33??, U+4E00-9FFF,
          U+F9000-FAFF, U+FE30-FE4F
          Something of a worst case in terms of verbosity, this very
          precisely indicates that this (extremely large) font contains
          only Chinese characters from ISO 10646, without including any
          characters that are uniquely Japanese or Korean. The range is
          3000 to 303F (CJK symbols and punctuation) plus 3100 to 312F
          (Bopomofo) plus 3200 to 32FF (enclosed CJK letters and months)
          plus 3300 to 33FF (CJK compatibility zone) plus 4E00 to 9FFF
          (CJK unified Ideographs) plus F900 to FAFF (CJK compatibility
          ideographs) plus FE30 to FE4F (CJK compatibility forms).
          
          A more likely representation for a typical Chinese font would
          be:
          
          unicode-range: U+3000-33FF, U+4E00-9FFF
          
   unicode-range: U+11E00-121FF
          This font covers a proposed registration for Aztec pictograms,
          covering the range 1E00 to 21FF in plane 1.
          
   unicode-range: U+1A00-1A1F
          This font covers a proposed registration for Irish Ogham
          covering the range 1A00 to 1A1F
          
  15.3.4 Descriptor for Numeric Values: 'units-per-em'
  
   The following descriptor specifies the number of "units" per em; these
   units may be used by several other descriptors to express various
   lengths, so 'units-per-em' is required if other descriptors depend on
   it.
   
   'units-per-em' (Descriptor)
          Value:   <number>
          Initial:   undefined
          Media:   visual
          
   This is the descriptor for the number of the coordinate units on the
   em square, the size of the design grid on which glyphs are laid out.
   
  15.3.5 Descriptor for Referencing: 'src'
  
   This descriptor is required for referencing actual font data, whether
   downloadable or locally installed.
   
   'src' (Descriptor)
          Value:   [ <uri> [format(<string> [, <string>]*)] |
          <font-face-name> ] [, <uri> [format(<string> [, <string>]*)] |
          <font-face-name> ]*
          Initial:   undefined
          Media:   visual
          
   This is a prioritized, comma-separated list of external references
   and/or locally installed font face names. The external reference
   points to the font data on the Web. This is required if the WebFont is
   to be downloaded. The font resource may be a subset of the source
   font, for example it may contain only the glyphs needed for the
   current page or for a set of pages.
   
   The external reference consists of a URI, followed by an optional hint
   regarding the format of font resource to be found at that URI, and
   this information should be used by clients to avoid following links to
   fonts in formats they are unable to use. As with any hypertext
   reference, there may be other formats available, but the client has a
   better idea of what is likely to be there, in a more robust way than
   trying to parse filename extensions in URIs.
   
   The format hint contains a comma-separated list of format strings that
   denote well-known font formats. The user agent will recognize the name
   of font formats that it supports, and will avoid downloading fonts in
   formats that it does not recognize.
   
   An initial list of format strings defined by this specification and
   representing formats likely to be used by implementations on various
   platforms is:
   
   String Font Format Examples of common extensions
   "truedoc-pfr" TrueDoc® Portable Font Resource .pfr
   "embedded-opentype" Embedded OpenType .eot
   "type-1" PostScript® Type 1 .pfb, .pfa
   "truetype" TrueType .ttf
   "opentype" OpenType, including TrueType Open .ttf
   "truetype-gx" TrueType with GX extensions
   "speedo" Speedo
   "intellifont" Intellifont
   
   As with other URIs in CSS, the URI may be partial, in which case it is
   resolved relative to the location of the style sheet containing the
   @font-face.
   
   The <font-face-name> is the full font name of a locally installed
   font. The full font name is the name of the font as reported by the
   operating system and is the name most likely to be used in reader
   style sheets, browser default style sheets or possibly author style
   sheets on an intranet. Adornments such as bold, italic, underline are
   often used to differentiate faces within a font family. For more
   information about full font names please consult the notes below.
   
   Examples:
   
   src: url(http://foo/bar)
          a full URI and no information about the font format(s)
          available there
          
   src: local(BT Century 751 No. 2 Semi Bold Italic)
          references a particular face of a locally installed font
          
   src: url(../fonts/bar) format("truedoc-pfr")
          a partial URI which has a font available in TrueDoc format
          
   src: url(http://cgi-bin/bar?stuff) format("opentype", "intellifont")
          a full URI, in this case to a script, which can generate two
          different formats - OpenType and Intellifont
          
   src: local(T-26 Typeka Mix), url(http://site/magda-extra)
          format("type-1")
          two alternatives are given, firstly a locally installed font
          and secondly a downloadable font available in Type 1 format.
          
   Access to locally installed fonts is via the <font-face-name>. The
   font face name is not truly unique, nor is it truly platform or font
   format independent, but at the moment it is the best way to identify
   locally installed font data. The use of the font face name can be made
   more accurate by providing an indication of the glyph complement
   required. This may be done by indicating the range of ISO 10646
   character positions for which the font provides some glyphs (see
   'unicode-range').
   
  15.3.6 Descriptors for Matching: 'panose-1', 'stemv', 'stemh', 'slope',
  'cap-height', 'x-height', 'ascent', and 'descent'
  
   These descriptors are optional for a CSS2 definition, but may be used
   if intelligent font matching or font size adjustment is desired by the
   author.
   
   'panose-1' (Descriptor)
          Value:   [<number>]{10}
          Initial:   0 0 0 0 0 0 0 0 0 0
          Media:   visual
          
   This is the descriptor for the Panose-1 number and consists of ten
   decimal numbers, separated by whitespace. A comma-separated list is
   not permitted for this descriptor, because the Panose-1 system can
   indicate that a range of values are matched. The initial value is
   zero, which means "any", for each PANOSE digit; all fonts will match
   the Panose number if this value is used. Use of the Panose-1
   descriptor is strongly recommended for latin fonts.
   
   'stemv' (Descriptor)
          Value:   <number>
          Initial:   undefined
          Media:   visual
          
   This is the descriptor for the vertical stem width of the font. If the
   value is undefined, the descriptor is not used for matching. If this
   descriptor is used, the 'units-per-em' descriptor must also be used.
   
   'stemh' (Descriptor)
          Value:   <number>
          Initial:   undefined
          Media:   visual
          
   This is the descriptor for the horizontal stem width of the font. If
   the value is undefined, the descriptor is not used for matching. If
   this descriptor is used, the 'units-per-em' descriptor must also be
   used.
   
   'slope' (Descriptor)
          Value:   <number>
          Initial:   0
          Media:   visual
          
   This is the descriptor for the vertical stroke angle of the font.
   
   'cap-height' (Descriptor)
          Value:   <number>
          Initial:   undefined
          Media:   visual
          
   This is the descriptor for the number of the height of uppercase
   glyphs of the font. If the value is undefined, the descriptor is not
   used for matching. If this descriptor is used, the 'units-per-em'
   descriptor must also be used.
   
   'x-height' (Descriptor)
          Value:   <number>
          Initial:   undefined
          Media:   visual
          
   This is the descriptor for the height of lowercase glyphs of the font.
   If the value is undefined, the descriptor is not used for matching. If
   this descriptor is used, the 'units-per-em' descriptor must also be
   used. This descriptor can be very useful when using the
   'font-size-adjust' property, because computation of the z value of
   candidate fonts requires both the font size and the x-height; it is
   therefore recommended to include this descriptor.
   
   'ascent' (Descriptor)
          Value:   <number>
          Initial:   undefined
          Media:   visual
          
   This is the descriptor for the maximum unaccented height of the font.
   If the value is undefined, the descriptor is not used for matching. If
   this descriptor is used, the 'units-per-em' descriptor must also be
   used.
   
   'descent' (Descriptor)
          Value:   <number>
          Initial:   undefined
          Media:   visual
          
   This is the descriptor for the Maximum unaccented depth of the font.
   If the value is undefined, the descriptor is not used for matching. If
   this descriptor is used, the 'units-per-em' descriptor must also be
   used.
   
  15.3.7 Descriptors for Synthesis: 'widths', 'bbox' and 'definition-src'
  
   Synthesizing a font means, at minimum, matching the width metrics of
   the specified font. Therefore, for synthesis, this metric information
   must be available. Similarly, progressive rendering requires width
   metrics in order to avoid reflow of the content when the actual font
   has been loaded. Although the following descriptors are optional for a
   CSS2 definition, some are required if synthesizing (or reflow-free
   progressive rendering) is desired by the author. Should the actual
   font become available, the substitute should be replaced by the actual
   font. Any of these descriptors that are present will be used to
   provide a better or faster approximation of the intended font.
   
   Of these descriptors, the most important are the 'widths' descriptor
   and 'bbox' which are used to prevent text reflow should the actual
   font become available. In addition, the descriptors in the set of
   descriptors used for matching can be used to provide a better
   synthesis of the actual font appearance.
   
   'widths' (Descriptor)
          Value:   [<urange> ]? [<number> ]+ [,[<urange> ]? <number> ]+]
          Initial:   undefined
          Media:   visual
          
   This is the descriptor for the glyph widths. The value is a
   comma-separated list of <urange> values each followed by one or more
   glyph widths. If this descriptor is used, the 'units-per-em'
   descriptor must also be used.
   
   If the <urange> is omitted, a range of U+0-7FFFFFFF is assumed which
   covers all characters and their glyphs. If not enough glyph widths are
   given, the last in the list is replicated to cover that urange. If too
   many widths are provided, the extras are ignored.
   
   For example:
widths: U+4E00-4E1F 1736 1874 1692
widths: U+1A?? 1490, U+215? 1473 1838 1927 1684 1356 1792
    1815 1848 1870 1492 1715 1745 1584 1992 1978 1770

   In the first example a range of 32 characters is given, from 4E00 to
   4E1F. The glyph corresponding to the first character (4E00) has a
   width of 1736, the second has a width of 1874 and the third, 1692.
   Because not enough widths have been provided, the last width
   replicates to cover the rest of the specified range. The second
   example sets a single width, 1490, for an entire range of 256 glyphs
   and then explicit widths for a range of 16 glyphs.
   
   This descriptor cannot describe multiple glyphs corresponding to a
   single character, or ligatures of multiple characters. Thus, this
   descriptor can only be used for scripts which do not have contextual
   forms or mandatory ligatures. It is nevertheless useful in those
   situations. Scripts which require a one-to-many or many-to-many
   mapping of characters to glyphs cannot at present use this descriptor
   to enable font synthesis although they can still use font downloading
   or intelligent matching.
   
   'bbox' (Descriptor)
          Value:   <number>, <number>, <number>, <number>
          Initial:   undefined
          Media:   visual
          
   This is the descriptor for the maximal bounding box of the font. The
   value is a comma-separated list of exactly four numbers specifying, in
   order, the lower left x, lower left y, upper right x, and upper right
   y of the bounding box for the complete font.
   
   'definition-src' (Descriptor)
          Value:   <uri>
          Initial:   undefined
          Media:   visual
          
   The font descriptors may either be within the font definition in the
   style sheet, or may be provided within a separate font definition
   resource identified by a URI. The latter approach can reduce network
   traffic when multiple style sheets reference the same fonts.
   
  15.3.8 Descriptors for Alignment: 'baseline', 'centerline', 'mathline', and
  'topline'
  
   These optional descriptors are used to align runs of different scripts
   with one another.
   
   'baseline' (Descriptor)
          Value:   <number>
          Initial:   0
          Media:   visual
          
   This is the descriptor for the lower baseline of a font. If this
   descriptor is given a non-default (non-zero) value, the 'units-per-em'
   descriptor must also be used.
   
   'centerline' (Descriptor)
          Value:   <number>
          Initial:   undefined
          Media:   visual
          
   This is the descriptor for the central baseline of a font. If the
   value is undefined, the UA may employ various heuristics such as the
   midpoint of the ascent and descent values. If this descriptor is used,
   the 'units-per-em' descriptor must also be used.
   
   'mathline' (Descriptor)
          Value:   <number>
          Initial:   undefined
          Media:   visual
          
   This is the descriptor for the mathematical baseline of a font. If
   undefined, the UA may use the center baseline. If this descriptor is
   used, the 'units-per-em' descriptor must also be used.
   
   'topline' (Descriptor)
          Value:   <number>
          Initial:   undefined
          Media:   visual
          
   This is the descriptor for the top baseline of a font. If undefined,
   the UA may use an approximate value such as the ascent. If this
   descriptor is used, the 'units-per-em' descriptor must also be used.
   
  15.3.9 Examples
  
   Given the following list of fonts:
   Swiss 721 light light & light italic
   Swiss 721 roman, bold, italic, bold italic
   Swiss 721 medium medium & medium italic
   Swiss 721 heavy heavy & heavy italic
   Swiss 721 black black, black italic, & black #2
   Swiss 721 Condensed roman, bold, italic, bold italic
   Swiss 721 Expanded roman, bold, italic, bold italic

@font-face {
    font-family: "Swiss 721";
    src: url(swiss721lt.pfr); /* Swiss 721 light */
    font-style: normal, italic;
    font-weight: 200;
}
@font-face {
    font-family: "Swiss 721";
    src: url(swiss721.pfr); /* The regular Swiss 721 */
}
@font-face {
    font-family: "Swiss 721";
    src: url(swiss721md.pfr); /* Swiss 721 medium */
    font-style: normal, italic;
    font-weight: 500;
}
@font-face {
    font-family: "Swiss 721";
    src: url(swiss721hvy.pfr); /* Swiss 721 heavy */
    font-style: normal, italic;
    font-weight: 700;
}
@font-face {
    font-family: "Swiss 721";
    src: url(swiss721blk.pfr); /* Swiss 721 black */
    font-style: normal, italic;
    font-weight: 800,900; /* note the interesting problem that
                               the 900 weight italic doesn't exist */
}
@font-face {
    font-family: "Swiss 721";
    src: url(swiss721.pfr); /* The condensed Swiss 721 */
        font-stretch: condensed;
}
@font-face {
    font-family: "Swiss 721";
    src: url(swiss721.pfr); /* The expanded Swiss 721 */
        font-stretch: expanded;
}

15.4 Font Characteristics

  15.4.1 Introducing Font Characteristics
  
   In this section are listed the font characteristics that have been
   found useful for client-side font matching, synthesis, and download
   for heterogeneous platforms accessing the Web. The data may be useful
   for any medium that needs to use fonts on the Web by some other means
   than physical embedding of the font data inside the medium.
   
   These characteristics are used to characterize fonts. They are not
   specific to CSS, or to style sheets. In CSS, each characteristic is
   described by a font descriptor. These characteristics could also be
   mapped onto VRML nodes, or CGM Application Structures, or a Java API,
   or alternative style sheet languages. Fonts retrieved by one medium
   and stored in a proxy cache could be re-used by another medium, saving
   download time and network bandwidth, if a common system of font
   characteristics are used throughout.
   
   A non-exhaustive list of examples of such media includes:
   
     * 2-D vector formats
          + Computer Graphics Metafile
          + Simple Vector Format
     * 3-D graphics formats
          + VRML
          + 3DMF
     * Object embedding technologies
          + Java
          + Active-X
          + Obliq
       
  15.4.2 Full font name
  
   This is the full name of a particular face of a font family. It
   typically includes a variety of non-standardized textual qualifiers or
   adornments appended to the font family name. It may also include a
   foundry name or abbreviation, often prepended to the font family name.
   It is only used to refer to locally installed fonts, because the
   format of the adorned name can vary from platform to platform.
   
   For example, the font family name of the TrueType font and the
   PostScript name may differ in the use of space characters,
   punctuation, and in the abbreviation of some words (e.g., to meet
   various system or printer interpreter constraints on length of names).
   For example, spaces are not allow in a PostScript name, but are common
   in full font names. The TrueType name table can also contain the
   PostScript name, which has no spaces.
   
   The name of the font definition is important because it is the link to
   any locally installed fonts. It is important that the name be robust,
   both with respect to platform and application independence. For this
   reason, the name should be one which is not application or language
   specific.
   
   The ideal solution would be to have a name which uniquely identifies
   each collection of font data. This name does not exist in current
   practice for font data. Fonts with the same face name can vary over a
   number of descriptors. Some of these descriptors, such as different
   complements of glyphs in the font, may be insignificant if the needed
   glyphs are in the font. Other descriptors, such as different width
   metrics, make fonts with the same name incompatible. It does not seem
   possible to define a rule that will always identify incompatibilities,
   but will not prevent the use of a perfectly suitable local copy of the
   font data with a given name. Therefore, only the range of ISO 10646
   characters will be used to qualify matches for the font face name.
   
   Since a prime goal of the font face name in the font definition is to
   allow a user agent to determine when there is a local copy of the
   specified font data, the font face name must be a name which will be
   in all legitimate copies of the font data. Otherwise, unnecessary Web
   traffic may be generated due to missed matches for the local copy.
   
  15.4.3 Coordinate units on the em square
  
   Certain values, such as width metrics, are expressed in units that are
   relative to an abstract square whose height is the intended distance
   between lines of type in the same type size. This square is called the
   em square and it is the design grid on which the glyph outlines are
   defined. The value of this descriptor specifies how many units the EM
   square is divided into. Common values are for example 250
   (Intellifont), 1000 (Type 1) and 2048 (TrueType, TrueType GX and
   OpenType).
   
   If this value is not specified, it becomes impossible to know what any
   font metrics mean. For example, one font has lowercase glyphs of
   height 450; another has smaller ones of height 890! The numbers are
   actually fractions; the first font has 450/1000 and the second has
   890/2048 which is indeed smaller.
   
  15.4.4 Central Baseline
  
   This gives the position in the em square of the central baseline. The
   central baseline is used by ideographic scripts for alignment, just as
   the bottom baseline is used for Latin, Greek and Cyrillic scripts.
   
  15.4.5 Font Encoding
  
   Either explicitly or implicitly, each font has a table associated with
   it, the font encoding table, that tells what character each glyph
   represents. This table is also referred to as an encoding vector.
   
   In fact, many fonts contain several glyphs for the same character.
   Which of those glyphs should be used depends either on the rules of
   the language, or on the preference of the designer.
   
   In Arabic, for example, all letters have four (or two) different
   shapes, depending on whether the letter is used at the start of a
   word, in the middle, at the end, or in isolation. It is the same
   character in all cases, and thus there is only one character in the
   HTML document, but when printed, it looks different each time.
   
   There are also fonts that leave it to the graphic designer to choose
   from among various alternative shapes provided. Unfortunately, CSS2
   doesn't yet provide the means to select those alternatives. Currently,
   it is always the default shape that is chosen from such fonts.
   
  15.4.6 Font family name
  
   This specifies the family name portion of the font face name. For
   example, the family name for Helvetica-Bold is Helvetica and the
   family name of ITC Stone Serif Semibold Italic is ITC Stone Serif.
   Some systems treat adornments relating to condensed or expanded faces
   as if they were part of the family name.
   
  15.4.7 Glyph widths
  
   This is a list of widths, on the design grid, for the glyph
   corresponding to each character. The list is ordered by ISO10646 code
   point. Widths cannot usefully be specified when more than one glyph
   maps to the same character or when there are mandatory ligatures.
   
  15.4.8 Horizontal stem width
  
   This value refers to the dominant stem of the font. There may be two
   or more designed widths. For example, the main vertical stems of Roman
   characters will differ from the thin stems on serifed "M" and "N",
   plus there may be different widths for uppercase and lowercase
   characters in the same font. Also, either by design or by error, all
   stems may have slightly different widths.
   
  15.4.9 Height of uppercase glyphs
  
   This measurement is the y-coordinate of the top of flat uppercase
   letters in Latin, Greek and Cyrillic scripts, measured from the
   baseline. This descriptor is not necessarily useful for fonts that do
   not contain any glyphs from these scripts.
   
  15.4.10 Height of lowercase glyphs
  
   This measurement is the y-coordinate of the top of unaccented,
   non-ascending lowercase letters in Latin, Greek and Cyrillic scripts,
   measured from the baseline. Flat-topped letters are used, ignoring any
   optical correction zone. This is usually used as a ratio of lowercase
   to uppercase heights, as a means of comparison between font families.
   
   Illustration of x-height
   
   This descriptor is not useful for fonts that do not contain any glyphs
   from these scripts. Since the heights of lowercase and uppercase
   letters are often formed into a ratio for comparing different fonts,
   it may be useful to set both the lowercase and uppercase heights to
   the same value for unicameral scripts such as Hebrew, where for mixed
   Latin and Hebrew text the Hebrew characters are typically set at a
   height midway between the uppercase and lowercase heights of the Latin
   font.
   
   Height of Hebrew characters
   
  15.4.11 Lower Baseline
  
   This gives the position in the em square of the lower baseline. The
   lower baseline is used by Latin, Greek and Cyrillic scripts for
   alignment, just as the upper baseline is used for Sanscrit-derived
   scripts.
   
  15.4.12 Mathematical Baseline
  
   This gives the position in the em square of the mathematical baseline.
   The mathematical baseline is used by mathematical symbols for
   alignment, just as the lower baseline is used for Latin, Greek, and
   Cyrillic scripts.
   
  15.4.13 Maximal bounding box
  
   The maximal bounding box is the smallest rectangle enclosing the shape
   that results if all glyphs in the font are placed with their origins
   coincident, and then painted.
   
   If a dynamically downloadable font has been generated by subsetting a
   parent font, the bbox should be that of the parent font.
   
  15.4.14 Maximum unaccented height
  
   This measurement, on the em square, is from the baseline to the
   highest point reached by any glyph, excluding any accents or
   diacritical marks.
   
   Diagram showing several glyphs and the maximum unaccented height
   
  15.4.15 Maximum unaccented depth
  
   This measurement, on the em square, is from the baseline to the lowest
   point reached by any glyph, excluding any accents or diacritical
   marks.
   
   Diagram showing several glyphs and the maximum unaccented depth
   
  15.4.16 Panose-1 number
  
   Panose-1 is an industry standard TrueType font classification and
   matching technology. The PANOSE system consists of a set of ten
   numbers that categorize the key attributes of a Latin typeface, a
   classification procedure for creating those numbers, and Mapper
   software that determines the closest possible font match given a set
   of typefaces. The system could, with modification, also be used for
   Greek and Cyrillic, but is not suitable for unicameral and ideographic
   scripts (Hebrew, Armenian, Arabic, Chinese/Japanese/Korean).
   
  15.4.17 Range of ISO 10646 characters
  
   This indicates the glyph repertoire of the font, relative to ISO 10646
   (Unicode). Since this is sparse (most fonts do not cover the whole of
   ISO 10646) this descriptor lists blocks or ranges which do have some
   coverage (no promise is made of complete coverage) and is used to
   eliminate unsuitable fonts (ones that will not have the required
   glyphs). It does not indicate that the font definitely has the
   required glyphs, only that it is worth downloading and looking at the
   font. See [ISO10646] for information about useful documents.
   
   This method is extensible to future allocation of characters in
   Unicode, without change of syntax and without invalidating existing
   content.
   
   Font formats that do not include this information, explicitly or
   indirectly, may still use this characteristic, but the value must be
   supplied by the document or style sheet author.
   
   There are other classifications into scripts, such as the Monotype
   system (see [MONOTYPE]) and a proposed ISO script system. These are
   not readily extensible.
   
   Because of this, classification of glyph repertoires by the range of
   ISO 10646 characters that may be represented with a particular font is
   used in this specification. This system is extensible to cover any
   future allocation.
   
  15.4.18 Top Baseline
  
   This gives the position in the em square of the top baseline. The top
   baseline is used by Sanscrit-derived scripts for alignment, just as
   the bottom baseline is used for Latin, Greek and Cyrillic scripts.
   
  15.4.19 Vertical stem width
  
   This is the width of vertical (or near-vertical) stems of glyphs. This
   information is often tied to hinting, and may not be directly
   accessible in some font formats. The measurement should be for the
   dominant vertical stem in the font because there might be different
   groupings of vertical stems (e.g., one main one, and one lighter
   weight one as for an uppercase M or N).
   
  15.4.20 Vertical stroke angle
  
   This is the angle, in degrees counterclockwise from the vertical, of
   the dominant vertical strokes of the font. The value is negative for
   fonts that slope to the right, as almost all italic fonts do. This
   descriptor may also be specified for oblique fonts, slanted fonts,
   script fonts, and in general for any font whose vertical strokes are
   not precisely vertical. A non-zero value does not of itself indicate
   an italic font.
   
15.5 Font matching algorithm

   This specification extends the algorithm given in the CSS1
   specification. This algorithm reduces down to the algorithm in the
   CSS1 specification when the author and reader style sheets do not
   contain any @font-face rules.
   
   Matching of descriptors to font faces must be done carefully. The
   descriptors are matched in a well-defined order to insure that the
   results of this matching process are as consistent as possible across
   UAs (assuming that the same library of font faces and font
   descriptions is presented to each of them). This algorithm may be
   optimized, provided that an implementation behaves as if the algorithm
   had been followed exactly.
   
    1. The user agent makes (or accesses) a database of relevant
       font-face descriptors of all the fonts of which the UA is aware.
       If there are two fonts with exactly the same descriptors, one of
       them is ignored. The UA may be aware of a font because:
          + it has been installed locally
          + it is declared using an @font-face rule in one of the style
            sheets linked to or contained in the current document
          + it is used in the UA default style sheet, which conceptually
            exists in all UAs and is considered to have full @font-face
            rules for all fonts which the UA will use for default
            presentation, plus @font-face rules for the five special
            generic font families (see 'font-family') defined in CSS2
    2. At a given element and for each character in that element, the UA
       assembles the font properties applicable to that element. Using
       the complete set of properties, the UA uses the 'font-family'
       descriptor to choose a tentative font family. Thus, matching on a
       family name will succeed before matching on some other descriptor.
       The remaining properties are tested against the family according
       to the matching criteria described with each descriptor. If there
       are matches for all the remaining properties, then that is the
       matching font face for the given element.
    3. If there is no matching font face within the 'font-family' being
       processed by step 2, UAs which implement intelligent matching may
       proceed to examine other descriptors such as x-height, glyph
       widths, and panose-1 to identify a different tentative font
       family. If there are matches for all the remaining descriptors,
       then that is the matching font face for the given element. The
       font-family descriptor that is reflected into the CSS2 properties
       is the font family that was requested, not whatever name the
       intelligently matched font may have. UAs that do not implement
       intelligent matching are considered to fail at this step.
    4. If there is no matching font face within the 'font-family' being
       processed by step 3, UAs that implement font downloading may
       proceed to examine the src descriptor of the tentative font face
       identified in step 2 or 3 to identify a network resource that is
       available, and of the correct format. If there are matches for all
       the remaining descriptors, then that is the matching font face for
       the given element and the UA may attempt to download this font
       resource. The UA may choose to block on this download or may
       choose to proceed to the next step while the font downloads. UAs
       that do not implement font download, or are not connected to a
       network, or where the user preferences have disabled font
       download, or where the requested resource is unavailable for
       whatever reason, or where the downloaded font cannot be used for
       whatever reason, are considered to fail at this step.
    5. If there is no matching font face within the 'font-family' being
       processed by step 3, UAs that implement font synthesis may proceed
       to examine other descriptors such as x-height, glyph widths, and
       panose-1 to identify a different tentative font family for
       synthesis. If there are matches for all the remaining descriptors,
       then that is the matching font face for the given element and
       synthesis of the faux font may begin. UAs that do not implement
       font synthesis are considered to fail at this step.
    6. If all of steps 3, 4 and 5 fail, and if there is a next
       alternative 'font-family' in the font set, then repeat from step 2
       with the next alternative 'font-family'.
    7. If there is a matching font face, but it doesn't contain glyph(s)
       for the current character(s), and if there is a next alternative
       'font-family' in the font sets, then repeat from step 2 with the
       next alternative 'font-family'. The 'unicode-range' descriptor may
       be used to rapidly eliminate from consideration those font faces
       that do not have the correct glyphs. If the 'unicode-range'
       descriptor indicates that a font contains some glyphs in the
       correct range, it may be examined by the UA to see if it has that
       particular one.
    8. If there is no font within the family selected in 2, then use the
       inherited or UA-dependent 'font-family' value and repeat from step
       2, using the best match that can be obtained within this font. If
       a particular character cannot be displayed using this font, the UA
       should indicate that a character is not being displayed (for
       example, using the 'missing character' glyph).
    9. UAs that implement progressive rendering and have pending font
       downloads may, once download is successful, use the downloaded
       font as a font family. If the downloaded font is missing some
       glyphs that the temporary progressive font did contain, the
       downloaded font is not used for that character and the temporary
       font continues to be used.
       
   Note. The above algorithm can be optimized to avoid having to revisit
   the CSS2 properties for each character. 
   
   The per-descriptor matching rules from (2) above are as follows:
   
    1. 'font-style' is tried first. 'italic' will be satisfied if there
       is either a face in the UA's font database labeled with the CSS
       keyword 'italic' (preferred) or 'oblique'. Otherwise the values
       must be matched exactly or font-style will fail.
    2. 'font-variant' is tried next. 'normal' matches a font not labeled
       as 'small-caps'; 'small-caps' matches (1) a font labeled as
       'small-caps', (2) a font in which the small caps are synthesized,
       or (3) a font where all lowercase letters are replaced by
       uppercase letters. A small-caps font may be synthesized by
       electronically scaling uppercase letters from a normal font.
    3. 'font-weight' is matched next, it will never fail. (See
       'font-weight' below.)
    4. 'font-size' must be matched within a UA-dependent margin of
       tolerance. (Typically, sizes for scalable fonts are rounded to the
       nearest whole pixel, while the tolerance for bitmapped fonts could
       be as large as 20%.) Further computations, e.g. by 'em' values in
       other properties, are based on the 'font-size' value that is used,
       not the one that is specified.
       
  15.5.1 Mapping font weight values to font names
  
   The 'font-weight' property values are given on a numerical scale in
   which the value '400' (or 'normal') corresponds to the "normal" text
   face for that family. The weight name associated with that face will
   typically be Book, Regular, Roman, Normal or sometimes Medium.
   
   The association of other weights within a family to the numerical
   weight values is intended only to preserve the ordering of weights
   within that family. User agents must map names to values in a way that
   preserves visual order; a face mapped to a value must not be lighter
   than faces mapped to lower values. There is no guarantee on how a user
   agent will map font faces within a family to weight values. However,
   the following heuristics tell how the assignment is done in typical
   cases:
   
     * If the font family already uses a numerical scale with nine values
       (as e.g. OpenType does), the font weights should be mapped
       directly.
     * If there is both a face labeled Medium and one labeled Book,
       Regular, Roman or Normal, then the Medium is normally assigned to
       the '500'.
     * The font labeled "Bold" will often correspond to the weight value
       '700'.
     * If there are fewer then 9 weights in the family, the default
       algorithm for filling the "holes" is as follows. If '500' is
       unassigned, it will be assigned the same font as '400'. If any of
       the values '600', '700', '800', or '900' remains unassigned, they
       are assigned to the same face as the next darker assigned keyword,
       if any, or the next lighter one otherwise. If any of '300', '200',
       or '100' remains unassigned, it is assigned to the next lighter
       assigned keyword, if any, or the next darker otherwise.
       
   There is no guarantee that there will be a darker face for each of the
   'font-weight' values; for example, some fonts may have only a normal
   and a bold face, others may have eight different face weights.
   
   The following two examples show typical mappings.
   
   Assume four weights in the "Rattlesnake" family, from lightest to
   darkest: Regular, Medium, Bold, Heavy.
   
   CAPTION: First example of font-weight mapping
   
   Available faces Assignments Filling the holes
   "Rattlesnake Regular" 400 100, 200, 300
   "Rattlesnake Medium" 500
   "Rattlesnake Bold" 700 600
   "Rattlesnake Heavy" 800 900
   
   Assume six weights in the "Ice Prawn" family: Book, Medium, Bold,
   Heavy, Black, ExtraBlack. Note that in this instance the user agent
   has decided not to assign a numeric value to "Example2 ExtraBlack".
   
   CAPTION: Second example of font-weight mapping
   
   Available faces Assignments Filling the holes
   "Ice Prawn Book" 400 100, 200, 300
   "Ice Prawn Medium" 500
   "Ice Prawn Bold" 700 600
   "Ice Prawn Heavy" 800
   "Ice Prawn Black" 900
   "Ice Prawn ExtraBlack" (none)
   
  15.5.2 Examples of font matching
  
   The following example defines a specific font face, Alabama Italic. A
   panose font description and source URI for retrieving a truetype
   server font are also provided. Font-weight and font-style descriptors
   are provided to describe the font. The declaration says that the
   weight will also match any request in the range 300 to 500. The font
   family is Alabama and the adorned font name is Alabama Italic.
   
@font-face {
  src: local(Alabama Italic),
       url(http://www.fonts.org/A/alabama-italic) format(truetype);
  panose-1: 2 4 5 2 5 4 5 9 3 3;
  font-family: Alabama, serif;
  font-weight:   300, 400, 500;
  font-style:  italic, oblique;
}

   The next example defines a family of fonts. A single URI is provided
   for retrieving the font data. This data file will contain multiple
   styles and weights of the named font. Once one of these @font-face
   definitions has been dereferenced, the data will be in the UA cache
   for other faces that use the same URI.
   
@font-face {
  src: local(Helvetica Medium),
       url(http://www.fonts.org/sans/Helvetica_family) format(truedoc);
  font-family: "Helvetica";
  font-style: normal
}
@font-face {
  src: local(Helvetica Oblique),
       url(http://www.fonts.org/sans/Helvetica_family) format(truedoc);
  font-family: "Helvetica";
  font-style: oblique;
  slope: -18
}

   The following example groups three physical fonts into one virtual
   font with extended coverage. In each case, the adorned font name is
   given in the src descriptor to allow locally installed versions to be
   preferentially used if available. A fourth rule points to a font with
   the same coverage, but contained in a single resource.

@font-face {
  font-family: Excelsior;
  src: local(Excelsior Roman), url(http://site/er) format(intellifont);
  unicode-range: U+??; /* Latin-1 */
}
@font-face {
  font-family: Excelsior;
  src: local(Excelsior EastA Roman), url(http://site/ear) format(intellifont);
  unicode-range: U+100-220; /* Latin Extended A and B */
}
@font-face {
  font-family: Excelsior;
  src: local(Excelsior Cyrillic Upright), url(http://site/ecr) format(intellifo
nt);
  unicode-range: U+4??; /* Cyrillic */
}
@font-face {
  font-family: Excelsior;
  src: url(http://site/excels) format(truedoc);
  unicode-range: U+??,U+100-220,U+4??;
}

   This next example might be found in a UA's default style sheet. It
   implements the CSS2 generic font family, serif by mapping it to a wide
   variety of serif fonts that might exist on various platforms. No
   metrics are given since these vary between the possible alternatives.

@font-face {
  src: local(Palatino),
          local(Times New Roman),
          local(New York),
          local(Utopia),
          url(http://somewhere/free/font);
  font-family: serif;
  font-weight: 100, 200, 300, 400, 500;
  font-style: normal;
  font-variant: normal;
  font-size: all
}
     _________________________________________________________________
     _________________________________________________________________
   
                                  16 Text
                                      
   Contents
     * 16.1 Indentation: the 'text-indent' property
     * 16.2 Alignment: the 'text-align' property
     * 16.3 Decoration
          + 16.3.1 Underlining, overlining, striking, and blinking: the
            'text-decoration' property
          + 16.3.2 Text shadows: the 'text-shadow' property
     * 16.4 Letter and word spacing: the 'letter-spacing' and
       'word-spacing' properties
     * 16.5 Case
          + 16.5.1 Capitalization: the 'text-transform' property
          + 16.5.2 Special first letter/first line
     * 16.6 White space: the 'white-space' property
          + 16.6.1 Line breaks
       
   The properties defined in the following sections affect the visual
   presentation of characters, spaces, words, and paragraphs.
   
16.1 Indentation: the 'text-indent' property

   'text-indent'
          Value:   <length> | <percentage> | inherit
          Initial:   0
          Applies to:   block-level elements
          Inherited:   yes
          Percentages:   refer to width of containing block
          Media:   visual
          
   This property specifies the indentation of the first line of text in a
   block. More precisely, it specifies the indentation of the first box
   that flows into the block's first line box. The box is indented with
   respect to the left (or right, for right-to-left layout) edge of the
   line box. User agents should render this indentation as blank space.
   
   Values have the following meanings:
   
   <length>
          The indentation is a fixed length.
          
   <percentage> 
          The indentation is a percentage of the containing block width.
          
   The value of 'text-indent' may be negative, but there may be
   implementation-specific limits.
   
   The following example causes a 3em text indent.
  P { text-indent: 3em }

16.2 Alignment: the 'text-align' property

   'text-align'
          Value:   left | right | center | justify | <string> | inherit
          Initial:   depends on user agent and writing direction
          Applies to:   block-level elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property describes how a block of text is aligned. Values have
   the following meanings:
   
   left, right, center, and justify
          Left, right, center, and double justify text, respectively.
          
   <string>
          Specifies a string on which cells in a table column will align
          (see the section on horizontal alignment in a column for
          details and an example). This value applies only to table
          columns.
          
   A block of text is a stack of line boxes. In all cases except for
   'justify', this property specifies how the inline boxes within each
   line box align with respect to the line box's left and right sides;
   alignment is not with respect to the viewport. In the case of
   'justify', the UA may stretch the inline boxes in addition to
   adjusting their positions.
   
   In this example, note that since 'text-align' is inherited, all
   block-level elements inside the DIV element with 'class=center' will
   be centered.

  DIV.center { text-align: center }

   Note. The actual justification algorithm used is user-agent and
   written language dependent.
   
   Conforming HTML user agents may interpret the value 'justify' as
   'left' or 'right', depending on whether the element's default writing
   direction is left-to-right or right-to-left, respectively.
   
16.3 Decoration

  16.3.1 Underlining, overlining, striking, and blinking: the 'text-decoration'
  property
  
   'text-decoration'
          Value:   none | [ underline || overline || line-through ||
          blink ] | inherit
          Initial:   none
          Applies to:   all elements
          Inherited:   no (see prose)
          Percentages:   N/A
          Media:   visual
          
   This property describes decorations that are added to the text of an
   element. If the property is specified for a block-level element, it
   affects all inline-level descendants of the element. If it is
   specified for (or affects) an inline-level element, it affects all
   boxes generated by the element. If the element has no content or no
   text content (e.g., the IMG element in HTML), user agents must ignore
   this property.
   
   Values have the following meanings:
   
   none
          Produces no text decoration.
          
   underline
          Each line of text is underlined.
          
   overline
          Each line of text has a line above it.
          
   line-through
          Each line of text has a line through the middle
          
   blink
          Text blinks (alternates between visible and invisible).
          Conforming user agents are not required to support this value.
          
   The color(s) required for the text decoration should be derived from
   the 'color' property value.
   
   This property is not inherited, but descendant boxes of a block box
   should be rendered with the same decoration (e.g., they should all be
   underlined). The color of decorations should remain the same even if
   descendant elements have different 'color' values.
   
   In the following example for HTML, the text content of all A elements
   acting as hyperlinks will be underlined:
   
  A[href] { text-decoration: underline }

  16.3.2 Text shadows: the 'text-shadow' property
  
   'text-shadow'
          Value:   none | [<color> || <length> <length> <length>? ,]*
          [<color> || <length> <length> <length>?] | inherit
          Initial:   none
          Applies to:   all
          Inherited:   no (see prose)
          Percentages:   N/A
          Media:   visual
          
   This property accepts a comma-separated list of shadow effects to be
   applied to the text of the element. The shadow effects are applied in
   the order specified and may thus overlay each other, but they will
   never overlay the text itself. Shadow effects do not alter the size of
   a box, but may extend beyond its boundaries. The stack level of the
   shadow effects is the same as for the element itself.
   
   Each shadow effect must specify a shadow offset and may optionally
   specify a blur radius and a shadow color.
   
   A shadow offset is specified with two <length> values that indicate
   the distance from the text. The first length value specifies the
   horizontal distance to the right of the text. A negative horizontal
   length value places the shadow to the left of the text. The second
   length value specifies the vertical distance below the text. A
   negative vertical length value places the shadow above the text.
   
   A blur radius may optionally be specified after the shadow offset. The
   blur radius is a length value that indicates the boundaries of the
   blur effect. The exact algorithm for computing the blur effect is not
   specified.
   
   A color value may optionally be specified before or after the length
   values of the shadow effect. The color value will be used as the basis
   for the shadow effect. If no color is specified, the value of the
   'color' property will be used instead.
   
   Text shadows may be used with the :first-letter and :first-line
   pseudo-elements.
   
   The example below will set a text shadow to the right and below the
   element's text. Since no color has been specified, the shadow will
   have the same color as the element itself, and since no blur radius is
   specified, the text shadow will not be blurred:
   
  H1 { text-shadow: 0.2em 0.2em }

   The next example will place a shadow to the right and below the
   element's text. The shadow will have a 5px blur radius and will be
   red.

  H2 { text-shadow: 3px 3px 5px red }

   The next example specifies a list of shadow effects. The first shadow
   will be to the right and below the element's text and will be red with
   no blurring. The second shadow will overlay the first shadow effect,
   and it will be yellow, blurred, and placed to the left and below the
   text. The third shadow effect will be placed to the right and above
   the text. Since no shadow color is specified for the third shadow
   effect, the value of the element's 'color' property will be used:
   
  H2 { text-shadow: 3px 3px red, yellow -3px 3px 2px, 3px -3px }

   Consider this example:
  SPAN.glow {
    background: white;
    color: white;
    text-shadow: black 0px 0px 5px;
  }

   Here, the 'background' and 'color' properties have the same value and
   the 'text-shadow' property is used to create a "solar eclipse" effect:
   
   Solar eclipse effect
   
   Note. This property is not defined in CSS1. Some shadow effects may
   render text invisible in UAs that only support CSS1. 
   
16.4 Letter and word spacing: the 'letter-spacing' and 'word-spacing'
properties

   'letter-spacing'
          Value:   normal | <length> | inherit
          Initial:   normal
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property specifies spacing behavior between text characters.
   Values have the following meanings:
   
   normal
          This value allows the user agent to alter the space between
          characters in order to justify text.
          
   <length>
          This value indicates inter-character space in addition to the
          default space between characters. Values may be negative, but
          there may be implementation-specific limits.
          
   Character spacing algorithms are user agent-dependent. Character
   spacing may also be influenced by justification (see the 'text-align'
   property).
   
   In this example, the space between characters in BLOCKQUOTE elements
   is increased by '0.1em'.

  BLOCKQUOTE { letter-spacing: 0.1em }

   In the following example, the user agent is not permitted to alter
   inter-character space, nor to add space:
   
  BLOCKQUOTE { letter-spacing: 0cm }   /* Same as '0' */

   When the resultant space between two characters is not the same as the
   default space, user agents should not use ligatures.
   
   Conforming HTML user agents may consider the value of the
   'letter-spacing' property to be 'normal'.
   
   'word-spacing'
          Value:   normal | <length> | inherit
          Initial:   normal
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property specifies spacing behavior between words. Values have
   the following meanings:
   
   normal
          This value allows the user agent to alter the space between
          words in order to justify text.
          
   <length>
          This value indicates inter-word space in addition to the
          default space between words. Values may be negative, but there
          may be implementation-specific limits.
          
   Word spacing algorithms are user agent-dependent. Word spacing may
   also be influenced by justification (see the 'text-align' property).
   
   In this example, the word-spacing between each word in H1 elements is
   increased by '1em'.

  H1 { word-spacing: 1em }

   Conforming HTML user agents may consider the value of the
   'word-spacing' property to be 'normal'.
   
16.5 Case

  16.5.1 Capitalization: the 'text-transform' property
  
   'text-transform'
          Value:   capitalize | uppercase | lowercase | none | inherit
          Initial:   none
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property controls capitalization effects of an element's text.
   Values have the following meanings:
   
   capitalize
          Puts the first character of each word in uppercase.
          
   uppercase
          Puts all characters of each word in uppercase.
          
   lowercase
          Puts all characters of each word in lowercase.
          
   none
          No capitalization effects.
          
   The actual transformation in each case is written language dependent.
   See RFC 2070 ([RFC2070]) for ways to find the language of an element.
   
   Conforming HTML user agents may consider the value of 'text-transform'
   to be 'none' for characters that are not from the Latin-1 repertoire
   and for elements in languages for which the transformation is
   different from that specified by the case-conversion tables of ISO
   10646 ([ISO10646]).
   
   In this example, all text in an H1 element is transformed to uppercase
   text.

  H1 { text-transform: uppercase }

  16.5.2 Special first letter/first line
  
   Please consult the sections on first line and first letter for
   information on specially formatting the first letter or line of a
   paragraph.
   
16.6 White space: the 'white-space' property

   'white-space'
          Value:   normal | pre | nowrap | inherit
          Initial:   normal
          Applies to:   block-level elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property declares how whitespace inside the element is handled.
   Values have the following meanings:
   
   normal
          This value allows user agents to collapse sequences of white
          space. Line breaks may be created by characters or elements
          (e.g., the BR element in HTML).
          
   pre
          This value prevents user agents from collapsing sequences of
          white space.
          
   nowrap
          This value suppresses line breaks within text except for those
          created by other elements (e.g., the BR element in HTML).
          
   The following examples show what whitespace behavior is expected from
   the PRE and P elements in HTML.

  PRE { white-space: pre }
  P   { white-space: normal }

   Conforming HTML user agents may ignore the 'white-space' property in
   author and user style sheets but must specify a value for it in the
   default style sheet.
   
  16.6.1 Line breaks
  
   To force a line break with CSS2, authors may specify one with the
   ':before' or ':after' pseudo-elements. Thus, the BR element in HTML
   may be described as follows:
   
  BR:before { content: "\A"}

   See "Generated content and automatic numbering" for explanations of
   the 'content' property and the use of the "\A" escape sequence.
     _________________________________________________________________
     _________________________________________________________________
   
                                  17 Lists
                                      
   Contents
     * 17.1 Visual formatting of lists
          + 17.1.1 List properties: 'list-style-type',
            'list-style-image', 'list-style-position', and 'list-style'
       
17.1 Visual formatting of lists

   CSS allows authors to control the visual presentation of lists in a
   number of ways:
     * Authors may specify a marker that appears before each list item.
     * Markers may be placed outside or inside the list item's content.
     * Markers may be represented by predefined shapes (bullets, circles,
       squares), numerals (arabic, roman, letters, etc.), or images.
     * With descendant selectors and child selectors, it's possible to
       specify different marker types depending on the depth of embedded
       lists.
       
   An element with a 'display' property value of 'list-item' generates
   two boxes: a block box that contains its content and an inline box
   that contains a marker. Only the content box is involved with
   positioning (e.g, in the normal flow). The position of the marker box
   (see the 'list-style-position' property) does not affect the position
   of the content box. CSS properties allow authors to specify the marker
   type (image, glyph, or number) and its position with respect to the
   content box (outside the content or at the beginning of content). CSS
   properties do not allow authors to specify distinct style (colors,
   fonts, alignment, etc.) for the list marker.
   
   The background properties apply to the content box only; the marker
   box is transparent.
   
   The declaration in the following HTML program causes LI elements to
   generate 'list-item' boxes. The 'list-style' value 'none' suppresses
   preceding markers.

<HTML>
<HEAD>
   <STYLE type="text/css">
      LI { display: list-item; list-style: none }
   </STYLE>
</HEAD>
<BODY>
   <UL>
      <LI> This is the first list item, formatted as a block.
      <LI> This is the second list item.
      <LI> This is the third.
   </UL>
</BODY>
</HTML>

   The list might be formatted as follows:
   
   A list with no markers.
   
   The illustration shows the relationship between the current left
   margin and the margins and padding of the list (UL) box and the list
   item (LI) boxes. (The lines delimiting the margins and padding are not
   rendered).
   
   If we change the 'list-style' to "square":
  LI { display: list-item; list-style: square }

   each list item will be preceded by a small square. However, the
   placement of the square does not affect the block formatting of the
   list item box:
   
   A list with square markers.
   
   The list properties in this chapter do not allow authors to control
   the separation between a list marker and the content of its list item.
   Instead, this may be achieved with markers. Note that markers
   specified with 'display: marker' replace list markers specified with
   the list properties defined in this chapter.
   
   Note. There is no "list" presentation for other types of list
   structures (e.g., "definition lists" declared by DL, DT, and DD in
   HTML). Each part of a definition list is simply a block element.
   
  17.1.1 List properties: 'list-style-type', 'list-style-image',
  'list-style-position', and 'list-style'
  
   'list-style-type'
          Value:   disc | circle | square | decimal | leading-zero |
          western-decimal | lower-roman | upper-roman | lower-greek |
          lower-alpha | lower-latin | upper-alpha | upper-latin | hebrew
          | armenian | georgian | cjk-ideographic | hiragana | katakana |
          hiragana-iroha | katakana-iroha | none | inherit
          Initial:   disc
          Applies to:   elements with the 'display' property set to
          'list-item'
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property specifies appearance of the list item marker if
   'list-style-image' has the value 'none' or if the image pointed to by
   the URI cannot be displayed. The value 'none' specifies no marker,
   otherwise there are three types of marker: glyphs, numbering systems,
   and alphabetic systems.
   
   Glyphs are specified with disc, circle, and square. Their exact
   rendering depends on the user agent.
   
   Numbering systems are specified with:
   
   western-decimal or decimal
          Decimal numbers, beginning with 1.
          
   leading-zero
          Decimal numbers 01, 02, 03, ... (or 001, 002, 003, ... if more
          than 99 items)
          
   lower-roman
          Lower case roman numerals (i, ii, iii, iv, v, etc.).
          
   upper-roman
          Upper case roman numerals (I, II, III, IV, V, etc.).
          
   hebrew
          Traditional Hebrew numbering.
          
   georgian
          Traditional Georgian numbering (an, ban, gan, ..., he, tan, in,
          in-an, ...).
          
   armenian
          Traditional Armenian numbering.
          
   cjk-ideographic
          Plain ideographic numbers
          
   hiragana
          a, i, u, e, o, ka, ki, ...
          
   katakana
          A, I, U, E, O, KA, KI, ...
          
   hiragana-iroha
          i, ro, ha, ni, ho, he, to, ...
          
   katakana-iroha
          I, RO, HA, NI, HO, HE, TO, ...
          
   A user agent that does not recognize a numbering system should use
   'western-decimal'.
   
   Note. This document does not specify the exact mechanism of each
   numbering system (e.g., how roman numerals are calculated). A future
   W3C Note may provide further clarifications. 
   
   Alphabetic systems are specified with:
   
   lower-latin or lower-alpha
          Lower case ascii letters (a, b, c, ... z).
          
   upper-latin or upper-alpha
          Upper case ascii letters (A, B, C, ... Z).
          
   lower-greek
          Lower case classical Greek alpha, beta, gamma, ... (&#941;,
          &#942;, &#943;, ...)
          
   This specification does not define how alphabetic systems wrap at the
   end of the alphabet. For instance, after 26 list items, 'lower-latin'
   rendering is undefined. Therefore, for long lists, we recommend that
   authors specify true numbers.
   
   For example, the following HTML document:
<HTML>
   <HEAD>
     <STYLE type="text/css">
          OL { list-style-type: lower-roman }
     </STYLE>
  </HEAD>
  <BODY>
    <OL>
      <LI> This is the first item.
      <LI> This is the second item.
      <LI> This is the third item.
    </OL>
  </BODY>
</HTML>

   might produce something like this:
  i This is the first item.
 ii This is the second item.
iii This is the third item.

   Note that the list marker alignment (here, right justified) depends on
   the user agent.
   
   Note. Future versions of CSS may provide more complete mechanisms for
   international numbering styles. 
   
   'list-style-image'
          Value:   <uri> | none | inherit
          Initial:   none
          Applies to:   elements with the 'display' property set to
          'list-item'
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property sets the image that will be used as the list item
   marker. When the image is available, it will replace the marker set
   with the 'list-style-type' marker.
   
   The following example sets the marker at the beginning of each list
   item to be the image "ellipse.png".

  UL { list-style-image: url(http://png.com/ellipse.png) }

   'list-style-position'
          Value:   inside | outside | inherit
          Initial:   outside
          Applies to:   elements with the 'display' property set to
          'list-item'
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property specifies the position of the marker box with respect to
   line item content box. Values have the following meanings:
   
   outside
          The list item marker is outside the box that is generated for
          the list item.
          
   inside
          The list item marker is the first inline box generated for the
          list item. The list item's contents flow after the marker box.
          
   For example:
<HTML>
  <HEAD>
    <STYLE type="text/css">
      UL         { list-style: outside }
      UL.compact { list-style: inside }
    </STYLE>
  </HEAD>
  <BODY>
    <UL>
      <LI>first list item comes first
      <LI>second list item comes second
    </UL>

    <UL class="compact">
      <LI>first list item comes first
      <LI>second list item comes second
    </UL>
  </BODY>
</HTML>

   The above example may be formatted as:
   
   Difference between inside and outside list style position
   
   In right-to-left text, the markers would have been on the right side
   of the box.
   
   'list-style'
          Value:   [ <'list-style-type'> || <'list-style-position'> ||
          <'list-style-image'> ] | inherit
          Initial:   not defined for shorthand properties
          Applies to:   elements with the 'display' property set to
          'list-item'
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   The 'list-style' property is a shorthand notation for setting the
   three properties 'list-style-type', 'list-style-image', and
   'list-style-position' at the same place in the style sheet.
   
  UL { list-style: upper-roman inside }  /* Any UL*/
  UL > UL { list-style: circle outside } /* Any UL child of a UL*/

   Although authors may specify 'list-style' information directly on list
   item elements (e.g., LI in HTML), they should do so with care. The
   following rules look similar, but the first declares a descendant
   selector and the second a (more specific) child selector.

  OL.alpha LI  { list-style: lower-alpha } /* Any LI descendant of an OL */
  OL.alpha > LI  { list-style: lower-alpha } /* Any LI child of an OL */

   Authors who use only the descendant selector may not achieve the
   results they expect. Consider the following rules:

<HTML>
  <HEAD>
    <STYLE type="text/css">
      OL.alpha LI  { list-style: lower-alpha }
      UL LI        { list-style: disc }
    </STYLE>
  </HEAD>
  <BODY>
    <OL class="alpha">
      <LI>level 1
      <UL>
         <LI>level 2
      </UL>
    </OL>
  </BODY>
</HTML>

   The desired rendering would have level 1 list items with 'lower-alpha'
   labels and level 2 items with 'disc' labels. However, the cascading
   order will cause the first style rule (which includes specific class
   information) to mask the second. The following rules solve the problem
   by employing a child selector instead:

    OL.alpha > LI  { list-style: lower-alpha }
    UL LI   { list-style: disc }

   Another solution would be to specify 'list-style' information only on
   the list type elements:

    OL.alpha  { list-style: lower-alpha }
    UL        { list-style: disc }

   Inheritance will transfer the 'list-style' values from OL and UL
   elements to LI elements. This is the recommended way to specify list
   style information.
   
   A URI value may be combined with any other value, as in:
  UL { list-style: url(http://png.com/ellipse.png) disc }

   In the example above, the 'disc' will be used when the image is
   unavailable.
   
   With a value of 'none', both 'list-style-type' and 'list-style-image'
   are set to 'none':

  UL { list-style: none }

   The result is that no list-item marker is displayed.
     _________________________________________________________________
     _________________________________________________________________
   
                                 18 Tables
                                      
   Contents
     * 18.1 Introduction to tables
     * 18.2 The CSS table model
          + 18.2.1 Anonymous table boxes
     * 18.3 Column selectors
     * 18.4 Tables in the visual rendering model
          + 18.4.1 Caption position and alignment
     * 18.5 Visual layout of table contents
          + 18.5.1 Row and column spans: 'column-span', and 'row-span'
          + 18.5.2 Table layers and transparency
          + 18.5.3 Table size algorithms: the 'table-layout' property
               o Fixed table layout
               o Automatic table layout
          + 18.5.4 Alignment of cell boxes
               o Vertical alignment in a row
               o Horizontal alignment in a column
          + 18.5.5 Dynamic row and column effects
     * 18.6 Borders
          + 18.6.1 The separated borders model
               o Borders around empty cells: the 'empty-cells' property
          + 18.6.2 The collapsing border model
               o Border conflict resolution
          + 18.6.3 Border styles
     * 18.7 Audio rendering of tables
          + 18.7.1 Speaking headers: the 'speak-header' property
       
18.1 Introduction to tables

   Tables represent relationships between data. Authors specify these
   relationships in the document language and specify their presentation
   in CSS, in two ways: visually and aurally.
   
   Authors may specify the visual rendering of a table as a rectangular
   grid of cells. Rows and columns of cells may be organized into row
   groups and column groups. Rows, columns, row groups, row columns, and
   cells may have borders drawn around them (there are two border models
   in CSS2). Authors may align data vertically or horizontally within a
   cell and align data in all cells of a row or column.
   
   Authors may also specify the aural rendering of a table; how headers
   and data will be spoken. In the document language, authors may label
   cells and groups of cells so that when rendered aurally, cell headers
   are spoken before cell data. In effect, this "serializes" the table:
   users browsing the table aurally hear a sequence of headers followed
   by data.
   
   Here is a simple three-row, three-column table described in HTML 4.0:
<TABLE>
<CAPTION>This is a simple 3x3 table</CAPTION>
<TR id="row1">
   <TH>Header 1      <TD>Cell 1        <TD>Cell 2
<TR id="row2">
   <TH>Header 2      <TD>Cell 3        <TD>Cell 4
<TR id="row3">
   <TH>Header 3      <TD>Cell 5        <TD>Cell 6
</TABLE>

   This code creates one table (the TABLE element), three rows (the TR
   elements), three header cells (the TH elements), and six data cells
   (the TD elements). Note that the three columns of this example are
   specified implicitly: there are as many columns in the table as
   required by header and data cells.
   
   The following CSS rule centers the text horizontally in the header
   cells and present the data with a bold font weight:
   
TH { text-align: center; font-weight: bold }

   The next rules align the text of the header cells on their baseline
   and vertically centers the text in each data cell:
   
TH { vertical-align: baseline }
TD { vertical-align: middle }

   The next rules specify that the top row will be surrounded by a 3px
   solid blue border and each of the other rows will be surrounded by a
   1px solid black border:
   
TABLE { border-spacing: none }
TR#row1 { border-top: 3px solid blue }
TR#row2 { border-top: 1px solid black }
TR#row3 { border-top: 1px solid black }

   Note, however, that the borders around the rows overlap where the rows
   meet. What color (black or blue) and thickness (1px or 3px) will the
   border between row1 and row2 be? We discuss this in the section on
   border conflict resolution.
   
   The following rule puts the table caption above the table:
   
CAPTION { caption-side: top }

   Finally, the following rule specifies that, when rendered aurally,
   each row of data is to be spoken as a "Header, Data, Data":
   
TH { speak-header: once }

   For instance, the first row would be spoken "Header1 Cell1 Cell2". On
   the other hand, with the following rule:
   
TH { speak-header: always }

   it would be spoken "Header1 Cell1 Header1 Cell2".
   
   The preceding example shows how CSS works with HTML 4.0 elements; in
   HTML 4.0, the semantics of the various table elements (TABLE, CAPTION,
   THEAD, TBODY, TFOOT, COL, COLGROUP, TH, and TD) are well-defined. In
   other document languages (such as XML applications), there may not be
   pre-defined table elements. Therefore, CSS2 allows authors to "map"
   document language elements to table elements via the 'display'
   property. For example, the following rule makes the FOO element act
   like an HTML TABLE element and the BAR element act like a CAPTION
   element:
   
FOO { display : table }
BAR { display : table-caption }

   We discuss the various table elements in the following section. In
   this specification, the term table element refers to any element
   involved in the creation of a table. An "internal" table element is
   one that produces a row, row group, column, column group, or cell.
   
18.2 The CSS table model

   The CSS table model is based on the HTML 4.0 table model, in which the
   structure of a table closely parallels the visual layout of the table.
   In this model, a table consists of an optional caption and any number
   of rows of cells. The table model is said to be "row primary" since
   authors specify rows, not columns, explicitly in the document
   language. Columns are derived once all the rows have been specified --
   the first cell of each row belongs to the first column, the second to
   the second column, etc.). Rows and columns may be grouped structurally
   and this grouping reflected in presentation (e.g., a border may be
   drawn around a group of rows).
   
   Thus, the table model consists of tables, captions, rows, row groups,
   columns, column groups, and cells.
   
   The CSS model does not require that the document language include
   elements that correspond to each of these components. For document
   languages (such as XML applications) that do not have pre-defined
   table elements, authors must map document language elements to table
   elements; this is done with the 'display' property. The following
   'display' values assign table semantics to an arbitrary element:
   
   table (In HTML: TABLE)
          Specifies that an element defines a block-level table: it is a
          rectangular block that participates in a block formatting
          context.
          
   inline-table (In HTML: TABLE)
          Specifies that an element defines an inline-level table: it is
          a rectangular block that participates in an inline formatting
          context).
          
   table-row (In HTML: TR)
          Specifies that an element is a row of cells.
          
   table-row-group (In HTML: TBODY)
          Specifies that an element groups one or more rows.
          
   table-header-group (In HTML: THEAD)
          Like 'table-row-group', but for visual rendering, the row group
          is always displayed before all other rows and rowgroups and
          after any top captions.
          
   table-footer-group (In HTML: TFOOT)
          Like 'table-row-group', but for visual rendering, the row group
          is always displayed after all other rows and rowgroups and
          before any bottom captions.
          
   table-column (In HTML: COL)
          Specifies that an element describes a column of cells.
          
   table-column-group (In HTML: COLGROUP)
          Specifies that an element groups one or more columns.
          
   table-cell (In HTML: TD, TH)
          Specifies that an element represents a table cell.
          
   table-caption (In HTML: CAPTION)
          Specifies a caption for the table.
          
   Elements with 'display' set to 'table-column' or 'table-column-group'
   are not rendered (exactly as if they had 'display: none'), but they
   are useful, because they may have attributes which induce a certain
   style for the columns they represent.
   
   The default style sheet for HTML 4.0 in the appendix illustrates the
   use of these values for HTML 4.0:
   
TABLE    { display: table }
TR       { display: table-row }
THEAD    { display: table-header-group }
TBODY    { display: table-row-group }
TFOOT    { display: table-footer-group }
COL      { display: table-column }
COLGROUP { display: table-column-group }
TD, TH   { display: table-cell }
CAPTION  { display: table-caption }

   User agents may ignore these 'display' property values for HTML
   documents, since authors should not alter an element's expected
   behavior.
   
  18.2.1 Anonymous table boxes
  
   Document languages other than HTML may not contain all the elements in
   the CSS2 table model. In these cases, the "missing" elements must be
   assumed in order for the table model to work. The missing elements
   generate anonymous boxes according to the following rules:
   
    1. Any table element will automatically generate necessary table
       boxes around itself, consisting of at least three nested boxes
       corresponding to a 'table'/'inline-table' element, a 'table-row'
       element, and a 'table-cell' element.
    2. If the parent of a 'table-cell' is not a 'table-row', a
       'table-row' element will be assumed as its parent, and this
       element will generate an anonymous box that spans all consecutive
       'table-cell' siblings.
    3. If the parent of a 'table-row' is not a 'table', 'inline-table',
       or 'row-group' element, the 'table-row' will be assumed to have a
       parent 'table' element that generates a box spanning all
       consecutive siblings also requiring a 'table' parent.
    4. If the parent of a 'table-row-group' is not a 'table' or
       'inline-table', the 'table-row-group' will be assumed to have a
       parent 'table' element that generates a box spanning all
       consecutive siblings also requiring a 'table' parent.
    5. 'table-cell' elements are inserted as children of a 'table-row'
       element to contain consecutive children that are not 'table-cell'
       elements.
       
   In this XML example, a 'table' element is assumed to contain the HBOX
   element:
   
<HBOX>
  <VBOX>George</VBOX>
  <VBOX>4287</VBOX>
  <VBOX>1998</VBOX>
</HBOX>

   because the associated style sheet is:
   
HBOX {display: table-row}
VBOX {display: table-cell}

   In this example, three 'table-cell' elements are assumed to contain
   the text in the ROWs. Note that the text is further encapsulated in
   anonymous inline boxes, as explained in visual rendering model:
   
<STACK>
  <ROW>This is the <D>top</D> row.</ROW>
  <ROW>This is the <D>middle</D> row.</ROW>
  <ROW>This is the <D>bottom</D> row.</ROW>
</STACK>

   The style sheet is:
   
STACK {display: inline-table}
ROW {display: table-row}
D {display: inline; font-weight: bolder}

   HTML user agents are not required to create anonymous boxes according
   to the above rules.
   
18.3 Column selectors

   Table cells may belong to two contexts: rows and columns. However, in
   the source document cells are descendants of rows, never of columns.
   Nevertheless, some aspects of cells can be influenced by setting
   properties on columns.
   
   The following properties apply to column and column-group elements:
   
   'border'
          The various border properties apply to columns only if
          'border-collapse' is set to 'collapse' on the table element. In
          that case, borders set on columns and column groups are input
          to the conflict resolution algorithm that selects the border
          styles at every cell edge.
          
   'background'
          The background properties set the background for cells in the
          column, but only if both the cell and row have transparent
          backgrounds. See "Table layers and transparency."
          
   'width'
          The 'width' property of the column only applies if the fixed
          layout algorithm is selected on the 'table-layout' property.
          
   'column-span'
          The number of grid columns spanned by this column or column
          group.
          
   'visibility'
          If the 'visibility' of a column is set to 'collapse', none of
          the cells in the column are rendered, and cells that span into
          other columns are clipped. In addition, the width of the table
          is diminished by the width the column would have taken up. See
          "Dynamic effects" below. Other values for 'visibility' have no
          effect.
          
   Here are some examples of style rules that set properties on columns.
   The first two rules together implement the "rules" attribute of HTML
   4.0 with a value of "cols". The third rule makes the "totals" column
   blue, the final two rules shows how to make a column a fixed size, by
   using the fixed layout algorithm.

COL {border-style: none solid}
TABLE {border-style: hidden}
COL.totals {background: blue}
TABLE {table-layout: fixed}
COL.totals {width: 5em}

18.4 Tables in the visual rendering model

   In terms of the visual rendering model, a table may behave like a
   block-level or replaced inline-level element.
   
   In both cases, the table element generates an anonymous box that
   contains the table box itself and the caption's box (if present). The
   table and caption boxes retain their own content, padding, margin, and
   border areas, and the dimensions of the rectangular anonymous box are
   the smallest required to contain both. Vertical margins collapse where
   the table box and caption box touch. Any repositioning of the table
   must move the entire anonymous box, not just the table box, so that
   the caption follows the table.
   
   A table with a caption above it; both have margins and the margins
   between them are collapsed, as is normal for vertical margins.
   
   Diagram of a table with a caption above it; the bottom margin of the
   caption is collapsed with the top margin of the table.
   
  18.4.1 Caption position and alignment
  
   'caption-side'
          Value:   top | bottom | left | right | inherit
          Initial:   top
          Applies to:   'table-caption' elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property specifies the position of the caption box with respect
   to the table box. Values have the following meanings:
   
   top
          Positions the caption box above the table box.
          
   bottom
          Positions the caption box below the table box.
          
   left
          Positions the caption box to the left of the table box.
          
   right
          Positions the caption box to the right of the table box.
          
   Captions above or below a 'table' element are rendered very much as if
   they were a block element before or after the table, except that (1)
   they inherit inheritable properties from the table, and (2) are not
   considered to be a block box for the purposes of any 'compact' or
   'run-in' element that may precede the table.
   
   The width of a caption that is above or below a 'table' element is
   computed as if the caption were a block-level child of the table's
   parent. In other words, the width of the caption is independent of the
   width of the table.
   
   The width of a caption that is on the left or right side of the table
   must be set explicitly. The default value ('auto') will result in the
   narrowest possible box.
   
   To align caption content horizontally within the caption box, use the
   'text-align' property. For vertical alignment of captions on the left
   or right side, use the 'vertical-align' property. The only meaningful
   values in this case are 'top', 'middle', and 'bottom'. All other
   values are treated the same as 'top'.
   
   In this example, the 'caption-side' property places captions below
   tables. The caption will be as wide as the parent of the table, and
   caption text will be left-justified.

CAPTION { caption-side: bottom;
          width: auto;    /* default */
          text-align: left }

   The following example shows how to put a caption in the left margin.
   The table itself is centered, by setting its left and right margins to
   'auto', and the whole box with table and caption is shifted into the
   left margin by the same amount as the width of the caption.

BODY {
    margin-left: 8em
}
TABLE {
    margin-left: auto;
    margin-right: auto
}
CAPTION {
    caption-side: left;
    margin-left: -8em;
    width: 8em;
    text-align: right;
    vertical-align: bottom
}

   Assuming the width of the table is less than the available width, the
   rendering will be similar to this:
   
   A centered table with a caption in the left margin of the page
   
   Diagram showing a centered table with the caption extending into the
   left margin, as a result of a negative 'margin-left' property.
   
18.5 Visual layout of table contents

   Like other elements of the document language, table elements generate
   rectangular boxes with content, padding, border, and margin areas.
   
  18.5.1 Row and column spans: 'column-span', and 'row-span'
  
   'row-span'
          Value:   <integer> | inherit
          Initial:   1
          Applies to:   'table-cell' elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   This property specifies the <integer> number of rows spanned by a
   cell.
   
   'column-span'
          Value:   <integer> | inherit
          Initial:   1
          Applies to:   'table-cell', 'table-column', and
          'table-column-group' elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   This property specifies the <integer> number of grid columns spanned
   by a cell, column, or column group.
   
   The visual layout of these boxes is governed by a rectangular,
   irregular grid of rows and columns. Each box occupies a whole number
   of grid cells, determined according to the following rules. These
   rules do not apply to HTML 4.0 or earlier HTML versions; HTML imposes
   its own limitations on row and column spans.
   
    1. Each row box occupies one row of grid cells. Together, the row
       boxes fill the table from top to bottom in the order they occur in
       the source document (i.e., the table occupies exactly as many grid
       rows as there are row elements).
    2. A row group occupies the same grid cells as the rows it contains.
    3. Columns are placed next to each other in the order they occur.
       Each one occupies the number of grid columns given by its
       'column-span' property. The first column may be either on the left
       or on the right, depending on the value of the 'direction'
       property of the table.
    4. A column group occupies the same grid cells as the columns it
       contains.
       [Not true, need correct description.]
    5. Structurally speaking, each cell belongs to one row and column;
       this row and column determine the coordinates of the cell.
       Visually, each cell occupies a rectangle of 'column-span' grid
       cells wide and 'row-span' grid cells high. The top row of this
       rectangle of grid cells must be the row specified by the cell's
       parent. The rectangle must be as far to the left as possible, but
       it may not overlap with any other cell, and must be to the right
       of all cells in the same row that are earlier in the source
       document. (If the 'direction' of the table is 'right-to-left',
       interchange "left" and "right" in the previous sentence.)
    6. Cells are 'row-span' high only if there are enough rows: a cell
       cannot extend below the last row box; it is made shorter until it
       fits.
       
   Here is an example:
<TABLE>
<TR><TD>1 <TD rowspan=2>2 <TD>3 <TD>4
<TR><TD colspan=2>5
</TABLE>

   This table is in error. According to HTML 4.0, the rendering on the
   left is allowed. However, CSS2 UAs must render this table as in the
   figure on the right:
   
   two renderings of an erroneous table
   
   Two renderings of an erroneous HTML 4.0 table. The rendering on the
   left is allowed by HTML 4.0, but in CSS2 the one on the right is
   compulsory.
   
  18.5.2 Table layers and transparency
  
   For the purposes of finding the background of each table cell, the
   different table elements may be thought of as being on six
   superimposed layers. The background set on an element in one of the
   layers will only be visible if the layers above it have a transparent
   background.
   
   schema of table layers
   
   Schema of table layers.
   
    1. The lowest layer is a single plane, representing the table box
       itself. Like all boxes, it may be transparent.
    2. The next layer contains the column groups. The columns groups are
       as tall as the table, but they need not cover the whole table
       horizontally.
    3. On top of the column groups are the areas representing the column
       boxes. Like column groups, columns are as tall as the table, but
       need not cover the whole table horizontally.
    4. Next is the layer containing the row groups. Each row group is as
       wide as the table. Together, the row groups completely cover the
       table from top to bottom.
    5. The last but one layer contains the rows. The rows also cover the
       whole table.
    6. The topmost layer contains the cells themselves. As the figure
       shows, although all rows contain the same number of cells, not
       every cell may have specified content These "empty" cells are
       transparent, letting lower layers shine through.
       
   In the following example, the first row contains four cells, but the
   second row contains no cells, and thus the table background shines
   through, except where a cell from the first row spans into this row.
   The following HTML code and style rules
   
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0//EN">
<HTML>
  <HEAD>
    <STYLE type="text/css">
      TABLE { background: #ff0; border-collapse: collapse }
      TD { background: red; border: double black }
    </STYLE>
  </HEAD>
  <BODY>
    <P>
    <TABLE>
      <TR>
        <TD> 1
        <TD rowspan="2"> 2
        <TD> 3
        <TD> 4
      </TR>
      <TR><TD></TD></TR>
    </TABLE>
  </BODY>
</HTML>

   might be rendered as follows:
   
   Table with three empty cells in bottom row
   
   Table with three empty cells in the bottom row.
   
  18.5.3 Table size algorithms: the 'table-layout' property
  
   CSS does not define an "optimal" layout for tables since, in many
   cases, what is optimal is a matter of taste. CSS does define
   constraints that user agents must respect when laying out a table.
   User agents may use any algorithm they wish to do so, and are free to
   prefer rendering speed over precision, except when the "fixed layout
   algorithm" is selected.
   
   'table-layout'
          Value:   auto | fixed | inherit
          Initial:   auto
          Applies to:   'table' and 'inline-table' elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual
          
   The 'table-layout' property controls the algorithm used to lay out the
   table cells, rows, and columns. Values have the following meaning:
   
   fixed
          Use the fixed table layout algorithm
          
   auto
          Use any automatic table layout algorithm
          
   The two algorithms are described below.
   
    Fixed table layout
    
   With this (fast) algorithm, the horizontal layout of the table does
   not depend on the contents of the cells; it only depends on the
   table's width and the width of the columns.
   
   The table's width is determined by the 'width' property. If the value
   is 'auto', the table is as wide as the available horizontal space.
   
   The width of each column is determined as follows:
   
    1. A column element with a value other than 'auto' for the 'width'
       property sets the width for that columns.
    2. Otherwise, a cell in the first row with a value other than 'auto'
       for the 'width' property sets the width for that column. If the
       cell spans columns, the width is divided over the columns.
    3. Any remaining columns equally divide the remaining space.
       
   In this manner, the user agent lays out the first row of the table
   immediately upon receiving the content. All subsequent rows have the
   same widths of columns of cells; nothing in subsequent rows can affect
   the widths of the columns. Any cell that has content that overflows
   its dimensions uses the 'overflow' property to determine how to handle
   the overflow content. However, a value of 'visible' will not increase
   the cell box dimensions; cell content will flow into the adjacent
   cell.
   
   With this algorithm, the height of a row of cells may either be
   computed dynamically (the 'auto' value), or may be set explicitly, in
   which case overflow is handled in the same manner as with the width
   dimension.
   
   It is possible that the sum of the widths of the columns exceeds the
   table's width. In that case the larger width is used as the actual
   value of the table's 'width' property.
   
    Automatic table layout
    
   This is a multiple-pass algorithm in which a table width is given by
   the width of its columns (and intervening borders). This algorithm
   reflects the behavior of several popular HTML user agents at the
   writing of this specification. UAs are not required to implement this
   algorithm to determine the table layout in the case that
   'table-layout' is 'auto'; they can use any other algorithm.
   
   In this algorithm, the width of each column is based on the largest
   unbreakable element in a cell in that column. This algorithm may be
   inefficient since it may demand multiple passes and requires the user
   agent to have access to all the content in the table before
   determining the final layout.
   
   For this algorithm, a value of 'auto' for the 'width' property for the
   table element means that the final table width is computed
   dynamically: it is the sum of the column widths and the borders
   between them.
   
   Column widths are determined as follows:
   
    1. For each cell determine the minimum and maximum widths needed.
       Cells with a given 'width' get a minimum width equal to the
       greater of the specified width and the minimum needed width.
    2. For each column determine a maximum and minimum width from the
       cells with a colspan of 1. If the column has a 'width' greater
       than the minimum over the cells, then the 'width' is used as the
       minimum width for the column.
    3. For each cell with a colspan of more than one, increase the
       minimum and maximum widths of the columns it spans enough so the
       combined minimum/maximum widths are at least those of the cell. If
       possible, widen all spanned columns by approximately the same
       amount.
       
   Now we have a maximum and minimum width per column. We now determine
   final column widths. Cell spacing is appropriately added into these
   calculations.
   
   If there is a table width given, and it is larger than the minimum
   width needed, use it, and distribute the width over the columns in
   some way.
   
   Note that a table may thus be wider than its 'width' property.
   
   If the table width is 'auto', there are three cases:
    1. If the maximum needed width for the table is less than the width
       of the table's containing block, use the maximum width.
    2. If the minimum width needed is greater than the width of the
       containing block, use the minimum width.
    3. Otherwise, use the width of the containing block and distribute
       the width over the columns in some way.
       
   A percentage is relative to the table width. If the table's width is
   'auto', a percentage represents a constraint on the column's width,
   which a UA should try to satisfy. (Obviously, this is not always
   possible: if the column's width is '110%', the constraint cannot be
   satisfied.)
   
   Note. In this algorithm, rows (and row groups) and columns (and column
   groups) both constrain and are constrained by the dimensions of the
   cells they contain. Setting the width of a column may indirectly
   influence the height of a row, and vice versa.
   
  18.5.4 Alignment of cell boxes
  
   Cells may be aligned vertically (within a row) and horizontally
   (within a column).
   
   Note. Table cells may be relatively and absolutely positioned, but
   this is not recommended: positioning and floating remove a box from
   the flow, affecting table alignment. 
   
    Vertical alignment in a row
    
   The height of a cell's box is constrained by the rows that contain it.
   A cell may be smaller than a row, in which case its vertical alignment
   is governed by the 'vertical-align' property (much as an inline box is
   aligned within a line box).
   
   Each cell's content has a baseline, a top, a middle, and a bottom, and
   so does the row itself. The value of the 'vertical-align' property of
   the cells determines on which of these lines they are aligned. In the
   context of tables, values have the following meanings:
   
   baseline
          The baseline of the cell is put at the same height as the
          baseline of the row (see below for the definition of baselines
          of cells and rows)
          
   top
          The top of the cell box is aligned with the top of the row
          
   bottom
          The bottom of the cell box is aligned with the bottom of the
          row
          
   middle
          The center of the cell is aligned with the center of the row
          
   sub, super, text-top, text-bottom
          These values do not apply to cells; the cell is aligned at the
          baseline instead
          
   The baseline of a cell is the baseline of the first line of text in
   the cell. If there is no text, the baseline is the baseline of
   whatever object is displayed in the cell, or, if it has none, the
   bottom of the cell box. The maximum distance between the top of the
   cell box and the baseline over all cells that have
   'vertical-align:baseline' is used to set the baseline of the row. Here
   is an example:
   
   Example of vertically aligning the cells
   
   Diagram showing the effect of various values of 'vertical-align' on
   table cells.
   
   Cell boxes 1 and 2 are aligned at their baselines. Cell box 2 has the
   largest height above the baseline, so that determines the baseline of
   the row. Note that if there is no cell box aligned at its baseline,
   the row will not have (nor need) a baseline.
   
   To avoid ambiguous situations, the alignment of cells proceeds in a
   certain order. First the cells that are aligned on their baseline are
   positioned. This will establish the baseline of the row. Next the
   cells with alignment 'top' are positioned.
   
   The row now has a top, possibly a baseline, and a provisional height,
   which is the distance from the top to the lowest bottom of the cells
   positioned so far. (See conditions on the cell padding below.)
   
   If any of the remaining cells, those aligned at the bottom or the
   middle, have a height that is larger than the current height of the
   row, the height of the row will be increased to the maximum of those
   cells, by lowering the bottom.
   
   Finally the remaining cells are positioned.
   
   Cells that are smaller than the height of the row will get extra
   padding added at their top or bottom. As a result, the padding area at
   the top and bottom of each cell box after positioning must be at least
   as large as the 'padding' property specifies.
   
    Horizontal alignment in a column
    
   The horizontal alignment of a cell's contents within a cell box is
   specified with the 'text-align' property.
   
   Cell boxes in the same column may also be aligned horizontally along a
   common axis, specified by the 'text-align' property. The <string>
   value of this property specifies how cell boxes in the same column
   will align horizontally.
   
   When the 'text-align' property for more than one cell in a column is
   set to a <string> the content of those cells is placed in such a way
   that the beginnings of the first occurrence of the string in the
   respective cells are placed directly over each other.
   
   If a cell has a string-values 'text-align', but the string doesn't
   occur in the cell, the cell is aligned at the end of its content.
   
   Note that the strings do not have to be the same for each cell,
   although they usually are.
   
   Aligning text in this way is only useful if the text fits on one line.
   The result is undefined if the text spans more than one line.
   
   The following style sheet:
   
   TD { text-align: "." }
   TD:before { text-align: right; content: "$" }

   will cause the column of dollar figures in the following HTML table:
   
  <TABLE>
  <COL width="40">
  <TR> <TH>Long distance calls
  <TR> <TD> 1.30
  <TR> <TD> 2.50
  <TR> <TD> 10.80
  <TR> <TD> 111.01
  <TR> <TD> 85.
  <TR> <TD> 90
  <TR> <TD> .05
  <TR> <TD> .06
  </TABLE>

   to align along the decimal point. For fun, we have used the :before
   pseudo-element to insert a dollar sign before each figure:
   
Long distance calls
              $1.30
              $2.50
             $10.80
            $111.01
             $85.
             $90
               $.05
               $.06

  18.5.5 Dynamic row and column effects
  
   The 'visibility' property takes the value 'collapse' for row, row
   group, column, and column group elements. This value causes the entire
   row or column to be removed from the display, and the space normally
   taken up by the row or column to be made available for other content.
   The suppression of the row or column, however, does not otherwise
   affect the layout of the table. This allows dynamic effects to remove
   table rows or columns without forcing a re-layout of the table in
   order to account for the potential change in column constraints.
   
18.6 Borders

   There are two distinct models for setting borders on table cells in
   CSS. One is most suitable for so-called "2½D" borders around
   individual cells, the other is suitable for borders that are
   continuous from one end of the table to the other. Many border styles
   can be achieved with either model, so it is often a matter of taste
   which one is used.
   
   'border-collapse'
          Value:   collapse | separate | inherit
          Initial:   collapse
          Applies to:   'table' and 'inline-table' elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   This property selects a table's border model. The value 'separate'
   selects the separated borders border model. The value 'collapse'
   selects the collapsing borders model. The models are described below.
   
  18.6.1 The separated borders model
  
   'border-spacing'
          Value:   <length> <length>? | inherit
          Initial:   0
          Applies to:   'table' and 'inline-table' elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   <length> <length>?
          Use the separated borders model. In this case, the lengths
          specify the distance that separate adjacent cell borders. If
          one length is specified, it gives both the horizontal and
          vertical spacing. If two are specified, the first gives the
          horizontal spacing and the second the vertical spacing. Lengths
          may not be negative.
          
   In this model, each cell has an individual border. The
   'border-spacing' property specifies the distance between the borders
   of adjacent cells. This space is filled with the background of the
   table element. Rows, columns, row groups, and column groups cannot
   have borders (i.e., user agents must ignore the border properties for
   those elements.
   
   The table in the figure below could be the result of a style sheet
   like this:

  TABLE      { border: outset 10pt;
               border-collapse: separate;
               border-spacing: 15pt }
  TD         { border: inset 5pt }
  TD.special { border: inset 10pt }  /* The top-left cell */

   A table with border-spacing
   
   A table with 'border-spacing' set to a length value. Note that each
   cell has its own border, and the table has a separate border as well.
   
   When this border model is used, the overall width of the table is the
   sum of the cells plus the border spacing between all borders. See the
   section on automatic table layout for more information about table
   dimension calculations.
   
    Borders around empty cells: the 'empty-cells' property
    
   'empty-cells'
          Value:   borders | no-borders | inherit
          Initial:   borders
          Applies to:   'table-cell' elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual
          
   In the separated borders model, this property controls the rendering
   of borders around cells that have no visible content. Empty cells and
   cells with the 'visibility' property set to 'hidden' are considered to
   have no visible content. Visible content includes "&nbsp;" and other
   whitespace except ASCII CR ("\0D"), LF ("\0A"), tab ("\09"), and space
   ("\20").
   
   When this property has the value 'borders', borders are drawn around
   empty cells (like normal cells).
   
   A value of 'no-borders' means that no borders are drawn around empty
   cells. Furthermore, if all the cells in a row have a value of
   'no-borders' and have no visible content, the entire row behaves as if
   it had 'display : none'.
   
   The following rule causes borders to be drawn around all cells:
   
TABLE { empty-cells: borders }

  18.6.2 The collapsing border model
  
   In the collapsing border model, it is possible to specify borders that
   surround all or part of a cell, row, row group, column, and column
   group. Borders for HTML's "rule" attribute can be specified this way.
   
   Borders are centered on the grid lines between the cells. User agents
   must find a consistent rule for rounding off in the case of an odd
   number of discrete units (screen pixels, printer dots).
   
   The diagram below shows how the width of the table, the widths of the
   borders, the padding, and the cell width interact. Their relation is
   given by the following equation, which holds for every row of the
   table:
   
     row-width = border-width0 + padding-left1 + width1 + padding-right1
     + border-width1 + padding-left2 +...+ padding-rightn +
     border-widthn
     
   Here n is the number of cells in the row, and border-widthi refers to
   the border between cells i and i + 1.
   
   Schema showing the widths of cells and borders and the padding of
   cells
   
   Schema showing the widths of cells and borders and the padding of
   cells.
   
   Note that in this model, the width of the table includes half the
   table border. Also, in this model, a table doesn't have padding (but
   does have margins).
   
    Border conflict resolution
    
   In the collapsing border model, borders at every edge of every cell
   may be specified by border properties on a variety of elements that
   meet at hat edge (cells, rows, row groups, columns, column groups, and
   the table itself), and these borders may vary in width, style, and
   color. The following rules determine which border style "wins" in case
   of a conflict:
   
   The rule of thumb is that at each edge the most "eye catching" border
   style is chosen, except that any occurrence of the style 'hidden'
   unconditionally turns the border off.
    1. Borders with the 'border-style' of 'hidden' take precedence over
       all other conflicting borders. Any border with this value
       suppresses all borders at this location.
    2. Borders with a style of 'none' have the lowest priority. Only if
       the border properties of all the elements meeting at this edge are
       'none' will the border be omitted (but note that 'none' is the
       default value for the border style.)
    3. If none of the styles is 'hidden' and at least one of them is not
       'none', then narrow borders are discarded in favor of wider ones.
       If several have the same 'border-width' than styles are preferred
       in this order: 'double', 'solid', 'dashed', 'dotted', 'ridge',
       'outset', 'groove', and the lowest: 'inset'.
    4. If border styles differ only in color, then a style set on a cell
       wins over one on a row, which wins over a row group, column,
       column group and, lastly, table.
       
   The following example illustrates the application of these precedence
   rules. This style sheet:
   
  TABLE          { border-collapse: collapse;
                   border: 5px solid yellow; }
  *#col1         { border: 1px solid black; }
  TD             { border: 5px solid red; }
  TD.solid-blue  { border: 11px solid blue; }
  TD.solid-green { border: 7px solid green; }

   with this HTML source:
   
<P>
<TABLE>
<COL id="col1"><COL id="col2"><COL id="col3">
<TR id="row1">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
</TR>
<TR id="row2">
    <TD>&nbsp;</TD>
    <TD class="solid-blue">&nbsp;</TD>
    <TD class="solid-green">&nbsp;</TD>
</TR>
<TR id="row3">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
</TR>
<TR id="row4">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
</TR>
<TR id="row5">
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
    <TD>&nbsp;</TD>
</TR>
</TABLE>

   would produce something like this:
   
   [IMAGE HERE]
   
   An example of a table with collapsed borders.
   
   The next example shows a table with horizontal rules between the rows.
   The top border of the table is set to 'hidden' to suppress the top
   border of the first row. This implements the RULES="rows" attribute of
   HTML 4.0.

TABLE[rules=rows] TR {border-top: solid}
TABLE[rules=rows] {border-collapse: collapse;
                   border-top: hidden}

   Table with horizontal rules
   
   Table with horizontal rules between the rows.
   
   In this case the same effect can also be achieved without setting a
   'hidden' border on TABLE, by addressing the first row separately.
   Which method is preferred is a matter of taste.

TR:first-child {border-top: none}
TR {border-top: solid}

   Here is another example of hidden collapsing borders:
   
   Table with two omitted borders
   
   Table with two omitted internal borders.
   
   HTML source:
   
<TABLE style="border-collapse: collapse; border: solid;">
<TR><TD style="border-right: hidden; border-bottom: hidden">foo</TD>
    <TD style="border: solid">bar</TD></TR>
<TR><TD style="border: none">foo</TD>
    <TD style="border: solid">bar</TD></TR>
</TABLE>

  18.6.3 Border styles
  
   Some of the values of the 'border-style' have different meanings in
   tables than for other elements. In the list below they are marked with
   an asterisk.
   
   none
          No border.
          
   *hidden
          Same as 'none', but in the collapsing border model, also
          inhibits any other border (see the section on border
          conflicts).
          
   dotted
          The border is a series of dots.
          
   dashed
          The border is a series of short line segments.
          
   solid
          The border is a single line segment.
          
   double
          The border is two solid lines. The sum of the two lines and the
          space between them equals the value of 'border-width'.
          
   groove
          The border looks as though it were carved into the canvas.
          
   ridge
          The opposite of 'grove': the border looks as though it were
          coming out of the canvas.
          
   *inset
          In the 2½D border model, the border makes the entire box look
          as though it were embedded in the canvas. In the collapsing
          border model, same as 'groove'.
          
   *outset
          In the 2½D border model, the border makes the entire box look
          as though it were coming out of the canvas. In the collapsing
          border model, same as 'ridge'.
          
18.7 Audio rendering of tables

   When a table is spoken by a speech generator, the relation between the
   data cells and the header cells must be expressed in a different way
   than by horizontal and vertical alignment. Some speech browsers may
   allow a user to move around in the 2-dimensional space, thus giving
   them the opportunity to map out the spatially represented relations.
   When that is not possible, the style sheet must specify at which
   points the headers are spoken.
   
  18.7.1 Speaking headers: the 'speak-header' property
  
   'speak-header'
          Value:   once | always | inherit
          Initial:   once
          Applies to:   elements that have header information
          Inherited:   yes
          Percentages:   N/A
          Media:   aural
          
   This property specifies whether table headers are spoken before every
   cell, or only before a cell when that cell is associated with a
   different header than the previous cell. Values have the following
   meanings:
   
   once
          The header is spoken one time, before a series of cells.
          
   always
          The header is before every pertinent cell.
          
   Each document language may have different mechanisms that allow
   authors to specify headers. For example, in HTML 4.0 ([HTML40]), it is
   possible to specify header information with three different attributes
   ("headers", "scope", and "axis"), and the specification gives an
   algorithm for determining header information when these attributes
   have not been specified.
   
   Image of a table created in MS Word
   
   Image of a table with header cells ("San Jose" and "Seattle") that are
   not in the same column or row as the data they apply to.
   
   This HTML example presents the money spent on meals, hotels and
   transport in two locations (San Jose and Seattle) for successive days.
   Conceptually, you can think of the table in terms of a n-dimensional
   space. The headers of this space are: location, day, category and
   subtotal. Some cells define marks along an axis while others give
   money spent at points within this space. The markup for this table is:
   
<TABLE>
<CAPTION>Travel Expense Report</CAPTION>
<TR>
  <TH></TH>
  <TH>Meals</TH>
  <TH>Hotels</TH>
  <TH>Transport</TH>
  <TH>subtotal</TH>
</TR>
<TR>
  <TH id="san-jose" axis="san-jose">San Jose</TH>
</TR>
<TR>
  <TH headers="san-jose">25-Aug-97</TH>
  <TD>37.74</TD>
  <TD>112.00</TD>
  <TD>45.00</TD>
  <TD></TD>
</TR>
<TR>
  <TH headers="san-jose">26-Aug-97</TH>
  <TD>27.28</TD>
  <TD>112.00</TD>
  <TD>45.00</TD>
  <TD></TD>
</TR>
<TR>
  <TH headers="san-jose">subtotal</TH>
  <TD>65.02</TD>
  <TD>224.00</TD>
  <TD>90.00</TD>
  <TD>379.02</TD>
</TR>
<TR>
  <TH id="seattle" axis="seattle">Seattle</TH>
</TR>
<TR>
  <TH headers="seattle">27-Aug-97</TH>
  <TD>96.25</TD>
  <TD>109.00</TD>
  <TD>36.00</TD>
  <TD></TD>
</TR>
<TR>
  <TH headers="seattle">28-Aug-97</TH>
  <TD>35.00</TD>
  <TD>109.00</TD>
  <TD>36.00</TD>
  <TD></TD>
</TR>
<TR>
  <TH headers="seattle">subtotal</TH>
  <TD>131.25</TD>
  <TD>218.00</TD>
  <TD>72.00</TD>
  <TD>421.25</TD>
</TR>
<TR>
  <TH>Totals</TH>
  <TD>196.27</TD>
  <TD>442.00</TD>
  <TD>162.00</TD>
  <TD>800.27</TD>
</TR>
</TABLE>

   By providing the data model in this way, authors make it possible for
   speech enabled-browsers to explore the table in rich ways, e.g. each
   cell could be spoken as a list, repeating the applicable headers
   before each data cell:
   
  San Jose, 25-Aug-97, Meals:  37.74
  San Jose, 25-Aug-97, Hotels:  112.00
  San Jose, 25-Aug-97, Transport:  45.00
 ...

   The browser could also speak the headers only when they change:
   
San Jose, 25-Aug-97, Meals: 37.74
    Hotels: 112.00
    Transport: 45.00
  26-Aug-97, Meals: 27.28
    Hotels: 112.00
...
     _________________________________________________________________
     _________________________________________________________________
   
                             19 User interface
                                      
   Contents
     * 19.1 Cursors: the 'cursor' property
     * 19.2 User preferences for colors
     * 19.3 User preferences for fonts
     * 19.4 Dynamic outlines: the 'outline' property
          + 19.4.1 Outlines and the focus
     * 19.5 Magnification
       
19.1 Cursors: the 'cursor' property

   'cursor'
          Value:   [ [<uri> ,]* [ auto | crosshair | default | pointer |
          move | e-resize | ne-resize | nw-resize | n-resize | se-resize
          | sw-resize | s-resize | w-resize| text | wait | help ] ] |
          inherit
          Initial:   auto
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   visual, interactive
          
   This property specifies the type of cursor to be displayed for the
   pointing device. Values have the following meanings:
   
   auto
          The UA determines the cursor to display based on the current
          context.
          
   crosshair
          A simple crosshair (e.g., short line segments resembling a "+"
          sign).
          
   default
          The platform-dependent default cursor. Often rendered as an
          arrow.
          
   pointer
          The cursor is a pointer that indicates a link.
          
   move
          Indicates something is to be moved
          
   *-resize
          Indicates that the edge is to be moved.
          
   text
          Indicates text that may be selected. Often rendered as an
          I-bar.
          
   wait
          A cursor to indicate that the program is busy and the user
          should wait. Often rendered as a watch or hourglass.
          
   help
          Help is available for the object under the cursor. Often
          rendered as a question mark or a balloon.
          
   <uri>
          The user agent retrieves the cursor from the resource
          designated by the URI. If the user agent cannot handle the
          first cursor of a list of cursors, it should attempt to handle
          the second, etc. If the user agent cannot handle any
          user-defined cursor, it must use the generic cursor at the end
          of the list.
          
  P { cursor : url(mything.cur), url(second.csr), text; }

19.2 User preferences for colors

   In addition to being able to assign pre-defined color values to text,
   backgrounds, etc., CSS2 allows authors to specify colors in a manner
   that integrates them into the user's graphic environment. Style rules
   that take into account user preferences thus offer the following
   advantages:
    1. They produce pages that fit the user's defined look and feel.
    2. They produce pages that may be more accessible as the current user
       settings may be related to a disability.
       
   The set of values defined for system colors is intended to be
   exhaustive. For systems that do not have a corresponding value, the
   specified value should be mapped to the nearest system attribute, or
   to a default color.
   
   The following lists additional values for color related CSS attributes
   and their general meaning. Any color property (e.g., 'color' or
   'background-color') can take one of the following names:
   
   active-border
          Active window border.
          
   active-caption
          Active window caption.
          
   app-workspace
          Background color of multiple document interface.
          
   background
          Desktop background.
          
   button-face
          Face color for three-dimensional display elements.
          
   button-highlight
          Dark shadow for three-dimensional display elements (for edges
          facing away from the light source).
          
   
          Shadow color for three-dimensional display elements.
          
   button-text
          Text on push buttons.
          
   caption-text
          Text in caption, size box, and scroll bar arrow box.
          
   gray-text
          Grayed (disabled) text. This color is set to #000 if the
          current display driver does not support a solid gray color.
          
   highlight
          Item(s) selected in a control.
          
   highlight-text
          Text of item(s) selected in a control.
          
   inactive-border
          Inactive window border.
          
   inactive-caption
          Inactive window caption.
          
   inactive-caption-text
          Color of text in an inactive caption.
          
   info-background
          Background color for tooltip controls.
          
   info-text
          Text color for tooltip controls.
          
   menu
          Menu background.
          
   menu-text
          Text in menus.
          
   scrollbar
          Scroll bar gray area.
          
   three-d-dark-shadow
          Dark shadow for three-dimensional display elements.
          
   three-d-face
          Face color for three-dimensional display elements.
          
   three-d-highlight
          Highlight color for three-dimensional display elements.
          
   three-d-light-shadow
          Light color for three-dimensional display elements (for edges
          facing the light source).
          
   three-d-shadow
          Dark shadow for three-dimensional display elements.
          
   window
          Window background.
          
   window-frame
          Window frame.
          
   window-text
          Text in windows.
          
   For example, to set the foreground and background colors of a
   paragraph to the same foreground and background colors of the user's
   window, write the following:

  P { color: windowtext; background-color: window }

19.3 User preferences for fonts

   As for colors, authors may specify fonts in a way that makes use of a
   user's system resources. Please consult the 'font' property for
   details.
   
19.4 Dynamic outlines: the 'outline' property

   At times, style sheet authors may want to create outlines around
   visual objects such as buttons, active form fields, image maps, etc.,
   to make them stand out. CSS2 outlines differ from borders in the
   following ways:
   
    1. Displaying or suppressing outlines does not cause reflow.
    2. Outlines may be non-rectangular.
       
   The outline properties control the style of these dynamic outlines.
   
   'outline'
          Value:   <'outline-color'> || <'outline-style'> ||
          <'outline-width'> | inherit
          Initial:   see individual properties
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual, interactive
          
   'outline-width'
          Value:   <border-width> | inherit
          Initial:   medium
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual, interactive
          
   'outline-style'
          Value:   <border-style> | inherit
          Initial:   none
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual, interactive
          
   'outline-color'
          Value:   <color> | invert | inherit
          Initial:   invert
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   visual, interactive
          
   The outline created with the outline properties is drawn "over" a box,
   i.e., the outline is always on top, and doesn't influence the position
   or size of the box, or of any other boxes.
   
   The outline is drawn starting just outside the border edge.
   
   Outlines may be non-rectangular. For example, if the element is broken
   across several lines, the outline is the minimum outline that encloses
   all the element's boxes. In contrast to borders, the outline is not
   open at the line box's end or start, but is always fully connected.
   
   The 'outline-width' property accepts the same values as
   'border-width'.
   
   The 'outline-style' property accepts the same values as
   'border-style', except that 'hidden' is not a legal outline style.
   
   The 'outline-color' accepts all colors, as well as the keyword
   'invert'. 'Invert' is expected to perform a color inversion on the
   pixels on the screen. This is a common trick to ensure the focus
   border is visible, regardless of color background.
   
   The 'outline' property is a shorthand property, and sets all three of
   'outline-style', 'outline-width', and 'outline-color'.
   
   Note that the outline is the same on all sides. In contrast to
   borders, there is no "outline-top" or "outline-left" property.
   
   This specification does not define how multiple overlapping outlines
   are drawn, or how outlines are drawn for boxes that are partially
   obscured behind other elements.
   
   Note. Since the focus outline does not affect formatting (i.e., no
   space is left for it in the box model), it may well overlap other
   elements on the page. 
   
   Here's an example of drawing a thick outline around a BUTTON element:
BUTTON { outline-width : thick }

   Scripts may be used to dynamically change the width of the outline,
   without provoking reflow.
   
  19.4.1 Outlines and the focus
  
   Graphical user interfaces may use outlines to tell the user which
   element on the page has the focus. The focus is the subject of user
   interaction in a document (e.g., for entering text, selecting a
   button, etc.). User agents supporting the interactive media group must
   keep track of where the focus lies and must also represent the focus.
   This may be done by using dynamic outlines in conjunction with the
   :focus pseudo-class.
   
   For example, to draw a thick black line around an element when it has
   the focus, and a thick red line when it is active, the following rules
   can be used:

:focus {outline: thick solid black}
:active {outline: thick solid red}

19.5 Magnification

   The CSS working group considers that the magnification of a document
   or portions of a document should not be specified through style
   sheets. User agents may support such magnification in different ways
   (e.g., larger images, louder sounds, etc.)
   
   When magnifying a page, UAs should preserve the relationships between
   positioned elements. For example, a comic strip may be composed of
   images with overlaid text elements. When magnifying this page, a user
   agent should keep the text within the comic strip balloon.
     _________________________________________________________________
     _________________________________________________________________
   
                           20 Aural style sheets
                                      
   Contents
     * 20.1 Introduction to aural style sheets
     * 20.2 Volume properties: 'volume'
     * 20.3 Speaking properties: 'speak'
     * 20.4 Pause properties: 'pause-before', 'pause-after', and 'pause'
     * 20.5 Cue properties: 'cue-before', 'cue-after', and 'cue'
     * 20.6 Mixing properties: 'play-during'
     * 20.7 Spatial properties: 'azimuth' and 'elevation'
     * 20.8 Voice characteristic properties: 'speech-rate',
       'voice-family', 'pitch', 'pitch-range', 'stress', and 'richness'
     * 20.9 Speech properties: 'speak-punctuation' and 'speak-numeral'
       
20.1 Introduction to aural style sheets

   The aural rendering of a document, already commonly used by the blind
   and print-impaired communities, combines speech synthesis and
   "auditory icons." Often such aural presentation occurs by converting
   the document to plain text and feeding this to a screen reader --
   software or hardware that simply reads all the characters on the
   screen. This results in less effective presentation than would be the
   case if the document structure were retained. Style sheet properties
   for aural presentation may be used together with visual properties
   (mixed media) or as an aural alternative to visual presentation.
   
   Besides the obvious accessibility advantages, there are other large
   markets for listening to information, including in-car use, industrial
   and medical documentation systems (intranets), home entertainment, and
   to help users learning to read or who have difficulty reading.
   
   When using aural properties, the canvas consists of a
   three-dimensional physical space (sound surrounds) and a temporal
   space (one may specify sounds before, during, and after other sounds).
   The CSS properties also allow authors to vary the quality of
   synthesized speech (voice type, frequency, inflection, etc.).
   
   Example:
H1, H2, H3, H4, H5, H6 {
    voice-family: paul;
    stress: 20;
    richness: 90;
    cue-before: url("ping.au")
}
P.heidi {azimuth: center-left}
P.peter {azimuth: right}
P.goat {volume: x-soft}

   This will direct the speech synthesizer to speak headers in a voice
   called "paul" (cf. 'font-family'), on a flat tone, but in a very rich
   voice. Before speaking the headers, a sound sample will be played from
   the given URL. Paragraphs with class "heidi" will appear to come from
   front left (if the sound system is capable of spatial audio), and
   paragraphs of class "peter" from the right. Paragraphs with class
   "goat" will be very soft.
   
20.2 Volume properties: 'volume'

   'volume'
          Value:   <number> | <percentage> | silent | x-soft | soft |
          medium | loud | x-loud | inherit
          Initial:   medium
          Applies to:   all elements
          Inherited:   yes
          Percentages:   relative to inherited value
          Media:   aural
          
   Volume refers to the median volume of the waveform. In other words, a
   highly inflected voice at a volume of 50 might peak well above that.
   The overall values are likely to be human adjustable for comfort, for
   example with a physical volume control (which would increase both the
   0 and 100 values proportionately); what this property does is adjust
   the dynamic range.
   
   Values have the following meanings:
   
   <number> 
          Any number between '0' and '100'. '0' represents the minimum
          audible volume level and 100 corresponds to the maximum
          comfortable level.
          
   <percentage>
          Percentage values are calculated relative to the inherited
          value, and are then clipped to the range '0' to '100'.
          
   silent
          No sound at all. The value '0' does not mean the same as
          'silent'.
          
   x-soft
          Same as '0'.
          
   soft
          Same as '25'.
          
   medium
          Same as '50'.
          
   loud
          Same as '75'.
          
   x-loud
          Same as '100'.
          
   User agents should allow the values corresponding to '0' and '100' to
   be set by the listener. No one setting is universally applicable;
   suitable values depend on the equipment in use (speakers, headphones),
   the environment (in car, home theater, library) and personal
   preferences. Some examples:
   
     * A browser for in-car use has a setting for when there is lots of
       background noise. '0' would map to a fairly high level and '100'
       to a quite high level. The speech is easily audible over the road
       noise but the overall dynamic range is compressed. Cars with
       better insulation might allow a wider dynamic range.
     * Another speech browser is being used in an apartment, late at
       night, or in a shared study room. '0' is set to a very quiet level
       and '100' to a fairly quiet level, too. As with the first example,
       there is a low slope; the dynamic range is reduced. The actual
       volumes are low here, whereas they were high in the first example.
     * In a quiet and isolated house, an expensive hi-fi home theater
       setup. '0' is set fairly low and '100' to quite high; there is
       wide dynamic range.
       
   The same author style sheet could be used in all cases, simply by
   mapping the '0' and '100' points suitably at the client side.
   
20.3 Speaking properties: 'speak'

   'speak'
          Value:   normal | none | spell-out | inherit
          Initial:   normal
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   aural
          
   This property specifies whether text will be rendered aurally and if
   so, in what manner (somewhat analogous to the 'display' property). The
   possible values are:
   
   none
          Suppresses aural rendering so that the element requires no time
          to render. Note, however, that descendants may override this
          value and will be spoken. (To be sure to suppress rendering of
          an element and its children, use the 'display' property).
          
   normal
          Uses language-dependent pronunciation rules for rendering an
          element and its children.
          
   spell-out
          Spells the text one letter at a time (useful for acronyms and
          abbreviations).
          
   Note the difference between an element whose 'volume' property has a
   value of 'silent' and an element whose 'speak' property has the value
   'none'. The former takes up the same time as if it had been spoken,
   including any pause before and after the element, but no sound is
   generated.
   
20.4 Pause properties: 'pause-before', 'pause-after', and 'pause'

   'pause-before'
          Value:   <time> | <percentage> | inherit
          Initial:   depends on user agent
          Applies to:   all elements
          Inherited:   no
          Percentages:   see prose
          Media:   aural
          
   'pause-after'
          Value:   <time> | <percentage> | inherit
          Initial:   depends on user agent
          Applies to:   all elements
          Inherited:   no
          Percentages:   see prose
          Media:   aural
          
   These properties specify a pause to be observed before (or after)
   speaking an element's content. Values have the following meanings:
   
   <time>
          Expresses the pause in absolute time units (seconds and
          milliseconds).
          
   <percentage>
          Refers to the inverse of the value of the 'speech-rate'
          property. For example, if the speech-rate is 120 words per
          minute (i.e., a word takes half a second, or 500ms) then a
          'pause-before' of 100% means a pause of 500 ms and a
          'pause-before' of 20% means 100ms.
          
   The pause is inserted between the element's content and any
   'cue-before' or 'cue-after' content.
   
   Authors should use relative units to create more robust style sheets
   in the face of large changes in speech-rate.
   
   'pause'
          Value:   [ [<time> | <percentage>]{1,2} ] | inherit
          Initial:   depends on user agent
          Applies to:   all elements
          Inherited:   no
          Percentages:   see descriptions of 'pause-before' and
          'pause-after'
          Media:   aural
          
   The 'pause' property is a shorthand for setting 'pause-before' and
   'pause-after'. If two values are given, the first value is
   'pause-before' and the second is 'pause-after'. If only one value is
   given, it applies to both properties.
   
   Examples:
  H1 { pause: 20ms } /* pause-before: 20ms; pause-after: 20ms */
  H2 { pause: 30ms 40ms } /* pause-before: 30ms; pause-after: 40ms */
  H3 { pause-after: 10ms } /* pause-before: ?; pause-after: 10ms */

20.5 Cue properties: 'cue-before', 'cue-after', and 'cue'

   'cue-before'
          Value:   <uri> | none | inherit
          Initial:   none
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   aural
          
   'cue-after'
          Value:   <uri> | none | inherit
          Initial:   none
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   aural
          
   Auditory icons are another way to distinguish semantic elements.
   Sounds may be played before and/or after the element to delimit it.
   Values have the following meanings:
   
   <uri>
          The URI must designate an auditory icon resource. If the URI
          resolves to something other than an audio file, such as an
          image, the resource should be ignored and the property treated
          as if it had the value 'none'.
          
   none
          No auditory icon is specified.
          
   For example:
  A {cue-before: url(bell.aiff); cue-after: url(dong.wav) }
  H1 {cue-before: url(pop.au); cue-after: url(pop.au) }

   'cue'
          Value:   [ <'cue-before'> || <'cue-after'> ] | inherit
          Initial:   not defined for shorthand properties
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   aural
          
   The 'cue' property is a shorthand for setting 'cue-before' and
   'cue-after'. If two values are given, the first value is 'cue-before'
   and the second is 'cue-after'. If only one value is given, it applies
   to both properties.
   
   The following two rules are equivalent:
  H1 {cue-before: url(pop.au); cue-after: url(pop.au) }
  H1 {cue: url(pop.au) }

   If a user agent cannot render an auditory icon (e.g., the user's
   environment does not permit it), we recommend that it produce an
   alternative cue (e.g., popping up a warning, emitting a warning sound,
   etc.)
   
20.6 Mixing properties: 'play-during'

   'play-during'
          Value:   <uri> mix? repeat? | auto | none | inherit
          Initial:   auto
          Applies to:   all elements
          Inherited:   no
          Percentages:   N/A
          Media:   aural
          
   Similar to the 'cue-before' and 'cue-after' properties, this property
   specifies a sound to be played as a background while an element's
   content is spoken. Values have the following meanings:
   
   <uri>
          The sound designated by this <uri> is played as a background
          while the element's content is spoken.
          
   mix
          When present, this keyword means that the sound inherited from
          the parent element's 'play-during' property continues to play
          and the sound designated by the <uri> is mixed with it. If
          'mix' is not specified, the sound replaces the sound of the
          parent element.
          
   repeat
          When present, this keyword means that the sound will repeat if
          it is too short to fill the entire duration of the element.
          Otherwise, the sound plays once and then stops. This is similar
          to the 'background-repeat' property. If the sound is too long
          for the element, it is clipped once the element is spoken.
          
   auto
          The sound of the parent element continues to play (it is not
          restarted, which would have been the case if this property had
          been inherited).
          
   none
          This keyword means that there is silence. The sound of the
          parent element (if any) is silent during the current element
          and continues after the current element.
          
   Examples:
  BLOCKQUOTE.sad { play-during: url(violins.aiff) }
  BLOCKQUOTE Q { play-during: url(harp.wav) mix}
  SPAN.quiet { play-during: none }

20.7 Spatial properties: 'azimuth' and 'elevation'

   Spatial audio is an important stylistic property for aural
   presentation. It provides a natural way to tell several voices apart,
   as in real life (people rarely all stand in the same spot in a room).
   Stereo speakers produce a lateral sound stage. Binaural headphones or
   the increasingly popular 5-speaker home theater setups can generate
   full surround sound, and multi-speaker setups can create a true
   three-dimensional sound stage. VRML 2.0 also includes spatial audio,
   which implies that in time consumer-priced spatial audio hardware will
   become more widely available.
   
   'azimuth'
          Value:   <angle> | [[ left-side | far-left | left | center-left
          | center | center-right | right | far-right | right-side ] ||
          behind ] | leftwards | rightwards | inherit
          Initial:   center
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   aural
          
   Values have the following meanings:
   
   <angle>
          Position is described in terms of degrees, within the range
          '-360deg' to '360deg'. The value '0deg' means directly ahead in
          the center of the sound stage. '90deg' is to the right,
          '180deg' behind, and '270deg' (or, equivalently and more
          conveniently, '-90deg') to the left.
          
   left-side
          Same as '270deg'. With 'behind', '270deg'.
          
   far-left
          Same as '300deg'. With 'behind', '240deg'.
          
   left
          Same as '320deg'. With 'behind', '220deg'.
          
   center-left
          Same as '340deg'. With 'behind', '200deg'.
          
   center
          Same as '0deg'. With 'behind', '180deg'.
          
   center-right
          Same as '20deg'. With 'behind', '160deg'.
          
   right
          Same as '40deg'. With 'behind', '140deg'.
          
   far-right
          Same as '60deg'. With 'behind', '120deg'.
          
   right-side
          Same as '90deg'. With 'behind', '90deg'.
          
   leftwards
          Moves the sound to the left, relative to the current angle.
          More precisely, subtracts 20 degrees. Arithmetic is carried out
          modulo 360 degrees. Note that 'leftwards' is more accurately
          described as "turned counter-clockwise," since it always
          subtracts 20 degrees, even if the inherited azimuth is already
          behind the listener (in which case the sound actually appears
          to move to the right).
          
   rightwards
          Moves the sound to the right, relative to the current angle.
          More precisely, adds 20 degrees. See 'leftwards' for
          arithmetic.
          
   This property is most likely to be implemented by mixing the same
   signal into different channels at differing volumes. It might also use
   phase shifting, digital delay, and other such techniques to provide
   the illusion of a sound stage. The precise means used to achieve this
   effect and the number of speakers used to do so are user
   agent-dependent; this property merely identifies the desired end
   result.
   
   Examples:
  H1   { azimuth: 30deg }
  TD.a { azimuth: far-right }          /*  60deg */
  #12  { azimuth: behind far-right }   /* 120deg */
  P.comment { azimuth: behind }        /* 180deg */

   If spatial-azimuth is specified and the output device cannot produce
   sounds behind the listening position, user agents should convert
   values in the rearwards hemisphere to forwards hemisphere values. One
   method is as follows:
   
     * if 90deg < x <= 180deg then x := 180deg - x
     * if 180deg < x <= 270deg then x := 540deg - x
       
   'elevation'
          Value:   <angle> | below | level | above | higher | lower |
          inherit
          Initial:   level
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   aural
          
   Values of this property have the following meanings:
   
   <angle>
          Specifies the elevation as an angle, between '-90deg' and
          '90deg'. '0deg' means on the forward horizon, which loosely
          means level with the listener. '90deg' means directly overhead
          and '-90deg' means directly below.
          
   below
          Same as '-90deg'.
          
   level
          Same as '-0deg'.
          
   above
          Same as '90deg'.
          
   higher
          Adds 10 degrees to the current elevation.
          
   lower
          Subtracts 10 degrees from the current elevation.
          
   The precise means used to achieve this effect and the number of
   speakers used to do so are undefined. This property merely identifies
   the desired end result.
   
   Examples:
  H1   { elevation: above }
  TR.a { elevation: 60deg }
  TR.b { elevation: 30deg }
  TR.c { elevation: level }

20.8 Voice characteristic properties: 'speech-rate', 'voice-family', 'pitch',
'pitch-range', 'stress', and 'richness'

   'speech-rate'
          Value:   <number> | x-slow | slow | medium | fast | x-fast |
          faster | slower | inherit
          Initial:   medium
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   aural
          
   This property specifies the speaking rate. Note that both absolute and
   relative keyword values are allowed (compare with 'font-size'). Values
   have the following meanings:
   
   <number>
          Specifies the speaking rate in words per minute, a quantity
          that varies somewhat by language but is nevertheless widely
          supported by speech synthesizers.
          
   x-slow
          Same as 80 words per minute.
          
   slow
          Same as 120 words per minute
          
   medium
          Same as 180 - 200 words per minute.
          
   fast
          Same as 300 words per minute.
          
   x-fast
          Same as 500 words per minute.
          
   faster
          Adds 40 words per minute to the current speech rate.
          
   slower
          Subtracts 40 words per minutes from the current speech rate.
          
   'voice-family'
          Value:   [[<specific-voice> | <generic-voice> ],]*
          [<specific-voice> | <generic-voice> ] | inherit
          Initial:   depends on user agent
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   aural
          
   The value is a comma-separated, prioritized list of voice family names
   (compare with 'font-family'). Values have the following meanings:
   
   <generic-voice>
          Values are voice families. Possible values are 'male',
          'female', and 'child'.
          
   <specific-voice>
          Values are specific instances (e.g., comedian, trinoids,
          carlos, lani).
          
   Examples:
  H1 { voice-family: announcer, male }
  P.part.romeo  { voice-family: romeo, male }
  P.part.juliet { voice-family: juliet, female }

   'pitch'
          Value:   <frequency> | x-low | low | medium | high | x-high |
          inherit
          Initial:   medium
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   aural
          
   Specifies the average pitch (a frequency) of the speaking voice. The
   average pitch of a voice depends on the voice family. For example, the
   average pitch for a standard male voice is around 120hz, but for a
   female voice, it's around 210hz.
   
   Values have the following meanings:
   
   <frequency>
          Specifies the average pitch of the speaking voice in hertz
          (Hz).
          
   x-low, low, medium, high, x-high
          These values do not map to absolute frequencies since these
          values depend on the voice family. User agents should map these
          values to appropriate frequencies based on the voice family and
          user environment. However, user agents must map these values in
          order (i.e., 'x-low' is a lower frequency than 'low', etc.).
          
   'pitch-range'
          Value:   <number> | inherit
          Initial:   50
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   aural
          
   Specifies variation in average pitch. The perceived pitch of a human
   voice is determined by the fundamental frequency and typically has a
   value of 120Hz for a male voice and 200Hz for a female voice. Human
   languages are spoken with varying inflection and pitch; these
   variations convey additional meaning and emphasis. Thus, a highly
   animated voice, i.e., one that is heavily inflected, displays a high
   pitch range. This property specifies the range over which these
   variations occur, i.e., how much the fundamental frequency may deviate
   from the average pitch.
   
   Values have the following meanings:
   
   <number>
          A value between '0' and '100'. A pitch range of '0' produces a
          flat, monotonic voice. A pitch range of 50 produces normal
          inflection. Pitch ranges greater than 50 produce animated
          voices.
          
   'stress'
          Value:   <number> | inherit
          Initial:   50
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   aural
          
   Specifies the height of "local peaks" in the intonation contour of a
   voice. For example, English is a stressed language, and different
   parts of a sentence are assigned primary, secondary, or tertiary
   stress. The value of 'stress' controls the amount of inflection that
   results from these stress markers. This property is a companion to the
   'pitch-range' property and is provided to allow developers to exploit
   higher-end auditory displays.
   
   Values have the following meanings:
   
   <number>
          A value, between '0' and '100'. The meaning of values depends
          on the language being spoken. For example, a level of '50' for
          a standard, English-speaking male voice (average pitch =
          122Hz), speaking with normal intonation and emphasis would have
          a different meaning than '50' for an Italian voice.
          
   'richness'
          Value:   <number> | inherit
          Initial:   50
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   aural
          
   Specifies the richness, or brightness, of the speaking voice. A rich
   voice will "carry" in a large room, a smooth voice will not. (The term
   "smooth" refers to how the wave form looks when drawn.)
   
   Values have the following meanings:
   
   <number>
          A value between '0' and '100'. The higher the value, the more
          the voice will carry. A lower value will produce a soft,
          mellifluous voice.
          
20.9 Speech properties: 'speak-punctuation' and 'speak-numeral'

   An additional speech property, speak-header, is described in the
   chapter on tables
   
   'speak-punctuation'
          Value:   code | none | inherit
          Initial:   none
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   aural
          
   This property specifies how punctuation is spoken. Values have the
   following meanings:
   
   code
          Punctuation such as semicolons, braces, and so on are to be
          spoken literally.
          
   none
          Punctuation is not to be spoken, but instead rendered naturally
          as various pauses.
          
   'speak-numeral'
          Value:   digits | continuous | inherit
          Initial:   continuous
          Applies to:   all elements
          Inherited:   yes
          Percentages:   N/A
          Media:   aural
          
   This property controls how numerals are spoken. Values have the
   following meanings:
   
   digits
          Speak the numeral as individual digits. Thus, "237" is spoken
          "Two Three Seven".
          
   continuous
          Speak the numeral as a full number. Thus, "237" is spoken "Two
          hundred thirty seven". Word representations are
          language-dependent.
     _________________________________________________________________
     _________________________________________________________________
   
               Appendix A. A sample style sheet for HTML 4.0
                                      
   This appendix is informative, not normative.
   
   This style sheet describes the typical rendering of all HTML 4.0
   ([HTML40]) elements based on extensive research into current UA
   practice. Developers are encouraged to use it as a default style sheet
   in their implementations.
   
   The full presentation of some HTML elements cannot be expressed in
   CSS2, including replaced elements (IMG, OBJECT), scripting elements
   (SCRIPT, APPLET), form control elements, and frame elements.

ADDRESS,
BLOCKQUOTE,
BODY, DD, DIV,
DL, DT,
FIELDSET, FORM,
FRAME, FRAMESET,
H1, H2, H3, H4,
H5, H6, IFRAME,
NOSCRIPT,
NOFRAMES,
OBJECT, OL, P,
UL, APPLET,
CENTER, DIR,
HR, MENU, PRE   { display: block }
LI              { display: list-item }
HEAD            { display: none }
TABLE           { display: table }
TR              { display: table-row }
THEAD           { display: table-header-group }
TBODY           { display: table-footer-group }
TFOOT           { display: table-row-group }
COL             { display: table-column }
COLGROUP        { display: table-column-group }
TD, TH          { display: table-cell }
CAPTION         { display: table-caption }
TH              { font-weight: bolder; text-align: center }
CAPTION         { text-align: center }
BODY            { padding: 8px; line-height: 1.33 }
H1              { font-size: 2em; margin: .67em 0 }
H2              { font-size: 1.5em; margin: .83em 0 }
H3              { font-size: 1.17em; margin: 1em 0 }
H4, P,
BLOCKQUOTE, UL,
FIELDSET, FORM,
OL, DL, DIR,
MENU            { margin: 1.33em 0 }
H5              { font-size: .83em; line-height: 1.17em; margin: 1.67em 0 }
H6              { font-size: .67em; margin: 2.33em 0 }
H1, H2, H3, H4,
H5, H6, B,
STRONG          { font-weight: bolder }
BLOCKQUOTE      { margin-left: 40px; margin-right: 40px }
I, CITE, EM,
VAR, ADDRESS    { font-style: italic }
PRE, TT, CODE,
KBD, SAMP       { font-family: monospace }
PRE             { white-space: pre }
BIG             { font-size: 1.17em }
SMALL, SUB, SUP { font-size: .83em }
SUB             { vertical-align: sub }
SUP             { vertical-align: super }
S, STRIKE, DEL  { text-decoration: line-through }
HR              { border: 1px inset }
OL, UL, DIR,
MENU, DD        { margin-left: 40px }
OL              { list-style-type: decimal }
OL UL, UL OL,
UL UL, OL OL    { margin-top: 0; margin-bottom: 0 }
U, INS          { text-decoration: underline }
CENTER          { text-align: center }
BR:before       { content: "\A" }

/* An example of style for HTML 4.0's new
   ABBR/ACRONYM elements */

ABBR, ACRONYM   { font-variant: small-caps; letter-spacing: 0.1em }
A[href]         { text-decoration: underline }
:focus          { outline: thin dotted invert }

/* For Unicode bidi */
BDO[DIR="ltr"]  { direction: ltr; unicode-bidi: bidi-override }
BDO[DIR="rtl"]  { direction: rtl; unicode-bidi: bidi-override }

*[DIR="ltr"]    { direction: ltr; unicode-bidi: embed }
*[DIR="rtl"]    { direction: rtl; unicode-bidi: embed }

/* Elements that are block-level in HTML4 */
ADDRESS, BLOCKQUOTE, BODY, DD, DIV, DL, DT, FIELDSET,
FORM, FRAME, FRAMESET, H1, H2, H3, H4, H5, H6, IFRAME,
NOSCRIPT, NOFRAMES, OBJECT, OL, P, UL, APPLET, CENTER,
DIR, HR, MENU, PRE, LI, TABLE, TR, THEAD, TBODY, TFOOT,
COL, COLGROUP, TD, TH, CAPTION
                { unicode-bidi: embed }

@media print {
  @page         { margin: 10% }
  H1, H2, H3,
  H4, H5, H6    { page-break-after: avoid; page-break-inside: avoid }
  BLOCKQUOTE,
  PRE           { page-break-inside: avoid }
  UL, OL, DL    { page-break-before: avoid }
}

@media speech {
  H1, H2, H3,
  H4, H5, H6    { voice-family: paul, male; stress: 20; richness: 90 }
  H1            { pitch: x-low; pitch-range: 90 }
  H2            { pitch: x-low; pitch-range: 80 }
  H3            { pitch: low; pitch-range: 70 }
  H4            { pitch: medium; pitch-range: 60 }
  H5            { pitch: medium; pitch-range: 50 }
  H6            { pitch: medium; pitch-range: 40 }
  LI,DT,DD      { pitch: medium; richness: 60 }
  DT            { stress: 80 }
  PRE,CODE,TT   { pitch: medium; pitch-range: 0; stress: 0; richness: 80 }
  EM            { pitch: medium; pitch-range: 60; stress: 60; richness: 50 }
  STRONG        { pitch: medium; pitch-range: 60; stress: 90; richness: 90 }
  DFN           { pitch: high; pitch-range: 60; stress: 60 }
  S,STRIKE      { richness: 0}
  I             { pitch: medium; pitch-range: 60; stress: 60; richness: 50 }
  B             { pitch: medium; pitch-range: 60; stress: 90; richness: 90 }
  U             { richness: 0 }
  A:link        { voice-family: harry, male }
  A:visited     { voice-family: betty, female }
  A:active      { voice-family: betty, female; pitch-range: 80; pitch: x-high }
}
     _________________________________________________________________
     _________________________________________________________________
   
                       Appendix B. Changes from CSS1
                                      
   Contents
     * B.1 New functionality
     * B.2 Updated descriptions
     * B.3 Semantic changes from CSS1
       
   This appendix is informative, not normative.
   
   CSS2 builds on CSS1 and all valid CSS1 style sheets are valid CSS2
   style sheets. The changes between the CSS1 specification (see [CSS1])
   and this specification fall into three groups: new functionality,
   updated descriptions of CSS1 functionality, and changes to CSS1.
   
B.1 New functionality

   In addition to the functionality of CSS1, CSS2 supports:
   
     * The concept of media types.
     * Paged media
     * Aural style sheets
     * An extended font selection mechanism, including intelligent
       matching, synthesis, and downloadable fonts. Also, the concept of
       system fonts has been is introduced, and a new property,
       'font-size-adjust', has been added.
     * Tables, including new values on 'display' and 'vertical-align'.
     * Relative and Absolute positioning, including fixed positioning.
     * An extended selector mechanism, including child selectors,
       adjacent selectors and attribute selectors.
     * Generated content and automatic numbering
     * Text shadows, through the new
     * 'text-shadow' property.
     * Several new pseudo-classes, :first-child, :hover, :focus, :lang.
     * System colors
       
B.2 Updated descriptions

   The CSS1 specification was short and concise. This specification is
   much more voluminous and more readable. Much of the additional content
   describes new functionality, but the description of CSS1 features has
   also been extended. Except in a few cases described below, the
   rewritten descriptions do not indicate a change in syntax nor
   semantics.
   
B.3 Semantic changes from CSS1

   While all CSS1 style sheets are valid CSS2 style sheets, there are a
   few cases where the CSS1 style sheet will have a different meaning
   when interpreted as a CSS2 style sheet. Most changes are due to
   implementation experience feeding back into the specification, but
   there are also some error corrections.
     * In CSS2 color values are clipped with regard to the device gamut,
       not with regard to the sRGB gamut as in CSS1.
     * CSS1 simply said that 'margin-right' was ignored if the both
       'margin-left' and 'width' were set. In CSS2 the choice between
       relaxing 'margin-right' or 'margin-left' depends on the writing
       direction.
     * In CSS1, several properties (e.g., 'padding') had values referring
       to the width of the parent element. This was an error; the value
       should always refer to the width of a block-level element and this
       specification reflects this by introducing the term "containing
       block".
     * The initial value of 'display' is 'inline' in CSS2, not 'block' as
       in CSS1.
     * In CSS1, the 'clear' property applied to all elements. This was an
       error, and the property only applies to block-level elements in
       CSS2.
     * In CSS1, ':link', ':visited' and ':active' were mutually
       exclusive; in CSS2, ':active' can occur together with ':link' or
       ':visited'.
     * The suggested scaling factor between adjacent 'font-size' indexes
       in the table of font sizes has been reduced from 1.5 to 1.2.
     * Please also consult the section on the differences between the
       CSS1 and CSS2 tokenizer.
     _________________________________________________________________
     _________________________________________________________________
   
              Appendix C. Implementation and performance notes
                                      
   Contents
     * C.1 Fonts
          + C.1.1 Glossary of font terms
          + C.1.2 Font retrieval
          + C.1.3 Meaning of the Panose Digits
          + C.1.4 Deducing Unicode Ranges for TrueType
          + C.1.5 Automatic descriptor generation
       
   This appendix is informative, not normative.
   
C.1 Fonts

  C.1.1 Glossary of font terms
  
   DocLock®
          Bitstream's DocLock® technology ensures that TrueDoc PFRs can
          only be used with the site they are published for. A TrueDoc
          PFR moved to a different site or referenced from another site
          will not work.
          
   Digital Signature
          Part of a trust management technology, used to provide signed
          assertions about a resource.
          
   Font Caching
          Font caching allows for a temporary copy of fonts on the client
          system. They are often stored on disk with other cached items
          such as graphics specifically for the UA.
          
   Font Face
          A "handle" that refers to a specific face of a font, excluding
          the font size.
          
   Font Matching
          Font matching is a process of selecting a similar font based on
          using one or more attributes of the primary font. Common
          attribute include serif, sans serif, weight, cap height, x
          height, spacing, language, and posture. Font matching is
          dependent on the algorithm and the variety of candidate fonts.
          
   Glyph Representation Sub-setting
          Glyph Representation sub-setting is the process by which
          unwanted glyph representations (together with their side
          bearings and kerning information) are removed from a primary
          font to produce a smaller subset font that covers a particular
          document or set of documents. This is a particular win for
          documents that use ideographic scripts, where the glyph
          complement of the base font can be very large. Glyph
          representation sub-setting for documents using scripts that
          require ligatures, such as Arabic, is difficult without knowing
          the ligature formation rules of the final display system.
          
   Intellifont
          Intellifont technology was developed by Agfa and is the native
          format for Hewlett-Packard and other printers that use the PCL5
          language. It is also the native font format on the Amiga
          computers.
          
   Infinifont
          A font synthesis technique which, given a Panose-1 number (and,
          optionally, additional font description data) can generate a
          faux font without extrapolating from a single master outline or
          interpolating between two or more outlines (see [INFINIFONT]).
          
   Italic
          A class of letter forms for Latin scripts, that are more
          cursive than roman letter forms but less so than script forms.
          Often, a pair of fonts are designed to be used together; one is
          a serifed roman and one is italic. Other terms to describe this
          class of letter forms include cursive and, for Cyrillic
          scripts, kursiv. For sans-serif faces, the companion face is
          often a slanted or oblique variant rather than a different
          class of letter form.
          Italic forms
          
   Kerning
          Altering the spacing between selected glyph representations,
          which would otherwise appear to be too close or too far apart,
          to obtain a more even typographical color.
          
          Illustration of kerning
          
   Multiple Master Font
          A Multiple Master Font contain two primary fonts that are used
          with special rendering software to provide an interpolated
          result. Adobe Systems provides a mechanism that allows for
          parameters to be used to control the output or the interpolated
          output font. These parameters generally describe the
          characteristics of an original font and the multiple master
          result is referred to as a "synthesized font."
          
   Open Type
          Open Type is an extension to the TrueType font format that
          contains additional information that extends the capabilities
          of the fonts to support high-quality international typography.
          Open Type can associate a single character with multiple glyph
          representations, and combinations of characters with a single
          glyph representation (ligature formation). Open Type includes
          two-dimensional information to support features for complex
          positioning and glyph attachment. TrueType Open and OpenType
          contain explicit script and language information, so a
          text-processing application can adjust its behavior accordingly
          (see [OPENTYPE]).
          
   Server Font
          A Server Font is a font resource located on the web server that
          is referenced by the WebFont definition. The user agent may use
          this resource for rendering the page.
          
   Speedo
          Speedo font technology was developed by Bitstream and is the
          native font format on the Atari ST and Falcon computers. It is
          also used by computers running the X window system.
          
   TrueDoc
          TrueDoc technology was developed by Bitstream for the creation,
          transport, and imaging of platform independent scalable font
          objects on the web. Creation of font objects is done by the
          TrueDoc character shape recorder (CSR) and the rendering of the
          font objects is done by TrueDoc's character shape player (CSP).
          The technology is intended to be used on the web for viewing
          and printing.
          
   TrueDoc Portable Font Resource
          A TrueDoc Portable font resource (or, PFR) is a
          platform-independent scalable font object that is produced by a
          character shape player. Input may be either TrueType or Type 1
          of any flavor on either Windows, Mac, or Unix. TrueDoc Portable
          Font Resources provide good compression ratios, are platform
          independent, and because they are not in an native font format
          (TrueType or Type 1) they can not be easily installed.
          
   TrueType
          TrueType is a font format developed by Apple and licensed to
          Microsoft. TrueType is the native operating system font format
          for Windows and Macintosh. TrueType contains a hierarchical set
          of tables and glyph representations. Characters can be hinted
          on a per character and point size basis yielding excellent
          quality at screen resolutions. TrueType fonts for Windows and
          Mac have few differences, though they can be different enough
          to prevent cross platform usage.
          
   TrueType Collection
          A TrueType Collection (or TTC) is an extension to the TrueType
          format that includes tables that allow for multiple TrueType
          fonts to be contained within a single TrueType font file.
          TrueType collection files are relatively rare at this time.
          
   TrueType GX Fonts
          TrueType GX Fonts contain extensions to the standard TrueType
          format that allow for mutable fonts, similar to Multiple Master
          fonts. There may be several mutation axis such as weight,
          height, and slant. The axis can be defined to obtain almost any
          effect. TrueType GX can also supports alternate glyph
          representation substitution for ligatures, contextual forms,
          fractions, etc. To date, TrueType GX is available only on the
          Mac (see [TRUETYPEGX]).
          
   Type 1 font
          Type 1 fonts, developed by Adobe Systems, were one of first
          scalable formats available. Type 1 fonts generally contain 228
          characters with the glyph representations described using third
          degree bezier curves. Mac, Windows, and X have similar but
          separate formats; Adobe provides Adobe Type Manager for all
          three platforms. Type1c is a more recent losslessly-compressed
          storage form for Type 1 glyph representations.
          
   URI Binding
          A process of locking a particular font resource to a given Web
          site by embedding an encrypted URI or a digitally signed usage
          assertion into the font resource.
          
  C.1.2 Font retrieval
  
   There are many different font formats in use by many different
   platforms. To select a preferred font format, transparent content
   negotiation is used (see [NEGOT]). It is always possible to tell when
   a font is being dereferenced, because the URI is inside a font
   description. Thus, only the relevant Accept headers need be sent (not
   headers related to images, HTML, etc).
   
  C.1.3 Meaning of the Panose Digits
  
   If the "Family" digit has a value other than "2" (the most common
   case), the remaining nine digits have different meanings than those
   given here. For further details on Panose-1, see [PANOSE].
   
   Family
          
          + Any (0)
          + No Fit (1)
          + [PANOSE] Latin Text and Display (2)
          + [PANOSE] Latin Script (3)
          + [PANOSE] Latin Decorative (4)
          + [PANOSE] Latin Pictorial (5)
            
   Serif Style
          
          + Any (0)
          + No Fit (1)
          + Cove (2)
          + Obtuse Cove (3)
          + Square Cove (4)
          + Obtuse Square Cove (5)
          + Square (6)
          + Thin (7)
          + Bone (8)
          + Exaggerated (9)
          + Triangle (10)
          + Normal Sans (11)
          + Obtuse Sans (12)
          + Perp Sans (13)
          + Flared (14)
          + Rounded (15)
            
   Weight
          
          + Any (0)
          + No Fit (1)
          + Very Light (2)[100]
          + Light (3) [200]
          + Thin (4) [300]
          + Book (5) [400] same as CSS1 'normal'
          + Medium (6) [500]
          + Demi (7) [600]
          + Bold (8) [700] same as CSS1 'bold'
          + Heavy (9) [800]
          + Black (10) [900]
          + Extra Black / Nord (11) [900] force mapping to CSS1 100-900
            scale
            
   Proportion
          
          + Any (0)
          + No Fit (1)
          + Old Style (2)
          + Modern (3)
          + Even Width (4)
          + Expanded (5)
          + Condensed (6)
          + Very Expanded (7)
          + Very Condensed (8)
          + Monospaced (9)
            
   Contrast
          
          + Any (0)
          + No Fit (1)
          + None (2)
          + Very Low (3)
          + Low (4)
          + Medium Low (5)
          + Medium (6)
          + Medium High (7)
          + High (8)
          + Very High (9)
            
   Stroke Variation
          
          + Any (0)
          + No Fit (1)
          + No Variation (2)
          + Gradual/Diagonal (3)
          + Gradual/Transitional (4)
          + Gradual/Vertical (5)
          + Gradual/Horizontal (6)
          + Rapid/Vertical (7)
          + Rapid/Horizontal (8)
          + Instant/Horizontal (9)
          + Instant/Vertical (10)
            
   Arm Style
          
          + Any (0)
          + No Fit (1)
          + Straight Arms/Horizontal (2)
          + Straight Arms/Wedge (3)
          + Straight Arms/Vertical (4)
          + Straight Arms/Single Serif (5)
          + Straight Arms/Double Serif (6)
          + Non-Straight Arms/Horizontal (7)
          + Non-Straight Arms/Wedge (8)
          + Non-Straight Arms/Vertical 90)
          + Non-Straight Arms/Single Serif (10)
          + Non-Straight Arms/Double Serif (11)
            
   Letterform
          
          + Any (0)
          + No Fit (1)
          + Normal/Contact (2)
          + Normal/Weighted (3)
          + Normal/Boxed (4)
          + Normal/Flattened (5)
          + Normal/Rounded (6)
          + Normal/Off Center (7)
          + Normal/Square (8)
          + Oblique/Contact (9)
          + Oblique/Weighted (10)
          + Oblique/Boxed (11)
          + Oblique/Flattened (12)
          + Oblique/Rounded (13)
          + Oblique/Off Center (14)
          + Oblique/Square (15)
            
   Midline
          
          + Any (0)
          + No Fit (1)
          + Standard/Trimmed (2)
          + Standard/Pointed (3)
          + Standard/Serifed (4)
          + High/Trimmed (5)
          + High/Pointed (6)
          + High/Serifed (7)
          + Constant/Trimmed (8)
          + Constant/Pointed (9)
          + Constant/Serifed (10)
          + Low/Trimmed (11)
          + Low/Pointed (12)
          + Low/Serifed (13)
            
   XHeight
          
          + Any (0)
          + No Fit (1)
          + Constant/Small (2)
          + Constant/Standard (3)
          + Constant/Large (4)
          + Ducking/Small (5)
          + Ducking/Standard (6)
          + Ducking/Large (7)
            
  C.1.4 Deducing Unicode Ranges for TrueType
  
   This information is available in the font by looking at the
   'ulUnicodeRange' bits in the 'OS/2' table (if it has one), which holds
   a bitfield representation of the set. This table is defined in
   revision 1.66 of the TrueType specification, from Microsoft.
   Considering this information as a set, each element corresponds to a
   Unicode 1.1 character block, and the presence of that element in the
   set indicates that the font has one or more glyph representations to
   represent at least one character in that block. The set has 128
   elements as described below. The order generally follows that in the
   Unicode 1.1 standard. This table may be used to convert the
   information in a TrueType font into a CSS 'unicode-range' descriptor.
     _________________________________________________________________
   
   Block Add Block name Unicode range
     _________________________________________________________________
   
   0 1 Basic Latin U+0-7F
   1 2 Latin-1 Supplement U+80-FF
   2 4 Latin-1 Extended-A U+100-17F
   3 8 Latin Extended-B U+180-24F
     _________________________________________________________________
   
   4 1 IPA Extensions U+250-2AF
   5 2 Spacing Modifier Letters U+2B0-2FF
   6 4 Combining Diacritical Marks U+300-36F
   7 8 Greek U+370-3CF
     _________________________________________________________________
   
   8 1 Greek Symbols and Coptic U+3D0-3EF
   9 2 Cyrillic U+400-4FF
   10 4 Armenian U+530-58F
   11 8 Hebrew U+590-5FF
     _________________________________________________________________
   
   12 1 Hebrew Extended-A
   Hebrew Extended-B ?? what ranges ??
   13 2 Arabic U+600-69F
   14 4 Arabic Extended U+670-6FF
   15 8 Devanagari U+900-97F
     _________________________________________________________________
   
   16 1 Bengali U+980-9FF
   17 2 Gurmukhi U+A00-A7F
   18 4 Gujarati U+A80-AFF
   19 8 Oriya U+B00-B7F
     _________________________________________________________________
   
   20 1 Tamil U+B80-BFF
   21 2 Telugu U+C00-C7F
   22 4 Kannada U+C80-CFF
   23 8 Malayalam U+D00-D7F
     _________________________________________________________________
   
   24 1 Thai U+E00-E7F
   25 2 Lao U+E80-EFF
   26 4 Georgian U+10A0-10EF
   27 8 Georgian Extended U+10F0-10FF ??
     _________________________________________________________________
   
   28 1 Hangul Jamo U+1100-11FF
   29 2 Latin Extended Additional -
   30 4 Greek Extended U+1F00-1FFF
   31 8 General Punctuation U+2000-206F
     _________________________________________________________________
   
   32 1 Superscripts and Subscripts -
   33 2 Currency Symbols U+20A0-20CF
   34 4 Combining Marks for Symbols U+20D0-20FF
   35 8 Letterlike Symbols U+2100-214F
     _________________________________________________________________
   
   36 1 Number Forms U+2150-218F
   37 2 Arrows U+2190-21FF
   38 4 Mathematical Operators U+2200-22FF
   39 8 Miscellaneous Technical U+2300-23FF
     _________________________________________________________________
   
   40 1 Control Pictures U+2400-243F
   41 2 Optical Character Recognition U+2440-245F
   42 4 Enclosed Alphanumerics U+2460-24FF
   43 8 Box Drawing U+2500-257F
     _________________________________________________________________
   
   44 1 Block Elements U+2580-259F
   45 2 Geometric Shapes U+25A0-25FF
   46 4 Miscellaneous Symbols U+2600-26FF
   47 8 Dingbats U+2700-27BF
     _________________________________________________________________
   
   48 1 CJK Symbols and Punctuation U+3000-303F
   49 2 Hiragana U+3040-309F
   50 4 Katakana U+30A0-30FF
   51 8 Bopomofo U+3100-312F
     _________________________________________________________________
   
   52 1 Hangul Compatibility Jamo U+3130-318F
   53 2 CJK Miscellaneous ??
   54 4 Enclosed CJK Letters and Months U+3200-32FF
   55 8 CJK compatibility U+3300-33FF
     _________________________________________________________________
   
   56 1 Hangul U+AC00-D7FF
   59 8 CJK Unified Ideographs U+4E00-9FFF
     _________________________________________________________________
   
   60 1 Private Use Area U+E000-F8FF
   61 2 CJK Compatibility Ideographs U+F900-FAFF
   62 4 Alphabetic Presentation Forms U+FB00-FB4F
   63 8 Arabic Presentation Forms-A U+FB50-FDFF
     _________________________________________________________________
   
   64 1 Combining Half Marks U+FE20-FE2F
   65 2 CJK compatibility Forms U+FE30-FE4F
   66 4 Small Form Variants U+FE50-FE6F
   67 8 Arabic Presentation Forms-B U+FE70-FEFF
     _________________________________________________________________
   
   68 1 Halfwidth and Fullwidth Forms U+FF00-FFEF
   69 2 Specials U+FFF0-FFFD
   
   The TrueType bitfield system has the problem that it is tied to
   Unicode 1.1 and is unable to cope with Unicode expansion - it is
   unable to represent Tibetan for example, or other scripts introduced
   with Unicode 2.0 or later revisions.
   
  C.1.5 Automatic descriptor generation
  
   Authoring tools should allow style sheet authors to add and edit font
   descriptors. In some cases, however, authoring tools can help by
   examining locally installed fonts and automatically generating
   descriptors for fonts referenced in the style sheet. This is also a
   function that can be carried out by tools which subset or convert
   fonts ready for dynamic download.
   
   This table suggests where such information can be found, for common
   font formats.
   
   Descriptor Type 1 TrueType and OpenType TrueType GX [TRUETYPEGX]
   'ascent' 'Ascender' in AFM/PFM file 'Ascender' in 'hhea' table or
   (preferably) 'sTypoAscender' in 'OS/2' table 'horizontalBefore' in
   'fmtx' table
   'baseline' bsln table, see note
   'bbox' FontBBox, font dictionary 'xMin', 'xMax', 'yMin' and 'yMax'
   entries of the 'head' table
   'cap-height' CapHeight in AFM/PFM file
   'descent' 'Descender' in the AFM/PFM file.
   'mathline' bsln table
   'font-family' FamilyName, fontinfo dictionary name table
   'stemh' StdHW, private dictionary of AFM/PFM file
   'stemv' /StdVW, private dictionary cvt table
   'topline' bsln table
   'unicode-range' cmap file OS/2 table, see Appendix C
   'units-per-em' FontMatrix, font dictionary unitsPerEm, head table.
   'widths' hmtx table
     * Within the bsln table, the ideographic centered baseline may be
       used for stretches of predominantly ideographic characters and the
       ideographic low baseline is more suitable for ideographic
       characters in a run of predominantly Latin, Greek or Cyrillic
       characters.
     _________________________________________________________________
     _________________________________________________________________
   
                      Appendix D. The grammar of CSS2
                                      
   Contents
     * D.1 Grammar
     * D.2 Lexical scanner
     * D.3 Comparison of tokenization in CSS2 and CSS1
       
   This appendix is normative.
   
   The grammar below defines the syntax of CSS2. It is in some sense,
   however, a superset of CSS2 as this specification imposes additional
   semantic constraints not expressed in this grammar. A conforming UA
   must also adhere to the forward-compatible parsing rules, the property
   and value notation, and the unit notation. In addition, the document
   language may impose restrictions, e.g. HTML imposes restrictions on
   the possible values of the "class" attribute.
   
D.1 Grammar

   The grammar below is LL(1) (but note that most UA's should not use it
   directly, since it doesn't express the parsing conventions, only the
   CSS2 syntax). The format of the productions is optimized for human
   consumption and some shorthand notation beyond Yacc (see [YACC]) is
   used:
   
     * *: 0 or more
     * +: 1 or more
     * ?: 0 or 1
     * |: separates alternatives
     * [ ]: grouping
       
   The productions are:
stylesheet
  : [ CHARSET_SYM S* STRING S* ';' S* ]?
    [S|CDO|CDC]* [ import [S|CDO|CDC]* ]*
    [ [ ruleset | media | page | font_face ] [S|CDO|CDC]* ]*
  ;
import
  : IMPORT_SYM S*
    [STRING|URI] S* [ medium [ ',' S* medium]* ]? ';' S*
  ;
media
  : MEDIA_SYM S* medium [ ',' S* medium ]* '{' S* ruleset* '}' S*
  ;
medium
  : IDENT S*
  ;
page
  : PAGE_SYM S* pseudo_page?
    '{' S* declaration [ ';' S* declaration ]* '}' S*
  ;
pseudo_page
  : ':' IDENT S*
  ;
font_face
  : FONT_FACE_SYM S*
    '{' S* declaration [ ';' S* declaration ]* '}' S*
  ;
operator
  : '/' S* | ',' S* | /* empty */
  ;
combinator
  : '+' S* | '>' S* | /* empty */
  ;
unary_operator
  : '-' | '+'
  ;
property
  : IDENT S*
  ;
ruleset
  : selector [ ',' S* selector ]*
    '{' S* declaration [ ';' S* declaration ]* '}' S*
  ;
selector
  : simple_selector [ combinator simple_selector ]*
  ;
/*
 * simple selector cannot start with attrib selector
 */
simple_selector
  : element_name [ HASH | class | attrib | pseudo ]* S*
  | HASH [ HASH | class | attrib | pseudo ]* S*
  | pseudo [ HASH | class | attrib | pseudo ]* S*
  | class [ HASH | class | attrib | pseudo ]* S*
  ;
class
  : '.' IDENT
  ;
element_name
  : IDENT | '*'
  ;
attrib
  : '[' S* IDENT S* [ [ '=' | INCLUDES | DASHMATCH ] S*
    [ IDENT | STRING ] S* ]? ']'
  ;
pseudo
  : ':' IDENT [ '(' IDENT ')' ]?
  ;
declaration
  : property ':' S* expr prio?
  | /* empty */
  ;
prio
  : IMPORTANT_SYM S*
  ;
expr
  : term [ operator term ]*
  ;
term
  : unary_operator?
    [ NUMBER S* | PERCENTAGE S* | LENGTH S* | EMS S* | EXS S* | ANGLE S* |
      TIME S* | FREQ S* | function ]
  | STRING S* | IDENT S* | URI S* | RGB S* | UNICODERANGE S* | hexcolor
  ;
function
  : FUNCTION S* expr ')' S*
  ;
/*
 * There is a constraint on the color that it must
 * have either 3 or 6 hex-digits (i.e., [0-9a-fA-F])
 * after the "#"; e.g., "#000" is OK, but "#abcd" is not.
 */
hexcolor
  : HASH S*
  ;

D.2 Lexical scanner

   The following is the tokenizer, written in Flex (see [FLEX]) notation.
   The tokenizer is case-insensitive.
   
   The two occurrences of "\377" represent the highest character number
   that current versions of Flex can deal with (decimal 255). They should
   be read as "\4177777" (decimal 1114111), which is the highest possible
   code point in Unicode/ISO-10646.

%option case-insensitive

h               [0-9a-f]
nonascii        [\200-\377]
unicode         \\{h}{1,6}[ \t\r\n\f]?
escape          {unicode}|\\[ -~\200-\377]
nmstart         [a-z]|{nonascii}|{escape}
nmchar          [a-z0-9-]|{nonascii}|{escape}
string1         \"([\t !#$%&(-~]|\\\n|\'|{nonascii}|{escape})*\"
string2         \'([\t !#$%&(-~]|\\\n|\"|{nonascii}|{escape})*\'

ident           {nmstart}{nmchar}*
name            {nmchar}+
num             [0-9]+|[0-9]*"."[0-9]+
string          {string1}|{string2}
url             ([!#$%&*-~]|{nonascii}|{escape})*
w               [ \t\r\n\f]*

range           \?{1,6}|{h}(\?{0,5}|{h}(\?{0,4}|{h}(\?{0,3}|{h}(\?{0,2}|{h}(\??
|{h})))))

%%

[ \t\r\n\f]+            {return S;}

\/\*[^*]*\*+([^/][^*]*\*+)*\/   /* ignore comments */

"<!--"                  {return CDO;}
"-->"                   {return CDC;}
"~="                    {return INCLUDES;}
"|="                    {return DASHMATCH;}

{string}                {return STRING;}

{ident}                 {return IDENT;}

"#"{name}               {return HASH;}

"@import"               {return IMPORT_SYM;}
"@page"                 {return PAGE_SYM;}
"@media"                {return MEDIA_SYM;}
"@font-face"            {return FONT_FACE_SYM;}
"@charset"              {return CHARSET_SYM;}
"@"{ident}              {return ATKEYWORD;}

"!{w}important"         {return IMPORTANT_SYM;}

{num}em                 {return EMS;}
{num}ex                 {return EXS;}
{num}px                 {return LENGTH;}
{num}cm                 {return LENGTH;}
{num}mm                 {return LENGTH;}
{num}in                 {return LENGTH;}
{num}pt                 {return LENGTH;}
{num}pc                 {return LENGTH;}
{num}deg                {return ANGLE;}
{num}rad                {return ANGLE;}
{num}grad               {return ANGLE;}
{num}ms                 {return TIME;}
{num}s                  {return TIME;}
{num}Hz                 {return FREQ;}
{num}kHz                {return FREQ;}
{num}{ident}            {return DIMEN;}
{num}%                  {return PERCENTAGE;}
{num}                   {return NUMBER;}

"url("{w}{string}{w}")" {return URI;}
"url("{w}{url}{w}")"    {return URI;}
{ident}"("              {return FUNCTION;}

U\+{range}              {return UNICODERANGE;}
U\+{h}{1,6}-{h}{1,6}    {return UNICODERANGE;}

.                       {return *yytext;}

D.3 Comparison of tokenization in CSS2 and CSS1

   There are some differences in the syntax specified in the CSS1
   recommendation ([CSS1]), and the one above. Most of these are because
   of new tokens in CSS2, that didn't exist in CSS1, others are because
   the grammar has been rewritten to be more readable. However, there are
   some incompatible changes, that were felt to be errors in the CSS1
   syntax. They are explained below.
     * CSS1 style sheets could only be in 1-byte-per-character encodings,
       such as ASCII and ISO-8859-1. CSS2 has no such limitation. In
       practice, there was little difficulty in extrapolating the CSS1
       tokenizer, and some UAs have accepted 2-byte encodings.
     * CSS1 only allowed four hex-digits after the backslash (\) to refer
       to Unicode characters, CSS2 allows six. Furthermore, CSS2 allows a
       whitespace character to delimit the escape sequence. E.g.,
       according to CSS1, the string "\abcdef" has 3 letters (\abcd, e,
       and f), according to CSS2 it has only one (\abcdef).
     * The tab character (ASCII 9) was not allowed in strings. However,
       since strings in CSS1 were only used for font names and for URLs,
       the only way this can lead to incompatibility between CSS1 and
       CSS2 is if a style sheet contains a font family that has a tab in
       its name.
     * Similarly, newlines (escaped with a backslash) were not allowed in
       strings in CSS1.
     * CSS2 parses a number immediately followed by an identifier as a
       DIMEN token (i.e., an unknown unit), CSS1 parsed it as a number
       and an identifier. That means that in CSS1, the declaration 'font:
       10pt/1.2serif' was correct, as was 'font: 10pt/12pt serif'; in
       CSS2, a space is required before "serif". (Some UAs accepted the
       first example, but not the second.)
     * In CSS1, a class name could start with a digit (".55ft"), unless
       it was a dimension (".55in"). In CSS2, such classes are parsed as
       unknown dimensions (to allow for future additions of new units).
       To make ".55ft" a valid class, CSS2 requires the first digit to be
       escaped (".\55ft")
     _________________________________________________________________
     _________________________________________________________________
   
                           Appendix E. References
                                      
   Contents
     * E.1 Normative references
     * E.2 Informative references
       
E.1 Normative references

   [COLORIMETRY]
          "Colorimetry, Second Edition", CIE Publication 15.2-1986, ISBN
          3-900-734-00-3.
          Available at
          http://www.hike.te.chiba-u.ac.jp/ikeda/CIE/publ/abst/15-2-86.ht
          ml.
          
   [CSS1]
          "Cascading Style Sheets, level 1", H. W. Lie and B. Bos, 17
          December 1996.
          Available at http://www.w3.org/TR/REC-CSS1-961217.html
          
   [FLEX]
          "Flex: The Lexical Scanner Generator", Version 2.3.7, ISBN
          1882114213.
          
   [HTML40]
          "HTML 4.0 Specification", D. Raggett, A. Le Hors, I. Jacobs, 8
          July 1997.
          Available at http://www.w3.org/TR/REC-html40/. The
          Recommendation defines three document type definitions: Strict,
          Transitional, and Frameset, all reachable from the
          Recommendation.
          
   [IANA]
          "Assigned Numbers", STD 2, RFC 1700, USC/ISI, J. Reynolds and
          J. Postel, October 1994.
          Available at ftp://ftp.internic.net/rfc/rfc1700.txt
          
   [ICC32]
          "ICC Profile Format Specification, version 3.2", 1995.
          Available at ftp://sgigate.sgi.com/pub/icc/ICC32.pdf.
          
   [ISO8879]
          ISO 8879:1986 "Information Processing -- Text and Office
          Systems -- Standard Generalized Markup Language (SGML)", ISO
          8879:1986.
          For the list of SGML entities, consult
          ftp://ftp.ifi.uio.no/pub/SGML/ENTITIES/.
          
   [ISO10646]
          "Information Technology - Universal Multiple- Octet Coded
          Character Set (UCS) - Part 1: Architecture and Basic
          Multilingual Plane", ISO/IEC 10646-1:1993. The current
          specification also takes into consideration the first five
          amendments to ISO/IEC 10646-1:1993. Useful roadmap of the BMP
          and roadmap of plane 1 documents show which scripts sit at
          which numeric ranges.
          
   [PNG10]
          "PNG (Portable Network Graphics) Specification, Version 1.0
          specification", T. Boutell ed., 1 October 1996.
          Available at http://www.w3.org/pub/WWW/TR/REC-png-multi.html.
          
   [RFCCSS]
          [To be published] RFC defining the "text/css" type.
          
   [RFC1738]
          "Uniform Resource Locators", T. Berners-Lee, L. Masinter, and
          M. McCahill, December 1994.
          Available at ftp://ds.internic.net/rfc/rfc1738.txt.
          
   [RFC1808]
          "Relative Uniform Resource Locators", R. Fielding, June 1995.
          Available at ftp://ds.internic.net/rfc/rfc1808.txt.
          
   [RFC2045]
          "Multipurpose Internet Mail Extensions (MIME) Part One: Format
          of Internet Message Bodies", N. Freed and N. Borenstein,
          November 1996.
          Available at ftp://ftp.internic.net/rfc/rfc2045.txt. Note that
          this RFC obsoletes RFC1521, RFC1522, and RFC1590.
          
   [RFC2068]
          "HTTP Version 1.1 ", R. Fielding, J. Gettys, J. Mogul, H.
          Frystyk Nielsen, and T. Berners-Lee, January 1997.
          Available at ftp://ftp.internic.net/rfc/rfc2068.txt.
          
   [RFC2070]
          "Internationalization of the HyperText Markup Language", F.
          Yergeau, G. Nicol, G. Adams, and M. Dürst, January 1997.
          Available at ftp://ds.internic.net/rfc/rfc2070.txt.
          
   [RFC2119]
          "Key words for use in RFCs to Indicate Requirement Levels", S.
          Bradner, March 1997.
          Available at ftp://ds.internic.net/rfc/rfc2119.txt.
          
   [SRGB]
          "Proposal for a Standard Color Space for the Internet - sRGB",
          M Anderson, R Motta, S Chandrasekar, M Stokes.
          Available at http://www.w3.org/Graphics/Color/sRGB.html.
          
   [UNICODE]
          The latest version of Unicode. For more information, consult
          the Unicode Consortium's home page at http://www.unicode.org/
          
   [URI]
          "Uniform Resource Identifiers (URI): Generic Syntax and
          Semantics", T. Berners-Lee, R. Fielding, L. Masinter, 18
          November 1997.
          Available at
          http://www.ics.uci.edu/pub/ietf/uri/draft-fielding-uri-syntax-0
          1.txt. This is a work in progress that is expected to update
          [RFC1738] and [RFC1808].
          
   [XML10]
          "Extensible Markup Language (XML) 1.0" T. Bray, J. Paoli, C.M.
          Sperberg-McQueen, editors, 10 February 1998.
          Available at http://www.w3.org/TR/REC-xml/.
          
   [YACC]
          "YACC - Yet another compiler compiler", S. C. Johnson,
          Technical Report, Murray Hill, 1975.
          
E.2 Informative references

   [CHARSETS]
          Registered charset values. Download a list of registered
          charset values from
          ftp://ftp.isi.edu/in-notes/iana/assignments/character-sets.
          
   [DOM]
          "Document Object Model Specification", L. Wood, A. Le Hors, 9
          October 1997.
          Available at http://www.w3.org/TR/WD-DOM/
          
   [ISO10179]
          ISO/IEC 10179:1996 "Information technology -- Processing
          languages -- Document Style Semantics and Specification
          Language (DSSSL)"
          Available at http://occam.sjf.novell.com:8080/dsssl/dsssl96
          
   [GAMMA]
          "Gamma correction on the Macintosh Platform", C. A. Poynton.
          Available at
          ftp://ftp.inforamp.net/pub/users/poynton/doc/Mac/Mac_gamma.pdf.
          
   [HTML32]
          "HTML 3.2 Reference Specification", Dave Raggett, 14 January
          1997.
          Available at http://www.w3.org/TR/REC-html32.html
          
   [INFINIFONT]
          See http://www.fonts.com/hp/infinifont/moredet.html.
          
   [ISO9899]
          ISO/IEC 9899:1990 Programming languages -- C.
          
   [MONOTYPE]
          See http://www.monotype.com/html/oem/uni_scrmod.html
          
   [NEGOT]
          "Transparent Content Negotiation in HTTP", K. Holtman, A. Mutz,
          9 March, 1997.
          Available at
          http://gewis.win.tue.nl/~koen/conneg/draft-ietf-http-negotiatio
          n-01.html
          
   [OPENTYPE]
          See http://www.microsoft.com/OpenType/OTSpec/tablist.htm.
          
   [PANOSE]
          For information about PANOSE classification metrics, consult
          http://www.fonts.com/hp/panose/greybook and the following
          chapters: Latin Text, Latin Script, Latin Decorative, and Latin
          Pictorial.
          
          Panose numbers for some fonts are available online and may be
          queried.
          
   [PANOSE2]
          See http://www.w3.org/Fonts/Panose/pan2.html Panose-2 is not
          limited to Latin typefaces.
          
   [POSTSCRIPT]
          "The PostScript Language Reference Manual", Second Edition,
          Adobe Systems, Inc., Addision-Wesley Publishing Co., December
          1990.
          
   [RFC1630]
          "Universal Resource Identifiers in WWW: A Unifying Syntax for
          the Expression of Names and Addresses of Objects on the Network
          as used in the World-Wide Web", T. Berners-Lee, June 1994.
          Available at ftp://ftp.internic.net/rfc/rfc1630.txt.
          
   [RFC1766]
          "Tags for the Identification of Languages", H. Alvestrand,
          March 1995.
          Available at ftp://ftp.internic.net/rfc/rfc1766.txt.
          
   [RFC1866]
          "HyperText Markup Language 2.0", T. Berners-Lee and D.
          Connolly, November 1995.
          Available at ftp://ds.internic.net/rfc/rfc1866.txt.
          
   [RFC1942]
          "HTML Tables", Dave Raggett, May 1996.
          Available at ftp://ds.internic.net/rfc/rfc1942.txt.
          
   [TRUETYPEGX]
          See http://fonts.apple.com/TTRefMan/index.html for details
          about TrueType GX from Apple Computer, including descriptions
          of the added tables and font quality specifications
          
   [W3CSTYLE]
          W3C resource page on web style sheets.
          Examine at http://www.w3.org/pub/WWW/Style
     _________________________________________________________________
     _________________________________________________________________
   
                         Appendix F. Property index
                                      
   Name Values Initial value Applies to
   (Default: all) Inherited?
   (Default: no) Percentages
   (Default: N/A) Media groups
   'azimuth' <angle> | [[ left-side | far-left | left | center-left |
   center | center-right | right | far-right | right-side ] || behind ] |
   leftwards | rightwards | inherit center   yes   aural
   'background' ['background-color' || 'background-image' ||
   'background-repeat' || 'background-attachment' ||
   'background-position'] | inherit XX     allowed on
   'background-position' visual
   'background-attachment' scroll | fixed | inherit scroll       visual
   'background-color' <color> | transparent | inherit transparent
   visual
   'background-image' <uri> | none | inherit none       visual
   'background-position' [ [<percentage> | <length> ]{1,2} | [ [top |
   center | bottom] || [left | center | right] ] ] | inherit 0% 0%
   block-level and replaced elements   refer to the size of the element
   itself visual
   'background-repeat' repeat | repeat-x | repeat-y | no-repeat | inherit
   repeat       visual
   'border' [ 'border-width' || 'border-style' || <color> ] | inherit see
   individual properties       visual
   'border-collapse' collapse | separate | inherit collapse 'table' and
   'inline-table' elements yes   visual
   'border-color' <color>{1,4} | transparent | inherit see individual
   properties       visual
   'border-spacing' <length> <length>? | inherit 0 'table' and
   'inline-table' elements yes   visual
   'border-style' <border-style>{1,4} | inherit see individual properties
         visual
   'border-top border-right border-bottom border-left' [
   'border-top-width' || 'border-style' || <color> ] | inherit see
   individual properties       visual
   'border-top-color border-right-color border-bottom-color
   border-left-color' <color> | inherit the value of the 'color' property
         visual
   'border-top-style border-right-style border-bottom-style
   border-left-style' <border-style> | inherit none       visual
   'border-top-width border-right-width border-bottom-width
   border-left-width' <border-width> | inherit medium       visual
   'border-width' <border-width>{1,4} | inherit see individual properties
         visual
   'bottom' <length> | <percentage> | auto | inherit auto     refer to
   height of containing block visual
   'caption-side' top | bottom | left | right | inherit top
   'table-caption' elements yes   visual
   'clear' none | left | right | both | inherit none block-level elements
       visual
   'clip' <shape> | auto | inherit auto block-level and replaced elements
       visual
   'color' <color> | inherit depends on user agent   yes   visual
   'column-span' <integer> | inherit 1 'table-cell', 'table-column', and
   'table-column-group' elements     visual
   'content' [ <string> | <uri> | <counter> | attr(X) | open-quote |
   close-quote | no-open-quote | no-close-quote ]+ | inherit empty string
   :before and :after pseudo-elements     all
   'counter-increment' [ <identifier> <integer>? ]+ | none | inherit none
         all
   'counter-reset' [ <identifier> <integer>? ]+ | none | inherit none
     all
   'cue' [ 'cue-before' || 'cue-after' ] | inherit XX       aural
   'cue-after' <uri> | none | inherit none       aural
   'cue-before' <uri> | none | inherit none       aural
   'cursor' [ [<uri> ,]* [ auto | crosshair | default | pointer | move |
   e-resize | ne-resize | nw-resize | n-resize | se-resize | sw-resize |
   s-resize | w-resize| text | wait | help ] ] | inherit auto   yes
   visual, interactive
   'direction' ltr | rtl | inherit ltr all elements, but see prose yes
   visual
   'display' inline | block | list-item | run-in | compact | marker |
   table | inline-table | table-row-group | table-column-group |
   table-header-group | table-footer-group | table-row | table-cell |
   table-caption | none | inherit inline       all
   'elevation' <angle> | below | level | above | higher | lower | inherit
   level   yes   aural
   'empty-cells' borders | no-borders | inherit borders 'table-cell'
   elements yes   visual
   'float' left | right | none | inherit none elements that are not
   positioned absolutely     visual
   'font' [ [ 'font-style' || 'font-variant' || 'font-weight' ]?
   'font-size' [ / 'line-height' ]? 'font-family' ] | caption | icon |
   menu | message-box | small-caption | status-bar | inherit see
   individual properties   yes allowed on 'font-size' and 'line-height'
   visual
   'font-family' [[ <family-name> | <generic-family> ],]* [<family-name>
   | <generic-family>] | inherit depends on user agent   yes   visual
   'font-size' <absolute-size> | <relative-size> | <length> |
   <percentage> | inherit medium   yes, the computed value is inherited
   relative to parent element's font size visual
   'font-size-adjust' <number> | none | inherit none   yes relative to
   parent element's font size visual
   'font-stretch' normal | wider | narrower | ultra-condensed |
   extra-condensed | condensed | semi-condensed | semi-expanded |
   expanded | extra-expanded | ultra-expanded | inherit normal   yes
   visual
   'font-style' normal | italic | oblique | inherit normal   yes   visual
   'font-variant' normal | small-caps | inherit normal   yes   visual
   'font-weight' normal | bold | bolder | lighter | 100 | 200 | 300 | 400
   | 500 | 600 | 700 | 800 | 900 | inherit normal   yes   visual
   'height' <length> | <percentage> | auto | inherit auto all elements
   but non-replaced inline elements, table columns and column groups
   see prose visual
   'left' <length> | <percentage> | auto | inherit auto     refer to
   width of containing block visual
   'letter-spacing' normal | <length> | inherit normal   yes   visual
   'line-height' normal | <number> | <length> | <percentage> | inherit
   normal   yes relative to the font size of the element itself visual
   'list-style' [ 'list-style-type' || 'list-style-position' ||
   'list-style-image' ] | inherit XX elements with the 'display' property
   set to 'list-item' yes   visual
   'list-style-image' <uri> | none | inherit none elements with the
   'display' property set to 'list-item' yes   visual
   'list-style-position' inside | outside | inherit outside elements with
   the 'display' property set to 'list-item' yes   visual
   'list-style-type' disc | circle | square | decimal | leading-zero |
   western-decimal | lower-roman | upper-roman | lower-greek |
   lower-alpha | lower-latin | upper-alpha | upper-latin | hebrew |
   armenian | georgian | cjk-ideographic | hiragana | katakana |
   hiragana-iroha | katakana-iroha | none | inherit disc elements with
   the 'display' property set to 'list-item' yes   visual
   'margin' <margin-width>{1,4} | inherit XX     refer to width of
   containing block visual
   'margin-top margin-right margin-bottom margin-left' <margin-width> |
   inherit 0     refer to width of containing block visual
   'marker-offset' <length> | auto | inherit auto elements with 'display'
   set to 'marker'     visual
   'marks' [ crop || cross ] | none | inherit none page context N/A
   visual, paged
   'max-height' <length> | <percentage> | inherit 100% all   refer to
   height of containing block visual
   'max-width' <length> | <percentage> | inherit 100% all   refer to
   width of containing block visual
   'min-height' <length> | <percentage> | inherit 0 all   refer to height
   of containing block visual
   'min-width' <length> | <percentage> | inherit 0 all   refer to width
   of containing block visual
   'orphans' <integer> | inherit 2 block-level elements yes   visual,
   paged
   'outline' 'outline-color' || 'outline-style' || 'outline-width' |
   inherit see individual properties       visual, interactive
   'outline-color' <color> | invert | inherit invert       visual,
   interactive
   'outline-style' <border-style> | inherit none       visual,
   interactive
   'outline-width' <border-width> | inherit medium       visual,
   interactive
   'overflow' visible | hidden | scroll | auto | inherit visible
   block-level and replaced elements     visual
   'padding' <padding-width>{1,4} | inherit XX     refer to width of
   containing block visual
   'padding-top padding-right padding-bottom padding-left'
   <padding-width> | inherit 0     refer to width of containing block
   visual
   'page' <identifier> [ :left | :right ]? | auto auto block-level
   elements yes   visual, paged
   'page-break-after' auto | always | avoid | left | right | inherit auto
   block-level elements     visual, paged
   'page-break-before' auto | always | avoid | left | right | inherit
   auto block-level elements     visual, paged
   'page-break-inside' avoid | auto | inherit auto block-level elements
   yes   visual, paged
   'pause' [ [<time> | <percentage>]{1,2} ] | inherit depends on user
   agent     see descriptions of 'pause-before' and 'pause-after' aural
   'pause-after' <time> | <percentage> | inherit depends on user agent
     see prose aural
   'pause-before' <time> | <percentage> | inherit depends on user agent
     see prose aural
   'pitch' <frequency> | x-low | low | medium | high | x-high | inherit
   medium   yes   aural
   'pitch-range' <number> | inherit 50   yes   aural
   'play-during' <uri> mix? repeat? | auto | none | inherit auto
   aural
   'position' static | relative | absolute | fixed | inherit static
   (except generated content)     visual
   'quotes' [<string> <string>]+ | none | inherit depends on user agent
   yes   visual
   'richness' <number> | inherit 50   yes   aural
   'right' <length> | <percentage> | auto | inherit auto     refer to
   width of containing block visual
   'row-span' <integer> | inherit 1 'table-cell' elements     visual
   'size' <length>{1,2} | auto | portrait | landscape | inherit auto page
   context N/A   visual, paged
   'speak' normal | none | spell-out | inherit normal   yes   aural
   'speak-header' once | always | inherit once elements that have header
   information yes   aural
   'speak-numeral' digits | continuous | inherit continuous   yes   aural
   'speak-punctuation' code | none | inherit none   yes   aural
   'speech-rate' <number> | x-slow | slow | medium | fast | x-fast |
   faster | slower | inherit medium   yes   aural
   'stress' <number> | inherit 50   yes   aural
   'table-layout' auto | fixed | inherit auto 'table' and 'inline-table'
   elements     visual
   'text-align' left | right | center | justify | <string> | inherit
   depends on user agent and writing direction block-level elements yes
   visual
   'text-decoration' none | [ underline || overline || line-through ||
   blink ] | inherit none   no (see prose)   visual
   'text-indent' <length> | <percentage> | inherit 0 block-level elements
   yes refer to width of containing block visual
   'text-shadow' none | [<color> || <length> <length> <length>? ,]*
   [<color> || <length> <length> <length>?] | inherit none all no (see
   prose)   visual
   'text-transform' capitalize | uppercase | lowercase | none | inherit
   none   yes   visual
   'top' <length> | <percentage> | auto | inherit auto     refer to
   height of containing block visual
   'unicode-bidi' normal | embed | bidi-override | inherit normal all
   elements, but see prose     visual
   'vertical-align' baseline | sub | super | top | text-top | middle |
   bottom | text-bottom | <percentage> | <length> | inherit baseline
   inline-level and table cell elements   refer to the 'line-height' of
   the element itself visual
   'visibility' visible | hidden | collapse | inherit inherit
   visual
   'voice-family' [[<specific-voice> | <generic-voice> ],]*
   [<specific-voice> | <generic-voice> ] | inherit depends on user agent
     yes   aural
   'volume' <number> | <percentage> | silent | x-soft | soft | medium |
   loud | x-loud | inherit medium   yes relative to inherited value aural
   'white-space' normal | pre | nowrap | inherit normal block-level
   elements yes   visual
   'widows' <integer> | inherit 2 block-level elements yes   visual,
   paged
   'width' <length> | <percentage> | auto | inherit auto all elements but
   non-replaced inline elements, table rows and row groups   refer to
   width of containing block visual
   'word-spacing' normal | <length> | inherit normal   yes   visual
   'z-index' auto | <integer> | inherit auto elements that generate
   absolutely and relatively positioned boxes     visual
     _________________________________________________________________
     _________________________________________________________________
   
                        Appendix G. Descriptor index
                                      
   Name Values Initial value
   'ascent' <number> undefined
   'baseline' <number> 0
   'bbox' <number>, <number>, <number>, <number> undefined
   'cap-height' <number> undefined
   'centerline' <number> undefined
   'definition-src' <uri> undefined
   'descent' <number> undefined
   'font-family' [ <family-name> | <generic-family> ] [, [<family-name> |
   <generic-family> ]]* depends on user agent
   'font-size' all | [<length> [,[<length>]]* ] all
   'font-stretch' all | [ normal | ultra-condensed | extra-condensed |
   condensed | semi-condensed | semi-expanded | expanded | extra-expanded
   | ultra-expanded ] [, [ normal | ultra-condensed | extra-condensed |
   condensed | semi-condensed | semi-expanded | expanded | extra-expanded
   | ultra-expanded] ]* normal
   'font-style' all | [ normal | italic | oblique ] [, [normal | italic |
   oblique] ]* all
   'font-variant' [normal | small-caps] [,[normal | small-caps]]* normal
   'font-weight' all | [normal | bold | 100 | 200 | 300 | 400 | 500 | 600
   | 700 | 800 | 900] [, [normal | bold | 100 | 200 | 300 | 400 | 500 |
   600 | 700 | 800 | 900]]* all
   'mathline' <number> undefined
   'panose-1' [<number>]{10} 0 0 0 0 0 0 0 0 0 0
   'slope' <number> 0
   'src' [ <uri> [format(<string> [, <string>]*)] | <font-face-name> ] [,
   <uri> [format(<string> [, <string>]*)] | <font-face-name> ]* undefined
   'stemh' <number> undefined
   'stemv' <number> undefined
   'topline' <number> undefined
   'unicode-range' <urange>+ U+0-7FFFFFFF
   'units-per-em' <number> undefined
   'widths' [<urange> ]? [<number> ]+ [,[<urange> ]? <number> ]+]
   undefined
   'x-height' <number> undefined
     _________________________________________________________________
     _________________________________________________________________
   
                             Appendix H. Index
                                      
   A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
   
     * 2½D borders, 1
       
   
     * :active, 1, 2, 3
     * :after, 1, 2, 3
     * :before, 1, 2, 3
     * :first, 1
     * :first-child, 1
     * :first-letter, 1
     * :first-line, 1
     * :focus, 1
     * :hover, 1
     * :lang, 1
     * :left, 1
     * :link, 1, 2
     * :right, 1
     * :visited, 1, 2, 3
     * =, 1
     * ~=, 1
     * |=, 1
       
   
     * @-rules, 1, 2
     * @charset, 1, 2, 3
     * @font-face, 1, 2, 3, 4, 5, 6, 7
     * @import, 1, 2, 3
     * @media, 1, 2, 3, 4
     * @page, 1
       
   
     * absolute length, 1
     * <absolute-size>
          + definition of, 1
     * abstract glyph, 1
     * active (pseudo-class), 1, 2, 3
     * actual value, 1
     * after, 1
     * 'all' media group, 1
     * ancestor, 1
     * <angle>, 1, 2
     * definition of, 3
     * anonymous, 1
     * anonymous inline boxes, 1
     * armenian, 1
     * 'ascent' (descriptor), 1
     * at-rules, 1, 2
     * attr(), 1
     * attribute, 1
     * auditory icon, 1
     * 'aural' media group, 1
     * authoring tool, 1
     * automatic numbering, 1
     * 'azimuth', 1
       
   
     * 'background', 1
     * 'background-attachment', 1
     * 'background-color', 1
     * 'background-image', 1
     * 'background-position', 1
     * 'background-repeat', 1
     * backslash escapes, 1
     * 'baseline' (descriptor), 1
     * 'bbox' (descriptor), 1
     * before, 1
     * bicameral, 1, 2
     * bicameral, definition of, 1
     * bidirectionality (bidi), 1, 2
     * 'bitmap' media group, 1
     * block, 1
     * block box, 1
     * 'block', definition of, 1
     * block-level element, 1
     * border edge, 1
     * 'border', 1, 2
     * 'border-bottom', 1, 2
     * 'border-bottom-color', 1
     * 'border-bottom-style', 1, 2
     * 'border-bottom-width', 1
     * 'border-collapse', 1
     * 'border-color', 1
     * 'border-left', 1, 2
     * 'border-left-color', 1
     * 'border-left-style', 1, 2
     * 'border-left-width', 1
     * 'border-right', 1, 2
     * 'border-right-color', 1
     * 'border-right-style', 1, 2
     * 'border-right-width', 1
     * 'border-spacing', 1
     * <border-style>, 1
     * <border-style>, definition of, 1
     * 'border-style', 1, 2
     * 'border-top', 1, 2
     * 'border-top-color', 1
     * 'border-top-style', 1, 2
     * 'border-top-width', 1
     * <border-width>
          + definition of, 1
     * 'border-width', 1
     * border
          + of a box, 1
     * <bottom>
          + definition of, 1
     * 'bottom', 1
     * box
          + border, 1
          + content, 1
          + content height, 1
          + content width, 1
          + height, 1
          + margin, 1
          + overflow, 1
          + padding, 1
          + width, 1
       
   
     * canvas, 1, 2
     * 'cap-height' (descriptor), 1
     * 'caption-side', 1
     * cascade, 1
     * case sensitivity, 1
     * 'centerline' (descriptor), 1
     * character, 1
     * character encoding, 1
     * default, 2
     * user agent's determination of, 3
     * child, 1
     * child selector, 1
     * circle, 1
     * cjk-ideographic, 1
     * 'clear', 1, 2
     * 'clip', 1
     * clipping region, 1
     * close-quote, 1, 2
     * collapsing margin, 1
     * color, 1
     * <color>, 1, 2
     * definition of, 3
     * 'color', 1
     * 'column-span', 1
     * combinator, 1, 2
     * comments, 1
     * compact, 1
     * compact box, 1
     * 'compact', definition of, 1
     * computed value, 1
     * conditional import, 1
     * conformance, 1, 2, 3, 4, 5, 6, 7, 8, 9
     * containing block, 1, 2, 3, 4
     * initial, 5, 6
     * content, 1
     * content edge, 1
     * 'content', 1
     * content
          + of a box, 1
          + rendered, 1
     * 'continuous' media group, 1
     * <counter>, 1
     * <counter>, definition of, 1
     * counter(), 1
     * 'counter-increment', 1
     * 'counter-reset', 1
     * counters, 1
     * crop marks, 1
     * cross marks, 1
     * 'cue', 1
     * 'cue-after', 1
     * 'cue-before', 1
     * cursive, definition of, 1
     * 'cursor', 1
       
   
     * 'dashed', 1, 2
     * declaration, 1
     * declaration-block, 1
     * default style sheet, 1
     * default
          + character encoding, 1
     * 'definition-src' (descriptor), 1
     * descendant, 1
     * descendant-selectors, 1
     * 'descent' (descriptor), 1
     * 'direction', 1, 2
     * disc, 1
     * 'display', 1
     * document language, 1
     * document tree, 1
     * 'dotted', 1, 2
     * 'double', 1, 2, 3
     * drop caps, 1
     * DTD, 1, 2, 3
       
   
     * element, 1
     * following, 2
     * preceding, 3
     * 'elevation', 1
     * em (unit), 1
     * em square, 1, 2
     * empty, 1
     * 'empty-cells', 1
     * encoding vector, 1
     * ex (unit), 1
     * exact matching, 1
       
   
     * <family-name>
          + definition of, 1
     * fantasy, definition of, 1
     * fictional tag sequence, 1, 2, 3
     * first-child, 1
     * first-letter, 1
     * first-line, 1
     * float rules, 1
     * 'float', 1, 2
     * focus, 1
     * focus (pseudo-class), 1
     * 'focus-outline', 1
     * following element, 1
     * font, 1
     * font data, 1
     * font definition resource, 1
     * font description, 1
     * font download, 1
     * font encoding table, 1
     * font family, 1
     * font set, 1
     * font synthesis, 1
     * 'font', 1
     * <font-description>
          + definition of, 1
     * <font-face-name>
          + definition of, 1
     * 'font-family', 1
     * 'font-family' (descriptor), 1
     * 'font-size', 1
     * 'font-size' (descriptor), 1
     * 'font-size-adjust', 1
     * 'font-stretch', 1
     * 'font-stretch' (descriptor), 1
     * 'font-style', 1
     * 'font-style' (descriptor), 1
     * 'font-variant', 1
     * 'font-variant' (descriptor), 1
     * 'font-weight', 1
     * 'font-weight' (descriptor), 1
     * formatting context, 1
     * <frequency>, 1
     * definition of, 2
     * full font name, 1
       
   
     * generated content, 1
     * <generic-family>
          + definition of, 1
     * <generic-voice>, definition of, 1
     * georgian, 1
     * glyph, 1
     * 'grid' media group, 1
     * 'groove', 1, 2, 3
       
   
     * half-leading, 1, 2
     * hebrew, 1
     * 'height', 1, 2
     * 'hidden, 1
     * 'hidden', 1
     * hiragana, 1
     * hiragana-iroha, 1
     * horizontal margin, 1, 2, 3
     * hover (pseudo-class), 1
     * hyphen-separated matching, 1
       
   
     * identifier, 1
     * identifier, definition of, 1
     * ignore, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
       18, 19, 20, 21, 22, 23, 24, 25, 26, 27
     * illegal, 1
     * important, 1, 2
     * inherit, definition of, 1
     * initial caps, 1
     * initial containing block, 1, 2
     * initial value, 1
     * 'inline', definition of, 1
     * inline-level element, 1
     * inline-table, 1
     * 'inline-table', 1
     * inner edge, 1
     * 'inset', 1, 2, 3
     * <integer>, 1, 2, 3
     * definition of, 4
     * intelligent font matching, 1
     * 'interactive media group, 1
     * internal table element, 1
     * intrinsic width, 1
     * invert, 1, 2
     * iso-10646, 1
     * Italic, definition of, 1
       
   
     * katakana, 1
     * katakana-iroha, 1
       
   
     * lang (pseudo-class), 1
     * language (human), 1
     * language code, 1, 2
     * leading, 1, 2
     * leading-zero, 1
     * <left>
          + definition of, 1
     * 'left', 1
     * <length>, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16,
       17, 18, 19, 20, 21, 22
     * definition of, 23
     * 'letter-spacing', 1
     * ligatures, 1
     * line box, 1, 2
     * line-box, 1, 2, 3
     * 'line-height', 1, 2
     * link (pseudo-class), 1, 2, 3
     * 'list-item', definition of, 1
     * 'list-style', 1, 2, 3
     * 'list-style-image', 1
     * 'list-style-position', 1
     * 'list-style-type', 1
     * LL(1), 1
     * local stacking context, 1
     * lower-greek, 1
     * lower-latin, 1
     * lower-roman, 1
       
   
     * mapping elements to table parts, 1
     * margin edge, 1
     * 'margin', 1
     * 'margin-bottom', 1
     * 'margin-left', 1
     * 'margin-right', 1
     * 'margin-top', 1
     * <margin-width>
          + definition of, 1
     * margin
          + horizontal, 1, 2, 3
          + of a box, 1
          + vertical, 1, 2, 3
     * marker', definition of, 1
     * 'marker-offset', 1
     * 'marks', 1
     * match, 1
     * 'mathline' (descriptor), 1
     * 'max-height', 1, 2
     * 'max-width', 1, 2
     * MAY, 1
     * media, 1
     * media group, 1
     * media type, 1
     * media-dependent import, 1
     * message entity, 1, 2
     * 'min-height', 1, 2
     * 'min-width', 1, 2
     * monospace, definition of, 1
     * MUST, 1
     * MUST NOT, 1
       
   
     * name matching, 1
     * newline, 1
     * no-close-quote, 1, 2
     * no-open-quote, 1, 2
     * 'none'
          + as border style, 1, 2
          + as display value, 1
     * <number>, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13
     * definition of, 14
       
   
     * open-quote, 1, 2
     * OPTIONAL, 1
     * 'orphans', 1
     * outer edge, 1
     * outline, 1, 2
     * 'outline', 1
     * 'outline-color', 1
     * 'outline-style', 1
     * 'outline-width', 1
     * 'outset', 1, 2, 3
     * overflow, 1
     * 'overflow', 1
       
   
     * padding edge, 1
     * 'padding', 1
     * 'padding-bottom', 1
     * 'padding-left', 1
     * 'padding-right', 1
     * 'padding-top', 1
     * <padding-width>
          + definition of, 1
     * padding
          + of a box, 1
     * page area, 1
     * page box, 1
     * page model, 1
     * page selector, 1
     * 'page', 1
     * 'page-break-after', 1
     * 'page-break-before', 1
     * 'page-break-inside', 1
     * page-context, 1
     * 'paged' media group, 1
     * Panose-1, 1
     * panose-1, 1
     * 'panose-1' (descriptor), 1
     * parent, 1
     * 'pause', 1
     * 'pause-after', 1
     * 'pause-before', 1
     * <percentage>, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
       16, 17, 18
     * definition of, 19
     * 'pitch', 1
     * 'pitch-range', 1
     * pixel, 1
     * 'play-during', 1
     * 'position', 1
     * positioning scheme, 1
     * preceding element, 1
     * principal block box, 1
     * progressive rendering, 1
     * property, 1
     * pseudo-class
          + :first, 1
          + :left, 1
          + :right, 1
     * pseudo-classes, 1
     * :active, 2, 3, 4
     * :focus, 5
     * :hover, 6
     * :lang, 7
     * :link, 8, 9
     * :visited, 10, 11, 12
     * pseudo-elements, 1
     * :after, 2, 3, 4
     * :before, 5, 6
     * :first-letter, 7
     * :first-line, 8, 9
       
   
     * quad width, 1
     * 'quotes', 1
       
   
     * RECOMMENDED, 1
     * reference pixel, 1
     * relative positioning, 1, 2
     * relative units, 1
     * <relative-size>
          + definition of, 1
     * rendered content, 1
     * rendering structure, 1
     * replaced element, 1
     * REQUIRED, 1
     * Resource Identifier (URI), 1
     * 'richness', 1
     * 'ridge', 1, 2, 3
     * <right>
          + definition of, 1
     * 'right', 1
     * root, 1
     * root stacking context, 1
     * 'row-span', 1
     * rule sets, 1
     * run-in, 1
     * run-in box, 1
     * 'run-in', definition of, 1
       
   
     * sans-serif, definition of, 1
     * scope, 1
     * screen reader, 1
     * selector, 1, 2, 3, 4
     * match, 5
     * subject of, 6
     * serif, definition of, 1
     * SHALL, 1
     * SHALL NOT, 1
     * <shape>
          + definition of, 1
     * sheet, 1
     * shorthand, 1, 2
     * SHOULD, 1
     * SHOULD NOT, 1
     * sibling, 1
     * simple selector, 1
     * 'size', 1
     * 'slope' (descriptor), 1
     * 'solid', 1, 2, 3
     * source document, 1
     * space-separated matching, 1
     * 'speak', 1
     * 'speak-header', 1
     * 'speak-numeral', 1
     * 'speak-punctuation', 1
     * 'speak-time', 1, 2
     * <specific-voice>
          + definition of, 1
     * specified value, 1
     * 'speech-rate', 1
     * square, 1
     * 'src' (descriptor), 1
     * stack level, 1, 2
     * stacking context, 1, 2
     * statements, 1
     * 'static' media group, 1
     * 'stemh' (descriptor), 1
     * 'stemv' (descriptor), 1
     * 'stress', 1
     * string, 1
     * <string>, 1, 2, 3, 4, 5
     * <string>, definition of, 1
     * style sheet, 1
     * subject (of selector), 1
     * system fonts, 1
       
   
     * table, 1
     * table element, 1
     * internal, 2
     * 'table', 1
     * table-caption, 1
     * 'table-caption', 1
     * table-cell, 1
     * 'table-cell', 1
     * table-column, 1
     * table-column-group, 1
     * 'table-column-group', 1
     * table-footer-group, 1
     * 'table-footer-group', 1
     * table-header-group, 1
     * 'table-header-group', 1
     * 'table-layout', 1
     * table-row, 1
     * 'table-row', 1
     * table-row-group, 1
     * 'table-row-group', 1
     * tables, 1
     * 'tactile' media group, 1
     * 'text-align', 1
     * 'text-decoration', 1
     * 'text-indent', 1
     * 'text-shadow', 1
     * 'text-transform', 1
     * text/css, 1, 2
     * <time>, 1
     * definition of, 2
     * tokenizer, 1
     * <top>
          + definition of, 1
     * 'top', 1
     * 'topline' (descriptor), 1
     * type selector, 1
       
   
     * UA, 1
     * unicameral, 1, 2
     * unicameral, definition of, 1
     * unicode, 1
     * 'unicode-bidi', 1, 2
     * 'unicode-range' (descriptor), 1
     * Uniform Resource Locator (URL), 1
     * Uniform Resource Name (URN), 1
     * 'units-per-em' (descriptor), 1
     * universal selector, 1
     * upper-latin, 1
     * upper-roman, 1
     * <urange>
          + definition of, 1
     * URI (Uniform Resource Identifier), 1
     * <uri>, 1, 2, 3, 4, 5, 6
     * definition of, 7
     * URL (Uniform Resource Locator), 1
     * URN (Uniform Resource Name), 1
     * user agent, 1
       
   
     * valid style sheet, 1
     * value, 1
     * vertical margin, 1, 2, 3
     * 'vertical-align', 1, 2
     * viewport, 1
     * 'visibility', 1
     * visited (pseudo-class), 1, 2, 3
     * visual rendering model, 1
     * 'visual' media group, 1
     * 'voice-family', 1
     * volume, 1
     * 'volume', 1
       
   
     * western-decimal, 1
     * 'white-space', 1
     * 'widows', 1
     * 'width', 1, 2
     * 'widths' (descriptor), 1
     * 'word-spacing', 1
       
   
     * x-height, 1, 2
     * 'x-height' (descriptor), 1
       
   
     * z value, 1
     * 'z-index', 1, 2
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