css-fonts/Fonts.html

Mon, 12 Aug 2013 16:46:57 +0900

author
John Daggett <jdaggett@mozilla.com>
date
Mon, 12 Aug 2013 16:46:57 +0900
changeset 8804
368c6ad02232
parent 8699
233e7213b876
child 8859
1bd7f210c461
permissions
-rw-r--r--

[css3-fonts] change feature precedence for features implied by other CSS properties

     1 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN"
     2 "http://www.w3.org/TR/html4/strict.dtd">
     4 <html lang=en>
     5  <head><meta content="text/html;charset=utf-8" http-equiv=Content-Type>
     7   <title>CSS Fonts Module Level 3</title>
     8   <!--
     9       FIXME when publishing: copy the current default.css and link to
    10       "default.css" rather than "../default.css"
    11    -->
    12   <link href="../default.css" rel=stylesheet type="text/css">
    13   <link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
    14   <!-- I'm just experimenting here, don't get your bee in a bonnet -->
    15   <script src="http://use.typekit.com/xon2bky.js"
    16   type="text/javascript"></script>
    17   <script type="text/javascript">try{Typekit.load();}catch(e){}</script>
    19   <style type="text/css">
    21   body, th, td, h1, h2, h3, h4, h5, h6 {
    22     font-family: "myriad-pro", sans-serif !important;
    23   }
    25   body {
    26     padding: 2em 70px 2em 70px;
    27   }
    29   p + p, p.mtb {
    30     margin-top: 0.8em;
    31     text-indent: 0px;
    32   }
    34   #bolderlighter {
    35     width: 40%;
    36   }
    38   #bolderlighter th {
    39     text-align: center;
    40   }
    42   #fontformats td, #eventhandlers td, #fontformats th, #eventhandlers th {
    43     padding-right: 2em;
    44     text-align: left;
    45   }
    47   dd {
    48     margin-bottom: 1em;
    49   }
    51   #authors dd {
    52     margin-bottom: 0;
    53   }
    55   #fontstylematchingalg {
    56     list-style-type: lower-alpha;
    57   }
    59   #fontmatchingalg ul, #fontmatchingalg ol {
    60     margin-top: 0.8em;
    61   }
    63   #fontmatchingalg li + li {
    64     margin-top: 0.8em;
    65   }
    67   div.example {
    68     padding: 1em;
    69     margin-top: 1em;
    70   }
    72   div.example + div.example {
    73     margin-top: 2em;
    74   }
    76   div.figure {
    77     page-break-inside: avoid;
    78   }
    80   pre.prod { white-space: pre-wrap; margin: 1em 0 1em 2em }
    82   div.featex {
    83     width: 700px;
    84   }
    86   div.featex img {
    87     margin: auto;
    88     display: block;
    89   }
    91   span.tag {
    92     font-family: monospace;
    93     font-size: 120%;
    94   }
    96   ol ol {
    97     list-style-type: lower-alpha;
    98   }
   100   .idl-code {
   101     font-weight: bold;
   102     color: #c50;
   103   }
   104   </style>
   105   <link href="http://www.w3.org/StyleSheets/TR/W3C-ED.css" rel=stylesheet
   106   type="text/css">
   107   <script defer=defer
   108   src="http://test.csswg.org/harness/annotate.js#CSS3-FONTS_DEV"
   109   type="text/javascript"></script>
   111  <body>
   112   <div class=head> <!--begin-logo-->
   113    <p><a href="http://www.w3.org/"><img alt=W3C height=48
   114     src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
   116    <h1>CSS Fonts Module Level 3</h1>
   118    <h2 class="no-num no-toc" id=editors-draft-12-august-2013>Editor's Draft
   119     12 August 2013</h2>
   121    <dl id=authors>
   122     <dt>This version:
   124     <dd><a
   125      href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
   126      <!-- <dd><a href="http://www.w3.org/TR/2013/ED-css-fonts-3-20130812/">http://www.w3.org/TR/2013/ED-css-fonts-3-20130812/</a>  -->
   129     <dt>Latest version:
   131     <dd><a
   132      href="http://www.w3.org/TR/css-fonts-3/">http://www.w3.org/TR/css-fonts-3/</a>
   134     <dt>Latest editor's draft:
   136     <dd><a
   137      href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
   138      (<a
   139      href="https://dvcs.w3.org/hg/csswg/log/tip/css-fonts/Fonts.html">change
   140      log</a>)
   142     <dt>Previous version:
   144     <dd><a
   145      href="http://www.w3.org/TR/2013/WD-css-fonts-3-20130711/">http://www.w3.org/TR/2013/WD-css-fonts-3-20130711/</a>
   147     <dt>Issues List:
   149     <dd><a href="http://www.w3.org/Style/CSS/Tracker/products/18">CSS3 Fonts
   150      issues in Tracker</a>
   152     <dd><a
   153      href="https://www.w3.org/Bugs/Public/buglist.cgi?query_format=advanced&amp;product=CSS&amp;component=Fonts&amp;bug_status=NEW&amp;bug_status=ASSIGNED&amp;bug_status=REOPENED">CSS3
   154      Fonts issues in Bugzilla</a>
   156     <dt>Discussion:
   158     <dd><a
   159      href="mailto:www-style@w3.org?subject=%5Bcss-fonts%5D%20feedback">www-style@w3.org</a>
   160      with subject line “<kbd>[css-fonts] <var>… message topic
   161      …</var></kbd>” (<a
   162      href="http://lists.w3.org/Archives/Public/www-style/"
   163      rel=discussion>archives</a>)
   165     <dt>Editor:
   167     <dd><a href="mailto:jdaggett@mozilla.com">John Daggett (Mozilla)</a>
   168    </dl>
   169    <!--begin-copyright-->
   170    <p class=copyright><a
   171     href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
   172     rel=license>Copyright</a> © 2013 <a href="http://www.w3.org/"><abbr
   173     title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a
   174     href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of
   175     Technology">MIT</abbr></a>, <a href="http://www.ercim.eu/"><abbr
   176     title="European Research Consortium for Informatics and
   177     Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>,
   178     <a href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C
   179     <a
   180     href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
   181     <a
   182     href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
   183     and <a
   184     href="http://www.w3.org/Consortium/Legal/copyright-documents">document
   185     use</a> rules apply.</p>
   186    <!--end-copyright-->
   187    <hr title="Separator for header">
   188   </div>
   190   <h2 class="no-num no-toc" id=abstract>Abstract</h2>
   192   <p>This CSS3 module describes how font properties are specified and how
   193    font resources are loaded dynamically. The contents of this specification
   194    are a consolidation of content previously divided into <a
   195    href="http://www.w3.org/TR/2002/WD-css3-fonts-20020802/">CSS3 Fonts</a>
   196    and <a href="http://www.w3.org/TR/2002/WD-css3-webfonts-20020802/">CSS3
   197    Web Fonts</a> modules. The description of font load events was moved into
   198    the <a href="http://dev.w3.org/csswg/css-font-load-events/">CSS3 Font Load
   199    Events</a> module.
   201   <h2 class="no-num no-toc" id=status>Status of this document</h2>
   202   <!--begin-status-->
   204   <p>This is a public copy of the editors' draft. It is provided for
   205    discussion only and may change at any moment. Its publication here does
   206    not imply endorsement of its contents by W3C. Don't cite this document
   207    other than as work in progress.
   209   <p>The (<a
   210    href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
   211    mailing list <a
   212    href="mailto:www-style@w3.org?Subject=%5Bcss3-fonts%5D%20PUT%20SUBJECT%20HERE">
   213    www-style@w3.org</a> (see <a
   214    href="http://www.w3.org/Mail/Request">instructions</a>) is preferred for
   215    discussion of this specification. When sending e-mail, please put the text
   216    “css3-fonts” in the subject, preferably like this:
   217    “[<!---->css3-fonts<!---->] <em>…summary of comment…</em>”
   219   <p>This document was produced by the <a
   220    href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
   221    the <a href="http://www.w3.org/Style/">Style Activity</a>).
   223   <p>This document was produced by a group operating under the <a
   224    href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
   225    2004 W3C Patent Policy</a>. W3C maintains a <a
   226    href="http://www.w3.org/2004/01/pp-impl/32061/status"
   227    rel=disclosure>public list of any patent disclosures</a> made in
   228    connection with the deliverables of the group; that page also includes
   229    instructions for disclosing a patent. An individual who has actual
   230    knowledge of a patent which the individual believes contains <a
   231    href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
   232    Claim(s)</a> must disclose the information in accordance with <a
   233    href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
   234    6 of the W3C Patent Policy</a>.</p>
   235   <!--end-status-->
   237   <h3 class="no-num no-toc" id=atrisk>Features at risk</h3>
   239   <p>The following features are at risk and may be removed when exiting CR:
   241   <ul>
   242    <li>fallback handling for text decoration in superscript/subscript variant
   243     glyphs (‘<a href="#propdef-font-variant-position"><code
   244     class=property>font-variant-position</code></a>’)
   246    <li>‘<a href="#propdef-font-language-override"><code
   247     class=property>font-language-override</code></a>’ property
   248   </ul>
   249   <!--
   250 <p>This draft is a <strong>Last Call Working Draft</strong>.
   251 Please send comments to the 
   252 <a href="http://lists.w3.org/Archives/Public/www-style/">www-style mailing list</a>
   253 as described above.  The <strong>deadline for comments</strong> 
   254 is six weeks after the date of publication in the header, 22 August 2013.</p>
   255 -->
   257   <h2 class="no-num no-toc" id=contents>Table of contents</h2>
   258   <!--begin-toc-->
   260   <ul class=toc>
   261    <li><a href="#introduction"><span class=secno>1 </span>Introduction</a>
   263    <li><a href="#typography-background"><span class=secno>2 </span>Typography
   264     Background</a>
   266    <li><a href="#basic-font-props"><span class=secno>3 </span>Basic Font
   267     Properties</a>
   268     <ul class=toc>
   269      <li><a href="#font-family-prop"><span class=secno>3.1 </span>Font
   270       family: the font-family property</a>
   271       <ul class=toc>
   272        <li><a href="#generic-font-families"><span class=secno>3.1.1
   273         </span>Generic font families</a>
   274       </ul>
   276      <li><a href="#font-weight-prop"><span class=secno>3.2 </span>Font
   277       weight: the font-weight property</a>
   279      <li><a href="#font-stretch-prop"><span class=secno>3.3 </span>Font
   280       width: the font-stretch property</a>
   282      <li><a href="#font-style-prop"><span class=secno>3.4 </span>Font style:
   283       the font-style property</a>
   285      <li><a href="#font-size-prop"><span class=secno>3.5 </span>Font size:
   286       the font-size property</a>
   288      <li><a href="#font-size-adjust-prop"><span class=secno>3.6
   289       </span>Relative sizing: the font-size-adjust property</a>
   291      <li><a href="#font-prop"><span class=secno>3.7 </span>Shorthand font
   292       property: the font property</a>
   294      <li><a href="#font-synthesis-prop"><span class=secno>3.8
   295       </span>Controlling synthetic faces: the font-synthesis property</a>
   296     </ul>
   298    <li><a href="#font-resources"><span class=secno>4 </span>Font
   299     Resources</a>
   300     <ul class=toc>
   301      <li><a href="#font-face-rule"><span class=secno>4.1 </span>The
   302       <code>@font-face</code> rule</a>
   304      <li><a href="#font-family-desc"><span class=secno>4.2 </span>Font
   305       family: the font-family descriptor</a>
   307      <li><a href="#src-desc"><span class=secno>4.3 </span>Font reference: the
   308       src descriptor</a>
   310      <li><a href="#font-prop-desc"><span class=secno>4.4 </span>Font property
   311       descriptors: the font-style, font-weight, font-stretch descriptors</a>
   313      <li><a href="#unicode-range-desc"><span class=secno>4.5 </span>Character
   314       range: the unicode-range descriptor</a>
   316      <li><a href="#composite-fonts"><span class=secno>4.6 </span>Using
   317       character ranges to define composite fonts</a>
   319      <li><a href="#font-rend-desc"><span class=secno>4.7 </span>Font
   320       features: the font-variant and font-feature-settings descriptors</a>
   322      <li><a href="#font-face-loading"><span class=secno>4.8 </span>Font
   323       loading guidelines</a>
   325      <li><a href="#same-origin-restriction"><span class=secno>4.9
   326       </span>Same-origin restriction for fonts</a>
   327       <ul class=toc>
   328        <li><a href="#default-same-origin-restriction"><span class=secno>4.9.1
   329         </span>Default same-origin restriction</a>
   331        <li><a href="#allowing-cross-origin-font-loading"><span
   332         class=secno>4.9.2 </span>Allowing cross-origin font loading</a>
   333       </ul>
   334     </ul>
   336    <li><a href="#font-matching-algorithm"><span class=secno>5 </span>Font
   337     Matching Algorithm</a>
   338     <ul class=toc>
   339      <li><a href="#font-family-casing"><span class=secno>5.1 </span>Case
   340       sensitivity of font family names</a>
   342      <li><a href="#font-style-matching"><span class=secno>5.2 </span>Matching
   343       font styles</a>
   345      <li><a href="#cluster-matching"><span class=secno>5.3 </span>Cluster
   346       matching</a>
   348      <li><a href="#char-handling-issues"><span class=secno>5.4
   349       </span>Character handling issues</a>
   351      <li><a href="#font-matching-changes"><span class=secno>5.5 </span>Font
   352       matching changes since CSS 2.1</a>
   354      <li><a href="#font-matching-examples"><span class=secno>5.6 </span>Font
   355       matching examples</a>
   356     </ul>
   358    <li><a href="#font-rend-props"><span class=secno>6 </span>Font Feature
   359     Properties</a>
   360     <ul class=toc>
   361      <li><a href="#glyph-selection-positioning"><span class=secno>6.1
   362       </span>Glyph selection and positioning</a>
   364      <li><a href="#language-specific-support"><span class=secno>6.2
   365       </span>Language-specific display</a>
   367      <li><a href="#font-kerning-prop"><span class=secno>6.3 </span>Kerning:
   368       the font-kerning property</a>
   370      <li><a href="#font-variant-ligatures-prop"><span class=secno>6.4
   371       </span>Ligatures: the font-variant-ligatures property</a>
   373      <li><a href="#font-variant-position-prop"><span class=secno>6.5
   374       </span>Subscript and superscript forms: the font-variant-position
   375       property</a>
   377      <li><a href="#font-variant-caps-prop"><span class=secno>6.6
   378       </span>Capitalization: the font-variant-caps property</a>
   380      <li><a href="#font-variant-numeric-prop"><span class=secno>6.7
   381       </span>Numerical formatting: the font-variant-numeric property</a>
   383      <li><a href="#font-variant-alternates-prop"><span class=secno>6.8
   384       </span>Alternates and swashes: the font-variant-alternates property</a>
   387      <li><a href="#font-feature-values"><span class=secno>6.9 </span>Defining
   388       font specific alternates: the <code>@font-feature-values</code>
   389       rule</a>
   390       <ul class=toc>
   391        <li><a href="#basic-syntax"><span class=secno>6.9.1 </span>Basic
   392         syntax</a>
   394        <li><a href="#multi-valued-feature-value-definitions"><span
   395         class=secno>6.9.2 </span>Multi-valued feature value definitions</a>
   396       </ul>
   398      <li><a href="#font-variant-east-asian-prop"><span class=secno>6.10
   399       </span>East Asian text rendering: the font-variant-east-asian
   400       property</a>
   402      <li><a href="#font-variant-prop"><span class=secno>6.11 </span>Overall
   403       shorthand for font rendering: the font-variant property</a>
   405      <li><a href="#font-feature-settings-prop"><span class=secno>6.12
   406       </span>Low-level font feature settings control: the
   407       font-feature-settings property</a>
   409      <li><a href="#font-language-override-prop"><span class=secno>6.13
   410       </span>Font language override: the font-language-override property</a>
   411     </ul>
   413    <li><a href="#font-feature-resolution"><span class=secno>7 </span>Font
   414     Feature Resolution </a>
   415     <ul class=toc>
   416      <li><a href="#default-features"><span class=secno>7.1 </span>Default
   417       features</a>
   419      <li><a href="#feature-precedence"><span class=secno>7.2 </span>Feature
   420       precedence</a>
   422      <li><a href="#feature-precedence-examples"><span class=secno>7.3
   423       </span>Feature precedence examples</a>
   424     </ul>
   426    <li><a href="#object-model"><span class=secno>8 </span>Object Model</a>
   427     <ul class=toc>
   428      <li><a href="#om-fontface"><span class=secno>8.1 </span>The
   429       <code>CSSFontFaceRule</code> interface</a>
   431      <li><a href="#om-fontfeaturevalues"><span class=secno>8.2 </span>The
   432       <code>CSSFontFeatureValuesRule</code> interface</a>
   433     </ul>
   435    <li class=no-num><a href="#platform-props-to-css">Appendix A: Mapping
   436     platform font properties to CSS properties</a>
   438    <li class=no-num><a href="#ch-ch-ch-changes">Changes</a>
   439     <ul class=toc>
   440      <li class=no-num><a href="#recent-changes"> Changes from the July 2013
   441       CSS3 Fonts Last Call Working Draft</a>
   442     </ul>
   444    <li class=no-num><a href="#acknowledgments">Acknowledgments</a>
   446    <li class=no-num><a href="#conformance"> Conformance</a>
   447     <ul class=toc>
   448      <li class=no-num><a href="#conventions"> Document Conventions</a>
   450      <li class=no-num><a href="#conformance-classes"> Conformance Classes</a>
   453      <li class=no-num><a href="#partial"> Partial Implementations</a>
   455      <li class=no-num><a href="#experimental"> Experimental
   456       Implementations</a>
   458      <li class=no-num><a href="#testing"> Non-Experimental
   459       Implementations</a>
   460     </ul>
   462    <li class=no-num><a href="#references">References</a>
   463     <ul class=toc>
   464      <li class=no-num><a href="#normative-references">Normative
   465       References</a>
   467      <li class=no-num><a href="#other-references">Other References</a>
   468     </ul>
   470    <li class=no-num><a href="#index">Index</a>
   472    <li class=no-num><a href="#property-index">Property index</a>
   473   </ul>
   474   <!--end-toc-->
   476   <h2 id=introduction><span class=secno>1 </span>Introduction</h2>
   478   <p>A font provides a resource containing the visual representation of
   479    characters. At the simplest level it contains information that maps
   480    character codes to shapes (called glyphs) that represent these characters.
   481    Fonts sharing a common design style are commonly grouped into font
   482    families classified by a set of standard font properties. Within a family,
   483    the shape displayed for a given character can vary by stroke weight, slant
   484    or relative width, among others. An individual font face is described by a
   485    unique combination of these properties. For a given range of text, CSS
   486    font properties are used to select a font family and a specific font face
   487    within that family to be used when rendering that text. As a simple
   488    example, to use the bold form of Helvetica one could use:
   490   <pre>body {
   491     font-family: Helvetica;
   492     font-weight: bold;
   493 }</pre>
   495   <p>Font resources may be installed locally on the system on which a user
   496    agent is running or downloadable. For local font resources descriptive
   497    information can be obtained directly from the font resource. For
   498    downloadable font resources (sometimes referred to as web fonts), the
   499    descriptive information is included with the reference to the font
   500    resource.
   502   <p>Families of fonts typically don't contain a single face for each
   503    possible variation of font properties. The CSS font selection mechanism
   504    describes how to match a given set of CSS font properties to a single font
   505    face.
   507   <h2 id=typography-background><span class=secno>2 </span>Typography
   508    Background</h2>
   510   <p><em>This section is non-normative.</em>
   512   <p> Typographic traditions vary across the globe, so there is no unique way
   513    to classify all fonts across languages and cultures. For even common Latin
   514    letters, wide variations are possible:
   516   <div class=figure><img alt="variations in glyphs for a single character"
   517    src=aaaaaa.png>
   518    <p class=caption>One character, many glyph variations
   519   </div>
   521   <p>Differences in the anatomy of letterforms is one way to distinguish
   522    fonts. For Latin fonts, flourishes at the ends of a character's main
   523    strokes, or serifs, can distinguish a font from those without. Similar
   524    comparisons exist in non-Latin fonts between fonts with tapered strokes
   525    and those using primarily uniform strokes:
   527   <div class=figure><img alt="serif vs. non-serifs" src=serifvssansserif.png>
   528    <p class=caption>Letterforms with and without serifs
   529   </div>
   531   <div class=figure><img alt="serif vs. non-serifs for japanese"
   532    src=minchovsgothic.png>
   533    <p class=caption>Similar groupings for Japanese typefaces
   534   </div>
   536   <p>Fonts contain letterforms and the data needed to map characters to these
   537    letterforms. Often this may be a simple one-to-one mapping, but more
   538    complex mappings are also possible. The use of combining diacritic marks
   539    creates many variations for an underlying letterform:
   541   <div class=figure><img alt="diacritic marks" src=aaaaaa-diacritics.png>
   542    <p class=caption>Variations with diacritic marks
   543   </div>
   545   <p>A sequence of characters can be represented by a single glyph known as a
   546    ligature:
   548   <div class=figure><img alt="example of a fi ligature"
   549    src=final-ligature.png>
   550    <p class=caption>Ligature example
   551   </div>
   553   <p>Visual transformations based on textual context are often stylistic
   554    option in European languages. They are required to correctly render
   555    languages like Arabic, the lam and alef characters below <em>must</em> be
   556    combined when they exist in sequence:
   558   <div class=figure><img alt="lam alef ligature" src=lamaleflig.png>
   559    <p class=caption>Required Arabic ligature
   560   </div>
   562   <p>The relative complexity of these shaping transformations requires
   563    additional data within the font.
   565   <p>Sets of font faces with various stylistic variations are often grouped
   566    together into font families. In the simplest case a regular face is
   567    supplemented with bold and italic faces, but much more extensive groupings
   568    are possible. Variations in the thickness of letterform strokes, the <dfn
   569    id=weight>weight</dfn>, and the overall proportions of the letterform, the
   570    <dfn id=width>width</dfn>, are most common. In the example below, each
   571    letter uses a different font face within the Univers font family. The
   572    width used increases from top to bottom and the weight increases from left
   573    to right:
   575   <div class=figure><img alt="various width and weight variations within a
   576    single family" src=weightwidthvariations.png>
   577    <p class=caption>Weight and width variations within a single font family
   578   </div>
   580   <p>Creating fonts that support multiple scripts is a difficult task;
   581    designers need to understand the cultural traditions surrounding the use
   582    of type in different scripts and come up with letterforms that somehow
   583    share a common theme. Many languages often share a common script and each
   584    of these languages may have noticeable stylistic differences. For example,
   585    the Arabic script is shared by Persian and Urdu and Cyrillic is used with
   586    many languages, not just Russian.
   588   <p>The <a href="#character-map"><em>character map</em></a> of a font
   589    defines the mapping of characters to glyphs for that font. If a document
   590    contains characters not supported by the <a href="#character-map"><em
   591    title="character map">character maps</em></a> of the fonts contained in a
   592    font family list, a user agent may use a <a
   593    href="#system-font-fallback"><em>system font fallback</em></a> procedure
   594    to locate an appropriate font that does. If no appropriate font can be
   595    found, some form of "missing glyph" character will be rendered by the user
   596    agent. System fallback can occur when the specified list of font families
   597    does not include a font that supports a given character.
   599   <p>Although the <a href="#character-map"><em>character map</em></a> of a
   600    font maps a given character to a glyph for that character, modern font
   601    technologies such as OpenType and AAT (Apple Advanced Typography) provide
   602    ways of mapping a character to different glyphs based upon feature
   603    settings. Fonts in these formats allow these features to be embedded in
   604    the font itself and controlled by applications. Common typographic
   605    features which can be specified this way include ligatures, swashes,
   606    contextual alternates, proportional and tabular figures, and automatic
   607    fractions, to list just a few. For a visual overview of OpenType features,
   608    see the <a href="#OPENTYPE-FONT-GUIDE"
   609    rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
   611   <h2 id=basic-font-props><span class=secno>3 </span>Basic Font Properties</h2>
   613   <p>The particular font face used to render a character is determined by the
   614    font family and other font properties that apply to a given element. This
   615    structure allows settings to be varied independent of each other.</p>
   616   <!-- prop: font-family -->
   618   <h3 id=font-family-prop><span class=secno>3.1 </span>Font family: the <a
   619    href="#propdef-font-family">font-family</a> property</h3>
   621   <table class=propdef id=namefont-familyvalue-ltfamily-namegt-ltg>
   622    <tbody>
   623     <tr>
   624      <td>Name:
   626      <td><dfn id=propdef-font-family
   627       title="font-family!!property">font-family</dfn>
   629     <tr>
   630      <td>Value:
   632      <td>[ <a href="#family-name-value"><var>&lt;family-name&gt;</var></a> |
   633       <a href="#generic-family-value"><var>&lt;generic-family&gt;</var></a> ]
   634       #
   636     <tr>
   637      <td>Initial:
   639      <td>depends on user agent
   641     <tr>
   642      <td>Applies to:
   644      <td>all elements
   646     <tr>
   647      <td>Inherited:
   649      <td>yes
   651     <tr>
   652      <td>Percentages:
   654      <td>N/A
   656     <tr>
   657      <td>Media:
   659      <td>visual
   661     <tr>
   662      <td>Computed value:
   664      <td>as specified
   666     <tr>
   667      <td>Animatable:
   669      <td>no
   670   </table>
   672   <p>This property specifies a prioritized list of font family names or
   673    generic family names. A font family defines a set of faces that vary in
   674    weight, width or slope. CSS uses the combination of a family name with
   675    other style attributes to select an individual face. Using this selection
   676    mechanism, rather than selecting a face via the style name as is often
   677    done in design applications, allows some degree of regularity in textual
   678    display when fallback occurs.
   680   <p class=note>Designers should note that the CSS definition of font
   681    attributes used for selection are explicitly not intended to define a font
   682    taxonomy. A type designer's idea of a family may often extend to a set of
   683    faces that vary along axes other than just the standard axes of weight,
   684    width and slope. A family may extend to include both a set of serif faces
   685    and a set of sans-serif faces or vary along axes that are unique to that
   686    family. The CSS font selection mechanism merely provides a way to
   687    determine the “closest” substitute when substitution is necessary.
   689   <p>Unlike other CSS properties, component values are a comma-separated list
   690    indicating alternatives. A user agent iterates through the list of family
   691    names until it matches an available font that contains a glyph for the
   692    character to be rendered. This allows for differences in available fonts
   693    across platforms and for differences in the range of characters supported
   694    by individual fonts.
   696   <p>A font family name only specifies a name given to a set of font faces,
   697    it does not specify an individual face. For example, given the
   698    availability of the fonts below, Futura would match but Futura Medium
   699    would not:
   701   <div class=figure><img alt="family and face names"
   702    src=familyvsfacename.png>
   703    <p class=caption>Family and individual face names
   704   </div>
   706   <p>Consider the example below:
   708   <div class=example>
   709    <pre>body {
   710     font-family: Helvetica, Verdana, sans-serif;
   711 }</pre>
   713    <p>If Helvetica is available it will be used when rendering. If neither
   714     Helvetica nor Verdana is present, then the user-agent-defined sans serif
   715     font will be used.</p>
   716   </div>
   718   <p>There are two types of font family names:
   720   <dl>
   721    <dt><dfn id=family-name-value><var>&lt;family-name&gt;</var></dfn>
   723    <dd>The name of a font family of choice such as Helvetica or Verdana in
   724     the previous example.
   726    <dt><dfn id=generic-family-value><var>&lt;generic-family&gt;</var></dfn>
   728    <dd> The following generic family keywords are defined: ‘<a
   729     href="#serif"><code class=property>serif</code></a>’, ‘<a
   730     href="#sans-serif"><code class=property>sans-serif</code></a>’, ‘<a
   731     href="#cursive"><code class=property>cursive</code></a>’, ‘<a
   732     href="#fantasy"><code class=property>fantasy</code></a>’, and ‘<a
   733     href="#monospace"><code class=property>monospace</code></a>’. These
   734     keywords can be used as a general fallback mechanism when an author's
   735     desired font choices are not available. As keywords, they must not be
   736     quoted. Authors are encouraged to append a generic font family as a last
   737     alternative for improved robustness.
   738   </dl>
   740   <p>Font family names other than generic families must either be given
   741    quoted as <a
   742    href="http://www.w3.org/TR/CSS21/syndata.html#strings">strings,</a> or
   743    unquoted as a sequence of one or more <a
   744    href="http://www.w3.org/TR/CSS21/syndata.html#value-def-identifier">identifiers.</a>
   745    This means most punctuation characters and digits at the start of each
   746    token must be escaped in unquoted font family names.
   748   <p>To illustrate this, the following declarations are invalid:
   750   <pre>
   751 font-family: Red/Black, sans-serif;
   752 font-family: "Lucida" Grande, sans-serif;
   753 font-family: Ahem!, sans-serif;
   754 font-family: test@foo, sans-serif;
   755 font-family: #POUND, sans-serif;
   756 font-family: Hawaii 5-0, sans-serif;
   757 </pre>
   759   <p>If a sequence of identifiers is given as a font family name, the
   760    computed value is the name converted to a string by joining all the
   761    identifiers in the sequence by single spaces.
   763   <p>To avoid mistakes in escaping, it is recommended to quote font family
   764    names that contain white space, digits, or punctuation characters other
   765    than hyphens:
   767   <pre>
   768 body { font-family: "New Century Schoolbook", serif }
   770 &lt;BODY STYLE="font-family: '21st Century', fantasy">
   771 </pre>
   773   <p>Font family <em>names</em> that happen to be the same as a keyword value
   774    (‘<code class=property>inherit</code>’, ‘<a href="#serif"><code
   775    class=property>serif</code></a>’, ‘<a href="#sans-serif"><code
   776    class=property>sans-serif</code></a>’, ‘<a href="#monospace"><code
   777    class=property>monospace</code></a>’, ‘<a href="#fantasy"><code
   778    class=property>fantasy</code></a>’, and ‘<a href="#cursive"><code
   779    class=property>cursive</code></a>’) must be quoted to prevent confusion
   780    with the keywords with the same names. The keywords ‘<code
   781    class=property>initial</code>’ and ‘<code
   782    class=property>default</code>’ are reserved for future use and must also
   783    be quoted when used as font names. UAs must not consider these keywords as
   784    matching the <a
   785    href="#family-name-value"><var>&lt;family-name&gt;</var></a> type.
   787   <p>The precise way a set of fonts are grouped into font families varies
   788    depending upon the platform font management API's. The Windows GDI API
   789    only allows four faces to be grouped into a family while the DirectWrite
   790    API and API's on OSX and other platforms support font families with a
   791    variety of weights, widths and slopes (see <a
   792    href="#platform-props-to-css">Appendix A</a> for more details).
   794   <p>Some font formats allow fonts to carry multiple localizations of the
   795    family name. User agents must recognize and correctly match all of these
   796    names independent of the underlying platform localization, system API used
   797    or document encoding:
   799   <div class=figure><img alt="examples of localized family names"
   800    src=localizedfamilynames.png>
   801    <p class=caption>Localized family names
   802   </div>
   804   <h4 id=generic-font-families><span class=secno>3.1.1 </span>Generic font
   805    families</h4>
   807   <p>All five generic font families are defined to exist in all CSS
   808    implementations (they need not necessarily map to five distinct actual
   809    fonts). User agents should provide reasonable default choices for the
   810    generic font families, which express the characteristics of each family as
   811    well as possible within the limits allowed by the underlying technology.
   812    User agents are encouraged to allow users to select alternative choices
   813    for the generic fonts.
   815   <h5 class="no-num no-toc"> <span class=index-def id=serif0 title="serif,
   816    definition of"><a name=serif-def><dfn id=serif>serif</dfn></a></span></h5>
   818   <p>Serif fonts represent the formal text style for a script. This often
   819    means but is not limited to glyphs that have finishing strokes, flared or
   820    tapering ends, or have actual serifed endings (including slab serifs).
   821    Serif fonts are typically proportionately-spaced. They often display a
   822    greater variation between thick and thin strokes than fonts from the ‘<a
   823    href="#sans-serif"><code class=property>sans-serif</code></a>’ generic
   824    font family. CSS uses the term ‘<a href="#serif"><code
   825    class=property>serif</code></a>’ to apply to a font for any script,
   826    although other names may be more familiar for particular scripts, such as
   827    Mincho (Japanese), Sung, Song or Kai (Chinese), Batang (Korean). For
   828    Arabic, the Naskh style would correspond to ‘<a href="#serif"><code
   829    class=property>serif</code></a>’ more due to its typographic role rather
   830    than its actual design style. Any font that is so described may be used to
   831    represent the generic ‘<a href="#serif"><code
   832    class=property>serif</code></a>’ family.
   834   <div class=figure><img alt="sample serif fonts" src=serifexamples.png>
   835    <p class=caption>Sample serif fonts
   836   </div>
   838   <h5 class="no-num no-toc"> <span class=index-def id=sans-serif0
   839    title="sans-serif, definition of"> <a name=sans-serif-def><dfn
   840    id=sans-serif>sans-serif</dfn></a></span></h5>
   842   <p>Glyphs in sans-serif fonts, as the term is used in CSS, are generally
   843    low contrast (vertical and horizontal stems have the close to the same
   844    thickness) and have stroke endings that are plain -- without any flaring,
   845    cross stroke, or other ornamentation. Sans-serif fonts are typically
   846    proportionately-spaced. They often have little variation between thick and
   847    thin strokes, compared to fonts from the ‘<a href="#serif"><code
   848    class=property>serif</code></a>’ family. CSS uses the term ‘<a
   849    href="#sans-serif"><code class=property>sans-serif</code></a>’ to apply
   850    to a font for any script, although other names may be more familiar for
   851    particular scripts, such as Gothic (Japanese), Hei (Chinese), or Gulim
   852    (Korean). Any font that is so described may be used to represent the
   853    generic ‘<a href="#sans-serif"><code
   854    class=property>sans-serif</code></a>’ family.
   856   <div class=figure><img alt="sample sans-serif fonts"
   857    src=sansserifexamples.png>
   858    <p class=caption>Sample sans-serif fonts
   859   </div>
   861   <h5 class="no-num no-toc"> <span class=index-def id=cursive0
   862    title="cursive, definition of"> <a name=cursive-def><dfn
   863    id=cursive>cursive</dfn></a></span></h5>
   865   <p>Glyphs in cursive fonts generally use a more informal script style, and
   866    the result looks more like handwritten pen or brush writing than printed
   867    letterwork. CSS uses the term ‘<a href="#cursive"><code
   868    class=property>cursive</code></a>’ to apply to a font for any script,
   869    although other names such as Chancery, Brush, Swing and Script are also
   870    used in font names.
   872   <div class=figure><img alt="sample cursive fonts" src=cursiveexamples.png>
   873    <p class=caption>Sample cursive fonts
   874   </div>
   876   <h5 class="no-num no-toc"> <span class=index-def id=fantasy0
   877    title="fantasy, definition of"> <a name=fantasy-def><dfn
   878    id=fantasy>fantasy</dfn></a></span></h5>
   880   <p>Fantasy fonts are primarily decorative or expressive fonts that contain
   881    playful representations of characters. These do not include Pi or Picture
   882    fonts which do not represent actual characters.
   884   <div class=figure><img alt="sample fantasy fonts" src=fantasyexamples.png>
   885    <p class=caption>Sample fantasy fonts
   886   </div>
   888   <h5 class="no-num no-toc"> <span class=index-def id=monospace0
   889    title="monospace, definition of"> <a name=monospace-def><dfn
   890    id=monospace>monospace</dfn></a></span></h5>
   892   <p>The sole criterion of a monospace font is that all glyphs have the same
   893    fixed width. This is often used to render samples of computer code.
   895   <div class=figure><img alt="sample monospace fonts"
   896    src=monospaceexamples.png>
   897    <p class=caption>Sample monospace fonts
   898   </div>
   899   <!-- prop: font-weight -->
   901   <h3 id=font-weight-prop><span class=secno>3.2 </span>Font weight: the <a
   902    href="#propdef-font-weight">font-weight</a> property</h3>
   904   <table class=propdef id=namefont-weightvaluenormal-bold-bolder-l>
   905    <tbody>
   906     <tr>
   907      <td>Name:
   909      <td><dfn id=propdef-font-weight
   910       title="font-weight!!property">font-weight</dfn>
   912     <tr>
   913      <td>Value:
   915      <td><a href="#font-weight-normal-value"
   916       title="normal!!font-weight">normal</a> | <a href="#bold">bold</a> | <a
   917       href="#bolder">bolder</a> | <a href="#lighter">lighter</a> | <a
   918       href="#font-weight-numeric-values" title="100...900 weight
   919       values">100</a> | <a href="#font-weight-numeric-values"
   920       title="100...900 weight values">200</a> | <a
   921       href="#font-weight-numeric-values" title="100...900 weight
   922       values">300</a> | <a href="#font-weight-numeric-values"
   923       title="100...900 weight values">400</a> | <a
   924       href="#font-weight-numeric-values" title="100...900 weight
   925       values">500</a> | <a href="#font-weight-numeric-values"
   926       title="100...900 weight values">600</a> | <a
   927       href="#font-weight-numeric-values" title="100...900 weight
   928       values">700</a> | <a href="#font-weight-numeric-values"
   929       title="100...900 weight values">800</a> | <a
   930       href="#font-weight-numeric-values" title="100...900 weight
   931       values">900</a>
   933     <tr>
   934      <td>Initial:
   936      <td>normal
   938     <tr>
   939      <td>Applies to:
   941      <td>all elements
   943     <tr>
   944      <td>Inherited:
   946      <td>yes
   948     <tr>
   949      <td>Percentages:
   951      <td>N/A
   953     <tr>
   954      <td>Media:
   956      <td>visual
   958     <tr>
   959      <td>Computed value:
   961      <td>numeric weight value (see description)
   963     <tr>
   964      <td>Animatable:
   966      <td>as <a
   967       href="http://dev.w3.org/csswg/css3-transitions/#animtype-font-weight">font
   968       weight</a>
   969   </table>
   971   <p>The <a href="#propdef-font-weight"
   972    title="font-weight!!property">‘<code
   973    class=property>font-weight</code>’</a> property specifies the weight of
   974    glyphs in the font, their degree of blackness or stroke thickness.
   976   <p>Values have the following meanings:
   978   <dl>
   979    <dt><dfn id=font-weight-numeric-values title="100...900 weight values">100
   980     to 900</dfn>
   982    <dd>These values form an ordered sequence, where each number indicates a
   983     weight that is at least as dark as its predecessor. These roughly
   984     correspond to the commonly used weight names below:
   985   </dl>
   987   <ul>
   988    <li>100 - Thin
   990    <li>200 - Extra Light (Ultra Light)
   992    <li>300 - Light
   994    <li>400 - Normal
   996    <li>500 - Medium
   998    <li>600 - Semi Bold (Demi Bold)
  1000    <li>700 - Bold
  1002    <li>800 - Extra Bold (Ultra Bold)
  1004    <li>900 - Black (Heavy)
  1005   </ul>
  1007   <dl>
  1008    <dt><dfn id=font-weight-normal-value
  1009     title="normal!!font-weight">normal</dfn>
  1011    <dd>Same as ‘<code class=css>400</code>’.
  1013    <dt><dfn id=bold>bold</dfn>
  1015    <dd>Same as ‘<code class=css>700</code>’.
  1017    <dt><dfn id=bolder>bolder</dfn>
  1019    <dd>Specifies a bolder weight than the inherited value.
  1021    <dt><dfn id=lighter>lighter</dfn>
  1023    <dd>Specifies a lighter weight than the inherited value.
  1024   </dl>
  1026   <p>Font formats that use a scale other than a nine-step scale should map
  1027    their scale onto the CSS scale so that 400 roughly corresponds with a face
  1028    that would be labeled as Regular, Book, Roman and 700 roughly matches a
  1029    face that would be labeled as Bold. Or weights may be inferred from the
  1030    style names, ones that correspond roughly with the scale above. The scale
  1031    is relative, so a face with a larger weight value must never appear
  1032    lighter. If style names are used to infer weights, care should be taken to
  1033    handle variations in style names across locales.
  1035   <p>Quite often there are only a few weights available for a particular font
  1036    family. When a weight is specified for which no face exists, a face with a
  1037    nearby weight is used. In general, bold weights map to faces with heavier
  1038    weights and light weights map to faces with lighter weights (see the <a
  1039    href="#font-matching-algorithm">font matching section below</a> for a
  1040    precise definition). The examples here illustrate which face is used for
  1041    different weights, grey indicates a face for that weight does not exist so
  1042    a face with a nearby weight is used:
  1044   <div class=figure><img alt="weight mappings for a family with 400, 700 and
  1045    900 weights" src=optimaweights.png>
  1046    <p class=caption>Weight mappings for a font family with 400, 700 and 900
  1047     weight faces
  1048   </div>
  1050   <div class=figure><img alt="weight mappings for a family with 300, 600
  1051    weights" src=hiraginoweights.png>
  1052    <p class=caption>Weight mappings for a font family with 300 and 600 weight
  1053     faces
  1054   </div>
  1056   <p>Although the practice is not well-loved by typographers, bold faces are
  1057    often synthesized by user agents for faces that lack actual bold faces.
  1058    For the purposes of style matching, these faces must be treated as if they
  1059    exist within the family. Authors can explicitly avoid this behavior by
  1060    using the ‘<a href="#propdef-font-synthesis"><code
  1061    class=property>font-synthesis</code></a>’ property.
  1063   <p>Specified values of ‘<a href="#bolder"><code
  1064    class=property>bolder</code></a>’ and ‘<a href="#lighter"><code
  1065    class=property>lighter</code></a>’ indicate weights relative to the
  1066    weight of the parent element. The computed weight is calculated based on
  1067    the inherited <a href="#propdef-font-weight"
  1068    title="font-weight!!property">‘<code
  1069    class=property>font-weight</code>’</a> value using the chart below.
  1071   <table class=data id=bolderlighter summary="Bolder/lighter mappings">
  1072    <thead>
  1073     <tr>
  1074      <th>Inherited value
  1076      <th>bolder
  1078      <th>lighter
  1080    <tbody>
  1081     <tr>
  1082      <th>100
  1084      <td>400
  1086      <td>100
  1088     <tr>
  1089      <th>200
  1091      <td>400
  1093      <td>100
  1095     <tr>
  1096      <th>300
  1098      <td>400
  1100      <td>100
  1102     <tr>
  1103      <th>400
  1105      <td>700
  1107      <td>100
  1109     <tr>
  1110      <th>500
  1112      <td>700
  1114      <td>100
  1116     <tr>
  1117      <th>600
  1119      <td>900
  1121      <td>400
  1123     <tr>
  1124      <th>700
  1126      <td>900
  1128      <td>400
  1130     <tr>
  1131      <th>800
  1133      <td>900
  1135      <td>700
  1137     <tr>
  1138      <th>900
  1140      <td>900
  1142      <td>700
  1143   </table>
  1145   <p>The table above is equivalent to selecting the next relative bolder or
  1146    lighter face, given a font family containing normal and bold faces along
  1147    with a thin and a heavy face. Authors who desire finer control over the
  1148    exact weight values used for a given element may use numerical values
  1149    instead of relative weights.</p>
  1150   <!-- prop: font-stretch -->
  1152   <h3 id=font-stretch-prop><span class=secno>3.3 </span>Font width: the <a
  1153    href="#propdef-font-stretch">font-stretch</a> property</h3>
  1155   <table class=propdef id=namefont-stretchvalue-normal-ultra-conde>
  1156    <tbody>
  1157     <tr>
  1158      <td>Name:
  1160      <td><dfn id=propdef-font-stretch
  1161       title="font-stretch!!property">font-stretch</dfn>
  1163     <tr>
  1164      <td>Value:
  1166      <td> <a href="#font-stretch-normal-value"
  1167       title="normal!!font-stretch">normal</a> | <a
  1168       href="#ultra-condensed">ultra-condensed</a> | <a
  1169       href="#extra-condensed">extra-condensed</a> | <a
  1170       href="#condensed">condensed</a> | <a
  1171       href="#semi-condensed-">semi-condensed</a> | <a
  1172       href="#semi-expanded">semi-expanded</a> | <a
  1173       href="#expanded">expanded</a> | <a
  1174       href="#extra-expanded">extra-expanded</a> | <a
  1175       href="#ultra-expanded">ultra-expanded</a>
  1177     <tr>
  1178      <td>Initial:
  1180      <td>normal
  1182     <tr>
  1183      <td>Applies to:
  1185      <td>all elements
  1187     <tr>
  1188      <td>Inherited:
  1190      <td>yes
  1192     <tr>
  1193      <td>Percentages:
  1195      <td>N/A
  1197     <tr>
  1198      <td>Media:
  1200      <td>visual
  1202     <tr>
  1203      <td>Computed value:
  1205      <td>as specified
  1207     <tr>
  1208      <td>Animatable:
  1210      <td>as <a href="#font-stretch-animation">font stretch</a>
  1211   </table>
  1213   <p>The <a href="#propdef-font-stretch"
  1214    title="font-stretch!!property">‘<code
  1215    class=property>font-stretch</code>’</a> property selects a normal,
  1216    condensed, or expanded face from a font family. Absolute keyword values
  1217    have the following ordering, from narrowest to widest:
  1219   <ul>
  1220    <li><dfn id=ultra-condensed>ultra-condensed</dfn>
  1222    <li><dfn id=extra-condensed>extra-condensed</dfn>
  1224    <li><dfn id=condensed>condensed</dfn>
  1226    <li><dfn id=semi-condensed->semi-condensed </dfn>
  1228    <li><dfn id=font-stretch-normal-value
  1229     title="normal!!font-stretch">normal</dfn>
  1231    <li><dfn id=semi-expanded>semi-expanded</dfn>
  1233    <li><dfn id=expanded>expanded</dfn>
  1235    <li><dfn id=extra-expanded>extra-expanded</dfn>
  1237    <li><dfn id=ultra-expanded>ultra-expanded</dfn>
  1238   </ul>
  1240   <p>When a face does not exist for a given width, normal or condensed values
  1241    map to a narrower face, otherwise a wider face. Conversely, expanded
  1242    values map to a wider face, otherwise a narrower face. The figure below
  1243    shows how the nine font-stretch property settings affect font selection
  1244    for font family containing a variety of widths, grey indicates a width for
  1245    which no face exists and a different width is substituted:
  1247   <div class=figure><img alt="width mappings for a family with condensed,
  1248    normal and expanded faces" src=universwidths.png>
  1249    <p class=caption>Width mappings for a font family with condensed, normal
  1250     and expanded width faces
  1251   </div>
  1253   <p id=font-stretch-animation>Animation of font stretch: Font stretch is
  1254    interpolated in discrete steps. The interpolation happens as though the
  1255    ordered values are equally spaced real numbers. The interpolation result
  1256    is rounded to the nearest value, with values exactly halfway between two
  1257    values rounded towards the later value in the list above.</p>
  1258   <!-- prop: font-style -->
  1260   <h3 id=font-style-prop><span class=secno>3.4 </span>Font style: the <a
  1261    href="#propdef-font-style">font-style</a> property</h3>
  1263   <table class=propdef id=namefont-stylevaluenormal-italic-oblique>
  1264    <tbody>
  1265     <tr>
  1266      <td>Name:
  1268      <td><dfn id=propdef-font-style
  1269       title="font-style!!property">font-style</dfn>
  1271     <tr>
  1272      <td>Value:
  1274      <td><a href="#font-style-normal-value"
  1275       title="normal!!font-style">normal</a> | <a href="#italic">italic</a> |
  1276       <a href="#oblique">oblique</a>
  1278     <tr>
  1279      <td>Initial:
  1281      <td>normal
  1283     <tr>
  1284      <td>Applies to:
  1286      <td>all elements
  1288     <tr>
  1289      <td>Inherited:
  1291      <td>yes
  1293     <tr>
  1294      <td>Percentages:
  1296      <td>N/A
  1298     <tr>
  1299      <td>Media:
  1301      <td>visual
  1303     <tr>
  1304      <td>Computed value:
  1306      <td>as specified
  1308     <tr>
  1309      <td>Animatable:
  1311      <td>no
  1312   </table>
  1314   <p>The <a href="#propdef-font-style" title="font-style!!property">‘<code
  1315    class=property>font-style</code>’</a> property allows italic or oblique
  1316    faces to be selected. Italic forms are generally cursive in nature while
  1317    oblique faces are typically sloped versions of the regular face. Oblique
  1318    faces can be simulated by artificially sloping the glyphs of the regular
  1319    face. Compare the artificially sloped renderings of Palatino ‘<code
  1320    class=property>a</code>’ and Baskerville ‘<code
  1321    class=property>N</code>’ in grey with the actual italic versions:
  1323   <div class=figure><img alt="artificial sloping vs. real italics"
  1324    src=realvsfakeitalics.png>
  1325    <p class=caption>Artificial sloping versus real italics
  1326   </div>
  1328   <p>Values have the following meanings:
  1330   <dl>
  1331    <dt><dfn id=font-style-normal-value
  1332     title="normal!!font-style">normal</dfn>
  1334    <dd>selects a face that is classified as a normal face, one that is
  1335     neither italic or obliqued
  1337    <dt><dfn id=italic>italic</dfn>
  1339    <dd>selects a font that is labeled as an italic face, or an oblique face
  1340     if one is not
  1342    <dt><dfn id=oblique>oblique</dfn>
  1344    <dd>selects a font that is labeled as an oblique face, or an italic face
  1345     if one is not
  1346   </dl>
  1348   <p>If no italic or oblique face is available, oblique faces can be
  1349    synthesized by rendering non-obliqued faces with an artificial obliquing
  1350    operation. The use of these artificially obliqued faces can be disabled
  1351    using the ‘<a href="#propdef-font-synthesis"><code
  1352    class=property>font-synthesis</code></a>’ property. The details of the
  1353    obliquing operation are not explicitly defined.</p>
  1354   <!-- resolution on the "undefined" nature of synthetics: http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
  1356   <p>Many scripts lack the tradition of mixing a cursive form within text
  1357    rendered with a normal face. Chinese, Japanese and Korean fonts almost
  1358    always lack italic or oblique faces. Fonts that support a mixture of
  1359    scripts will sometimes omit specific scripts such as Arabic from the set
  1360    of glyphs supported in the italic face. User agents should be careful
  1361    about making <a href="#character-map"><em>character map</em></a>
  1362    assumptions across faces when implementing support for <a
  1363    href="#system-font-fallback"><em>system font fallback</em></a>.</p>
  1364   <!-- prop: font-size -->
  1366   <h3 id=font-size-prop><span class=secno>3.5 </span>Font size: the <a
  1367    href="#propdef-font-size">font-size</a> property</h3>
  1369   <table class=propdef id=namefont-sizevalueltabsolute-sizegt-ltre>
  1370    <tbody>
  1371     <tr>
  1372      <td>Name:
  1374      <td><dfn id=propdef-font-size>font-size</dfn>
  1376     <tr>
  1377      <td>Value:
  1379      <td><a href="#absolute-size-value"><var>&lt;absolute-size&gt;</var></a>
  1380       | <a href="#relative-size-value"><var>&lt;relative-size&gt;</var></a> |
  1381       <a href="#length-size-value"><var>&lt;length&gt;</var></a> | <a
  1382       href="#percentage-size-value"><var>&lt;percentage&gt;</var></a>
  1384     <tr>
  1385      <td>Initial:
  1387      <td>medium
  1389     <tr>
  1390      <td>Applies to:
  1392      <td>all elements
  1394     <tr>
  1395      <td>Inherited:
  1397      <td>yes
  1399     <tr>
  1400      <td>Percentages:
  1402      <td>refer to parent element's font size
  1404     <tr>
  1405      <td>Media:
  1407      <td>visual
  1409     <tr>
  1410      <td>Computed value:
  1412      <td>absolute length
  1414     <tr>
  1415      <td>Animatable:
  1417      <td>as <a
  1418       href="http://dev.w3.org/csswg/css3-transitions/#animtype-length">length</a>
  1419   </table>
  1421   <p>This property indicates the desired height of glyphs from the font. For
  1422    scalable fonts, the font-size is a scale factor applied to the EM unit of
  1423    the font. (Note that certain glyphs may bleed outside their EM box.) For
  1424    non-scalable fonts, the font-size is converted into absolute units and
  1425    matched against the declared font-size of the font, using the same
  1426    absolute coordinate space for both of the matched values. Values have the
  1427    following meanings:
  1429   <dl>
  1430    <dt><dfn id=absolute-size-value><var>&lt;absolute-size&gt;</var></dfn>
  1432    <dd> An <a
  1433     href="#absolute-size-value"><var>&lt;absolute-size&gt;</var></a> keyword
  1434     refers to an entry in a table of font sizes computed and kept by the user
  1435     agent. Possible values are:
  1436     <p> [ xx-small | x-small | small | medium | large | x-large | xx-large ]</p>
  1438    <dt><dfn id=relative-size-value><var>&lt;relative-size&gt;</var></dfn>
  1440    <dd> A <a href="#relative-size-value"><var>&lt;relative-size&gt;</var></a>
  1441     keyword is interpreted relative to the table of font sizes and the
  1442     computed ‘<a href="#propdef-font-size"><code
  1443     class=property>font-size</code></a>’ of the parent element. Possible
  1444     values are:
  1445     <p> [ larger | smaller ]
  1447     <p> For example, if the parent element has a font size of ‘<code
  1448      class=property>medium</code>’, a value of ‘<code
  1449      class=property>larger</code>’ will make the font size of the current
  1450      element be ‘<code class=property>large</code>’. If the parent
  1451      element's size is not close to a table entry, the user agent is free to
  1452      interpolate between table entries or round off to the closest one. The
  1453      user agent may have to extrapolate table values if the numerical value
  1454      goes beyond the keywords.
  1456    <dt><dfn id=length-size-value><var>&lt;length&gt;</var></dfn>
  1458    <dd>A length value specifies an absolute font size (independent of the
  1459     user agent's font table). Negative lengths are illegal.
  1461    <dt><dfn id=percentage-size-value><var>&lt;percentage&gt;</var></dfn>
  1463    <dd>A percentage value specifies an absolute font size relative to the
  1464     parent element's font size. Use of percentage values, or values in
  1465     ‘<code class=property>em</code>’s, leads to more robust and
  1466     cascadable style sheets.
  1467   </dl>
  1469   <p>The following table provides user agent guidelines for the absolute-size
  1470    scaling factor and their mapping to HTML heading and absolute font-sizes.
  1471    The ‘<code class=property>medium</code>’ value is used as the
  1472    reference middle value. The user agent may fine-tune these values for
  1473    different fonts or different types of display devices.
  1475   <table class=data>
  1476    <thead>
  1477     <tr>
  1478      <th>CSS absolute-size values
  1480      <th>xx-small
  1482      <th>x-small
  1484      <th>small
  1486      <th>medium
  1488      <th>large
  1490      <th>x-large
  1492      <th>xx-large
  1494      <th> 
  1496    <tbody>
  1497     <tr>
  1498      <th>scaling factor
  1500      <td>3/5
  1502      <td>3/4
  1504      <td>8/9
  1506      <td>1
  1508      <td>6/5
  1510      <td>3/2
  1512      <td>2/1
  1514      <td>3/1
  1516     <tr>
  1517      <th>HTML headings
  1519      <td>h6
  1521      <td> 
  1523      <td>h5
  1525      <td>h4
  1527      <td>h3
  1529      <td>h2
  1531      <td>h1
  1533      <td> 
  1535     <tr>
  1536      <th>HTML font sizes
  1538      <td>1
  1540      <td> 
  1542      <td>2
  1544      <td>3
  1546      <td>4
  1548      <td>5
  1550      <td>6
  1552      <td>7
  1553   </table>
  1555   <p class=note><em><strong>Note 1.</strong> To preserve readability, an UA
  1556    applying these guidelines should nevertheless avoid creating font-size
  1557    resulting in less than 9 device pixels per EM unit on a computer
  1558    display.</em>
  1560   <p class=note><em><strong>Note 2.</strong> In CSS1, the suggested scaling
  1561    factor between adjacent indexes was 1.5 which user experience proved to be
  1562    too large. In CSS2, the suggested scaling factor for computer screen
  1563    between adjacent indexes was 1.2 which still created issues for the small
  1564    sizes. The new scaling factor varies between each index to provide a
  1565    better readability.</em>
  1567   <p>The actual value of this property may differ from the computed value due
  1568    a numerical value on ‘<a href="#propdef-font-size-adjust"><code
  1569    class=property>font-size-adjust</code></a>’ and the unavailability of
  1570    certain font sizes.
  1572   <p>Child elements inherit the computed <a class=noxref
  1573    href="#font-size-prop"> <span class=property>‘<code
  1574    class=property>font-size</code>’</span></a> value (otherwise, the effect
  1575    of <a class=noxref href="#font-size-adjust-prop"><span
  1576    class=property>‘<code
  1577    class=property>font-size-adjust</code>’</span></a> would compound).
  1579   <div class=example>
  1580    <p style="display:none">Example(s):</p>
  1582    <pre>p { font-size: 12pt; }
  1583 blockquote { font-size: larger }
  1584 em { font-size: 150% }
  1585 em { font-size: 1.5em }
  1586 </pre>
  1587   </div>
  1588   <!-- prop: font-size-adjust -->
  1590   <h3 id=font-size-adjust-prop><span class=secno>3.6 </span>Relative sizing:
  1591    the <a href="#propdef-font-size-adjust">font-size-adjust</a> property</h3>
  1593   <table class=propdef id=namefont-size-adjustvaluenone-auto-ltnum>
  1594    <tbody>
  1595     <tr>
  1596      <td>Name:
  1598      <td><dfn id=propdef-font-size-adjust>font-size-adjust</dfn>
  1600     <tr>
  1601      <td>Value:
  1603      <td><a href="#font-size-adjust-none-value"
  1604       title="none!!font-size-adjust">none</a> | <a
  1605       href="#font-size-adjust-auto-value"
  1606       title="auto!!font-size-adjust">auto</a> | <a
  1607       href="#aspect-ratio-value"><var>&lt;number&gt;</var></a>
  1609     <tr>
  1610      <td>Initial:
  1612      <td>none
  1614     <tr>
  1615      <td>Applies to:
  1617      <td>all elements
  1619     <tr>
  1620      <td>Inherited:
  1622      <td>yes
  1624     <tr>
  1625      <td>Percentages:
  1627      <td>N/A
  1629     <tr>
  1630      <td>Media:
  1632      <td>visual
  1634     <tr>
  1635      <td>Computed value:
  1637      <td>as specified
  1639     <tr>
  1640      <td>Animatable:
  1642      <td>as <a
  1643       href="http://dev.w3.org/csswg/css3-transitions/#animtype-number">number</a>
  1644   </table>
  1646   <p>For any given font size, the apparent size and legibility of text varies
  1647    across fonts. For scripts such as Latin or Cyrillic that distinguish
  1648    between upper and lowercase letters, the relative height of lowercase
  1649    letters compared to their uppercase counterparts is a determining factor
  1650    of legibility. This is commonly referred to as the <a class=index-def
  1651    href="#aspect-value" id=aspect-value0 title="aspect value"><dfn
  1652    id=aspect-value>aspect value</dfn></a>. Precisely defined, it is equal to
  1653    the x-height of a font divided by the font size.
  1655   <p>In situations where font fallback occurs, fallback fonts may not share
  1656    the same aspect ratio as the desired font family and will thus appear less
  1657    readable. The font-size-adjust property is a way to preserve the
  1658    readability of text when font fallback occurs. It does this by adjusting
  1659    the font-size so that the x-height is the same regardless of the font
  1660    used.
  1662   <div class=example>
  1663    <p>The style defined below defines Verdana as the desired font family, but
  1664     if Verdana is not available Futura or Times will be used.</p>
  1666    <pre>p {
  1667     font-family: Verdana, Futura, Times;
  1670 &lt;p>Lorem ipsum dolor sit amet, ...&lt;/p>
  1671 </pre>
  1673    <p>Verdana has a relatively high aspect ratio, lowercase letters are
  1674     relatively tall compared to uppercase letters, so at small sizes text
  1675     appears legible. Times has a lower aspect ratio and so if fallback
  1676     occurs, the text will be less legible at small sizes than Verdana.</p>
  1677   </div>
  1679   <p>How text rendered in each of these fonts compares is shown below, the
  1680    columns show text rendered in Verdana, Futura and Times. The same
  1681    font-size value is used across cells within each row and red lines are
  1682    included to show the differences in x-height. In the upper half each row
  1683    is rendered in the same font-size value. The same is true for the lower
  1684    half but in this half the font-size-adjust property is also set so that
  1685    the actual font size is adjusted to preserve the x-height across each row.
  1686    Note how small text remains relatively legible across each row in the
  1687    lower half.
  1689   <div class=figure><img alt="text with and without font-size-adjust"
  1690    src=fontsizeadjust.png>
  1691    <p class=caption>Text with and without the use of font-size-adjust
  1692   </div>
  1694   <p>This property allows authors to specify an <a
  1695    href="#aspect-value"><i>aspect value</i></a> for an element that will
  1696    effectively preserve the x-height of the first choice font, whether it is
  1697    substituted or not. Values have the following meanings:
  1699   <dl>
  1700    <dt><dfn id=font-size-adjust-none-value
  1701     title="none!!font-size-adjust">none</dfn>
  1703    <dd>Do not preserve the font's x-height.
  1705    <dt><dfn id=font-size-adjust-auto-value
  1706     title="auto!!font-size-adjust">auto</dfn>
  1708    <dd>Behaves just like &lt;number>, except the number used is the <a
  1709     href="#aspect-value"><i>aspect value</i></a> calculated by user agents
  1710     for the first font in the list of fonts defined for the initial value of
  1711     the <a href="#propdef-font-family" title="font-family!!property">‘<code
  1712     class=property>font-family</code>’</a> property. Effectively this is
  1713     the default font used when <a href="#propdef-font-family"
  1714     title="font-family!!property">‘<code
  1715     class=property>font-family</code>’</a> is not otherwise specified.
  1716     <p>Authors can use this value to specify that font size should be
  1717      normalized across fonts based on the x-height without the need to
  1718      specify the aspect ratio explicitly.</p>
  1720    <dt><dfn id=aspect-ratio-value><var>&lt;number&gt;</var></dfn>
  1722    <dd>Specifies the <a href="#aspect-value"><i>aspect value</i></a> used in
  1723     the calculation below to calculate the adjusted font size:
  1724     <pre>c  =  ( a / a' ) s
  1725 </pre>
  1727     <p>where:</p>
  1729     <pre>s  =  font-size value
  1730 a  =  <a href="#aspect-value"><i>aspect value</i></a> as specified by the font-size-adjust property
  1731 a' =  <a href="#aspect-value"><i>aspect value</i></a> of actual font
  1732 c  =  adjusted font-size to use
  1733 </pre>
  1735     <p>This value applies to any font that is selected but in typical usage
  1736      it should be based on the <a href="#aspect-value"><i>aspect
  1737      value</i></a> of the first font in the font-family list. If this is
  1738      specified accurately, the <tt>(a/a')</tt> term in the formula above is
  1739      effectively 1 for the first font and no adjustment occurs. If the value
  1740      is specified inaccurately, text rendered using the first font in the
  1741      family list will display differently in older user agents that don't
  1742      support font-size-adjust.</p>
  1743   </dl>
  1745   <p>The value of ‘<a href="#propdef-font-size-adjust"><code
  1746    class=property>font-size-adjust</code></a>’ affects the size of relative
  1747    units that are based on font metrics of the <a
  1748    href="#first-available-font"><i>first available font</i></a> such as
  1749    <code>ex</code> and <code>ch</code> but does not affect the size of
  1750    <code>em</code> units.
  1752   <p>Authors can calculate the <a href="#aspect-value"><i>aspect
  1753    value</i></a> for a given font by comparing spans with the same content
  1754    but different font-size-adjust properties. If the same font-size is used,
  1755    the spans will match when the font-size-adjust value is accurate for the
  1756    given font.
  1758   <div class=example>
  1759    <p>Two spans with borders are used to determine the <a
  1760     href="#aspect-value"><i>aspect value</i></a> of a font. The font-size is
  1761     the same for both spans but the font-size-adjust property is specified
  1762     only for the right span. Starting with a value of 0.5, the aspect value
  1763     can be adjusted until the borders around the two letters line up.</p>
  1765    <pre>p {
  1766     font-family: Futura;
  1767     font-size: 500px;
  1770 span {
  1771     border: solid 1px red;
  1774 .adjust {
  1775     font-size-adjust: 0.5;
  1778 &lt;p>&lt;span>b&lt;/span>&lt;span class="adjust">b&lt;/span>&lt;/p>
  1779 </pre>
  1781    <div class=figure><img alt="Futura with an <i>aspect value</i> of 0.5"
  1782     src=beforefontsizeadjust.png>
  1783     <p class=caption>Futura with an <a href="#aspect-value"><i>aspect
  1784      value</i></a> of 0.5
  1785    </div>
  1787    <p>The box on the right is a bit bigger than the one on the left, so the
  1788     <a href="#aspect-value"><i>aspect value</i></a> of this font is something
  1789     less than 0.5. Adjust the value until the boxes align.</p>
  1790   </div>
  1791   <!-- prop: font -->
  1793   <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
  1794    <a href="#propdef-font">font</a> property</h3>
  1796   <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
  1797    <tbody>
  1798     <tr>
  1799      <td>Name:
  1801      <td><dfn id=propdef-font>font</dfn>
  1803     <tr>
  1804      <td>Value:
  1806      <td>[ [ <var>&lt;<a href="#propdef-font-style"
  1807       title="font-style!!property">‘<code
  1808       class=property>font-style</code>’</a>&gt;</var> || <a
  1809       href="#font-variant-css21-values"><var>&lt;font-variant-css21&gt;</var></a>
  1810       || <var>&lt;<a href="#propdef-font-weight"
  1811       title="font-weight!!property">‘<code
  1812       class=property>font-weight</code>’</a>&gt;</var> || <var>&lt;<a
  1813       href="#propdef-font-stretch" title="font-stretch!!property">‘<code
  1814       class=property>font-stretch</code>’</a></var> ]? <var>&lt;‘<a
  1815       href="#propdef-font-size"><code
  1816       class=property>font-size</code></a>’&gt;</var> [ / <var>&lt;‘<code
  1817       class=property>line-height</code>’&gt;</var> ]? <var>&lt;<a
  1818       href="#propdef-font-family" title="font-family!!property">‘<code
  1819       class=property>font-family</code>’</a>&gt;</var> ] | caption | icon |
  1820       menu | message-box | small-caption | status-bar
  1822     <tr>
  1823      <td>Initial:
  1825      <td>see individual properties
  1827     <tr>
  1828      <td>Applies to:
  1830      <td>all elements
  1832     <tr>
  1833      <td>Inherited:
  1835      <td>yes
  1837     <tr>
  1838      <td>Percentages:
  1840      <td>see individual properties
  1842     <tr>
  1843      <td>Media:
  1845      <td>visual
  1847     <tr>
  1848      <td>Computed value:
  1850      <td>see individual properties
  1852     <tr>
  1853      <td>Animatable:
  1855      <td>see individual properties
  1856   </table>
  1858   <p>The <span class=property>‘<a href="#propdef-font"><code
  1859    class=property>font</code></a>’</span> property is, except as described
  1860    below, a shorthand property for setting <a href="#propdef-font-style"
  1861    title="font-style!!property">‘<code
  1862    class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
  1863    title="font-variant!!property">‘<code
  1864    class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
  1865    title="font-weight!!property">‘<code
  1866    class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
  1867    title="font-stretch!!property">‘<code
  1868    class=property>font-stretch</code>’</a>, <span class=property>‘<a
  1869    href="#propdef-font-size"><code
  1870    class=property>font-size</code></a>’</span>, <a class=property
  1871    href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
  1872    class=property>line-height</code>’</a>, <a href="#propdef-font-family"
  1873    title="font-family!!property">‘<code
  1874    class=property>font-family</code>’</a> at the same place in the
  1875    stylesheet. Values for the <a href="#propdef-font-variant"
  1876    title="font-variant!!property">‘<code
  1877    class=property>font-variant</code>’</a> property may also be included
  1878    but only those supported in CSS 2.1, none of the <a
  1879    href="#propdef-font-variant" title="font-variant!!property">‘<code
  1880    class=property>font-variant</code>’</a> values added in this
  1881    specification can be used in the <span class=property>‘<a
  1882    href="#propdef-font"><code class=property>font</code></a>’</span>
  1883    shorthand:
  1885   <pre
  1886    class=prod><dfn id=font-variant-css21-values><var>&lt;font-variant-css21&gt;</var></dfn> = [normal | small-caps]</pre>
  1888   <p>The syntax of this property is based on a traditional typographical
  1889    shorthand notation to set multiple properties related to fonts.
  1891   <p>All subproperties of the ‘<a href="#propdef-font"><code
  1892    class=property>font</code></a>’ property are first reset to their
  1893    initial values, including those listed above plus <span
  1894    class=property>‘<a href="#propdef-font-size-adjust"><code
  1895    class=property>font-size-adjust</code></a>’</span>, <span
  1896    class=property>‘<a href="#propdef-font-kerning"><code
  1897    class=property>font-kerning</code></a>’</span>, subproperties of <a
  1898    href="#propdef-font-variant" title="font-variant!!property">‘<code
  1899    class=property>font-variant</code>’</a> and and <span>‘<a
  1900    href="#propdef-font-language-override"><code
  1901    class=property>font-language-override</code></a>’</span>. Then, those
  1902    properties that are given explicit values in the <span
  1903    class=property>‘<a href="#propdef-font"><code
  1904    class=property>font</code></a>’</span> shorthand are set to those
  1905    values. For a definition of allowed and initial values, see the previously
  1906    defined properties. For reasons of backwards compatibility, it is not
  1907    possible to set <span class=property>‘<a
  1908    href="#propdef-font-size-adjust"><code
  1909    class=property>font-size-adjust</code></a>’</span> to anything other
  1910    than its initial value using the <span class=property>‘<a
  1911    href="#propdef-font"><code class=property>font</code></a>’</span>
  1912    shorthand property; instead, use the individual property.
  1914   <div class=example>
  1915    <p style="display:none">Example(s):</p>
  1917    <pre>p { font: 12pt/14pt sans-serif }
  1918 p { font: 80% sans-serif }
  1919 p { font: x-large/110% &quot;new century schoolbook&quot;, serif }
  1920 p { font: bold italic large Palatino, serif }
  1921 p { font: normal small-caps 120%/120% fantasy }
  1922 p { font: condensed oblique 12pt &quot;Helvetica Neue&quot;, serif; }
  1923 </pre>
  1925    <p> In the second rule, the font size percentage value (‘<code
  1926     class=css>80%</code>’) refers to the computed ‘<a
  1927     href="#propdef-font-size"><code class=property>font-size</code></a>’ of
  1928     the parent element. In the third rule, the line height percentage
  1929     (‘<code class=css>110%</code>’) refers to the font size of the
  1930     element itself.
  1932    <p>The first three rules do not specify the <a
  1933     href="#propdef-font-variant" title="font-variant!!property">‘<code
  1934     class=property>font-variant</code>’</a> and <a
  1935     href="#propdef-font-weight" title="font-weight!!property">‘<code
  1936     class=property>font-weight</code>’</a> explicitly, so these properties
  1937     receive their initial values (<span title="normal value">‘<code
  1938     class=property>normal</code>’</span>). Notice that the font family name
  1939     "new century schoolbook", which contains spaces, is enclosed in quotes.
  1940     The fourth rule sets the <a href="#propdef-font-weight"
  1941     title="font-weight!!property">‘<code
  1942     class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
  1943     class=property>bold</code></a>’, the <a href="#propdef-font-style"
  1944     title="font-style!!property">‘<code
  1945     class=property>font-style</code>’</a> to ‘<a href="#italic"><code
  1946     class=property>italic</code></a>’, and implicitly sets <a
  1947     href="#propdef-font-variant" title="font-variant!!property">‘<code
  1948     class=property>font-variant</code>’</a> to <a
  1949     href="#font-variant-normal-value" title="normal!!font-variant">‘<code
  1950     class=property>normal</code>’</a>.
  1952    <p> The fifth rule sets the <a href="#propdef-font-variant"
  1953     title="font-variant!!property">‘<code
  1954     class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
  1955     class=property>small-caps</code></a>’), the <span class=property>‘<a
  1956     href="#propdef-font-size"><code
  1957     class=property>font-size</code></a>’</span> (120% of the parent's font
  1958     size), the <a class=property
  1959     href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
  1960     class=property>line-height</code>’</a> (120% of the font size) and the
  1961     <a href="#propdef-font-family" title="font-family!!property">‘<code
  1962     class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
  1963     class=property>fantasy</code></a>’). It follows that the keyword <span
  1964     title="normal value">‘<code class=property>normal</code>’</span>
  1965     applies to the two remaining properties: <a href="#propdef-font-style"
  1966     title="font-style!!property">‘<code
  1967     class=property>font-style</code>’</a> and <a
  1968     href="#propdef-font-weight" title="font-weight!!property">‘<code
  1969     class=property>font-weight</code>’</a>.
  1971    <p>The sixth rule sets the <a href="#propdef-font-style"
  1972     title="font-style!!property">‘<code
  1973     class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
  1974     title="font-stretch!!property">‘<code
  1975     class=property>font-stretch</code>’</a>, <span class=property>‘<a
  1976     href="#propdef-font-size"><code
  1977     class=property>font-size</code></a>’</span>, and <a
  1978     href="#propdef-font-family" title="font-family!!property">‘<code
  1979     class=property>font-family</code>’</a>, the other font properties being
  1980     set to their initial values.
  1981   </div>
  1983   <p>Since the <a href="#propdef-font-stretch"
  1984    title="font-stretch!!property">‘<code
  1985    class=property>font-stretch</code>’</a> property was not defined in CSS
  1986    2.1, when using <a href="#propdef-font-stretch"
  1987    title="font-stretch!!property">‘<code
  1988    class=property>font-stretch</code>’</a> values within ‘<a
  1989    href="#propdef-font"><code class=property>font</code></a>’ rules,
  1990    authors should include a extra version compatible with older user agents:
  1992   <pre>p {
  1993   font: 80% sans-serif;   /* for older user agents */
  1994   font: condensed 80% sans-serif;
  1995 }</pre>
  1997   <p>The following values refer to system fonts:
  1999   <dl>
  2000    <dt><strong>caption</strong>
  2002    <dd>The font used for captioned controls (e.g., buttons, drop-downs,
  2003     etc.).
  2005    <dt><strong>icon</strong>
  2007    <dd>The font used to label icons.
  2009    <dt><strong>menu</strong>
  2011    <dd>The font used in menus (e.g., dropdown menus and menu lists).
  2013    <dt><strong>message-box</strong>
  2015    <dd>The font used in dialog boxes.
  2017    <dt><strong>small-caption</strong>
  2019    <dd>The font used for labeling small controls.
  2021    <dt><strong>status-bar</strong>
  2023    <dd>The font used in window status bars.
  2024   </dl>
  2026   <p>System fonts may only be set as a whole; that is, the font family, size,
  2027    weight, style, etc. are all set at the same time. These values may then be
  2028    altered individually if desired. If no font with the indicated
  2029    characteristics exists on a given platform, the user agent should either
  2030    intelligently substitute (e.g., a smaller version of the ‘<code
  2031    class=property>caption</code>’ font might be used for the ‘<code
  2032    class=property>small-caption</code>’ font), or substitute a user agent
  2033    default font. As for regular fonts, if, for a system font, any of the
  2034    individual properties are not part of the operating system's available
  2035    user preferences, those properties should be set to their initial values.
  2037   <p>That is why this property is "almost" a shorthand property: system fonts
  2038    can only be specified with this property, not with <a
  2039    href="#propdef-font-family" title="font-family!!property">‘<code
  2040    class=property>font-family</code>’</a> itself, so <span
  2041    class=property>‘<a href="#propdef-font"><code
  2042    class=property>font</code></a>’</span> allows authors to do more than
  2043    the sum of its subproperties. However, the individual properties such as
  2044    <a href="#propdef-font-weight" title="font-weight!!property">‘<code
  2045    class=property>font-weight</code>’</a> are still given values taken from
  2046    the system font, which can be independently varied.
  2048   <p>Note that the keywords used for the system fonts listed above are only
  2049    treated as keywords when they occur in the initial position, in other
  2050    positions the same string is treated as part of the font family name:
  2052   <pre>  font: menu;        /* use the font settings for system menus */
  2053   font: large menu;  /* use a font family named "menu" */</pre>
  2055   <div class=example>
  2056    <p style="display:none">Example(s):</p>
  2058    <pre>button { font: 300 italic 1.3em/1.7em &quot;FB Armada&quot;, sans-serif }
  2059 button p { font: menu }
  2060 button p em { font-weight: bolder }
  2061 </pre>
  2063    <p>If the font used for dropdown menus on a particular system happened to
  2064     be, for example, 9-point Charcoal, with a weight of 600, then P elements
  2065     that were descendants of BUTTON would be displayed as if this rule were
  2066     in effect:
  2068    <pre>button p { font: 600 9pt Charcoal }
  2069 </pre>
  2071    <p>Because the <span class=property>‘<a href="#propdef-font"><code
  2072     class=property>font</code></a>’</span> shorthand resets to its initial
  2073     value any property not explicitly given a value, this has the same effect
  2074     as this declaration:
  2076    <pre>button p {
  2077   font-style: normal;
  2078   font-variant: normal;
  2079   font-weight: 600;
  2080   font-size: 9pt;
  2081   line-height: normal;
  2082   font-family: Charcoal
  2084 </pre>
  2085   </div>
  2086   <!-- prop: font-synthesis -->
  2088   <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
  2089    synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
  2090    property</h3>
  2092   <table class=propdef id=namefont-synthesisvaluenone-weight-style>
  2093    <tbody>
  2094     <tr>
  2095      <td>Name:
  2097      <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
  2099     <tr>
  2100      <td>Value:
  2102      <td>none | [ weight || style ]
  2104     <tr>
  2105      <td>Initial:
  2107      <td>weight style
  2109     <tr>
  2110      <td>Applies to:
  2112      <td>all elements
  2114     <tr>
  2115      <td>Inherited:
  2117      <td>yes
  2119     <tr>
  2120      <td>Percentages:
  2122      <td>N/A
  2124     <tr>
  2125      <td>Media:
  2127      <td>visual
  2129     <tr>
  2130      <td>Computed value:
  2132      <td>as specified
  2134     <tr>
  2135      <td>Animatable:
  2137      <td>no
  2138   </table>
  2140   <p>This property controls whether user agents are allowed to synthesize
  2141    bold or oblique font faces when a font family lacks bold or italic faces.
  2142    If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
  2143    specified, user agents must not synthesize bold faces and if ‘<code
  2144    class=property>style</code>’ is not specified user agents must not
  2145    synthesize italic faces. A value of ‘<code class=property>none</code>’
  2146    disallows all synthetic faces.
  2148   <div class=example>
  2149    <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
  2151    <pre>*:lang(ar) { font-synthesis: none; }
  2152 </pre>
  2153   </div>
  2155   <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
  2157   <h3 id=font-face-rule><span class=secno>4.1 </span>The <dfn
  2158    id=at-font-face-rule style="font-weight: inherit; font-style:
  2159    inherit"><code>@font-face</code></dfn> rule</h3>
  2161   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule allows
  2162    for linking to fonts that are automatically fetched and activated when
  2163    needed. This allows authors to select a font that closely matches the
  2164    design goals for a given page rather than limiting the font choice to a
  2165    set of fonts available on all platforms. A set of font descriptors define
  2166    the location of a font resource, either locally or externally, along with
  2167    the style characteristics of an individual face. Multiple <a
  2168    href="#at-font-face-rule"><code>@font-face</code></a> rules can be used to
  2169    construct font families with a variety of faces. Using CSS font matching
  2170    rules, a user agent can selectively download only those faces that are
  2171    needed for a given piece of text.
  2173   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2174    consists of the <a href="#at-font-face-rule"><code>@font-face</code></a>
  2175    at-keyword followed by a block of descriptor declarations. In terms of the
  2176    grammar, this specification defines the following productions:
  2178   <pre><dfn id=fontfacerule>font_face_rule</dfn>
  2179   : <a href="#fontfacesym"><i>FONT_FACE_SYM</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#descriptordeclaration"><i>descriptor_declaration</i></a>? [ ';' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#descriptordeclaration"><i>descriptor_declaration</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
  2182 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
  2183   : <a href="http://www.w3.org/TR/CSS21/grammar.html#grammar"><i>property</i></a> ':' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/grammar.html#grammar"><i>expr</i></a>
  2184   ;</pre>
  2186   <p>The following new definitions are introduced:
  2188   <pre>-    -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
  2189 F    f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
  2191   <p>The following new token is introduced:
  2193   <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
  2195   <p>Each <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2196    specifies a value for every font descriptor, either implicitly or
  2197    explicitly. Those not given explicit values in the rule take the initial
  2198    value listed with each descriptor in this specification. These descriptors
  2199    apply solely within the context of the <a
  2200    href="#at-font-face-rule"><code>@font-face</code></a> rule in which they
  2201    are defined, and do not apply to document language elements. There is no
  2202    notion of which elements the descriptors apply to or whether the values
  2203    are inherited by child elements. When a given descriptor occurs multiple
  2204    times in a given <a href="#at-font-face-rule"><code>@font-face</code></a>
  2205    rule, only the last descriptor declaration is used and all prior
  2206    declarations for that descriptor are ignored.
  2208   <div class=example>
  2209    <p>To use a downloadable font called Gentium:</p>
  2211    <pre>
  2212 @font-face {
  2213   font-family: Gentium;
  2214   src: url(http://example.com/fonts/Gentium.ttf);
  2217 p { font-family: Gentium, serif; }
  2218 </pre>
  2220    <p>The user agent will download Gentium and use it when rendering text
  2221     within paragraph elements. If for some reason the site serving the font
  2222     is unavailable, the default serif font will be used.</p>
  2223   </div>
  2225   <p>A given set of <a href="#at-font-face-rule"><code>@font-face</code></a>
  2226    rules define a set of fonts available for use within the documents that
  2227    contain these rules. When font matching is done, fonts defined using these
  2228    rules are considered before other available fonts on a system.
  2230   <p>Downloaded fonts are only available to documents that reference them.
  2231    The process of activating these fonts must not make them available to
  2232    other applications or to documents that don't directly link to the same
  2233    font. User agent implementers might consider it convenient to use
  2234    downloaded fonts when rendering characters in other documents for which no
  2235    other available font exists as part of the <a
  2236    href="#system-font-fallback"><em>system font fallback</em></a> procedure.
  2237    However, this would cause a security leak since the contents of one page
  2238    would be able to affect other pages, something an attacker could use as an
  2239    attack vector. These restrictions do not affect caching behavior, fonts
  2240    are cached the same way other web resources are cached.
  2242   <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
  2243    properties in a declaration block, declarations of any descriptors that
  2244    are not supported by the user agent must be ignored. <a
  2245    href="#at-font-face-rule"><code>@font-face</code></a> rules require a
  2246    font-family and src descriptor; if either of these are missing, the <a
  2247    href="#at-font-face-rule"><code>@font-face</code></a> rule is invalid and
  2248    must be ignored entirely.
  2250   <p>In cases where user agents have limited platform resources or implement
  2251    the ability to disable downloadable font resources, <a
  2252    href="#at-font-face-rule"><code>@font-face</code></a> rules must simply be
  2253    ignored; the behavior of individual descriptors as defined in this
  2254    specification should not be altered.
  2256   <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
  2257    href="#descdef-font-family">font-family</a> descriptor</h3>
  2259   <table class=descdef>
  2260    <tbody>
  2261     <tr>
  2262      <td>Name:
  2264      <td><dfn id=descdef-font-family
  2265       title="font-family!!descriptor">font-family</dfn>
  2267     <tr>
  2268      <td>Value:
  2270      <td><a href="#family-name-value"><var>&lt;family-name&gt;</var></a>
  2272     <tr>
  2273      <td><em>Initial:</em>
  2275      <td>N/A
  2276   </table>
  2278   <p>This descriptor defines the font family name that will be used in all
  2279    CSS font family name matching. It is required for the <a
  2280    href="#at-font-face-rule"><code>@font-face</code></a> rule to be valid. It
  2281    overrides the font family names contained in the underlying font data. If
  2282    the font family name is the same as a font family available in a given
  2283    user's environment, it effectively hides the underlying font for documents
  2284    that use the stylesheet. This permits a web author to freely choose
  2285    font-family names without worrying about conflicts with font family names
  2286    present in a given user's environment. Likewise, platform substitutions
  2287    for a given font family name must not be used.
  2289   <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
  2290    href="#descdef-src">src</a> descriptor</h3>
  2292   <table class=descdef>
  2293    <tbody>
  2294     <tr>
  2295      <td>Name:
  2297      <td><dfn id=descdef-src>src</dfn>
  2299     <tr>
  2300      <td>Value:
  2302      <td>[ &lt;url> [format(&lt;string> #)]? | <a
  2303       href="#font-face-name-value"><var>&lt;font-face-name&gt;</var></a> ] #
  2305     <tr>
  2306      <td><em>Initial:</em>
  2308      <td>N/A
  2309   </table>
  2311   <p>This descriptor specifies the resource containing font data. It is
  2312    required for the <a href="#at-font-face-rule"><code>@font-face</code></a>
  2313    rule to be valid. Its value is a prioritized, comma-separated list of
  2314    external references or locally-installed font face names. When a font is
  2315    needed the user agent iterates over the set of references listed, using
  2316    the first one it can successfully activate. Fonts containing invalid data
  2317    or local font faces that are not found are ignored and the user agent
  2318    loads the next font in the list.
  2320   <p>As with other URLs in CSS, the URL may be relative, in which case it is
  2321    resolved relative to the location of the style sheet containing the <a
  2322    href="#at-font-face-rule"><code>@font-face</code></a> rule. In the case of
  2323    SVG fonts, the URL points to an element within a document containing SVG
  2324    font definitions. If the element reference is omitted, a reference to the
  2325    first defined font is implied. Similarly, font container formats that can
  2326    contain more than one font must load one and only one of the fonts for a
  2327    given <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  2328    Fragment identifiers are used to indicate which font to load. If a
  2329    container format lacks a defined fragment identifier scheme,
  2330    implementations should use a simple 1-based indexing scheme (e.g.
  2331    "font-collection#1" for the first font, "font-collection#2" for the second
  2332    font).
  2334   <pre>
  2335 src: url(fonts/simple.ttf);   /* load simple.ttf relative to stylesheet location */
  2336 src: url(/fonts/simple.ttf);  /* load simple.ttf from absolute location */
  2337 src: url(fonts.svg#simple);   /* load SVG font with id 'simple' */
  2338 </pre>
  2340   <p>External references consist of a URL, followed by an optional hint
  2341    describing the format of the font resource referenced by that URL. The
  2342    format hint contains a comma-separated list of format strings that denote
  2343    well-known font formats. Conformant user agents must skip downloading a
  2344    font resource if the format hints indicate only unsupported or unknown
  2345    font formats. If no format hints are supplied, the user agent should
  2346    download the font resource.
  2348   <pre>
  2349 /* load WOFF font if possible, otherwise use OpenType font */
  2350 @font-face {
  2351   font-family: bodytext;
  2352   src: url(ideal-sans-serif.woff) format("woff"),
  2353        url(basic-sans-serif.ttf) format("opentype");
  2355 </pre>
  2357   <p>Format strings defined by this specification:
  2359   <table class=data id=fontformats>
  2360    <thead>
  2361     <tr>
  2362      <th>String
  2364      <th>Font Format
  2366      <th>Common extensions
  2368    <tbody>
  2369     <tr>
  2370      <th>"woff"
  2372      <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
  2374      <td>.woff
  2376     <tr>
  2377      <th>"truetype"
  2379      <td><a
  2380       href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
  2382      <td>.ttf
  2384     <tr>
  2385      <th>"opentype"
  2387      <td><a
  2388       href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
  2390      <td>.ttf, .otf
  2392     <tr>
  2393      <th>"embedded-opentype"
  2395      <td><a
  2396       href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
  2397       OpenType</a>
  2399      <td>.eot
  2401     <tr>
  2402      <th>"svg"
  2404      <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
  2406      <td>.svg, .svgz
  2407   </table>
  2409   <p>Given the overlap in common usage between TrueType and OpenType, the
  2410    format hints "truetype" and "opentype" must be considered as synonymous; a
  2411    format hint of "opentype" does not imply that the font contains Postscript
  2412    CFF style glyph data or that it contains OpenType layout information (see
  2413    <a href="#platform-props-to-css">Appendix A</a> for more background on
  2414    this).
  2416   <p>When authors would prefer to use a locally available copy of a given
  2417    font and download it if it's not, <code>local()</code> can be used. The
  2418    locally-installed <dfn
  2419    id=font-face-name-value><var>&lt;font-face-name&gt;</var></dfn> argument
  2420    to <code>local()</code> is a format-specific string that uniquely
  2421    identifies a single font face within a larger family. The syntax for a <a
  2422    href="#font-face-name-value"><var>&lt;font-face-name&gt;</var></a> is a
  2423    unique font face name enclosed by "local(" and ")". The name can
  2424    optionally be enclosed in quotes. If unquoted, the unquoted font family
  2425    name processing conventions apply; the name must be a sequence of
  2426    identifiers separated by whitespace which is converted to a string by
  2427    joining the identifiers together separated by a single space.
  2429   <pre>
  2430 /* regular face of Gentium */
  2431 @font-face {
  2432   font-family: MyGentium;
  2433   src: local(Gentium),   /* use locally available Gentium */
  2434        url(Gentium.ttf); /* otherwise, download it */
  2436 </pre>
  2438   <p>For OpenType and TrueType fonts, this string is used to match only the
  2439    Postscript name or the full font name in the name table of locally
  2440    available fonts. Which type of name is used varies by platform and font,
  2441    so authors should include both of these names to assure proper matching
  2442    across platforms. Platform substitutions for a given font name must not be
  2443    used.
  2445   <pre>
  2446 /* bold face of Gentium */
  2447 @font-face {
  2448   font-family: MyGentium;
  2449   src: local(Gentium Bold),   /* full font name */
  2450        local(Gentium-Bold),   /* Postscript name */
  2451        url(GentiumBold.ttf);  /* otherwise, download it */
  2452   font-weight: bold;
  2454 </pre>
  2456   <p>Just as a <a href="#at-font-face-rule"><code>@font-face</code></a> rule
  2457    specifies the characteristics of a single font within a family, the unique
  2458    name used with <code>local()</code> specifies a single font, not an entire
  2459    font family. Defined in terms of OpenType font data, the Postscript name
  2460    is found in the font's <a
  2461    href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
  2462    in the name record with nameID = 6 (see <a href="#OPENTYPE"
  2463    rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
  2464    Postscript name is the commonly used key for all fonts on OSX and for
  2465    Postscript CFF fonts under Windows. The full font name (nameID = 4) is
  2466    used as a unique key for fonts with TrueType glyphs on Windows.
  2468   <p>For OpenType fonts with multiple localizations of the full font name,
  2469    the US English version is used (language ID = 0x409 for Windows and
  2470    language ID = 0 for Macintosh) or the first localization when a US English
  2471    full font name is not available (the OpenType specification recommends
  2472    that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
  2473    fonts minimally include US English names</a>). User agents that also match
  2474    other full font names, e.g. matching the Dutch name when the current
  2475    system locale is set to Dutch, are considered non-conformant. This is done
  2476    not to prefer English but to avoid matching inconsistencies across font
  2477    versions and OS localizations, since font style names (e.g. "Bold") are
  2478    frequently localized into many languages and the set of localizations
  2479    available varies widely across platform and font version. User agents that
  2480    match a concatenation of family name (nameID = 1) with style name (nameID
  2481    = 2) are considered non-conformant.
  2483   <p>This also allows for referencing faces that belong to larger families
  2484    that cannot otherwise be referenced.
  2486   <div class=example>
  2487    <p>Use a local font or reference an SVG font in another document:</p>
  2489    <pre>
  2490 @font-face {
  2491   font-family: Headline;
  2492   src: local(Futura-Medium),
  2493        url(fonts.svg#MyGeometricModern) format("svg");
  2495 </pre>
  2497    <p>Create an alias for local Japanese fonts on different platforms:</p>
  2499    <pre>
  2500 @font-face {
  2501   font-family: jpgothic;
  2502   src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
  2504 </pre>
  2506    <p>Reference a font face that cannot be matched within a larger family:</p>
  2508    <pre>
  2509 @font-face {
  2510   font-family: Hoefler Text Ornaments;
  2511   /* has the same font properties as Hoefler Text Regular */
  2512   src: local(HoeflerText-Ornaments);
  2514 </pre>
  2516    <p>Since localized fullnames never match, a document with the header style
  2517     rules below would always render using the default serif font, regardless
  2518     whether a particular system locale parameter is set to Finnish or not:</p>
  2520    <pre>
  2521 @font-face {
  2522   font-family: SectionHeader;
  2523   src: local("Arial Lihavoitu");  /* Finnish fullname for Arial Bold, should fail */
  2524   font-weight: bold;
  2527 h2 { font-family: SectionHeader, serif; }
  2528 </pre>
  2530    <p>A conformant user agent would never load the font ‘<code
  2531     class=css>gentium.eot</code>’ in the example below, since it is
  2532     included in the first definition of the ‘<a href="#descdef-src"><code
  2533     class=property>src</code></a>’ descriptor which is overridden by the
  2534     second definition in the same <a
  2535     href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
  2537    <pre>
  2538 @font-face {
  2539   font-family: MainText;
  2540   src: url(gentium.eot); /* for use with older non-conformant user agents */
  2541   src: local("Gentium"), url(gentium.ttf);  /* Overrides src definition */
  2543 </pre>
  2544   </div>
  2546   <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
  2547    descriptors: the <a href="#descdef-font-style">font-style</a>, <a
  2548    href="#descdef-font-weight">font-weight</a>, <a
  2549    href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
  2551   <table class=descdef>
  2552    <tbody>
  2553     <tr>
  2554      <td>Name:
  2556      <td><dfn id=descdef-font-style
  2557       title="font-style!!descriptor">font-style</dfn>
  2559     <tr>
  2560      <td>Value:
  2562      <td>normal | italic | oblique
  2564     <tr>
  2565      <td><em>Initial:</em>
  2567      <td>normal
  2568   </table>
  2570   <table class=descdef>
  2571    <tbody>
  2572     <tr>
  2573      <td>Name:
  2575      <td><dfn id=descdef-font-weight
  2576       title="font-weight!!descriptor">font-weight</dfn>
  2578     <tr>
  2579      <td>Value:
  2581      <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
  2583     <tr>
  2584      <td><em>Initial:</em>
  2586      <td>normal
  2587   </table>
  2589   <table class=descdef>
  2590    <tbody>
  2591     <tr>
  2592      <td>Name:
  2594      <td><dfn id=descdef-font-stretch
  2595       title="font-stretch!!descriptor">font-stretch</dfn>
  2597     <tr>
  2598      <td>Value:
  2600      <td>normal | ultra-condensed | extra-condensed | condensed |
  2601       semi-condensed | semi-expanded | expanded | extra-expanded |
  2602       ultra-expanded
  2604     <tr>
  2605      <td><em>Initial:</em>
  2607      <td>normal
  2608   </table>
  2610   <p>These descriptors define the characteristics of a font face and are used
  2611    in the process of matching styles to specific faces. For a font family
  2612    defined with several <a
  2613    href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
  2614    can either download all faces in the family or use these descriptors to
  2615    selectively download font faces that match actual styles used in document.
  2616    The values for these descriptors are the same as those for the
  2617    corresponding font properties except that relative keywords are not
  2618    allowed, ‘<a href="#bolder"><code class=property>bolder</code></a>’
  2619    and ‘<a href="#lighter"><code class=property>lighter</code></a>’. If
  2620    these descriptors are omitted, initial values are assumed.
  2622   <p>The value for these font face style attributes is used in place of the
  2623    style implied by the underlying font data. This allows authors to combine
  2624    faces in flexible combinations, even in situations where the original font
  2625    data was arranged differently. User agents that implement synthetic
  2626    bolding and obliquing must only apply synthetic styling in cases where the
  2627    font descriptors imply this is needed, rather than based on the style
  2628    attributes implied by the font data.
  2630   <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
  2631    <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
  2633   <table class=descdef>
  2634    <tbody>
  2635     <tr>
  2636      <td>Name:
  2638      <td><dfn id=descdef-unicode-range>unicode-range</dfn>
  2640     <tr>
  2641      <td>Value:
  2643      <td><a href="#urange-value"><var>&lt;urange&gt;</var></a> #
  2645     <tr>
  2646      <td><em>Initial:</em>
  2648      <td>U+0-10FFFF
  2649   </table>
  2651   <p>This descriptor defines the set of Unicode codepoints that may be
  2652    supported by the font face for which it is declared. The descriptor value
  2653    is a comma-delimited list of Unicode range (<a
  2654    href="#urange-value"><var>&lt;urange&gt;</var></a>) values. The union of
  2655    these ranges defines the set of codepoints that serves as a hint for user
  2656    agents when deciding whether or not to download a font resource for a
  2657    given text run.
  2659   <p>Each <dfn id=urange-value><var>&lt;urange&gt;</var></dfn> value is a <a
  2660    href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
  2661    title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
  2662    "U+" or "u+" prefix followed by a codepoint range in one of the three
  2663    forms listed below. Ranges that do not fit one of the these forms are
  2664    invalid and cause the declaration to be ignored.
  2666   <dl>
  2667    <dt>single codepoint (e.g. U+416)
  2669    <dd>a valid Unicode codepoint, represented as one to six hexadecimal
  2670     digits
  2672    <dt>interval range (e.g. U+400-4ff)
  2674    <dd>represented as two hyphen-separated valid Unicode codepoints
  2675     indicating the inclusive start and end codepoints of a range
  2677    <dt>wildcard range (e.g. U+4??)
  2679    <dd>defined by the set of codepoints implied when trailing ‘<code
  2680     class=css>?</code>’ characters signify any hexadeximal digit
  2681   </dl>
  2683   <p>Individual codepoints are written using hexadecimal values that
  2684    correspond to <a href="http://www.unicode.org/charts/">Unicode character
  2685    codepoints</a>. Valid Unicode codepoint values vary between 0 and 10FFFF
  2686    inclusive. Digit values of codepoints are ASCII case-insensitive. For
  2687    interval ranges, the start and end codepoints are valid Unicode values and
  2688    the end codepoint is greater than or equal to the start codepoint.
  2690   <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
  2691    "U+???") are valid and equivalent to a wildcard range with an initial zero
  2692    digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
  2693    the range of valid Unicode codepoints are invalid. Because of this, the
  2694    maximum number of trailing ‘<code class=css>?</code>’ wildcard
  2695    characters is five, even though the <a
  2696    href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
  2697    title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
  2699   <p>Within the comma-delimited list of Unicode ranges in a ‘<a
  2700    href="#descdef-unicode-range"><code
  2701    class=property>unicode-range</code></a>’ descriptor declaration, ranges
  2702    may overlap. The union of these ranges defines the set of codepoints for
  2703    which the corresponding font may be used. User agents must not download or
  2704    use the font for codepoints outside this set. User agents may normalize
  2705    the list of ranges into a list that is different but represents the same
  2706    set of codepoints.
  2708   <p>The associated font might not contain glyphs for the entire set of
  2709    codepoints defined by the ‘<a href="#descdef-unicode-range"><code
  2710    class=property>unicode-range</code></a>’ descriptor. When the font is
  2711    used, the <dfn id=effective-character-map>effective character map</dfn> is
  2712    the intersection of the codepoints defined by ‘<a
  2713    href="#descdef-unicode-range"><code
  2714    class=property>unicode-range</code></a>’ with the font's <a
  2715    href="#character-map"><em>character map</em></a>. This allows authors to
  2716    define supported ranges in terms of broad ranges without worrying about
  2717    the precise codepoint ranges supported by the underlying font.
  2719   <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
  2720    to define composite fonts</h3>
  2722   <p>Multiple <a href="#at-font-face-rule"><code>@font-face</code></a> rules
  2723    with different unicode ranges for the same family and style descriptor
  2724    values can be used to create composite fonts that mix the glyphs from
  2725    different fonts for different scripts. This can be used to combine fonts
  2726    that only contain glyphs for a single script (e.g. Latin, Greek, Cyrillic)
  2727    or it can be used by authors as a way of segmenting a font into fonts for
  2728    commonly used characters and less frequently used characters. Since the
  2729    user agent will only pull down the fonts it needs this helps reduce page
  2730    bandwidth.
  2732   <p>If the unicode ranges overlap for a set of <a
  2733    href="#at-font-face-rule"><code>@font-face</code></a> rules with the same
  2734    family and style descriptor values, the rules are ordered in the reverse
  2735    order they were defined; the last rule defined is the first to be checked
  2736    for a given character.
  2738   <p>Example ranges for specific languages or characters:
  2740   <dl>
  2741    <dt>unicode-range: U+A5;
  2743    <dd>a single code point, the yen/yuan symbol
  2745    <dt>unicode-range: U+0-7F;
  2747    <dd>code range for basic ASCII characters
  2749    <dt>unicode-range: U+590-5ff;
  2751    <dd>code range for Hebrew characters
  2753    <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
  2755    <dd>code range for Japanese kanji, hiragana and katakana characters plus
  2756     yen/yuan symbol
  2757   </dl>
  2759   <div class=example>
  2760    <p>The BBC provides news services in a wide variety of languages, many
  2761     that are not well supported across all platforms. Using an <a
  2762     href="#at-font-face-rule"><code>@font-face</code></a> rule, the BBC could
  2763     provide a font for any of these languages, as it already does via a
  2764     manual font download.</p>
  2766    <pre>
  2767 @font-face {
  2768   font-family: BBCBengali;
  2769   src: url(fonts/BBCBengali.ttf) format("opentype");
  2770   unicode-range: U+00-FF, U+980-9FF;
  2772 </pre>
  2773   </div>
  2775   <div class=example>
  2776    <p>Technical documents often require a wide range of symbols. The STIX
  2777     Fonts project is one project aimed at providing fonts to support a wide
  2778     range of technical typesetting in a standardized way. The example below
  2779     shows the use of a font that provides glyphs for many of the mathematical
  2780     and technical symbol ranges within Unicode:</p>
  2782    <pre>
  2783 @font-face {
  2784   font-family: STIXGeneral;
  2785   src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
  2786   unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
  2788 </pre>
  2789   </div>
  2791   <div class=example>
  2792    <p>This example shows how an author can override the glyphs used for Latin
  2793     characters in a Japanese font with glyphs from a different font. The
  2794     first rule specifies no range so it defaults to the entire range. The
  2795     range specified in the second rule overlaps but takes precedence because
  2796     it is defined later.</p>
  2798    <pre>
  2799 @font-face {
  2800   font-family: JapaneseWithGentium;
  2801   src: local(MSMincho);
  2802   /* no range specified, defaults to entire range */
  2805 @font-face {
  2806   font-family: JapaneseWithGentium;
  2807   src: url(../fonts/Gentium.ttf);
  2808   unicode-range: U+0-2FF;
  2810 </pre>
  2811   </div>
  2813   <div class=example>
  2814    <p>Consider a family constructed to optimize bandwidth by separating out
  2815     Latin, Japanese and other characters into different font files:</p>
  2817    <pre>
  2818 /* fallback font - size: 4.5MB */
  2819 @font-face {
  2820   font-family: DroidSans;
  2821   src: url(DroidSansFallback.ttf);
  2822   /* no range specified, defaults to entire range */
  2825 /* Japanese glyphs - size: 1.2MB */
  2826 @font-face {
  2827   font-family: DroidSans;
  2828   src: url(DroidSansJapanese.ttf);
  2829   unicode-range: U+3000-9FFF, U+ff??;
  2832 /* Latin, Greek, Cyrillic along with some
  2833    punctuation and symbols - size: 190KB */
  2834 @font-face {
  2835   font-family: DroidSans;
  2836   src: url(DroidSans.ttf);
  2837   unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
  2839 </pre>
  2841    <p>For simple Latin text, only the font for Latin characters is
  2842     downloaded:</p>
  2844    <pre>
  2845 body { font-family: DroidSans; }
  2847 &lt;p>This is that&lt;/p>
  2848 </pre>
  2850    <p>In this case the user agent first checks the unicode-range for the font
  2851     containing Latin characters (DroidSans.ttf). Since all the characters
  2852     above are in the range U+0-5FF, the user agent downloads the font and
  2853     renders the text with that font.</p>
  2855    <p>Next, consider text that makes use of an arrow character (⇨):</p>
  2857    <pre>
  2858 &lt;p>This &amp;#x21e8; that&lt;p>
  2859 </pre>
  2861    <p>The user agent again first checks the unicode-range of the font
  2862     containing Latin characters. Since U+2000-2300 includes the arrow code
  2863     point (U+21E8), the user agent downloads the font. For this character
  2864     however the Latin font does not have a matching glyph, so the effective
  2865     unicode-range used for font matching excludes this code point. Next, the
  2866     user agent evaluates the Japanese font. The unicode-range for the
  2867     Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
  2868     user agent does not download the Japanese font. Next the fallback font is
  2869     considered. The <a href="#at-font-face-rule"><code>@font-face</code></a>
  2870     rule for the fallback font does not define unicode-range so its value
  2871     defaults to the range of all Unicode code points. The fallback font is
  2872     downloaded and used to render the arrow character.</p>
  2873   </div>
  2875   <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
  2876    href="#descdef-font-variant">font-variant</a> and <a
  2877    href="#descdef-font-feature-settings">font-feature-settings</a>
  2878    descriptors</h3>
  2880   <table class=descdef>
  2881    <tbody>
  2882     <tr>
  2883      <td>Name:
  2885      <td><dfn id=descdef-font-variant
  2886       title="font-variant!!descriptor">font-variant</dfn>
  2888     <tr>
  2889      <td>Value:
  2891      <td><a href="#font-variant-normal-value"
  2892       title="normal!!font-variant">normal</a> | <a
  2893       href="#font-variant-none-value" title="none!!font-variant">none</a> | [
  2894       <a href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a>
  2895       || <a
  2896       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  2897       || <a
  2898       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  2899       || <a
  2900       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  2901       || <a href="#stylistic"><var
  2902       title=stylistic>stylistic(&lt;feature-value-name&gt;)</var></a> || <a
  2903       href="#historical-forms"><var>historical-forms</var></a> || <a
  2904       href="#styleset"><var
  2905       title=styleset>styleset(&lt;feature-value-name&gt; #)</var></a> || <a
  2906       href="#character-variant"><var
  2907       title=character-variant>character-variant(&lt;feature-value-name&gt;
  2908       #)</var></a> || <a href="#swash"><var
  2909       title=swash>swash(&lt;feature-value-name&gt;)</var></a> || <a
  2910       href="#ornaments"><var
  2911       title=ornaments>ornaments(&lt;feature-value-name&gt;)</var></a> || <a
  2912       href="#annotation"><var
  2913       title=annotation>annotation(&lt;feature-value-name&gt;)</var></a> || [
  2914       <a href="#small-caps"><i>small-caps</i></a> | <a
  2915       href="#all-small-caps"><i>all-small-caps</i></a> | <a
  2916       href="#petite-caps"><i>petite-caps</i></a> | <a
  2917       href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
  2918       href="#unicase"><i>unicase</i></a> | <a
  2919       href="#titling-caps"><i>titling-caps</i></a> ] || <a
  2920       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  2921       || <a
  2922       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  2923       || <a
  2924       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  2925       || <a href="#ordinal"><i>ordinal</i></a> || <a
  2926       href="#slashed-zero"><i>slashed-zero</i></a> || <a
  2927       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  2928       || <a
  2929       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  2930       || <a href="#ruby"><i>ruby</i></a> ]
  2932     <tr>
  2933      <td><em>Initial:</em>
  2935      <td>normal
  2936   </table>
  2938   <table class=descdef>
  2939    <tbody>
  2940     <tr>
  2941      <td>Name:
  2943      <td><dfn id=descdef-font-feature-settings
  2944       title="font-feature-settings!!descriptor">font-feature-settings</dfn>
  2946     <tr>
  2947      <td>Value:
  2949      <td><a href="#font-feature-settings-normal-value"
  2950       title="normal!!font-feature-settings">normal</a> | <a
  2951       href="#feature-tag-value"><var>&lt;feature-tag-value&gt;</var></a> #
  2953     <tr>
  2954      <td><em>Initial:</em>
  2956      <td>normal
  2957   </table>
  2959   <p>These descriptors define initial settings that apply when the font
  2960    defined by an <a href="#at-font-face-rule"><code>@font-face</code></a>
  2961    rule is rendered. They do not affect font selection. Values are identical
  2962    to those defined for the corresponding <a href="#propdef-font-variant"
  2963    title="font-variant!!property">‘<code
  2964    class=property>font-variant</code>’</a> and <a
  2965    href="#propdef-font-feature-settings"
  2966    title="font-feature-settings!!property">‘<code
  2967    class=property>font-feature-settings</code>’</a> properties defined
  2968    below except that the value ‘<code class=property>inherit</code>’ is
  2969    omitted. When multiple font feature descriptors or properties are used,
  2970    the cumulative effect on text rendering is detailed in the section <a
  2971    href="#font-feature-resolution">Font Feature Resolution</a> below. In
  2972    cases where specific values define synthesized fallback for certain <a
  2973    href="#propdef-font-variant" title="font-variant!!property">‘<code
  2974    class=property>font-variant</code>’</a> subproperties, the same
  2975    synthesized fallback applies when used within those values are used with
  2976    the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
  2977    class=property>font-variant</code>’</a> descriptor.
  2979   <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
  2980    guidelines</h3>
  2982   <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule is
  2983    designed to allow lazy loading of font resources that are only downloaded
  2984    when used within a document. A stylesheet can include <a
  2985    href="#at-font-face-rule"><code>@font-face</code></a> rules for a library
  2986    of fonts of which only a select set are used; user agents must only
  2987    download those fonts that are referred to within the style rules
  2988    applicable to a given page. User agents that download all fonts defined in
  2989    <a href="#at-font-face-rule"><code>@font-face</code></a> rules without
  2990    considering whether those fonts are in fact used within a page are
  2991    considered non-conformant. In cases where a font might be downloaded in
  2992    character fallback cases, user agents may download a font if it's
  2993    contained within the computed value of <a href="#propdef-font-family"
  2994    title="font-family!!property">‘<code
  2995    class=property>font-family</code>’</a> for a given text run.
  2997   <pre>
  2998 @font-face {
  2999   font-family: GeometricModern;
  3000   src: url(font.ttf);
  3003 p {
  3004   /* font will be downloaded for pages with p elements */
  3005   font-family: GeometricModern, sans-serif;
  3008 h2 {
  3009   /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
  3010   font-family: Futura, GeometricModern, sans-serif;
  3012 </pre>
  3014   <p>In cases where textual content is loaded before downloadable fonts are
  3015    available, user agents may render text as it would be rendered if
  3016    downloadable font resources are not available or they may render text
  3017    transparently with fallback fonts to avoid a flash of text using a
  3018    fallback font. In cases where the font download fails user agents must
  3019    display text, simply leaving transparent text is considered non-conformant
  3020    behavior. Authors are advised to use fallback fonts in their font lists
  3021    that closely match the metrics of the downloadable fonts to avoid large
  3022    page reflows where possible.
  3024   <h3 id=same-origin-restriction><span class=secno>4.9 </span>Same-origin
  3025    restriction for fonts</h3>
  3027   <h4 id=default-same-origin-restriction><span class=secno>4.9.1
  3028    </span>Default same-origin restriction</h4>
  3029   <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
  3030   http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
  3031   http://www.w3.org/2011/10/31-webapps-minutes.html#item02
  3032 -->
  3034   <p>User agents must implement a same-origin restriction when loading fonts
  3035    via the <a href="#at-font-face-rule"><code>@font-face</code></a>
  3036    mechanism. This restriction limits the loading of fonts for a given
  3037    document to fonts loaded from the same origin. Fonts can only be loaded
  3038    via the same host, port, and method combination as the containing
  3039    document, using the <a
  3040    href="http://www.w3.org/TR/html5/browsers.html#origin">origin matching
  3041    algorithm</a> described in the <a href="#HTML5"
  3042    rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification. The origin of
  3043    the stylesheet containing <a
  3044    href="#at-font-face-rule"><code>@font-face</code></a> rules is not used
  3045    when deciding whether a font is same origin or not, only the origin of the
  3046    containing document is used. The restriction applies to all font types.
  3048   <p>Given a document located at http://example.com/page.html, fonts defined
  3049    with ‘<a href="#descdef-src"><code class=property>src</code></a>’
  3050    definitions considered cross origin must not be loaded:
  3052   <pre>
  3053 /* same origin (i.e. domain, scheme, port match document) */
  3054 src: url(fonts/simple.ttf);
  3055 src: url(//fonts/simple.ttf);
  3057 /* cross origin, different scheme */
  3058 src: url(https://example.com/fonts/simple.ttf);
  3060 /* cross origin, different domain */
  3061 src: url(http://another.example.com/fonts/simple.ttf);
  3062 </pre>
  3064   <h4 id=allowing-cross-origin-font-loading><span class=secno>4.9.2
  3065    </span>Allowing cross-origin font loading</h4>
  3067   <p>User agents must also implement the ability to relax this restriction
  3068    using cross-site origin controls <a href="#CORS"
  3069    rel=biblioentry>[CORS]<!--{{!CORS}}--></a> for fonts loaded via HTTP.
  3070    Sites can explicitly allow cross-site downloading of font data using the
  3071    <code>Access-Control-Allow-Origin</code> HTTP header. For other schemes,
  3072    no explicit relaxation mechanism is defined or required.
  3074   <p>For font loads, user agents must use the <a
  3075    href="http://www.w3.org/TR/html5/infrastructure.html#cors-enabled-fetch">potentially
  3076    CORS-enabled fetch</a> method defined by the <a href="#HTML5"
  3077    rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification for URL's
  3078    defined within @font-face rules. When fetching, user agents must use
  3079    "Anonymous" mode, set the referrer source to the stylesheet's URL and set
  3080    the origin to the URL of the containing document.
  3082   <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
  3083    Algorithm</h2>
  3085   <p>The algorithm below describes how fonts are associated with individual
  3086    runs of text. For each character in the run a font family is chosen and a
  3087    particular font face is selected containing a glyph for that character.
  3089   <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
  3090    font family names</h3>
  3092   <p>As part of the font matching algorithm outlined below, user agents must
  3093    match font family names used in style rules with actual font family names
  3094    contained in fonts available in a given environment or with font family
  3095    names defined in <a href="#at-font-face-rule"><code>@font-face</code></a>
  3096    rules. User agents must match these names case insensitively, using the
  3097    "Default Caseless Matching" algorithm outlined in the Unicode
  3098    specification <a href="#UNICODE6"
  3099    rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This algorithm is
  3100    detailed in section 3.13 entitled "Default Case Algorithms". Specifically,
  3101    the algorithm must be applied without normalizing the strings involved and
  3102    without applying any language-specific tailorings. The case folding method
  3103    specified by this algorithm uses the case mappings with status field
  3104    ‘<code class=property>C</code>’ or ‘<code class=property>F</code>’
  3105    in the CaseFolding.txt file of the Unicode Character Database.
  3107   <p class=note> For authors this means that font family names are matched
  3108    case insensitively, whether those names exist in a platform font or in the
  3109    <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
  3110    in a stylesheet. Authors should take care to ensure that names use a
  3111    character sequence consistent with the actual font family name,
  3112    particularly when using combining characters such as diacritical marks.
  3113    For example, a family name that contains an uppercase A (U+0041) followed
  3114    by a combining ring (U+030A) will <strong>not</strong> match a name that
  3115    looks identical but which uses the precomposed lowercase a-ring character
  3116    (U+00E5) instead of the combining sequence.
  3118   <p class=note> Implementors should take care to verify that a given
  3119    caseless string comparison implementation uses this precise algorithm and
  3120    not assume that a given platform string matching routine follows it, as
  3121    many of these have locale-specific behavior or use some level of string
  3122    normalization.
  3124   <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
  3125    styles</h3>
  3127   <p>The procedure for choosing a font for a given character in a run of text
  3128    consists of iterating over the font families named by the <a
  3129    href="#propdef-font-family" title="font-family!!property">‘<code
  3130    class=property>font-family</code>’</a> property, selecting a font face
  3131    with the appropriate style based on other font properties and then
  3132    determining whether a glyph exists for the given character. This is done
  3133    using the <dfn id=character-map>character map</dfn> of the font, data
  3134    which maps characters to the default glyph for that character. A font is
  3135    considered to <dfn id=support>support</dfn> a given character if (1) the
  3136    character is contained in the font's <a
  3137    href="#character-map"><em>character map</em></a> and (2) if required by
  3138    the containing script, shaping information is available for that
  3139    character.
  3141   <p>Some legacy fonts may include a given character in the <a
  3142    href="#character-map"><em>character map</em></a> but lack the shaping
  3143    information (e.g. <a
  3144    href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
  3145    layout tables</a> or <a
  3146    href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&amp;item_id=graphite_techAbout">Graphite
  3147    tables</a>) necessary for correctly rendering text runs containing that
  3148    character.
  3150   <p>Codepoint sequences consisting of a base character followed by a
  3151    sequence of combining characters are treated slightly differently, see the
  3152    section on <a href="#cluster-matching">cluster matching</a> below.
  3154   <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
  3155    given font family is defined to be the face that would be selected if all
  3156    font style properties were set to their initial value.
  3158   <ol id=fontmatchingalg>
  3159    <li>Using the computed font property values for a given element, the user
  3160     agent starts with the first family name specified by the <a
  3161     href="#propdef-font-family" title="font-family!!property">‘<code
  3162     class=property>font-family</code>’</a> property.
  3164    <li>If the family name is a generic family keyword, the user agent looks
  3165     up the appropriate font family name to be used. User agents may choose
  3166     the generic font family to use based on the language of the containing
  3167     element or the Unicode range of the character.
  3169    <li>For other family names, the user agent attempts to find the family
  3170     name among fonts defined via <a
  3171     href="#at-font-face-rule"><code>@font-face</code></a> rules and then
  3172     among available system fonts, matching names with a <a
  3173     href="#font-family-casing">case-insensitive comparison</a> as outlined in
  3174     the section above. On systems containing fonts with multiple localized
  3175     font family names, user agents must match any of these names independent
  3176     of the underlying system locale or platform API used. If the font
  3177     resources defined for a given face in an <a
  3178     href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
  3179     available or contain invalid font data, then the face should be treated
  3180     as not present in the family. If no faces are present for a family
  3181     defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
  3182     rules, the family should be treated as missing; matching a platform font
  3183     with the same name must not occur in this case.
  3185    <li>If a font family match occurs, the user agent assembles the set of
  3186     font faces in that family and then narrows the set to a single face using
  3187     other font properties in the order given below. A group of faces defined
  3188     via <a href="#at-font-face-rule"><code>@font-face</code></a> rules with
  3189     identical font descriptor values but differing ‘<a
  3190     href="#descdef-unicode-range"><code
  3191     class=property>unicode-range</code></a>’ values are considered to be a
  3192     single <dfn id=composite-face>composite face</dfn> for this step:
  3193     <ol id=fontstylematchingalg>
  3194      <li><a href="#propdef-font-stretch"
  3195       title="font-stretch!!property">‘<code
  3196       class=property>font-stretch</code>’</a> is tried first. If the
  3197       matching set contains faces with width values matching the <a
  3198       href="#propdef-font-stretch" title="font-stretch!!property">‘<code
  3199       class=property>font-stretch</code>’</a> value, faces with other width
  3200       values are removed from the matching set. If there is no face that
  3201       exactly matches the width value the nearest width is used instead. If
  3202       the value of <a href="#propdef-font-stretch"
  3203       title="font-stretch!!property">‘<code
  3204       class=property>font-stretch</code>’</a> is <a
  3205       href="#font-stretch-normal-value" title="normal!!font-stretch">‘<code
  3206       class=property>normal</code>’</a> or one of the condensed values,
  3207       narrower width values are checked first, then wider values. If the
  3208       value of <a href="#propdef-font-stretch"
  3209       title="font-stretch!!property">‘<code
  3210       class=property>font-stretch</code>’</a> is one of the expanded
  3211       values, wider values are checked first, followed by narrower values.
  3212       Once the closest matching width has been determined by this process,
  3213       faces with other widths are removed from the matching set.
  3215      <li><a href="#propdef-font-style" title="font-style!!property">‘<code
  3216       class=property>font-style</code>’</a> is tried next. If the value of
  3217       <a href="#propdef-font-style" title="font-style!!property">‘<code
  3218       class=property>font-style</code>’</a> is ‘<a href="#italic"><code
  3219       class=property>italic</code></a>’, italic faces are checked first,
  3220       then oblique, then normal faces. If the value is ‘<a
  3221       href="#oblique"><code class=property>oblique</code></a>’, oblique
  3222       faces are checked first, then italic faces and then normal faces. If
  3223       the value is <a href="#font-style-normal-value"
  3224       title="normal!!font-style">‘<code
  3225       class=property>normal</code>’</a>, normal faces are checked first,
  3226       then oblique faces, then italic faces. Faces with other style values
  3227       are excluded from the matching set. User agents are permitted to
  3228       distinguish between italic and oblique faces within platform font
  3229       families but this is not required, so all italic or oblique faces may
  3230       be treated as italic faces. However, within font families defined via
  3231       <a href="#at-font-face-rule"><code>@font-face</code></a> rules, italic
  3232       and oblique faces must be distinguished using the value of the <a
  3233       href="#descdef-font-style" title="font-style!!descriptor">‘<code
  3234       class=property>font-style</code>’</a> descriptor. For families that
  3235       lack any italic or oblique faces, users agents may create artificial
  3236       oblique faces, if this is permitted by the value of the ‘<a
  3237       href="#propdef-font-synthesis"><code
  3238       class=property>font-synthesis</code></a>’ property.
  3240      <li><a href="#propdef-font-weight"
  3241       title="font-weight!!property">‘<code
  3242       class=property>font-weight</code>’</a> is matched next, so it will
  3243       always reduce the matching set to a single font face. If bolder/lighter
  3244       relative weights are used, the effective weight is calculated based on
  3245       the inherited weight value, as described in the definition of the <a
  3246       href="#propdef-font-weight" title="font-weight!!property">‘<code
  3247       class=property>font-weight</code>’</a> property. Given the desired
  3248       weight and the weights of faces in the matching set after the steps
  3249       above, if the desired weight is available that face matches. Otherwise,
  3250       a weight is chosen using the rules below:
  3251       <ul>
  3252        <li>If the desired weight is less than 400, weights below the desired
  3253         weight are checked in descending order followed by weights above the
  3254         desired weight in ascending order until a match is found.
  3256        <li>If the desired weight is greater than 500, weights above the
  3257         desired weight are checked in ascending order followed by weights
  3258         below the desired weight in descending order until a match is found.
  3260        <li>If the desired weight is 400, 500 is checked first and then the
  3261         rule for desired weights less than 400 is used.
  3263        <li>If the desired weight is 500, 400 is checked first and then the
  3264         rule for desired weights less than 400 is used.
  3265       </ul>
  3267      <li><span class=property>‘<a href="#propdef-font-size"><code
  3268       class=property>font-size</code></a>’</span> must be matched within a
  3269       UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
  3270       are rounded to the nearest whole pixel, while the tolerance for
  3271       bitmapped fonts could be as large as 20%.) Further computations, e.g.,
  3272       by ‘<code class=property>em</code>’ values in other properties, are
  3273       based on the <span class=property>‘<a href="#propdef-font-size"><code
  3274       class=property>font-size</code></a>’</span> value that is used, not
  3275       the one that is specified.
  3276     </ol>
  3278    <li>
  3279     <p>If the matched face is defined via <a
  3280      href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
  3281      must use the procedure below to select a single font:
  3283     <ol>
  3284      <li>If the font resource has not been loaded and the range of characters
  3285       defined by the ‘<a href="#descdef-unicode-range"><code
  3286       class=property>unicode-range</code></a>’ descriptor value includes
  3287       the character in question, load the font.
  3289      <li>After downloading, if the <a
  3290       href="#effective-character-map"><em>effective character map</em></a>
  3291       supports the character in question, select that font.
  3292     </ol>
  3294     <p>When the matched face is a <a href="#composite-face"><em>composite
  3295      face</em></a>, user agents must use the procedure above on each of the
  3296      faces in the <a href="#composite-face"><em>composite face</em></a> in
  3297      reverse order of <a
  3298      href="#at-font-face-rule"><code>@font-face</code></a> rule definition.</p>
  3300     <p>While the download occurs, user agents may either wait until the font
  3301      is downloaded or render once with substituted font metrics and render
  3302      again once the font is downloaded.</p>
  3304    <li>
  3305     <p>If no matching face exists or the matched face does not contain a
  3306      glyph for the character to be rendered, the next family name is selected
  3307      and the previous three steps repeated. Glyphs from other faces in the
  3308      family are not considered. The only exception is that user agents may
  3309      optionally substitute a synthetically obliqued version of the <a
  3310      href="#default-face"><em>default face</em></a> if that face supports a
  3311      given glyph and synthesis of these faces is permitted by the value of
  3312      the ‘<a href="#propdef-font-synthesis"><code
  3313      class=property>font-synthesis</code></a>’ property. For example, a
  3314      synthetic italic version of the regular face may be used if the italic
  3315      face doesn't support glyphs for Arabic.</p>
  3316     <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
  3319    <li>If there are no more font families to be evaluated and no matching
  3320     face has been found, then the user agent performs a <dfn
  3321     id=system-font-fallback>system font fallback</dfn> procedure to find the
  3322     best match for the character to be rendered. The result of this procedure
  3323     may vary across user agents.
  3325    <li>If a particular character cannot be displayed using any font, the user
  3326     agent should indicate by some means that a character is not being
  3327     displayed, displaying either a symbolic representation of the missing
  3328     glyph (e.g. using a <a
  3329     href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
  3330     Font</a>) or using the missing character glyph from a default font.
  3331   </ol>
  3333   <p>Optimizations of this process are allowed provided that an
  3334    implementation behaves as if the algorithm had been followed exactly.
  3335    Matching occurs in a well-defined order to insure that the results are as
  3336    consistent as possible across user agents, given an identical set of
  3337    available fonts and rendering technology.
  3339   <p>The <dfn id=first-available-font>first available font</dfn>, used in the
  3340    definition of <a
  3341    href="http://www.w3.org/TR/css3-values/#font-relative-lengths"><em>font-relative
  3342    lengths</em></a> such as ‘<code class=property>ex</code>’ and ‘<code
  3343    class=property>ch</code>’, is defined to be the first available font
  3344    that would match any character given font families in the ‘<code
  3345    class=property>font-family</code>’ list (or a user agent's default font
  3346    if none are available).
  3348   <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
  3350   <p>When text contains characters such as combining marks, ideally the base
  3351    character should be rendered using the same font as the mark, this assures
  3352    proper placement of the mark. For this reason, the font matching algorithm
  3353    for clusters is more specialized than the general case of matching a
  3354    single character by itself. For sequences containing variation selectors,
  3355    which indicate the precise glyph to be used for a given character, user
  3356    agents always attempt <a href="#system-font-fallback"><em>system font
  3357    fallback</em></a> to find the appropriate glyph before using the default
  3358    glyph of the base character.
  3360   <p>A sequence of codepoints containing combining mark or other modifiers is
  3361    termed a grapheme cluster (see <a href="#CSS3TEXT"
  3362    rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
  3363    description). For a given cluster containing a base character, <em>b</em>
  3364    and a sequence of combining characters <em>c1, c2…</em>, the entire
  3365    cluster is matched using these steps:
  3367   <ol>
  3368    <li>For each family in the font list, a face is chosen using the style
  3369     selection rules defined in the previous section.
  3370     <ol>
  3371      <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
  3372       completely supported by the font, select this font for the sequence.
  3374      <li>If a sequence of multiple codepoints is canonically equivalent to a
  3375       single character and the font <a href="#support"><em
  3376       title=support>supports</em></a> that character, select this font for
  3377       the sequence.
  3378     </ol>
  3380    <li>If no font was found in the font list in step 1:
  3381     <ol>
  3382      <li>If <em>c1</em> is a variation selector, system fallback must be used
  3383       to find a font that <a href="#support"><em
  3384       title=support>supports</em></a> the full sequence of <em>b + c1</em>.
  3385       If no font on the system <a href="#support"><em
  3386       title=support>supports</em></a> the full sequence, match the single
  3387       character <em>b</em> using the normal procedure for matching single
  3388       characters and ignore the variation selector. Note: a sequence with
  3389       more than one variation selector must be treated as an encoding error
  3390       and the trailing selectors must be ignored. <a href="#UNICODE6"
  3391       rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>
  3393      <li>Otherwise, the user agent may optionally use system font fallback to
  3394       match a font that <a href="#support"><em
  3395       title=support>supports</em></a> the entire cluster.
  3396     </ol>
  3398    <li>If no font is found in step 2, use the matching sequence from step 1
  3399     to determine the longest sequence that is completely <a
  3400     href="#support"><em title=support>supported</em></a> by a font in the
  3401     font list and attempt to match the remaining combining characters
  3402     separately using the rules for single characters.
  3403   </ol>
  3405   <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
  3406    issues</h3>
  3408   <p>CSS font matching is always performed on text runs containing Unicode
  3409    characters, so documents using legacy encodings are assumed to have been
  3410    transcoded before matching fonts. For fonts containing <a
  3411    href="#character-map"><em title="character map">character maps</em></a>
  3412    for both legacy encodings and Unicode, the contents of the legacy encoding
  3413    <a href="#character-map"><em>character map</em></a> must have no effect on
  3414    the results of the font matching process.
  3416   <p>The font matching process does not assume that text runs are in either
  3417    normalized or denormalized form (see <a href="#CHARMOD-NORM"
  3418    rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
  3419    details). Fonts may only support precomposed forms and not the decomposed
  3420    sequence of base character plus combining marks. Authors should always
  3421    tailor their choice of fonts to their content, including whether that
  3422    content contains normalized or denormalized character streams.
  3424   <p>If a given character is a Private-Use Area Unicode codepoint, user
  3425    agents must only match font families named in the ‘<code
  3426    class=property>font-family</code>’ list that are not generic families.
  3427    If none of the families named in the ‘<code
  3428    class=property>font-family</code>’ list contain a glyph for that
  3429    codepoint, user agents must display some form of missing glyph symbol for
  3430    that character rather than attempting <a
  3431    href="#system-font-fallback"><em>system font fallback</em></a> for that
  3432    codepoint. When matching the replacement character U+FFFD, user agents may
  3433    skip the font matching process and immediately display some form of
  3434    missing glyph symbol, they are not required to display the glyph from the
  3435    font that would be selected by the font matching process.
  3437   <p>In general, the fonts for a given family will all have the same or
  3438    similar <a href="#character-map"><em title="character map">character
  3439    maps</em></a>. The process outlined here is designed to handle even font
  3440    families containing faces with widely variant <a href="#character-map"><em
  3441    title="character map">character maps</em></a>. However, authors are
  3442    cautioned that the use of such families can lead to unexpected results.
  3444   <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
  3445    changes since CSS 2.1</h3>
  3447   <p>The algorithm above is different from CSS 2.1 in a number of key places.
  3448    These changes were made to better reflect actual font matching behavior
  3449    across user agent implementations.
  3451   <p>Differences compared to the font matching algorithm in CSS 2.1:
  3453   <ul>
  3454    <li>The algorithm includes font-stretch matching.
  3456    <li>All possible font-style matching scenarios are delineated.
  3458    <li>Small-caps fonts are not matched as part of the font matching process,
  3459     they are now handled via font features.
  3461    <li>Unicode variation selector matching is required.
  3463    <li>Cluster sequences are matched as a unit.
  3464   </ul>
  3466   <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
  3467    examples</h3>
  3469   <div class=example>
  3470    <p>It's useful to note that the CSS selector syntax may be used to create
  3471     language-sensitive typography. For example, some Chinese and Japanese
  3472     characters are unified to have the same Unicode code point, although the
  3473     abstract glyphs are not the same in the two languages.
  3475    <pre>*:lang(ja-jp) { font: 900 14pt/16pt &quot;Heisei Mincho W9&quot;, serif; }
  3476 *:lang(zh-tw) { font: 800 14pt/16.5pt &quot;Li Sung&quot;, serif; }
  3477 </pre>
  3479    <p>This selects any element that has the given language — Japanese or
  3480     Traditional Chinese — and uses the appropriate font.
  3481   </div>
  3483   <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
  3485   <p>Modern font technologies support a variety of advanced typographic and
  3486    language-specific font features. Using these features, a single font can
  3487    provide glyphs for a wide range of ligatures, contextual and stylistic
  3488    alternates, tabular and old-style figures, small capitals, automatic
  3489    fractions, swashes, and alternates specific to a given language. To allow
  3490    authors control over these font capabilities, the ‘<code
  3491    class=property>font-variant</code>’ property has been expanded for CSS3.
  3492    It now functions as a shorthand for a set of properties that provide
  3493    control over stylistic font features.
  3495   <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
  3496    selection and positioning</h3>
  3498   <p>Simple fonts used for displaying Latin text use a very basic processing
  3499    model. Fonts contain a <a href="#character-map"><em>character map</em></a>
  3500    which maps each character to a glyph for that character. Glyphs for
  3501    subsequent characters are simply placed one after the other along a run of
  3502    text. Modern font formats such as OpenType and AAT (Apple Advanced
  3503    Typography) use a richer processing model. The glyph for a given character
  3504    can be chosen and positioned not just based on the codepoint of the
  3505    character itself, but also on adjacent characters as well as the language,
  3506    script, and features enabled for the text. Font features may be required
  3507    for specific scripts, or recommended as enabled by default or they might
  3508    be stylistic features meant to be used under author control.
  3510   <p>For a good visual overview of these features, see the <a
  3511    href="#OPENTYPE-FONT-GUIDE"
  3512    rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
  3513    For a detailed description of glyph processing for OpenType fonts, see <a
  3514    href="#WINDOWS-GLYPH-PROC"
  3515    rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
  3517   <p>Stylistic font features can be classified into two broad categories:
  3518    ones that affect the harmonization of glyph shapes with the surrounding
  3519    context, such as kerning and ligature features, and ones such as the
  3520    small-caps, subscript/superscript and alternate features that affect shape
  3521    selection.
  3523   <p>The subproperties of <a href="#propdef-font-variant"
  3524    title="font-variant!!property">‘<code
  3525    class=property>font-variant</code>’</a> listed below are used to control
  3526    these stylistic font features. They do not control features that are
  3527    required for displaying certain scripts, such as the OpenType features
  3528    used when displaying Arabic or Indic language text. They affect glyph
  3529    selection and positioning, but do not affect font selection as described
  3530    in the font matching section (except in cases required for compatibility
  3531    with CSS 2.1).
  3533   <p>To assure consistent behavior across user agents, the equivalent
  3534    OpenType property settings are listed for individual properties and are
  3535    normative. When using other font formats these should be used as a
  3536    guideline to map CSS font feature property values to specific font
  3537    features.
  3539   <h3 id=language-specific-support><span class=secno>6.2
  3540    </span>Language-specific display</h3>
  3542   <p>OpenType also supports language-specific glyph selection and
  3543    positioning, so that text can be displayed correctly in cases where the
  3544    language dictates a specific display behavior. Many languages share a
  3545    common script, but the shape of certain letters can vary across those
  3546    languages. For example, certain Cyrillic letters have different shapes in
  3547    Russian text than in Bulgarian. In Latin text, it's common to render "fi"
  3548    with an explicit fi-ligature that lacks a dot on the "i". However, in
  3549    languages such as Turkish which uses both a dotted-i and a dotless-i, it's
  3550    important to not use this ligature or use a specialized version that
  3551    contains a dot over the "i". The example below shows language-specific
  3552    variations based on stylistic traditions found in Spanish, Italian and
  3553    French orthography:
  3555   <div class=featex><img alt="language specific forms, spanish"
  3556    src=locl-1.png></div>
  3558   <div class=featex><img alt="language specific forms, italian"
  3559    src=locl-2.png></div>
  3561   <div class=featex><img alt="language specific forms, french"
  3562    src=locl-3.png></div>
  3564   <p>If the content language of the element is known according to the rules
  3565    of the <a
  3566    href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
  3567    language</a>, user agents are required to infer the OpenType language
  3568    system from the content language and use that when selecting and
  3569    positioning glyphs using an OpenType font.
  3571   <p>For OpenType fonts, in some cases it may be necessary to explicitly
  3572    declare the OpenType language to be used, for example when displaying text
  3573    in a given language that uses the typographic conventions of another
  3574    language or when the font does not explicitly support a given language but
  3575    supports a language that shares common typographic conventions. The ‘<a
  3576    href="#propdef-font-language-override"><code
  3577    class=property>font-language-override</code></a>’ property is used for
  3578    this purpose.</p>
  3579   <!-- prop: font-kerning -->
  3581   <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
  3582    href="#propdef-font-kerning">font-kerning</a> property</h3>
  3584   <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
  3585    <tbody>
  3586     <tr>
  3587      <td>Name:
  3589      <td><dfn id=propdef-font-kerning>font-kerning</dfn>
  3591     <tr>
  3592      <td>Value:
  3594      <td><a href="#font-kerning-auto-value"
  3595       title="auto!!font-kerning">auto</a> | <a
  3596       href="#font-kerning-normal-value"
  3597       title="normal!!font-kerning">normal</a> | <a
  3598       href="#font-kerning-none-value" title="none!!font-kerning">none</a>
  3600     <tr>
  3601      <td>Initial:
  3603      <td>auto
  3605     <tr>
  3606      <td>Applies to:
  3608      <td>all elements
  3610     <tr>
  3611      <td>Inherited:
  3613      <td>yes
  3615     <tr>
  3616      <td>Percentages:
  3618      <td>N/A
  3620     <tr>
  3621      <td>Media:
  3623      <td>visual
  3625     <tr>
  3626      <td>Computed value:
  3628      <td>as specified
  3630     <tr>
  3631      <td>Animatable:
  3633      <td>no
  3634   </table>
  3636   <p>Kerning is the contextual adjustment of inter-glyph spacing. This
  3637    property controls metric kerning, kerning that utilizes adjustment data
  3638    contained in the font.
  3640   <dl>
  3641    <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
  3643    <dd>Specifies that kerning is applied at the discretion of the user agent
  3645    <dt><dfn id=font-kerning-normal-value
  3646     title="normal!!font-kerning">normal</dfn>
  3648    <dd>Specifies that kerning is applied
  3650    <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
  3652    <dd>Specifies that kerning is not applied
  3653   </dl>
  3655   <p>For fonts that do not include kerning data this property will have no
  3656    visible effect. When rendering with OpenType fonts, the <a
  3657    href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
  3658    specification suggests that kerning be enabled by default. When kerning is
  3659    enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
  3660    vertical text runs the <span class=tag>vkrn</span> feature is enabled
  3661    instead). User agents must also support fonts that only support kerning
  3662    via data contained in a <span class=tag>kern</span> font table, as
  3663    detailed in the OpenType specification. If the ‘<code
  3664    class=property>letter-spacing</code>’ property is defined, kerning
  3665    adjustments are considered part of the default spacing and letter spacing
  3666    adjustments are made after kerning has been applied.
  3668   <p>When set to ‘<code class=property>auto</code>’, user agents can
  3669    determine whether to apply kerning or not based on a number of factors:
  3670    text size, script, or other factors that influence text processing speed.
  3671    Authors who want proper kerning should use <a
  3672    href="#font-kerning-normal-value" title="normal!!font-kerning">‘<code
  3673    class=property>normal</code>’</a> to explicitly enable kerning.
  3674    Likewise, some authors may prefer to disable kerning in situations where
  3675    performance is more important than precise appearance. However, in
  3676    well-designed modern implementations the use of kerning generally does not
  3677    have a large impact on text rendering speed.</p>
  3678   <!-- prop: font-variant-ligatures -->
  3680   <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
  3681    the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
  3682    property</h3>
  3684   <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
  3685    <tbody>
  3686     <tr>
  3687      <td>Name:
  3689      <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
  3691     <tr>
  3692      <td>Value:
  3694      <td><a href="#font-variant-ligatures-normal-value"
  3695       title="normal!!font-variant-ligatures">normal</a> | <a
  3696       href="#font-variant-ligatures-none-value"
  3697       title="none!!font-variant-ligatures">none</a> | [ <a
  3698       href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a> ||
  3699       <a
  3700       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  3701       || <a
  3702       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  3703       || <a
  3704       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  3707     <tr>
  3708      <td>Initial:
  3710      <td>normal
  3712     <tr>
  3713      <td>Applies to:
  3715      <td>all elements
  3717     <tr>
  3718      <td>Inherited:
  3720      <td>yes
  3722     <tr>
  3723      <td>Percentages:
  3725      <td>N/A
  3727     <tr>
  3728      <td>Media:
  3730      <td>visual
  3732     <tr>
  3733      <td>Computed value:
  3735      <td>as specified
  3737     <tr>
  3738      <td>Animatable:
  3740      <td>no
  3741   </table>
  3743   <p>Ligatures and contextual forms are ways of combining glyphs to produce
  3744    more harmonized forms.
  3746   <pre
  3747    class=prod><dfn id=common-lig-values><var>&lt;common-lig-values&gt;</var></dfn>        = [ <a href="#common-ligatures">common-ligatures</a> | <a href="#no-common-ligatures">no-common-ligatures</a> ]</pre>
  3749   <pre
  3750    class=prod><dfn id=discretionary-lig-values><var>&lt;discretionary-lig-values&gt;</var></dfn> = [ <a href="#discretionary-ligatures">discretionary-ligatures</a> | <a href="#no-discretionary-ligatures">no-discretionary-ligatures</a> ]</pre>
  3752   <pre
  3753    class=prod><dfn id=historical-lig-values><var>&lt;historical-lig-values&gt;</var></dfn>    = [ <a href="#historical-ligatures">historical-ligatures</a> | <a href="#no-historical-ligatures">no-historical-ligatures</a> ]</pre>
  3755   <pre
  3756    class=prod><dfn id=contextual-alt-values><var>&lt;contextual-alt-values&gt;</var></dfn>    = [ <a href="#contextual">contextual</a> | <a href="#no-contextual">no-contextual</a> ]</pre>
  3758   <p>Individual values have the following meanings:
  3760   <dl>
  3761    <dt><dfn id=font-variant-ligatures-normal-value
  3762     title="normal!!font-variant-ligatures">normal</dfn>
  3764    <dd>A value of <a href="#font-variant-ligatures-normal-value"
  3765     title="normal!!font-variant-ligatures">‘<code
  3766     class=property>normal</code>’</a> specifies that common default
  3767     features are enabled, <a href="#font-feature-resolution">as described in
  3768     detail in the next section</a>. For OpenType fonts, common ligatures and
  3769     contextual forms are on by default, discretionary and historical
  3770     ligatures are not.
  3772    <dt><dfn id=font-variant-ligatures-none-value
  3773     title="none!!font-variant-ligatures">none</dfn>
  3775    <dd>Specifies that all types of ligatures and contextual forms covered by
  3776     this property are explicitly disabled. In situations where ligatures are
  3777     not considered necessary, this may improve the speed of text rendering.
  3779    <dt><dfn id=common-ligatures>common-ligatures</dfn>
  3781    <dd>Enables display of common ligatures (OpenType features: <span
  3782     class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
  3783     enabled by default.
  3784   </dl>
  3786   <div class=featex><img alt="common ligature example" src=liga.png></div>
  3788   <dl>
  3789    <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
  3791    <dd>Disables display of common ligatures (OpenType features: <span
  3792     class=tag>liga, clig</span>).
  3794    <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
  3796    <dd>Enables display of discretionary ligatures (OpenType feature: <span
  3797     class=tag>dlig</span>). Which ligatures are discretionary or optional is
  3798     decided by the type designer, so authors will need to refer to the
  3799     documentation of a given font to understand which ligatures are
  3800     considered discretionary.
  3801   </dl>
  3803   <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
  3805   <dl>
  3806    <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
  3808    <dd>Disables display of discretionary ligatures (OpenType feature: <span
  3809     class=tag>dlig</span>).
  3811    <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
  3813    <dd>Enables display of historical ligatures (OpenType feature: <span
  3814     class=tag>hlig</span>).
  3815   </dl>
  3817   <div class=featex><img alt="historical ligature example" src=hlig.png></div>
  3819   <dl>
  3820    <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
  3822    <dd>Disables display of historical ligatures (OpenType feature: <span
  3823     class=tag>hlig</span>).
  3825    <dt><dfn id=contextual>contextual</dfn>
  3827    <dd>Enables display of contextual alternates (OpenType feature: <span
  3828     class=tag>calt</span>). Although not strictly a ligature feature, like
  3829     ligatures this feature is commonly used to harmonize the shapes of glyphs
  3830     with the surrounding context. For OpenType fonts, this feature is on by
  3831     default.
  3832   </dl>
  3834   <div class=featex><img alt="contextual alternate example" src=calt.png></div>
  3836   <dl>
  3837    <dt><dfn id=no-contextual>no-contextual</dfn>
  3839    <dd>Disables display of contextual alternates (OpenType feature: <span
  3840     class=tag>calt</span>).
  3841   </dl>
  3843   <p>Required ligatures, needed for correctly rendering complex scripts, are
  3844    not affected by the settings above, including ‘<code
  3845    class=property>none</code>’ (OpenType feature: <span
  3846    class=tag>rlig</span>).</p>
  3847   <!-- prop: font-variant-position -->
  3849   <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
  3850    and superscript forms: the <a
  3851    href="#propdef-font-variant-position">font-variant-position</a> property</h3>
  3853   <table class=propdef id=namefont-variant-positionvaluenormal-sub>
  3854    <tbody>
  3855     <tr>
  3856      <td>Name:
  3858      <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
  3860     <tr>
  3861      <td>Value:
  3863      <td><a href="#font-variant-position-normal-value"
  3864       title="normal!!font-variant-position">normal</a> | <a
  3865       href="#sub">sub</a> | <a href="#super">super</a>
  3867     <tr>
  3868      <td>Initial:
  3870      <td>normal
  3872     <tr>
  3873      <td>Applies to:
  3875      <td>all elements
  3877     <tr>
  3878      <td>Inherited:
  3880      <td>yes
  3882     <tr>
  3883      <td>Percentages:
  3885      <td>N/A
  3887     <tr>
  3888      <td>Media:
  3890      <td>visual
  3892     <tr>
  3893      <td>Computed value:
  3895      <td>as specified
  3897     <tr>
  3898      <td>Animatable:
  3900      <td>no
  3901   </table>
  3903   <p>This property is used to enable typographic subscript and superscript
  3904    glyphs. These are alternate glyphs designed within the same em-box as
  3905    default glyphs and are intended to be laid out on the same baseline as the
  3906    default glyphs, with no resizing or repositioning of the baseline. They
  3907    are explicitly designed to match the surrounding text and to be more
  3908    readable without affecting the line height.
  3910   <div class=figure><img alt="comparison between real subscript glyphs and
  3911    synthesized ones" src=realsubscripts.png>
  3912    <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
  3913     (bottom)
  3914   </div>
  3916   <p>Individual values have the following meanings:
  3918   <dl>
  3919    <dt><dfn id=font-variant-position-normal-value
  3920     title="normal!!font-variant-position">normal</dfn>
  3922    <dd>None of the features listed below are enabled.
  3924    <dt><dfn id=sub>sub</dfn>
  3926    <dd>Enables display of subscript variants (OpenType feature: <span
  3927     class=tag>subs</span>).
  3929    <dt><dfn id=super>super</dfn>
  3931    <dd>Enables display of superscript variants (OpenType feature: <span
  3932     class=tag>sups</span>).
  3933   </dl>
  3935   <p>Because of the semantic nature of subscripts and superscripts, when the
  3936    value is either ‘<a href="#sub"><code class=property>sub</code></a>’
  3937    or ‘<a href="#super"><code class=property>super</code></a>’ for a
  3938    given contiguous run of text, if a variant glyph is not available for all
  3939    the characters in the run, simulated glyphs must be synthesized for all
  3940    characters using reduced forms of the glyphs that would be used without
  3941    this feature applied. This is done per run to avoid a mixture of variant
  3942    glyphs and synthesized ones that would not align correctly. In the case of
  3943    OpenType fonts that lack subscript or superscript glyphs for a given
  3944    character, user agents must use the appropriate subscript and superscript
  3945    metrics specified in the selected font's <a
  3946    href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
  3947    table</a> <a href="#OPENTYPE"
  3948    rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
  3949    and offset of the synthesized substitutes.
  3951   <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
  3952    using superscript metrics" src=superscript-alt-synth.png>
  3953    <p class=caption>Superscript alternate glyph (left), synthesized
  3954     superscript glyphs (middle), and incorrect mixture of the two (right)
  3955   </div>
  3957   <p>In situations where text decorations are only applied to runs of text
  3958    containing superscript or subscript glyphs, the synthesized glyphs must be
  3959    used to avoid problems with the placement of decorations.
  3961   <p>In the past, user agents have used font-size and vertical-align to
  3962    simulate subscripts and superscripts for the <code title="HTML sub
  3963    element">sub</code> and <code title="HTML sup element">sup</code>
  3964    elements. To allow a backwards compatible way of defining subscripts and
  3965    superscripts, it is recommended that authors use conditional rules <a
  3966    href="#CSS3-CONDITIONAL"
  3967    rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
  3968    older user agents will still render subscripts and superscripts via the
  3969    older mechanism.
  3971   <p>Authors should note that fonts typically only provide subscript and
  3972    superscript glyphs for a subset of all characters supported by the font.
  3973    For example, while subscript and superscript glyphs are often available
  3974    for Latin numbers, glyphs for punctuation and letter characters are less
  3975    frequently provided. The synthetic fallback rules defined for this
  3976    property assure that subscripts and superscripts will always appear but
  3977    the appearance may not match author expectations if the font used does not
  3978    provide the appropriate alternate glyph for all characters contained in a
  3979    subscript or superscript.
  3981   <p>This property is not cumulative. Applying it to elements within a
  3982    subscript or superscript won't nest the placement of a subscript or
  3983    superscript glyph. Images contained within text runs where the value of
  3984    this property is ‘<a href="#sub"><code class=property>sub</code></a>’
  3985    or ‘<a href="#super"><code class=property>super</code></a>’ will be
  3986    drawn just as they would if the value was <a
  3987    href="#font-variant-position-normal-value"
  3988    title="normal!!font-variant-position">‘<code
  3989    class=property>normal</code>’</a>.</p>
  3990   <!-- due to lack of consensus, couldn't resolve on exact positioning of text decorations:
  3991 http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
  3993   <p>Because of these limitations, ‘<a
  3994    href="#propdef-font-variant-position"><code
  3995    class=property>font-variant-position</code></a>’ is not recommended for
  3996    use in user agent stylesheets. Authors should use it in cases where
  3997    subscripts or superscripts will only contain the narrow range of
  3998    characters supported by the fonts specified.
  4000   <p class=note>The variant glyphs use the same baseline as the default
  4001    glyphs would use. There is no shift in the placement along the baseline,
  4002    so the use of variant glyphs doesn't affect the height of the inline box
  4003    or alter the height of the linebox. This makes superscript and subscript
  4004    variants ideal for situations where it's important that leading remain
  4005    constant, such as in multi-column layout.
  4007   <div class=example>
  4008    <p>A typical user agent default style for the <a class=tag
  4009     href="#sub">sub</a> element:</p>
  4011    <pre>sub {
  4012   vertical-align: sub;
  4013   font-size: smaller;
  4014   line-height: normal;
  4016 </pre>
  4018    <p>Using font-variant-position to specify typographic subscripts in a way
  4019     that will still show subscripts in older user agents:</p>
  4021    <pre>@supports ( font-variant-position: sub ) {
  4023   sub {
  4024     vertical-align: baseline;
  4025     font-size: 100%;
  4026     line-height: inherit;
  4027     font-variant-position: sub;
  4031 </pre>
  4033    <p>User agents that support the ‘<a
  4034     href="#propdef-font-variant-position"><code
  4035     class=property>font-variant-position</code></a>’ property will select a
  4036     subscript variant glyph and render this without adjusting the baseline or
  4037     font-size. Older user agents will ignore the ‘<a
  4038     href="#propdef-font-variant-position"><code
  4039     class=property>font-variant-position</code></a>’ property definition
  4040     and use the standard defaults for subscripts.</p>
  4041   </div>
  4042   <!-- prop: font-variant-caps -->
  4044   <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
  4045    the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
  4047   <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
  4048    <tbody>
  4049     <tr>
  4050      <td>Name:
  4052      <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
  4054     <tr>
  4055      <td>Value:
  4057      <td><a href="#font-variant-caps-normal-value"
  4058       title="normal!!font-variant-caps">normal</a> | <a
  4059       href="#small-caps">small-caps</a> | <a
  4060       href="#all-small-caps">all-small-caps</a> | <a
  4061       href="#petite-caps">petite-caps</a> | <a
  4062       href="#all-petite-caps">all-petite-caps</a> | <a
  4063       href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
  4065     <tr>
  4066      <td>Initial:
  4068      <td>normal
  4070     <tr>
  4071      <td>Applies to:
  4073      <td>all elements
  4075     <tr>
  4076      <td>Inherited:
  4078      <td>yes
  4080     <tr>
  4081      <td>Percentages:
  4083      <td>N/A
  4085     <tr>
  4086      <td>Media:
  4088      <td>visual
  4090     <tr>
  4091      <td>Computed value:
  4093      <td>as specified
  4095     <tr>
  4096      <td>Animatable:
  4098      <td>no
  4099   </table>
  4101   <p>This property allows the selection of alternate glyphs used for small or
  4102    petite capitals or for titling. These glyphs are specifically designed to
  4103    blend well with the surrounding normal glyphs, to maintain the weight and
  4104    readability which suffers when text is simply resized to fit this purpose.
  4106   <p>Individual values have the following meanings:
  4108   <dl>
  4109    <dt><dfn id=font-variant-caps-normal-value
  4110     title="normal!!font-variant-caps">normal</dfn>
  4112    <dd>None of the features listed below are enabled.
  4114    <dt><dfn id=small-caps>small-caps</dfn>
  4116    <dd>Enables display of small capitals (OpenType feature: <span
  4117     class=tag>smcp</span>). Small-caps glyphs typically use the form of
  4118     uppercase letters but are reduced to the size of lowercase letters.
  4119   </dl>
  4121   <div class=featex><img alt="small-caps example" src=smcp.png></div>
  4123   <dl>
  4124    <dt><dfn id=all-small-caps>all-small-caps</dfn>
  4126    <dd>Enables display of small capitals for both upper and lowercase letters
  4127     (OpenType features: <span class=tag>c2sc, smcp</span>).
  4129    <dt><dfn id=petite-caps>petite-caps</dfn>
  4131    <dd>Enables display of petite capitals (OpenType feature: <span
  4132     class=tag>pcap</span>).
  4134    <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
  4136    <dd>Enables display of petite capitals for both upper and lowercase
  4137     letters (OpenType features: <span class=tag>c2pc, pcap</span>).
  4139    <dt><dfn id=unicase>unicase</dfn>
  4141    <dd>Enables display of mixture of small capitals for uppercase letters
  4142     with normal lowercase letters (OpenType feature: <span
  4143     class=tag>unic</span>).
  4145    <dt><dfn id=titling-caps>titling-caps</dfn>
  4147    <dd>Enables display of titling capitals (OpenType feature: <span
  4148     class=tag>titl</span>). Uppercase letter glyphs are often designed for
  4149     use with lowercase letters. When used in all uppercase titling sequences
  4150     they can appear too strong. Titling capitals are designed specifically
  4151     for this situation.
  4152   </dl>
  4154   <p>The availability of these glyphs is based on whether a given feature is
  4155    defined or not in the feature list of the font. User agents can optionally
  4156    decide this on a per-script basis but should explicitly not decide this on
  4157    a per-character basis.
  4159   <p>Some fonts may only support a subset or none of the features described
  4160    for this property. For backwards compatibility with CSS 2.1, if ‘<a
  4161    href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
  4162    href="#all-small-caps"><code class=property>all-small-caps</code></a>’
  4163    is specified but small-caps glyphs are not available for a given font,
  4164    user agents should simulate a small-caps font, for example by taking a
  4165    normal font and replacing the glyphs for lowercase letters with scaled
  4166    versions of the glyphs for uppercase characters (replacing the glyphs for
  4167    both upper and lowercase letters in the case of ‘<a
  4168    href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
  4170   <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
  4171    real small-caps" class=hires src=synthetic-vs-real-small-caps.png
  4172    width=512>
  4173    <p class=caption>Synthetic vs. real small-caps
  4174   </div>
  4176   <p>To match the surrounding text, a font may provide alternate glyphs for
  4177    caseless characters when these features are enabled but when a user agent
  4178    simulates small capitals, it must not attempt to simulate alternates for
  4179    codepoints which are considered caseless.
  4181   <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
  4182    characters with small-caps, all-small-caps enabled" class=hires
  4183    src=small-capitals-variations.png width=418>
  4184    <p class=caption>Caseless characters with small-caps, all-small-caps
  4185     enabled
  4186   </div>
  4188   <p>If either ‘<a href="#petite-caps"><code
  4189    class=property>petite-caps</code></a>’ or ‘<a
  4190    href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
  4191    is specified for a font that doesn't support these features, the property
  4192    behaves as if ‘<a href="#small-caps"><code
  4193    class=property>small-caps</code></a>’ or ‘<a
  4194    href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
  4195    respectively, had been specified. If ‘<a href="#unicase"><code
  4196    class=property>unicase</code></a>’ is specified for a font that doesn't
  4197    support that feature, the property behaves as if ‘<a
  4198    href="#small-caps"><code class=property>small-caps</code></a>’ was
  4199    applied only to lowercased uppercase letters. If ‘<a
  4200    href="#titling-caps"><code class=property>titling-caps</code></a>’ is
  4201    specified with a font that does not support this feature, this property
  4202    has no visible effect. When simulated small capital glyphs are used, for
  4203    scripts that lack uppercase and lowercase letters, ‘<a
  4204    href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
  4205    href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
  4206    ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
  4207    ‘<a href="#all-petite-caps"><code
  4208    class=property>all-petite-caps</code></a>’ and ‘<a
  4209    href="#unicase"><code class=property>unicase</code></a>’ have no visible
  4210    effect.
  4212   <p>When casing transforms are used to simulate small capitals, the casing
  4213    transformations must match those used for the <span
  4214    class=property>‘<code class=property>text-transform</code>’</span>
  4215    property.
  4217   <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
  4218    replace glyphs in a small-caps font so that the text appears in all
  4219    uppercase letters.
  4221   <div class=figure style="padding: 0; margin: auto;"><img alt="using
  4222    all-small-caps in acronym-laden text" class=hires
  4223    src=acronym-laden-text.png width=596>
  4224    <p class=caption>Using small capitals to improve readability in
  4225     acronym-laden text
  4226   </div>
  4228   <div class=example>
  4229    <p>Quotes rendered italicised, with small-caps on the first line:</p>
  4231    <pre>blockquote            { font-style: italic; }
  4232 blockquote:first-line { font-variant: small-caps; }
  4234 &lt;blockquote><a href="http://lists.w3.org/Archives/Public/www-style/2009Dec/0036.html" style="text-decoration: none; border: none;">I'll be honor-bound to slap them like a haddock.</a>&lt;/blockquote>
  4235 </pre>
  4236   </div>
  4237   <!-- prop: font-variant-numeric -->
  4239   <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
  4240    formatting: the <a
  4241    href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
  4243   <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
  4244    <tbody>
  4245     <tr>
  4246      <td>Name:
  4248      <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
  4250     <tr>
  4251      <td>Value:
  4253      <td><a href="#font-variant-numeric-normal-value"
  4254       title="normal!!font-variant-numeric">normal</a> | [ <a
  4255       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  4256       || <a
  4257       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  4258       || <a
  4259       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  4260       || <a href="#ordinal">ordinal</a> || <a
  4261       href="#slashed-zero">slashed-zero</a> ]
  4263     <tr>
  4264      <td>Initial:
  4266      <td>normal
  4268     <tr>
  4269      <td>Applies to:
  4271      <td>all elements
  4273     <tr>
  4274      <td>Inherited:
  4276      <td>yes
  4278     <tr>
  4279      <td>Percentages:
  4281      <td>N/A
  4283     <tr>
  4284      <td>Media:
  4286      <td>visual
  4288     <tr>
  4289      <td>Computed value:
  4291      <td>as specified
  4293     <tr>
  4294      <td>Animatable:
  4296      <td>no
  4297   </table>
  4299   <p>Specifies control over numerical forms. The example below shows how some
  4300    of these values can be combined to influence the rendering of tabular data
  4301    with fonts that support these features. Within normal paragraph text,
  4302    proportional numbers are used while tabular numbers are used so that
  4303    columns of numbers line up properly:
  4305   <div class=figure style="padding: 0; margin: auto;"><img alt="combining
  4306    number styles" src=numberstyles.png>
  4307    <p class=caption>Using number styles
  4308   </div>
  4310   <p>Possible combinations:
  4312   <pre
  4313    class=prod><dfn id=numeric-figure-values><var>&lt;numeric-figure-values&gt;</var></dfn>   = [ <a href="#lining-nums">lining-nums</a> | <a href="#oldstyle-nums">oldstyle-nums</a> ]</pre>
  4315   <pre
  4316    class=prod><dfn id=numeric-spacing-values><var>&lt;numeric-spacing-values&gt;</var></dfn>  = [ <a href="#proportional-nums">proportional-nums</a> | <a href="#tabular-nums">tabular-nums</a> ]</pre>
  4318   <pre
  4319    class=prod><dfn id=numeric-fraction-values><var>&lt;numeric-fraction-values&gt;</var></dfn> = [ <a href="#diagonal-fractions">diagonal-fractions</a> | <a href="#stacked-fractions">stacked-fractions</a> ]</pre>
  4321   <p>Individual values have the following meanings:
  4323   <dl>
  4324    <dt><dfn id=font-variant-numeric-normal-value
  4325     title="normal!!font-variant-numeric">normal</dfn>
  4327    <dd>None of the features listed below are enabled.
  4329    <dt><dfn id=lining-nums>lining-nums</dfn>
  4331    <dd>Enables display of lining numerals (OpenType feature: <span
  4332     class=tag>lnum</span>).
  4334    <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
  4336    <dd>Enables display of old-style numerals (OpenType feature: <span
  4337     class=tag>onum</span>).
  4339    <dt><dfn id=proportional-nums>proportional-nums</dfn>
  4341    <dd>Enables display of proportional numerals (OpenType feature: <span
  4342     class=tag>pnum</span>).
  4344    <dt><dfn id=tabular-nums>tabular-nums</dfn>
  4346    <dd>Enables display of tabular numerals (OpenType feature: <span
  4347     class=tag>tnum</span>).
  4349    <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
  4351    <dd>Enables display of lining diagonal fractions (OpenType feature: <span
  4352     class=tag>frac</span>).
  4353   </dl>
  4355   <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
  4357   <dl>
  4358    <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
  4360    <dd>Enables display of lining stacked fractions (OpenType feature: <span
  4361     class=tag>afrc</span>).
  4362   </dl>
  4364   <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
  4366   <dl>
  4367    <dt><dfn id=ordinal>ordinal</dfn>
  4369    <dd>Enables display of forms used with ordinal numbers (OpenType feature:
  4370     <span class=tag>ordn</span>).
  4372    <dt><dfn id=slashed-zero>slashed-zero</dfn>
  4374    <dd>Enables display of slashed zeros (OpenType feature: <span
  4375     class=tag>zero</span>).
  4376   </dl>
  4378   <div class=featex><img alt="slashed zero example" src=zero.png></div>
  4380   <div class=example id=steak-marinade>
  4381    <p>A simple flank steak marinade recipe, rendered with automatic fractions
  4382     and old-style numerals:</p>
  4384    <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
  4386 &lt;h4>Steak marinade:&lt;/h4>
  4387 &lt;ul>
  4388   &lt;li>&lt;span class="amount">2&lt;/span> tbsp olive oil&lt;/li>
  4389   &lt;li>&lt;span class="amount">1&lt;/span> tbsp lemon juice&lt;/li>
  4390   &lt;li>&lt;span class="amount">1&lt;/span> tbsp soy sauce&lt;/li>
  4391   &lt;li>&lt;span class="amount">1 1/2&lt;/span> tbsp dry minced onion&lt;/li>
  4392   &lt;li>&lt;span class="amount">2 1/2&lt;/span> tsp italian seasoning&lt;/li>
  4393   &lt;li>Salt &amp;amp; pepper&lt;/li>
  4394 &lt;/ul>
  4396 &lt;p>Mix the meat with the marinade and let it sit covered in the refrigerator
  4397 for a few hours or overnight.&lt;/p>
  4398 </pre>
  4400    <p>Note that the fraction feature is only applied to values not the entire
  4401     paragraph. Fonts often implement this feature using contextual rules
  4402     based on the use of the slash (‘<code class=css>/</code>’) character.
  4403     As such, it's not suitable for use as a paragraph-level style.</p>
  4404   </div>
  4405   <!-- prop: font-variant-alternates -->
  4407   <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
  4408    and swashes: the <a
  4409    href="#propdef-font-variant-alternates">font-variant-alternates</a>
  4410    property</h3>
  4412   <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
  4413    <tbody>
  4414     <tr>
  4415      <td>Name:
  4417      <td><dfn
  4418       id=propdef-font-variant-alternates>font-variant-alternates</dfn>
  4420     <tr>
  4421      <td>Value:
  4423      <td>normal | [ <a href="#stylistic"
  4424       title=stylistic>stylistic(&lt;feature-value-name&gt;)</a> || <a
  4425       href="#historical-forms">historical-forms</a> || <a href="#styleset"
  4426       title=styleset>styleset(&lt;feature-value-name&gt; #)</a> || <a
  4427       href="#character-variant"
  4428       title=character-variant>character-variant(&lt;feature-value-name&gt;
  4429       #)</a> || <a href="#swash"
  4430       title=swash>swash(&lt;feature-value-name&gt;)</a> || <a
  4431       href="#ornaments"
  4432       title=ornaments>ornaments(&lt;feature-value-name&gt;)</a> || <a
  4433       href="#annotation"
  4434       title=annotation>annotation(&lt;feature-value-name&gt;)</a> ]
  4436     <tr>
  4437      <td>Initial:
  4439      <td>normal
  4441     <tr>
  4442      <td>Applies to:
  4444      <td>all elements
  4446     <tr>
  4447      <td>Inherited:
  4449      <td>yes
  4451     <tr>
  4452      <td>Percentages:
  4454      <td>N/A
  4456     <tr>
  4457      <td>Media:
  4459      <td>visual
  4461     <tr>
  4462      <td>Computed value:
  4464      <td>as specified
  4466     <tr>
  4467      <td>Animatable:
  4469      <td>no
  4470   </table>
  4472   <p>For any given character, fonts can provide a variety of alternate glyphs
  4473    in addition to the default glyph for that character. This property
  4474    provides control over the selection of these alternate glyphs.
  4476   <p>For many of the property values listed below, several different
  4477    alternate glyphs are available. How many alternates are available and what
  4478    they represent is font-specific, so these are each marked <dfn
  4479    id=font-specific>font specific</dfn> in the value definitions below.
  4480    Because the nature of these alternates is font-specific, the <a
  4481    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4482    rule is used to define values for a specific font family or set of
  4483    families that associate a font-specific numeric
  4484    <code>&lt;feature-index&gt;</code> with a custom
  4485    <code>&lt;feature-value-name&gt;</code>, which is then used in this
  4486    property to select specific alternates:
  4488   <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
  4490 p {
  4491   font-family: Noble Script;
  4492   font-variant-alternates: swash(flowing); /* use swash alternate #2 */
  4493 }</pre>
  4495   <p>When a particular <code>&lt;feature-value-name&gt;</code> has not been
  4496    defined for a given family or for a particular feature type, the computed
  4497    value must be the same as if it had been defined. However, property values
  4498    that contain these undefined <code>&lt;feature-value-name&gt;</code>
  4499    identifiers must be ignored when choosing glyphs.
  4501   <pre>/* these two style rules are effectively the same */
  4502 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
  4503 p { font-variant-alternates: normal; }
  4504 </pre>
  4506   <p>This allows values to be defined and used for a given set of font
  4507    families but ignored if fallback occurs, since the font family name would
  4508    be different. If a given value is outside the range supported by a given
  4509    font, the value is ignored. These values never apply to generic font
  4510    families.
  4512   <p>Individual values have the following meanings:
  4514   <dl>
  4515    <dt><dfn id=font-variant-alternates-normal-value
  4516     title="normal!!font-variant-alternates">normal</dfn>
  4518    <dd>None of the features listed below are enabled.
  4520    <dt><dfn id=historical-forms>historical-forms</dfn>
  4522    <dd>Enables display of historical forms (OpenType feature: <span
  4523     class=tag>hist</span>).
  4524   </dl>
  4526   <div class=featex><img alt="historical form example" src=hist.png></div>
  4528   <dl>
  4529    <dt><dfn id=stylistic
  4530     title=stylistic>stylistic(&lt;feature-value-name&gt;)</dfn>
  4532    <dd>Enables display of stylistic alternates (<a
  4533     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4534     class=tag>salt &lt;feature-index&gt;</span>).
  4535   </dl>
  4537   <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
  4539   <dl>
  4540    <dt><dfn id=styleset title=styleset>styleset(&lt;feature-value-name&gt;
  4541     #)</dfn>
  4543    <dd>Enables display with stylistic sets (<a href="#font-specific"><em>font
  4544     specific</em></a>, OpenType feature: <span
  4545     class=tag>ss&lt;feature-index&gt;</span> OpenType currently defines <span
  4546     class=tag>ss01</span> through <span class=tag>ss20</span>).
  4547   </dl>
  4549   <div class=featex><img alt="styleset example" src=ssnn.png></div>
  4551   <dl>
  4552    <dt><dfn id=character-variant
  4553     title=character-variant>character-variant(&lt;feature-value-name&gt;
  4554     #)</dfn>
  4556    <dd>Enables display of specific character variants (<a
  4557     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4558     class=tag>cv&lt;feature-index&gt;</span> OpenType currently defines <span
  4559     class=tag>cv01</span> through <span class=tag>cv99</span>).
  4561    <dt><dfn id=swash title=swash>swash(&lt;feature-value-name&gt;)</dfn>
  4563    <dd>Enables display of swash glyphs (<a href="#font-specific"><em>font
  4564     specific</em></a>, OpenType feature: <span class=tag>swsh
  4565     &lt;feature-index&gt;, cswh &lt;feature-index&gt;</span>).
  4566   </dl>
  4568   <div class=featex><img alt="swash example" src=swsh.png></div>
  4570   <dl>
  4571    <dt><dfn id=ornaments
  4572     title=ornaments>ornaments(&lt;feature-value-name&gt;)</dfn>
  4574    <dd>Enables replacement of default glyphs with ornaments, if provided in
  4575     the font (<a href="#font-specific"><em>font specific</em></a>, OpenType
  4576     feature: <span class=tag>ornm &lt;feature-index&gt;</span>). Some fonts
  4577     may offer ornament glyphs as alternates for a wide collection of
  4578     characters; however, displaying arbitrary characters (e.g.,
  4579     alphanumerics) as ornaments is poor practice as it distorts the semantics
  4580     of the data. Font designers are encouraged to encode all ornaments
  4581     (except those explicitly encoded in the Unicode Dingbats blocks, etc.) as
  4582     alternates for the bullet character (U+2022) to allow authors to select
  4583     the desired glyph using ‘<a href="#ornaments"><code
  4584     class=property>ornaments</code></a>’.
  4585   </dl>
  4587   <div class=featex><img alt="ornaments example" src=ornm.png></div>
  4589   <dl>
  4590    <dt><dfn id=annotation
  4591     title=annotation>annotation(&lt;feature-value-name&gt;)</dfn>
  4593    <dd>Enables display of alternate annotation forms (<a
  4594     href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
  4595     class=tag>nalt &lt;feature-index&gt;</span>).
  4596   </dl>
  4598   <div class=featex><img alt="alternate annotation form example"
  4599    src=nalt.png></div>
  4601   <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
  4602    specific alternates: the <dfn id=at-font-feature-values-rule
  4603    style="font-weight: inherit; font-style:
  4604    inherit"><code>@font-feature-values</code></dfn> rule</h3>
  4606   <p>Several of the possible values of ‘<a
  4607    href="#propdef-font-variant-alternates"><code
  4608    class=property>font-variant-alternates</code></a>’ listed above are
  4609    labeled as <a href="#font-specific"><em>font specific</em></a>. For these
  4610    features fonts may define not just a single glyph but a set of alternate
  4611    glyphs with an index to select a given alternate. Since these are font
  4612    family specific, the <a
  4613    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4614    rule is used to define named values for these indices for a given family.
  4616   <p class=note>See the <a href="#om-fontfeaturevalues">object model
  4617    reference section</a> for a description of the interfaces used to modify
  4618    these rules via the CSS Object Model.
  4620   <div class=example>
  4621    <p>In the case of the swash Q in the example shown above, the swash could
  4622     be specified using these style rules:</p>
  4624    <pre>
  4626 @font-feature-values Jupiter Sans {
  4627   @swash {
  4628     delicate: 1;
  4629     flowing: 2;
  4633 h2 { font-family: Jupiter Sans, sans-serif; }
  4635 /* show the second swash variant in h2 headings */
  4636 h2:first-letter { font-variant-alternates: swash(flowing); }
  4638 &lt;h2>Quick&lt;/h2></pre>
  4640    <p>When Jupiter Sans is present, the second alternate swash alternate will
  4641     be displayed. When not present, no swash character will be shown, since
  4642     the specific named value "flowing" is only defined for the Jupiter Sans
  4643     family. The @-mark indicates the name of the property value for which a
  4644     named value can be used. The name "flowing" is chosen by the author. The
  4645     index that represents each alternate is defined within a given font's
  4646     data.</p>
  4647   </div>
  4649   <h4 id=basic-syntax><span class=secno>6.9.1 </span>Basic syntax</h4>
  4651   <p>An <a
  4652    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4653    rule is composed of a list of font families followed by a block containing
  4654    individual <a href="#featurevalueblock"><i
  4655    title="feature_value_block">feature value blocks</i></a> that take the
  4656    form of @-rules. Each block defines a set of named values for a specific
  4657    font feature when a given set of font families is used. Effectively, they
  4658    define a mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
  4659    ⟨values⟩ are the numeric indices used for specific features defined
  4660    for a given font.
  4662   <p>In terms of the grammar, this specification defines the following
  4663    productions:
  4665   <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
  4666   : <a href="#fontfeaturevaluessym"><i>FONT_FEATURE_VALUES_SYM</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#fontfamilynamelist"><i>font_family_name_list</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
  4667     '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevalueblock"><i>feature_value_block</i></a>? [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevalueblock"><i>feature_value_block</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
  4670 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
  4671   : <a href="#fontfamilyname"><i>font_family_name</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ',' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#fontfamilyname"><i>font_family_name</i></a> ]*
  4674 <dfn id=fontfamilyname>font_family_name</dfn>
  4675   : <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>STRING</i></a> | [ <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> ]* ]
  4678 <dfn id=featurevalueblock>feature_value_block</dfn>
  4679   : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
  4680     '{' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevaluedefinition"><i>feature_value_definition</i></a>? [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ';' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="#featurevaluedefinition"><i>feature_value_definition</i></a>? ]* '}' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
  4683 <dfn id=featuretype>feature_type</dfn>:
  4684   <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
  4687 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
  4688   : <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>IDENT</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ':' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>NUMBER</i></a> [ <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>NUMBER</i></a> ]*
  4690 </pre>
  4692   <p>The following new token is introduced:
  4694   <pre>@{F}{O}{N}{T}{-}{F}{E}{A}{T}{U}{R}{E}{-}{V}{A}{L}{U}{E}{S}   {return <dfn id=fontfeaturevaluessym>FONT_FEATURE_VALUES_SYM</dfn>;}
  4695 </pre>
  4697   <p><a href="#featurevalueblock"><i title="feature_value_block">Feature
  4698    value blocks</i></a> are handled as <a
  4699    href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">at-rules</a>, they
  4700    consist of everything up to the next block or semi-colon, whichever comes
  4701    first.
  4703   <p>The <a href="#fontfamilynamelist"><i title="font_family_name_list">font
  4704    family list</i></a> is a comma-delimited list of <a
  4705    href="#fontfamilyname"><i title="font_family_name">font family
  4706    names</i></a> that match the definition of <a
  4707    href="#family-name-value"><var>&lt;family-name&gt;</var></a> for the <a
  4708    href="#propdef-font-family" title="font-family!!property">‘<code
  4709    class=property>font-family</code>’</a> property. This means that only
  4710    named font families are allowed, rules that include generic or system
  4711    fonts in the list of font families are syntax errors. However, if a user
  4712    agent defines a generic font to be a specific named font (e.g. Helvetica),
  4713    the settings associated with that family name will be used. If syntax
  4714    errors occur within the font family list, the entire rule must be ignored.
  4716   <p>Within <a href="#featurevalueblock"><i
  4717    title="feature_value_block">feature value blocks</i></a>, the <a
  4718    href="#featuretype"><i title="feature_type">feature type</i></a> is
  4719    ‘<code class=css>@</code>’ followed by the name of one of the <a
  4720    href="#font-specific"><em>font specific</em></a> property values of ‘<a
  4721    href="#propdef-font-variant-alternates"><code
  4722    class=property>font-variant-alternates</code></a>’ (e.g. <a
  4723    href="#swash"><code>@swash</code></a>). The identifiers used within
  4724    feature value definitions follow the rules of CSS user identifiers and are
  4725    case-sensitive. They are unique only for a given set of font families and
  4726    <a href="#featuretype"><i title="feature_type">feature type</i></a>. The
  4727    same identifier used with a different <a href="#featuretype"><i
  4728    title="feature_type">feature type</i></a> is treated as a separate and
  4729    distinct value. If the same identifier is defined mulitple times for a
  4730    given <a href="#featuretype"><i title="feature_type">feature type</i></a>
  4731    and font family, the last defined value is used. Values associated with a
  4732    given identifier are limited to integer values 0 or greater.
  4734   <p>When syntax errors occur within a <a href="#featurevaluedefinition"><i
  4735    title="feature_value_definition">feature value definition</i></a>, such as
  4736    invalid identifiers or values, the entire <a
  4737    href="#featurevaluedefinition"><i title="feature_value_definition">feature
  4738    value definition</i></a> must be omitted, just as syntax errors in style
  4739    declarations are handled. When the <a href="#featuretype"><i
  4740    title="feature_type">feature type</i></a> is invalid, the entire
  4741    associated <a href="#featurevalueblock"><i
  4742    title="feature_value_block">feature value block</i></a> must be ignored.
  4744   <div class=example>
  4745    <p>Rules that are equivalent given syntax error handling:</p>
  4747    <pre>@font-feature-values Bongo {
  4748   @swash { ornate: 1; }
  4749   annotation { boxed: 4; } /* should be @annotation! */
  4750   @swash { double-loops: 1; flowing: -1; } /* negative value */
  4751   @ornaments ; /* incomplete definition */
  4752   @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
  4753   <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none; border: none;">redrum</a>  /* random editing mistake */
  4754 }</pre>
  4756    <p>The example above is equivalent to:</p>
  4758    <pre>@font-feature-values Bongo {
  4759   @swash { ornate: 1; }
  4760   @swash { double-loops: 1; }
  4761   @styleset { double-W: 14; sharp-terminals: 16 1; }
  4762 }</pre>
  4763   </div>
  4765   <p>If multiple <a
  4766    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  4767    rules are defined for a given family, the resulting values definitions are
  4768    the union of the definitions contained within these rules. This allows a
  4769    set of named values to be defined for a given font family globally for a
  4770    site and specific additions made per-page.
  4772   <div class=example>
  4773    <p>Using both site-wide and per-page feature values:</p>
  4775    <pre>
  4776 site.css:
  4778   @font-feature-values Mercury Serif {
  4779     @styleset {
  4780       stacked-g: 3; /* "two-storey" versions of g, a */
  4781       stacked-a: 4;
  4785 page.css:
  4787   @font-feature-values Mercury Serif {
  4788     @styleset {
  4789       geometric-m: 7; /* alternate version of m */
  4793   body {
  4794     font-family: Mercury Serif, serif;
  4796     /* enable both the use of stacked g and alternate m */
  4797     font-variant-alternates: styleset(stacked-g, geometric-m);
  4798   }</pre>
  4799   </div>
  4801   <div class=example>
  4802    <p>Using a commonly named value allows authors to use a single style rule
  4803     to cover a set of fonts for which the underlying selector is different
  4804     for each font. If either font in the example below is found, a circled
  4805     number glyph will be used:</p>
  4807    <pre>@font-feature-values Taisho Gothic {
  4808   @annotation { boxed: 1; circled: 4; }
  4811 @font-feature-values Otaru Kisa {
  4812   @annotation { circled: 1; black-boxed: 3; }
  4815 h3.title {
  4816   /* circled form defined for both fonts */
  4817   font-family: Taisho Gothic, Otaru Kisa;
  4818   font-variant: annotation(circled);
  4819 }</pre>
  4820   </div>
  4822   <h4 id=multi-valued-feature-value-definitions><span class=secno>6.9.2
  4823    </span>Multi-valued feature value definitions</h4>
  4825   <p>Most <a href="#font-specific"><em>font specific</em></a> ‘<a
  4826    href="#propdef-font-variant-alternates"><code
  4827    class=property>font-variant-alternates</code></a>’ property values take
  4828    a single value (e.g. ‘<a href="#swash"><code
  4829    class=property>swash</code></a>’). The ‘<a
  4830    href="#character-variant"><code
  4831    class=property>character-variant</code></a>’ property value allows two
  4832    values and ‘<a href="#styleset"><code
  4833    class=property>styleset</code></a>’ allows an unlimited number.
  4835   <p>For the styleset property value, multiple values indicate the style sets
  4836    to be enabled. Values between 1 and 99 enable OpenType features <span
  4837    class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
  4838    OpenType standard only officially defines <span class=tag>ss01</span>
  4839    through <span class=tag>ss20</span>. For OpenType fonts, values greater
  4840    than 99 or equal to 0 do not generate a syntax error when parsed but
  4841    enable no OpenType features.
  4843   <pre>@font-feature-values Mars Serif {
  4844   @styleset {
  4845     alt-g: 1;        /* implies ss01 = 1 */
  4846     curly-quotes: 3; /* implies ss03 = 1 */
  4847     code: 4 5;       /* implies ss04 = 1, ss05 = 1 */
  4850   @styleset {
  4851     dumb: 125;        /* &gt;99, ignored */
  4854   @swash {
  4855     swishy: 3 5;     /* more than 1 value for swash, syntax error */
  4859 p.codeblock {
  4860   /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
  4861   font-variant-alternates: styleset(curly-quotes, code);
  4862 }</pre>
  4864   <p>For character-variant, a single value between 1 and 99 indicates the
  4865    enabling of OpenType feature <span class=tag>cv01</span> through <span
  4866    class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
  4867    to 0 are ignored but do not generate a syntax error when parsed but enable
  4868    no OpenType features. When two values are listed, the first value
  4869    indicates the feature used and the second the value passed for that
  4870    feature. If more than two values are assigned to a given name, a syntax
  4871    error occurs and the entire <a href="#featurevaluedefinition"><i
  4872    title="feature_value_definition">feature value definition</i></a> is
  4873    ignored.
  4875   <pre>@font-feature-values MM Greek {
  4876   @character-variant { alpha-2: 1 2; }   /* implies cv01 = 2 */
  4877   @character-variant { beta-3: 2 3; }    /* implies cv02 = 3 */
  4878   @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, definition ignored */
  4879   @character-variant { gamma: 12; }      /* implies cv12 = 1 */
  4880   @character-variant { zeta:   20 3; }   /* implies cv20 = 3 */
  4881   @character-variant { zeta-2: 20 2; }   /* implies cv20 = 2 */
  4882   @character-variant { silly: 105; }     /* &gt;99, ignored */
  4883   @character-variant { dumb: 323 3; }    /* &gt;99, ignored */
  4886 #title {
  4887   /* use the third alternate beta, first alternate gamma */
  4888   font-variant-alternates: character-variant(beta-3, gamma);
  4891 p {
  4892   /* zeta-2 follows zeta, implies cv20 = 2  */
  4893   font-variant-alternates: character-variant(zeta, zeta-2);
  4896 .special {
  4897   /* zeta follows zeta-2, implies cv20 = 3  */
  4898   font-variant-alternates: character-variant(zeta-2, zeta);
  4899 }</pre>
  4901   <div class=figure><img alt="Matching text on Byzantine seals using
  4902    character variants" src=byzantineseal.png>
  4903    <p class=caption>Byzantine seal text displayed with character variants
  4904   </div>
  4906   <div class=example>
  4907    <p>In the figure above, the text in red is rendered using a font
  4908     containing character variants that mimic the character forms found on a
  4909     Byzantine seal from the 8th century A.D. Two lines below is the same text
  4910     displayed in a font without variants. Note the two variants for U and N
  4911     used on the seal.</p>
  4913    <pre>@font-feature-values Athena Ruby {
  4914   @character-variant {
  4915     leo-B: 2 1;
  4916     leo-M: 13 3;
  4917     leo-alt-N: 14 1;
  4918     leo-N: 14 2;
  4919     leo-T: 20 1;
  4920     leo-U: 21 2;
  4921     leo-alt-U: 21 4;
  4925 p {
  4926   font-variant: discretionary-ligatures,
  4927                 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
  4930 span.alt-N {
  4931   font-variant-alternates: character-variant(leo-alt-N);
  4934 span.alt-U {
  4935   font-variant-alternates: character-variant(leo-alt-U);
  4938 &lt;p>ENO....UP͞RSTU&lt;span class="alt-U">U&lt;/span>͞&lt;span class="alt-U">U&lt;/span>ΚΑΙTỤẠG̣IUPNS&lt;/p>
  4940 &lt;p>LEON|ΚΑΙCONSTA|NTI&lt;span class="alt-N">N&lt;/span>OS..|STOIBAṢ.|LIṢROM|AIO&lt;span class="alt-N">N&lt;/span>&lt;/p>
  4941 </pre>
  4942   </div>
  4944   <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
  4945    Asian text rendering: the <a
  4946    href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
  4947    property</h3>
  4949   <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
  4950    <tbody>
  4951     <tr>
  4952      <td>Name:
  4954      <td><dfn
  4955       id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
  4957     <tr>
  4958      <td>Value:
  4960      <td><a href="#font-variant-east-asian-normal-value"
  4961       title="normal!!font-variant-east-asian">normal</a> | [ <a
  4962       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  4963       || <a
  4964       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  4965       || <a href="#ruby">ruby</a> ]
  4967     <tr>
  4968      <td>Initial:
  4970      <td>normal
  4972     <tr>
  4973      <td>Applies to:
  4975      <td>all elements
  4977     <tr>
  4978      <td>Inherited:
  4980      <td>yes
  4982     <tr>
  4983      <td>Percentages:
  4985      <td>N/A
  4987     <tr>
  4988      <td>Media:
  4990      <td>visual
  4992     <tr>
  4993      <td>Computed value:
  4995      <td>as specified
  4997     <tr>
  4998      <td>Animatable:
  5000      <td>no
  5001   </table>
  5003   <p>Allows control of glyph substitution and sizing in East Asian text.
  5005   <pre
  5006    class=prod><dfn id=east-asian-variant-values><var>&lt;east-asian-variant-values&gt;</var></dfn> = [ <a href="#jis78">jis78</a> | <a href="#jis83">jis83</a> | <a href="#jis90">jis90</a> | <a href="#jis04">jis04</a> | <a href="#simplified">simplified</a> | <a href="#traditional">traditional</a> ]</pre>
  5008   <pre
  5009    class=prod><dfn id=east-asian-width-values><var>&lt;east-asian-width-values&gt;</var></dfn>   = [ <a href="#full-width">full-width</a> | <a href="#proportional-width">proportional-width</a> ]</pre>
  5011   <p>Individual values have the following meanings:
  5013   <dl>
  5014    <dt><dfn id=font-variant-east-asian-normal-value
  5015     title="normal!!font-variant-east-asian">normal</dfn>
  5017    <dd>None of the features listed below are enabled.
  5019    <dt><dfn id=jis78>jis78</dfn>
  5021    <dd>Enables rendering of JIS78 forms (OpenType feature: <span
  5022     class=tag>jp78</span>).
  5023   </dl>
  5025   <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
  5027   <dl>
  5028    <dt><dfn id=jis83>jis83</dfn>
  5030    <dd>Enables rendering of JIS83 forms (OpenType feature: <span
  5031     class=tag>jp83</span>).
  5033    <dt><dfn id=jis90>jis90</dfn>
  5035    <dd>Enables rendering of JIS90 forms (OpenType feature: <span
  5036     class=tag>jp90</span>).
  5038    <dt><dfn id=jis04>jis04</dfn>
  5040    <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
  5041     class=tag>jp04</span>).
  5042     <p>The various JIS variants reflect the glyph forms defined in different
  5043      Japanese national standards. Fonts generally include glyphs defined by
  5044      the most recent national standard but it's sometimes necessary to use
  5045      older variants, to match signage for example.</p>
  5047    <dt><dfn id=simplified>simplified</dfn>
  5049    <dd>Enables rendering of simplified forms (OpenType feature: <span
  5050     class=tag>smpl</span>).
  5052    <dt><dfn id=traditional>traditional</dfn>
  5054    <dd>Enables rendering of traditional forms (OpenType feature: <span
  5055     class=tag>trad</span>).
  5056   </dl>
  5058   <p>The ‘<a href="#simplified"><code
  5059    class=property>simplified</code></a>’ and ‘<a
  5060    href="#traditional"><code class=property>traditional</code></a>’ values
  5061    allow control over the glyph forms for characters which have been
  5062    simplified over time but for which the older, traditional form is still
  5063    used in some contexts. The exact set of characters and glyph forms will
  5064    vary to some degree by context for which a given font was designed.
  5066   <div class=featex><img alt="tradtional form example" src=trad.png></div>
  5068   <dl>
  5069    <dt><dfn id=full-width>full-width</dfn>
  5071    <dd>Enables rendering of full-width variants (OpenType feature: <span
  5072     class=tag>fwid</span>).
  5074    <dt><dfn id=proportional-width>proportional-width</dfn>
  5076    <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
  5077     <span class=tag>pwid</span>).
  5078   </dl>
  5080   <div class=featex><img alt="proportionally spaced Japanese example"
  5081    src=pwid.png></div>
  5083   <dl>
  5084    <dt><dfn id=ruby>ruby</dfn>
  5086    <dd>Enables display of ruby variant glyphs (OpenType feature: <span
  5087     class=tag>ruby</span>). Since ruby text is generally smaller than the
  5088     associated body text, font designers can design special glyphs for use
  5089     with ruby that are more readable than scaled down versions of the default
  5090     glyphs. Only glyph selection is affected, there is no associated font
  5091     scaling or other change that affects line layout. The red ruby text below
  5092     is shown with default glyphs (top) and with ruby variant glyphs (bottom).
  5093     Note the slight difference in stroke thickness.
  5094   </dl>
  5096   <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
  5098   <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
  5099    for font rendering: the <a href="#propdef-font-variant">font-variant</a>
  5100    property</h3>
  5102   <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
  5103    <tbody>
  5104     <tr>
  5105      <td>Name:
  5107      <td><dfn id=propdef-font-variant
  5108       title="font-variant!!property">font-variant</dfn>
  5110     <tr>
  5111      <td>Value:
  5113      <td><a href="#font-variant-normal-value"
  5114       title="normal!!font-variant">normal</a> | <a
  5115       href="#font-variant-none-value" title="none!!font-variant">none</a> | [
  5116       <a href="#common-lig-values"><var>&lt;common-lig-values&gt;</var></a>
  5117       || <a
  5118       href="#discretionary-lig-values"><var>&lt;discretionary-lig-values&gt;</var></a>
  5119       || <a
  5120       href="#historical-lig-values"><var>&lt;historical-lig-values&gt;</var></a>
  5121       || <a
  5122       href="#contextual-alt-values"><var>&lt;contextual-alt-values&gt;</var></a>
  5123       || <a href="#stylistic"><var
  5124       title=stylistic>stylistic(&lt;feature-value-name&gt;)</var></a> || <a
  5125       href="#historical-forms"><var>historical-forms</var></a> || <a
  5126       href="#styleset"><var
  5127       title=styleset>styleset(&lt;feature-value-name&gt; #)</var></a> || <a
  5128       href="#character-variant"><var
  5129       title=character-variant>character-variant(&lt;feature-value-name&gt;
  5130       #)</var></a> || <a href="#swash"><var
  5131       title=swash>swash(&lt;feature-value-name&gt;)</var></a> || <a
  5132       href="#ornaments"><var
  5133       title=ornaments>ornaments(&lt;feature-value-name&gt;)</var></a> || <a
  5134       href="#annotation"><var
  5135       title=annotation>annotation(&lt;feature-value-name&gt;)</var></a> || [
  5136       <a href="#small-caps"><i>small-caps</i></a> | <a
  5137       href="#all-small-caps"><i>all-small-caps</i></a> | <a
  5138       href="#petite-caps"><i>petite-caps</i></a> | <a
  5139       href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
  5140       href="#unicase"><i>unicase</i></a> | <a
  5141       href="#titling-caps"><i>titling-caps</i></a> ] || <a
  5142       href="#numeric-figure-values"><var>&lt;numeric-figure-values&gt;</var></a>
  5143       || <a
  5144       href="#numeric-spacing-values"><var>&lt;numeric-spacing-values&gt;</var></a>
  5145       || <a
  5146       href="#numeric-fraction-values"><var>&lt;numeric-fraction-values&gt;</var></a>
  5147       || <a href="#ordinal"><i>ordinal</i></a> || <a
  5148       href="#slashed-zero"><i>slashed-zero</i></a> || <a
  5149       href="#east-asian-variant-values"><var>&lt;east-asian-variant-values&gt;</var></a>
  5150       || <a
  5151       href="#east-asian-width-values"><var>&lt;east-asian-width-values&gt;</var></a>
  5152       || <a href="#ruby"><i>ruby</i></a> ]
  5154     <tr>
  5155      <td>Initial:
  5157      <td>normal
  5159     <tr>
  5160      <td>Applies to:
  5162      <td>all elements
  5164     <tr>
  5165      <td>Inherited:
  5167      <td>yes
  5169     <tr>
  5170      <td>Percentages:
  5172      <td>see individual properties
  5174     <tr>
  5175      <td>Media:
  5177      <td>visual
  5179     <tr>
  5180      <td>Computed value:
  5182      <td>see individual properties
  5184     <tr>
  5185      <td>Animatable:
  5187      <td>see individual properties
  5188   </table>
  5190   <p>The <a href="#propdef-font-variant"
  5191    title="font-variant!!property">‘<code
  5192    class=property>font-variant</code>’</a> property is a shorthand for all
  5193    font-variant subproperties. The value <dfn id=font-variant-normal-value
  5194    title="normal!!font-variant">‘<code
  5195    class=property>normal</code>’</dfn> resets all subproperties of <a
  5196    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5197    class=property>font-variant</code>’</a> to their inital value. The <dfn
  5198    id=font-variant-none-value title="none!!font-variant">‘<code
  5199    class=property>none</code>’</dfn> value sets ‘<a
  5200    href="#propdef-font-variant-ligatures"><code
  5201    class=property>font-variant-ligatures</code></a>’ to ‘<code
  5202    class=property>none</code>’ and resets all other font feature properties
  5203    to their initial value. Like other shorthands, using <a
  5204    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5205    class=property>font-variant</code>’</a> resets unspecified <a
  5206    href="#propdef-font-variant" title="font-variant!!property">‘<code
  5207    class=property>font-variant</code>’</a> subproperties to their initial
  5208    values. It does not reset the values of either ‘<a
  5209    href="#propdef-font-language-override"><code
  5210    class=property>font-language-override</code></a>’ or <a
  5211    href="#propdef-font-feature-settings"
  5212    title="font-feature-settings!!property">‘<code
  5213    class=property>font-feature-settings</code>’</a>.
  5215   <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
  5216    font feature settings control: the <a
  5217    href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
  5219   <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
  5220    <tbody>
  5221     <tr>
  5222      <td>Name:
  5224      <td><dfn id=propdef-font-feature-settings
  5225       title="font-feature-settings!!property">font-feature-settings</dfn>
  5227     <tr>
  5228      <td>Value:
  5230      <td><a href="#font-feature-settings-normal-value"
  5231       title="normal!!font-feature-settings">normal</a> | <a
  5232       href="#feature-tag-value"><var>&lt;feature-tag-value&gt;</var></a> #
  5234     <tr>
  5235      <td>Initial:
  5237      <td>normal
  5239     <tr>
  5240      <td>Applies to:
  5242      <td>all elements
  5244     <tr>
  5245      <td>Inherited:
  5247      <td>yes
  5249     <tr>
  5250      <td>Percentages:
  5252      <td>N/A
  5254     <tr>
  5255      <td>Media:
  5257      <td>visual
  5259     <tr>
  5260      <td>Computed value:
  5262      <td>as specified
  5264     <tr>
  5265      <td>Animatable:
  5267      <td>no
  5268   </table>
  5270   <p>This property provides low-level control over OpenType font features. It
  5271    is intended as a way of providing access to font features that are not
  5272    widely used but are needed for a particular use case.
  5274   <p>Authors should generally use <a href="#propdef-font-variant"
  5275    title="font-variant!!property">‘<code
  5276    class=property>font-variant</code>’</a> and its related subproperties
  5277    whenever possible and only use this property for special cases where its
  5278    use is the only way of accessing a particular infrequently used font
  5279    feature.
  5281   <pre>/* enable small caps and use second swash alternate */
  5282 font-feature-settings: "smcp", "swsh" 2;</pre>
  5284   <p>A value of <dfn id=font-feature-settings-normal-value
  5285    title="normal!!font-feature-settings">‘<code
  5286    class=property>normal</code>’</dfn> means that no change in glyph
  5287    selection or positioning occurs due to this property.
  5289   <p>Feature tag values have the following syntax:
  5291   <pre
  5292    class=prod><dfn id=feature-tag-value><var>&lt;feature-tag-value&gt;</var></dfn> = &lt;string&gt; [ &lt;integer&gt; | on | off ]?</pre>
  5294   <p>The &lt;string&gt; is a case-sensitive OpenType feature tag. As
  5295    specified in the OpenType specification, feature tags contain four ASCII
  5296    characters. Tag strings longer or shorter than four characters, or
  5297    containing characters outside the U+20–7E codepoint range are invalid.
  5298    Feature tags need only match a feature tag defined in the font, so they
  5299    are not limited to explicitly registered OpenType features. Fonts defining
  5300    custom feature tags should follow the <a
  5301    href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
  5302    rules</a> defined in the OpenType specification <a
  5303    href="#OPENTYPE-FEATURES"
  5304    rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
  5305    Feature tags not present in the font are ignored; a user agent must not
  5306    attempt to synthesize fallback behavior based on these feature tags.
  5308   <p>This means that explicitly disabling the <span class=tag>kern</span>
  5309    feature will not affect the application of kerning data found in the
  5310    ‘<code class=property>kern</code>’ table (as opposed to kerning data
  5311    associated with the <span class=tag>kern</span> feature in the ‘<code
  5312    class=property>GPOS</code>’ table). Authors should use the ‘<a
  5313    href="#propdef-font-kerning"><code
  5314    class=property>font-kerning</code></a>’ property to explictly enable or
  5315    disable kerning since this property affects both types of kerning.
  5317   <p>If present, a value indicates an index used for glyph selection. An
  5318    &lt;integer&gt; value must be 0 or greater. A value of 0 indicates that
  5319    the feature is disabled. For boolean features, a value of 1 enables the
  5320    feature. For non-boolean features, a value of 1 or greater enables the
  5321    feature and indicates the feature selection index. A value of ‘<code
  5322    class=property>on</code>’ is synonymous with 1 and ‘<code
  5323    class=property>off</code>’ is synonymous with 0. If the value is
  5324    omitted, a value of 1 is assumed.
  5326   <pre>
  5327 font-feature-settings: "dlig" 1;       /* dlig=1 enable discretionary ligatures */
  5328 font-feature-settings: "smcp" on;      /* smcp=1 enable small caps */
  5329 font-feature-settings: 'c2sc';         /* c2sc=1 enable caps to small caps */
  5330 font-feature-settings: "liga" off;     /* liga=0 no common ligatures */
  5331 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
  5332 font-feature-settings: "tnum" "hist";  /* invalid, need a comma-delimited list */
  5333 font-feature-settings: "palin" off;    /* good idea but invalid tagname */
  5334 font-feature-settings: "PKRN";         /* PKRN=1 enable custom feature */
  5335 font-feature-settings: dlig;           /* invalid, tag must be a string */
  5336 </pre>
  5338   <p>When values greater than the range supported by the font are specified,
  5339    the behavior is explicitly undefined. For boolean features, in general
  5340    these will enable the feature. For non-boolean features, out of range
  5341    values will in general be equivalent to a 0 value. However, in both cases
  5342    the exact behavior will depend upon the way the font is designed
  5343    (specifically, which type of lookup is used to define the feature).
  5345   <p>Although specifically defined for OpenType feature tags, feature tags
  5346    for other modern font formats that support font features may be added in
  5347    the future. Where possible, features defined for other font formats should
  5348    attempt to follow the pattern of registered OpenType tags.
  5350   <div class=example>
  5351    <p>The Japanese text below will be rendered with half-width kana
  5352     characters:</p>
  5354    <pre lang=ja>
  5355 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
  5357 &lt;p>毎日<a href="http://images.google.com/images?q=%E3%82%AB%E3%83%AC%E3%83%BC" style="text-decoration: none;">カレー</a>食べてるのに、飽きない&lt;/p>
  5358 </pre>
  5359   </div>
  5361   <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
  5362    language override: the <a
  5363    href="#propdef-font-language-override">font-language-override</a> property</h3>
  5365   <table class=propdef id=namefont-language-overridevaluenormal-lt>
  5366    <tbody>
  5367     <tr>
  5368      <td>Name:
  5370      <td><dfn id=propdef-font-language-override>font-language-override</dfn>
  5372     <tr>
  5373      <td>Value:
  5375      <td><a href="#font-language-override-normal-value"
  5376       title="normal!!font-language-override">normal</a> | <a
  5377       href="#font-language-override-string-value"><var>&lt;string&gt;</var></a>
  5379     <tr>
  5380      <td>Initial:
  5382      <td><a href="#font-language-override-normal-value"
  5383       title="normal!!font-language-override">normal</a>
  5385     <tr>
  5386      <td>Applies to:
  5388      <td>all elements
  5390     <tr>
  5391      <td>Inherited:
  5393      <td>yes
  5395     <tr>
  5396      <td>Percentages:
  5398      <td>N/A
  5400     <tr>
  5401      <td>Media:
  5403      <td>visual
  5405     <tr>
  5406      <td>Computed value:
  5408      <td>as specified
  5410     <tr>
  5411      <td>Animatable:
  5413      <td>no
  5414   </table>
  5416   <p>Normally, authors can control the use of language-specific glyph
  5417    substitutions and positioning by setting the content language of an
  5418    element, as <a href="#language-specific-support">described above</a>:
  5420   <pre>&lt;!-- Display text using S'gaw Karen specific features -->
  5421 &lt;p lang="ksw">...&lt;/p></pre>
  5423   <p>In some cases, authors may need to specify a language system that
  5424    differs from the content language, for example due to the need to mimic
  5425    another language's typographic traditions. The ‘<a
  5426    href="#propdef-font-language-override"><code
  5427    class=property>font-language-override</code></a>’ property allows
  5428    authors to explicitly specify the language system of the font, overriding
  5429    the language system implied by the content language.
  5431   <p>Values have the following meanings:
  5433   <dl>
  5434    <dt><dfn id=font-language-override-normal-value
  5435     title="normal!!font-language-override">normal</dfn>
  5437    <dd>specifies that when rendering with OpenType fonts, the content
  5438     language of the element is used to infer the OpenType language system
  5440    <dt><dfn
  5441     id=font-language-override-string-value><var>&lt;string&gt;</var></dfn>
  5443    <dd>single three-letter case-sensitive OpenType <a
  5444     href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
  5445     system tag</a>, specifies the OpenType language system to be used instead
  5446     of the language system implied by the language of the element
  5447   </dl>
  5448   <!-- For this level, string represents a single language code, there's no concept of "fallback" 
  5449 http://www.w3.org/2013/06/07-css-minutes.html#item04 -->
  5451   <p>Use of invalid OpenType language system tags must not generate a parse
  5452    error but must be ignored when doing glyph selection and placement.
  5454   <div class=example>
  5455    <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
  5456     Declaration of Human Rights</a> has been translated into a wide variety
  5457     of languages. In Turkish, Article 9 of this document might be marked up
  5458     as below:</p>
  5460    <pre lang=tr>&lt;body lang="tr">
  5462 &lt;h4>Madde 9&lt;/h4>
  5463 &lt;p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.&lt;/p>
  5464 </pre>
  5466    <p>Here the user agent uses the value of the ‘<code
  5467     class=property>lang</code>’ attribute when rendering text and
  5468     appropriately renders this text without ‘<code
  5469     class=property>fi</code>’ ligatures. There is no need to use the ‘<a
  5470     href="#propdef-font-language-override"><code
  5471     class=property>font-language-override</code></a>’ property.</p>
  5473    <p>However, a given font may lack support for a specific language. In this
  5474     situation authors may need to use the typographic conventions of a
  5475     related language that are supported by that font:</p>
  5477    <pre lang=mk>&lt;body lang="mk">     &lt;!-- Macedonian lang code --&gt;
  5479 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
  5481 &lt;h4>Члeн 9&lt;/h4>
  5482 &lt;p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.&lt;/p>
  5484 </pre>
  5486    <p>The Macedonian text here will be rendered using Serbian typographic
  5487     conventions, with the assumption that the font specified supports
  5488     Serbian.</p>
  5489   </div>
  5491   <p><a id=rendering-considerations></a>
  5493   <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
  5494    Resolution</h2>
  5496   <p>As described in the previous section, font features can be enabled in a
  5497    variety of ways, either via the use of <a href="#propdef-font-variant"
  5498    title="font-variant!!property">‘<code
  5499    class=property>font-variant</code>’</a> or <a
  5500    href="#propdef-font-feature-settings"
  5501    title="font-feature-settings!!property">‘<code
  5502    class=property>font-feature-settings</code>’</a> in a style rule or
  5503    within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5504    The resolution order for the union of these settings is defined below.
  5505    Features defined via CSS properties are applied on top of layout engine
  5506    default features.
  5508   <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
  5510   <p>For OpenType fonts, user agents must enable the default features defined
  5511    in the OpenType documentation for a given script and writing mode.
  5512    Required ligatures, common ligatures and contextual forms must be enabled
  5513    by default (OpenType features: <span class=tag>rlig, liga, clig,
  5514    calt</span>), along with localized forms (OpenType feature: <span
  5515    class=tag>locl</span>), and features required for proper display of
  5516    composed characters and marks (OpenType features: <span class=tag>ccmp,
  5517    mark, mkmk</span>). These features must always be enabled, even when the
  5518    value of the <a href="#propdef-font-variant"
  5519    title="font-variant!!property">‘<code
  5520    class=property>font-variant</code>’</a> and <a
  5521    href="#propdef-font-feature-settings"
  5522    title="font-feature-settings!!property">‘<code
  5523    class=property>font-feature-settings</code>’</a> properties is <span
  5524    title="normal value">‘<code class=property>normal</code>’</span>.
  5525    Individual features are only disabled when explicitly overridden by the
  5526    author, as when ‘<a href="#propdef-font-variant-ligatures"><code
  5527    class=property>font-variant-ligatures</code></a>’ is set to ‘<a
  5528    href="#no-common-ligatures"><code
  5529    class=property>no-common-ligatures</code></a>’. For handling complex
  5530    scripts such as <a
  5531    href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
  5532    <a
  5533    href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
  5534    or <a
  5535    href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
  5536    additional features are required. For upright text within vertical text
  5537    runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
  5538    must be enabled.
  5540   <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
  5542   <p>General and <a href="#font-specific"><em>font specific</em></a> font
  5543    feature property settings are resolved in the order below, in ascending
  5544    order of precedence. This ordering is used to construct a combined list of
  5545    font features that affect a given text run.
  5547   <ol>
  5548    <li>Font features enabled by default, including features required for a
  5549     given script.
  5551    <li>If the font is defined via an <a
  5552     href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
  5553     features implied by the font-variant descriptor in the <a
  5554     href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5556    <li>If the font is defined via an <a
  5557     href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
  5558     features implied by the font-feature-settings descriptor in the <a
  5559     href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5561    <li>Font features implied by the value of the <a
  5562     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5563     class=property>font-variant</code>’</a> property, the related <a
  5564     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5565     class=property>font-variant</code>’</a> subproperties and any other CSS
  5566     property that uses OpenType features (e.g. the ‘<a
  5567     href="#propdef-font-kerning"><code
  5568     class=property>font-kerning</code></a>’ property).</li>
  5569    <!-- other CSS props override 'font-variant' but not 'font-feature-settings' -->
  5570    <!-- http://lists.w3.org/Archives/Public/www-style/2013Aug/0110.html -->
  5572    <li>Feature settings determined by properties other than <a
  5573     href="#propdef-font-variant" title="font-variant!!property">‘<code
  5574     class=property>font-variant</code>’</a> or <a
  5575     href="#propdef-font-feature-settings"
  5576     title="font-feature-settings!!property">‘<code
  5577     class=property>font-feature-settings</code>’</a>. For example, setting
  5578     a non-default value for the ‘<code
  5579     class=property>letter-spacing</code>’ property disables common
  5580     ligatures.
  5582    <li>Font features implied by the value of <a
  5583     href="#propdef-font-feature-settings"
  5584     title="font-feature-settings!!property">‘<code
  5585     class=property>font-feature-settings</code>’</a> property.
  5586   </ol>
  5588   <p>This ordering allows authors to set up a general set of defaults for
  5589    fonts within their <a
  5590    href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
  5591    them with property settings for specific elements. General property
  5592    settings override the settings in <a
  5593    href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
  5594    font feature settings override <a href="#propdef-font-variant"
  5595    title="font-variant!!property">‘<code
  5596    class=property>font-variant</code>’</a> property settings.
  5598   <p>For situations where the combined list of font feature settings contains
  5599    more than one value for the same feature, the last value is used. When a
  5600    font lacks support for a given underlying font feature, text is simply
  5601    rendered as if that font feature was not enabled; font fallback does not
  5602    occur and no attempt is made to synthesize the feature except where
  5603    explicitly defined for specific properties.
  5605   <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
  5606    precedence examples</h3>
  5608   <div class=example>
  5609    <p>With the styles below, numbers are rendered proportionally when used
  5610     within a paragraph but are shown in tabular form within tables of prices:</p>
  5612    <pre>body {
  5613   font-variant-numeric: proportional-nums;
  5616 table.prices td {
  5617   font-variant-numeric: tabular-nums;
  5619 </pre>
  5620   </div>
  5622   <div class=example>
  5623    <p>When the <a href="#descdef-font-variant"
  5624     title="font-variant!!descriptor">font-variant</a> descriptor is used
  5625     within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule,
  5626     it only applies to the font defined by that rule.</p>
  5628    <pre>@font-face {
  5629   font-family: MainText;
  5630   src: url(http://example.com/font.ttf);
  5631   font-variant: oldstyle-nums proportional-nums styleset(1,3);
  5634 body {
  5635   font-family: MainText, Helvetica;
  5638 table.prices td {
  5639   font-variant-numeric: tabular-nums;
  5641 </pre>
  5643    <p>In this case, old-style numerals will be used throughout but only where
  5644     the font "MainText" is used. Just as in the previous example, tabular
  5645     values will be used in price tables since ‘<a
  5646     href="#tabular-nums"><code class=property>tabular-nums</code></a>’
  5647     appears in a general style rule and its use is mutually exclusive with
  5648     ‘<a href="#proportional-nums"><code
  5649     class=property>proportional-nums</code></a>’. Stylistic alternate sets
  5650     will only be used where MainText is used.</p>
  5651   </div>
  5653   <div class=example>
  5654    <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
  5655     also be used to access font features in locally available fonts via the
  5656     use of <code>local()</code> in the ‘<a href="#descdef-src"><code
  5657     class=property>src</code></a>’ descriptor of the <a
  5658     href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
  5660    <pre>@font-face {
  5661   font-family: BodyText;
  5662   src: local("HiraMaruPro-W4");
  5663   font-variant: proportional-width;
  5664   font-feature-settings: "ital"; /* Latin italics within CJK text feature */
  5667 body { font-family: BodyText, serif; }
  5668 </pre>
  5670    <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
  5671     text rendering occurs, Japanese kana will be proportionally spaced and
  5672     Latin text will be italicised. Text rendered with the fallback serif font
  5673     will use default rendering properties.</p>
  5674   </div>
  5676   <div class=example>
  5677    <p>In the example below, discretionary ligatures are enabled only for a
  5678     downloadable font but are disabled within spans of class "special":</p>
  5680    <pre>@font-face {
  5681   font-family: main;
  5682   src: url(fonts/ffmeta.woff) format("woff");
  5683   font-variant: discretionary-ligatures;
  5686 body         { font-family: main, Helvetica; }
  5687 span.special { font-variant-ligatures: no-discretionary-ligatures; }
  5688 </pre>
  5690    <p>Suppose one adds a rule using ‘<code
  5691     class=property>font-feature-settings</code>’ to enable discretionary
  5692     ligatures:</p>
  5694    <pre>body         { font-family: main, Helvetica; }
  5695 span         { font-feature-settings: "dlig"; }
  5696 span.special { font-variant-ligatures: no-discretionary-ligatures; }
  5697 </pre>
  5699    <p>In this case, discretionary ligatures <em>will</em> be rendered within
  5700     spans of class "special". This is because both the <a
  5701     href="#propdef-font-feature-settings"
  5702     title="font-feature-settings!!property">‘<code
  5703     class=property>font-feature-settings</code>’</a> and ‘<a
  5704     href="#propdef-font-variant-ligatures"><code
  5705     class=property>font-variant-ligatures</code></a>’ properties apply to
  5706     these spans. Although the ‘<code class=css>no-discretionary
  5707     ligatures</code>’ setting of ‘<a
  5708     href="#propdef-font-variant-ligatures"><code
  5709     class=property>font-variant-ligatures</code></a>’ effectively disables
  5710     the OpenType <span class=tag>dlig</span> feature, because the <a
  5711     href="#propdef-font-feature-settings"
  5712     title="font-feature-settings!!property">‘<code
  5713     class=property>font-feature-settings</code>’</a> is resolved after
  5714     that, the ‘<code class=property>dlig</code>’ value reenables
  5715     discretionary ligatures.</p>
  5716   </div>
  5718   <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
  5720   <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
  5721    and <a
  5722    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5723    rules can be accessed via the following extensions to the CSS Object
  5724    Model.
  5726   <h3 id=om-fontface><span class=secno>8.1 </span>The <a
  5727    href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
  5729   <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
  5730    <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
  5732   <pre class=idl>
  5733 interface CSSFontFaceRule : CSSRule {
  5734   attribute DOMString family;
  5735   attribute DOMString src;
  5736   attribute DOMString style;
  5737   attribute DOMString weight;
  5738   attribute DOMString stretch;
  5739   attribute DOMString unicodeRange;
  5740   attribute DOMString variant;
  5741   attribute DOMString featureSettings;
  5742 }</pre>
  5744   <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
  5745    rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
  5746    defined a different variant of this rule. This definition supercedes that
  5747    one.
  5749   <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
  5750    href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
  5751    interface</h3>
  5753   <p>The <code>CSSRule</code> interface is extended as follows:
  5755   <pre class=idl>partial interface CSSRule {
  5756   const unsigned short FONT_FEATURE_VALUES_RULE = 14;
  5757 }</pre>
  5759   <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
  5760    interface represents a <a
  5761    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5762    rule.
  5764   <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
  5765   attribute DOMString fontFamily;
  5766   readonly attribute CSSFontFeatureValuesMap annotation;
  5767   readonly attribute CSSFontFeatureValuesMap ornaments;
  5768   readonly attribute CSSFontFeatureValuesMap stylistic;
  5769   readonly attribute CSSFontFeatureValuesMap swash;
  5770   readonly attribute CSSFontFeatureValuesMap characterVariant;
  5771   readonly attribute CSSFontFeatureValuesMap styleset;
  5774 [MapClass(DOMString, sequence&lt;unsigned long&gt;)]
  5775 interface CSSFontFeatureValuesMap {
  5776   void set(DOMString featureValueName,
  5777            (unsigned long or sequence&lt;unsigned long&gt;) values);
  5778 }</pre>
  5780   <dl class=idl-attributes>
  5781    <dt><var>fontFamily</var> of type <code>DOMString</code>
  5783    <dd>The list of one or more font families for which a given set of feature
  5784     values is defined.
  5786    <dt>value maps of type <code>CSSFontFeatureValuesMap</code>, readonly
  5788    <dd>Maps of feature values associated with feature value names for a given
  5789     ‘<a href="#propdef-font-variant-alternates"><code
  5790     class=property>font-variant-alternates</code></a>’ value type
  5791   </dl>
  5793   <p>Each value map attribute of <a
  5794    href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
  5795    reflects the values defined via a corresponding <a
  5796    href="#featurevalueblock"><i title="feature_value_block">feature value
  5797    block</i></a>. Thus, the <var title="annotation
  5798    attribute">annotation</var> attribute contains the values contained within
  5799    a <code title="@annotation">@annotation</code> <a
  5800    href="#featurevalueblock"><i title="feature_value_block">feature value
  5801    block</i></a>, the <var title="ornaments attribute">ornaments</var>
  5802    attribute contains the values contained with a <code
  5803    title="@ornaments">@ornaments</code> <a href="#featurevalueblock"><i
  5804    title="feature_value_block">feature value block</i></a> and so forth.
  5806   <p>The <code>CSSFontFeatureValuesMap</code> interface uses the <a
  5807    href="http://dev.w3.org/2006/webapi/WebIDL/#es-map-members">default map
  5808    class methods</a> but the <code>set</code> method has different behavior.
  5809    It takes a sequence of unsigned integers and associates it with a given
  5810    <code>featureValueName</code>. The method behaves the same as the default
  5811    map class method except that a single unsigned long value is treated as a
  5812    sequence of a single value. The method throws an exception if an invalid
  5813    number of values is passed in. If the associated <a
  5814    href="#featurevalueblock"><i title="feature_value_block">feature value
  5815    block</i></a> only allows a limited number of values, the <code>set</code>
  5816    method throws an <code>InvalidAccessError</code> exception when the input
  5817    sequence to <code>set</code> contains more than the limited number of
  5818    values. See the description of <a
  5819    href="#multi-valued-feature-value-definitions">multi-valued feature value
  5820    definitions</a> for details on the maximum number of values allowed for a
  5821    given type of <a href="#featurevalueblock"><i
  5822    title="feature_value_block">feature value block</i></a>. The
  5823    <code>get</code> method always returns a sequence of values, even if the
  5824    sequence only contains a single value.
  5826   <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
  5827    properties to CSS properties</h2>
  5829   <p><em>This appendix is included as background for some of the problems and
  5830    situations that are described in other sections. It should be viewed as
  5831    informative only.</em>
  5833   <p>Font properties in CSS are designed to be independent of the underlying
  5834    font formats used; they can be used to specify bitmap fonts, Type1 fonts,
  5835    SVG fonts in addition to the common TrueType and OpenType fonts. But there
  5836    are facets of the TrueType and OpenType formats that often cause confusion
  5837    for authors and present challenges to implementers on different platforms.
  5839   <p>Originally developed at Apple, TrueType was designed as an outline font
  5840    format for both screen and print. Microsoft joined Apple in developing the
  5841    TrueType format and both platforms have supported TrueType fonts since
  5842    then. Font data in the TrueType format consists of a set of tables
  5843    distinguished with common four-letter tag names, each containing a
  5844    specific type of data. For example, naming information, including
  5845    copyright and license information, is stored in the ‘<code
  5846    class=property>name</code>’ table. The <a
  5847    href="#character-map"><em>character map</em></a> (‘<code
  5848    class=property>cmap</code>’) table contains a mapping of character
  5849    encodings to glyphs. Apple later added additional tables for supporting
  5850    enhanced typographic functionality; these are now called Apple Advanced
  5851    Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
  5852    tables for advanced typography and called their format OpenType <a
  5853    href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
  5855   <p>In many cases the font data used under Microsoft Windows or Linux is
  5856    slightly different from the data used under Apple's Mac OS X because the
  5857    TrueType format allowed for explicit variation across platforms. This
  5858    includes font metrics, names and <a href="#character-map"><em>character
  5859    map</em></a> data.
  5861   <p>Specifically, font family name data is handled differently across
  5862    platforms. For TrueType and OpenType fonts these names are contained in
  5863    the ‘<code class=property>name</code>’ table, in name records with
  5864    name ID 1. Mulitple names can be stored for different locales, but
  5865    Microsoft recommends fonts always include at least a US English version of
  5866    the name. On Windows, Microsoft made the decision for backwards
  5867    compatibility to limit this family name to a maximum of four faces; for
  5868    larger groupings the "preferred family" (name ID 16) or "WWS family" (name
  5869    ID 21) can be used. Other platforms such as OSX don't have this
  5870    limitation, so the family name is used to define all possible groupings.
  5872   <p>Other name table data provides names used to uniquely identify a
  5873    specific face within a family. The full font name (name ID 4) and the
  5874    Postscript name (name ID 6) describe a single face uniquely. For example,
  5875    the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
  5876    and a Postscript name of "GillSans-Bold". There can be multiple localized
  5877    versions of the fullname for a given face, but the Postscript name is
  5878    always a unique name made from a limited set of ASCII characters.
  5880   <p>On various platforms, different names are used to search for a font. For
  5881    example, with the Windows GDI CreateIndirectFont API, either a family or
  5882    fullname can be used to lookup a face, while on Mac OS X the
  5883    CTFontCreateWithName API call is used to lookup a given face using the
  5884    fullname and Postscript name. Under Linux, the fontconfig API allows fonts
  5885    to be searched using any of these names. In situations where platform
  5886    API's automatically substitute other font choices, it may be necessary to
  5887    verify a returned font matches a given name.
  5889   <p>The weight of a given face can be determined via the usWeightClass field
  5890    of the OS/2 table or inferred from the style name (name ID 2). Likewise,
  5891    the width can be determined via the usWidthClass of the OS/2 table or
  5892    inferred from the style name. For historical reasons related to synthetic
  5893    bolding at weights 200 or lower with the Windows GDI API, font designers
  5894    have sometimes skewed values in the OS/2 table to avoid these weights.
  5896   <p>Rendering complex scripts that use contextual shaping such as Thai,
  5897    Arabic and Devanagari requires features present only in OpenType or AAT
  5898    fonts. Currently, complex script rendering is supported on Windows and
  5899    Linux using OpenType font features while both OpenType and AAT font
  5900    features are used under Mac OS X.
  5902   <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
  5904   <h3 class=no-num id=recent-changes> Changes from the <a
  5905    href="http://www.w3.org/TR/2013/WD-css-fonts-3-20130711/">July 2013 CSS3
  5906    Fonts Last Call Working Draft</a></h3>
  5908   <p>Major changes include:
  5910   <ul>
  5911    <li>reorder feature precedence such that features implied by other CSS
  5912     properties override ‘<code class=property>font-variant</code>’
  5913     settings
  5914   </ul>
  5916   <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
  5918   <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
  5919    their help and feedback. John Hudson was kind enough to take the time to
  5920    explain the subtleties of OpenType language tags and provided the example
  5921    of character variant usage for displaying text on Byzantine seals. Ken
  5922    Lunde and Eric Muller provided valuable feedback on CJK OpenType features
  5923    and Unicode variation selectors. The idea for supporting font features by
  5924    using <a href="#propdef-font-variant"
  5925    title="font-variant!!property">‘<code
  5926    class=property>font-variant</code>’</a> subproperties originated with
  5927    Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
  5928    of the initial design ideas for the <a
  5929    href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
  5930    rule. Thanks also to House Industries for allowing the use of Ed Interlock
  5931    in the discretionary ligatures example.
  5933   <p>A special thanks to Robert Bringhurst for the sublime mind expansion
  5934    that is <em>The Elements of Typographic Style</em>.
  5936   <h2 class=no-num id=conformance> Conformance</h2>
  5938   <h3 class=no-num id=conventions> Document Conventions</h3>
  5940   <p>Conformance requirements are expressed with a combination of descriptive
  5941    assertions and RFC 2119 terminology. The key words “MUST”, “MUST
  5942    NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
  5943    “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
  5944    normative parts of this document are to be interpreted as described in RFC
  5945    2119. However, for readability, these words do not appear in all uppercase
  5946    letters in this specification.
  5948   <p>All of the text of this specification is normative except sections
  5949    explicitly marked as non-normative, examples, and notes. <a
  5950    href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
  5952   <p>Examples in this specification are introduced with the words “for
  5953    example” or are set apart from the normative text with
  5954    <code>class="example"</code>, like this:
  5956   <div class=example>
  5957    <p>This is an example of an informative example.
  5958   </div>
  5960   <p>Informative notes begin with the word “Note” and are set apart from
  5961    the normative text with <code>class="note"</code>, like this:
  5963   <p class=note>Note, this is an informative note.
  5965   <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
  5967   <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
  5968    classes:
  5970   <dl>
  5971    <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
  5972     sheet</dfn>
  5974    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
  5975     style sheet</a>.
  5977    <dt><dfn id=renderer>renderer</dfn>
  5979    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
  5980     that interprets the semantics of a style sheet and renders documents that
  5981     use them.
  5983    <dt><dfn id=authoring-tool>authoring tool</dfn>
  5985    <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
  5986     that writes a style sheet.
  5987   </dl>
  5989   <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
  5990    declarations that use properties defined in this module have values that
  5991    are valid according to the generic CSS grammar and the individual grammars
  5992    of each property as given in this module.
  5994   <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
  5995    interpreting the style sheet as defined by the appropriate specifications,
  5996    it supports all the features defined by CSS Fonts Level 3 Module by
  5997    parsing them correctly and rendering the document accordingly. However,
  5998    the inability of a UA to correctly render a document due to limitations of
  5999    the device does not make the UA non-conformant. (For example, a UA is not
  6000    required to render color on a monochrome monitor.)
  6002   <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
  6003    style sheets that are syntactically correct according to the generic CSS
  6004    grammar and the individual grammars of each feature in this module, and
  6005    meet all other conformance requirements of style sheets as described in
  6006    this module.
  6008   <h3 class=no-num id=partial> Partial Implementations</h3>
  6010   <p>So that authors can exploit the forward-compatible parsing rules to
  6011    assign fallback values, CSS renderers <strong>must</strong> treat as
  6012    invalid (and <a
  6013    href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
  6014    appropriate</a>) any at-rules, properties, property values, keywords, and
  6015    other syntactic constructs for which they have no usable level of support.
  6016    In particular, user agents <strong>must not</strong> selectively ignore
  6017    unsupported component values and honor supported values in a single
  6018    multi-value property declaration: if any value is considered invalid (as
  6019    unsupported values must be), CSS requires that the entire declaration be
  6020    ignored.
  6022   <h3 class=no-num id=experimental> Experimental Implementations</h3>
  6024   <p>To avoid clashes with future CSS features, the CSS2.1 specification
  6025    reserves a <a
  6026    href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
  6027    syntax</a> for proprietary and experimental extensions to CSS.
  6029   <p>Prior to a specification reaching the Candidate Recommendation stage in
  6030    the W3C process, all implementations of a CSS feature are considered
  6031    experimental. The CSS Working Group recommends that implementations use a
  6032    vendor-prefixed syntax for such features, including those in W3C Working
  6033    Drafts. This avoids incompatibilities with future changes in the draft.
  6035   <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
  6037   <p>Once a specification reaches the Candidate Recommendation stage,
  6038    non-experimental implementations are possible, and implementors should
  6039    release an unprefixed implementation of any CR-level feature they can
  6040    demonstrate to be correctly implemented according to spec.
  6042   <p>To establish and maintain the interoperability of CSS across
  6043    implementations, the CSS Working Group requests that non-experimental CSS
  6044    renderers submit an implementation report (and, if necessary, the
  6045    testcases used for that implementation report) to the W3C before releasing
  6046    an unprefixed implementation of any CSS features. Testcases submitted to
  6047    W3C are subject to review and correction by the CSS Working Group.
  6049   <p>Further information on submitting testcases and implementation reports
  6050    can be found from on the CSS Working Group's website at <a
  6051    href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
  6052    Questions should be directed to the <a
  6053    href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
  6054    mailing list.
  6056   <h2 class=no-num id=references>References</h2>
  6058   <h3 class=no-num id=normative-references>Normative References</h3>
  6059   <!--begin-normative-->
  6060   <!-- Sorted by label -->
  6062   <dl class=bibliography>
  6063    <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
  6064     <!---->
  6066    <dt id=CHARMOD>[CHARMOD]
  6068    <dd>Martin J. Dürst; et al. <a
  6069     href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
  6070     Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
  6071     2005. W3C Recommendation. URL: <a
  6072     href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
  6073     </dd>
  6074    <!---->
  6076    <dt id=CORS>[CORS]
  6078    <dd>Anne van Kesteren. <a
  6079     href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
  6080     Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
  6081     Recommendation. (Work in progress.) URL: <a
  6082     href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
  6083     </dd>
  6084    <!---->
  6086    <dt id=CSS21>[CSS21]
  6088    <dd>Bert Bos; et al. <a
  6089     href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
  6090     Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
  6091     2011. W3C Recommendation. URL: <a
  6092     href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
  6093     </dd>
  6094    <!---->
  6096    <dt id=CSS3VAL>[CSS3VAL]
  6098    <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
  6099     href="http://www.w3.org/TR/2013/CR-css3-values-20130404/"><cite>CSS
  6100     Values and Units Module Level 3.</cite></a> 4 April 2013. W3C Candidate
  6101     Recommendation. (Work in progress.) URL: <a
  6102     href="http://www.w3.org/TR/2013/CR-css3-values-20130404/">http://www.w3.org/TR/2013/CR-css3-values-20130404/</a>
  6103     </dd>
  6104    <!---->
  6106    <dt id=HTML5>[HTML5]
  6108    <dd>Ian Hickson. <a
  6109     href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
  6110     17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
  6111     <a
  6112     href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
  6113     </dd>
  6114    <!---->
  6116    <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
  6118    <dd><a
  6119     href="http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=52136"><cite>Information
  6120     technology — Coding of audio-visual objects — Part 22: Open Font
  6121     Format.</cite></a> International Organization for Standardization.
  6122     ISO/IEC 14496-22:2009. URL: <a
  6123     href="http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=52136">http://www.iso.org/iso/home/store/catalogue_ics/catalogue_detail_ics.htm?csnumber=52136</a>
  6124     </dd>
  6125    <!---->
  6127    <dt id=OPENTYPE>[OPENTYPE]
  6129    <dd><a
  6130     href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
  6131     specification.</cite></a> Microsoft. URL: <a
  6132     href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
  6133     </dd>
  6134    <!---->
  6136    <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
  6138    <dd><a
  6139     href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
  6140     feature registry.</cite></a> Microsoft. URL: <a
  6141     href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
  6142     </dd>
  6143    <!---->
  6145    <dt id=RFC2119>[RFC2119]
  6147    <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
  6148     words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
  6149     RFC 2119. URL: <a
  6150     href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
  6151     </dd>
  6152    <!---->
  6154    <dt id=UAX15>[UAX15]
  6156    <dd>Mark Davis; Ken Whistler. <a
  6157     href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
  6158     Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
  6159     href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
  6160     </dd>
  6161    <!---->
  6163    <dt id=UAX29>[UAX29]
  6165    <dd>Mark Davis. <a
  6166     href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
  6167     Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
  6168     URL: <a
  6169     href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
  6170     </dd>
  6171    <!---->
  6173    <dt id=UNICODE6>[UNICODE6]
  6175    <dd>The Unicode Consortium. <a
  6176     href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
  6177     Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
  6178     Version 6.2.0 URL: <a
  6179     href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
  6180     </dd>
  6181    <!---->
  6182   </dl>
  6183   <!--end-normative-->
  6184   <!--{{!CSS21}}-->
  6185   <!--{{!CSS3VAL}}-->
  6186   <!--{{!OPENTYPE}}-->
  6187   <!--{{!OPENTYPE-FEATURES}}-->
  6188   <!--{{!OPEN-FONT-FORMAT}}-->
  6189   <!--{{!UNICODE6}}-->
  6190   <!--{{!UAX15}}-->
  6191   <!--{{!UAX29}}-->
  6192   <!--{{!CORS}}-->
  6193   <!--{{!HTML5}}-->
  6194   <!--{{!CHARMOD}}-->
  6196   <h3 class=no-num id=other-references>Other References</h3>
  6197   <!--begin-informative-->
  6198   <!-- Sorted by label -->
  6200   <dl class=bibliography>
  6201    <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
  6202     <!---->
  6204    <dt id=AAT-FEATURES>[AAT-FEATURES]
  6206    <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
  6207     Advanced Typography font feature registry.</cite></a> Apple. URL: <a
  6208     href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
  6209     </dd>
  6210    <!---->
  6212    <dt id=ARABIC-TYPO>[ARABIC-TYPO]
  6214    <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
  6215     Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
  6216    <!---->
  6218    <dt id=CHARMOD-NORM>[CHARMOD-NORM]
  6220    <dd>François Yergeau; et al. <a
  6221     href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
  6222     Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
  6223     W3C Working Draft. (Work in progress.) URL: <a
  6224     href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
  6225     </dd>
  6226    <!---->
  6228    <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
  6230    <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
  6231     O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
  6232    <!---->
  6234    <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
  6236    <dd>L. David Baron. <a
  6237     href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/"><cite>CSS
  6238     Conditional Rules Module Level 3.</cite></a> 4 April 2013. W3C Candidate
  6239     Recommendation. (Work in progress.) URL: <a
  6240     href="http://www.w3.org/TR/2013/CR-css3-conditional-20130404/">http://www.w3.org/TR/2013/CR-css3-conditional-20130404/</a>
  6241     </dd>
  6242    <!---->
  6244    <dt id=CSS3TEXT>[CSS3TEXT]
  6246    <dd>Elika J. Etemad; Koji Ishii. <a
  6247     href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
  6248     Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
  6249     progress.) URL: <a
  6250     href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
  6251     </dd>
  6252    <!---->
  6254    <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
  6256    <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
  6257     and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
  6258     ISBN 0-201-17633-5.</dd>
  6259    <!---->
  6261    <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
  6263    <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
  6264     href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
  6265     Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
  6266     2000. W3C Recommendation. URL: <a
  6267     href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/">http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/</a>
  6268     </dd>
  6269    <!---->
  6271    <dt id=ELEMTYPO>[ELEMTYPO]
  6273    <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
  6274     4.</cite> Hartley &amp; Marks. 2013. ISBN 0-88179-212-8.</dd>
  6275    <!---->
  6277    <dt id=LANGCULTTYPE>[LANGCULTTYPE]
  6279    <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
  6280     ISBN 1-932026-01-0.</dd>
  6281    <!---->
  6283    <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
  6285    <dd><a
  6286     href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
  6287     User Guide.</cite></a> FontShop International. URL: <a
  6288     href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
  6289     </dd>
  6290    <!---->
  6292    <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
  6294    <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
  6295     Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
  6296     href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
  6297    <!---->
  6299    <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
  6301    <dd>John Hudson. <a
  6302     href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
  6303     Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
  6304     href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
  6305     </dd>
  6306    <!---->
  6307   </dl>
  6308   <!--end-informative-->
  6309   <!--{{ARABIC-TYPO}}-->
  6310   <!--{{CJKV-INFO-PROCESSING}}-->
  6311   <!--{{DIGITAL-TYPOGRAPHY}}-->
  6312   <!--{{DOM-LEVEL-2-STYLE}}-->
  6313   <!--{{ELEMTYPO}}-->
  6314   <!--{{LANGCULTTYPE}}-->
  6315   <!--{{OPENTYPE-FONT-GUIDE}}-->
  6316   <!--{{RASTER-TRAGEDY}}-->
  6317   <!--{{WINDOWS-GLYPH-PROC}}-->
  6318   <!--{{CHARMOD-NORM}}-->
  6319   <!--{{AAT-FEATURES}}-->
  6320   <!--{{CSS3-CONDITIONAL}}-->
  6321   <!--{{CSS3TEXT}}-->
  6323   <h2 class=no-num id=index>Index</h2>
  6324   <!--begin-index-->
  6326   <ul class=indexlist>
  6327    <li>100...900 weight values, <a href="#font-weight-numeric-values"
  6328     title="100...900 weight values"><strong>3.2</strong></a>
  6330    <li><var>&lt;absolute-size&gt;</var>, <a href="#absolute-size-value"
  6331     title="&lt;absolute-size&gt;"><strong>3.5</strong></a>
  6333    <li><var>&lt;common-lig-values&gt;</var>, <a href="#common-lig-values"
  6334     title="&lt;common-lig-values&gt;"><strong>6.4</strong></a>
  6336    <li><var>&lt;contextual-alt-values&gt;</var>, <a
  6337     href="#contextual-alt-values"
  6338     title="&lt;contextual-alt-values&gt;"><strong>6.4</strong></a>
  6340    <li><var>&lt;discretionary-lig-values&gt;</var>, <a
  6341     href="#discretionary-lig-values"
  6342     title="&lt;discretionary-lig-values&gt;"><strong>6.4</strong></a>
  6344    <li><var>&lt;east-asian-variant-values&gt;</var>, <a
  6345     href="#east-asian-variant-values"
  6346     title="&lt;east-asian-variant-values&gt;"><strong>6.10</strong></a>
  6348    <li><var>&lt;east-asian-width-values&gt;</var>, <a
  6349     href="#east-asian-width-values"
  6350     title="&lt;east-asian-width-values&gt;"><strong>6.10</strong></a>
  6352    <li><var>&lt;family-name&gt;</var>, <a href="#family-name-value"
  6353     title="&lt;family-name&gt;"><strong>3.1</strong></a>
  6355    <li><var>&lt;feature-tag-value&gt;</var>, <a href="#feature-tag-value"
  6356     title="&lt;feature-tag-value&gt;"><strong>6.12</strong></a>
  6358    <li><var>&lt;font-face-name&gt;</var>, <a href="#font-face-name-value"
  6359     title="&lt;font-face-name&gt;"><strong>4.3</strong></a>
  6361    <li><var>&lt;font-variant-css21&gt;</var>, <a
  6362     href="#font-variant-css21-values"
  6363     title="&lt;font-variant-css21&gt;"><strong>3.7</strong></a>
  6365    <li><var>&lt;generic-family&gt;</var>, <a href="#generic-family-value"
  6366     title="&lt;generic-family&gt;"><strong>3.1</strong></a>
  6368    <li><var>&lt;historical-lig-values&gt;</var>, <a
  6369     href="#historical-lig-values"
  6370     title="&lt;historical-lig-values&gt;"><strong>6.4</strong></a>
  6372    <li><var>&lt;length&gt;</var>, <a href="#length-size-value"
  6373     title="&lt;length&gt;"><strong>3.5</strong></a>
  6375    <li><var>&lt;number&gt;</var>, <a href="#aspect-ratio-value"
  6376     title="&lt;number&gt;"><strong>3.6</strong></a>
  6378    <li><var>&lt;numeric-figure-values&gt;</var>, <a
  6379     href="#numeric-figure-values"
  6380     title="&lt;numeric-figure-values&gt;"><strong>6.7</strong></a>
  6382    <li><var>&lt;numeric-fraction-values&gt;</var>, <a
  6383     href="#numeric-fraction-values"
  6384     title="&lt;numeric-fraction-values&gt;"><strong>6.7</strong></a>
  6386    <li><var>&lt;numeric-spacing-values&gt;</var>, <a
  6387     href="#numeric-spacing-values"
  6388     title="&lt;numeric-spacing-values&gt;"><strong>6.7</strong></a>
  6390    <li><var>&lt;percentage&gt;</var>, <a href="#percentage-size-value"
  6391     title="&lt;percentage&gt;"><strong>3.5</strong></a>
  6393    <li><var>&lt;relative-size&gt;</var>, <a href="#relative-size-value"
  6394     title="&lt;relative-size&gt;"><strong>3.5</strong></a>
  6396    <li><var>&lt;string&gt;</var>, <a
  6397     href="#font-language-override-string-value"
  6398     title="&lt;string&gt;"><strong>6.13</strong></a>
  6400    <li><var>&lt;urange&gt;</var>, <a href="#urange-value"
  6401     title="&lt;urange&gt;"><strong>4.5</strong></a>
  6403    <li><code>@font-face</code>, <a href="#at-font-face-rule"
  6404     title="@font-face"><strong>4.1</strong></a>
  6406    <li><code>@font-feature-values</code>, <a
  6407     href="#at-font-feature-values-rule"
  6408     title="@font-feature-values"><strong>6.9</strong></a>
  6410    <li>all-petite-caps, <a href="#all-petite-caps"
  6411     title=all-petite-caps><strong>6.6</strong></a>
  6413    <li>all-small-caps, <a href="#all-small-caps"
  6414     title=all-small-caps><strong>6.6</strong></a>
  6416    <li>annotation, <a href="#annotation"
  6417     title=annotation><strong>6.8</strong></a>
  6419    <li>aspect value, <a href="#aspect-value0" title="aspect
  6420     value"><strong>3.6</strong></a>
  6422    <li>authoring tool, <a href="#authoring-tool" title="authoring
  6423     tool"><strong>#</strong></a>
  6425    <li>auto
  6426     <ul>
  6427      <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
  6428       font-kerning"><strong>6.3</strong></a>
  6430      <li>font-size-adjust, <a href="#font-size-adjust-auto-value"
  6431       title="auto, font-size-adjust"><strong>3.6</strong></a>
  6432     </ul>
  6434    <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
  6436    <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
  6438    <li>character map, <a href="#character-map" title="character
  6439     map"><strong>5.2</strong></a>
  6441    <li>character-variant, <a href="#character-variant"
  6442     title=character-variant><strong>6.8</strong></a>
  6444    <li>common-ligatures, <a href="#common-ligatures"
  6445     title=common-ligatures><strong>6.4</strong></a>
  6447    <li>composite face, <a href="#composite-face" title="composite
  6448     face"><strong>5.2</strong></a>
  6450    <li>condensed, <a href="#condensed"
  6451     title=condensed><strong>3.3</strong></a>
  6453    <li>contextual, <a href="#contextual"
  6454     title=contextual><strong>6.4</strong></a>
  6456    <li>CSSFontFaceRule, <a href="#cssfontfacerule"
  6457     title=CSSFontFaceRule><strong>8.1</strong></a>
  6459    <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
  6460     title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
  6462    <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
  6463     of"><strong>#</strong></a>
  6465    <li>default face, <a href="#default-face" title="default
  6466     face"><strong>5.2</strong></a>
  6468    <li>descriptor_declaration, <a href="#descriptordeclaration"
  6469     title="descriptor_declaration"><strong>4.1</strong></a>
  6471    <li>diagonal-fractions, <a href="#diagonal-fractions"
  6472     title=diagonal-fractions><strong>6.7</strong></a>
  6474    <li>discretionary-ligatures, <a href="#discretionary-ligatures"
  6475     title=discretionary-ligatures><strong>6.4</strong></a>
  6477    <li>effective character map, <a href="#effective-character-map"
  6478     title="effective character map"><strong>4.5</strong></a>
  6480    <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
  6482    <li>extra-condensed, <a href="#extra-condensed"
  6483     title=extra-condensed><strong>3.3</strong></a>
  6485    <li>extra-expanded, <a href="#extra-expanded"
  6486     title=extra-expanded><strong>3.3</strong></a>
  6488    <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
  6489     of"><strong>#</strong></a>
  6491    <li>feature_type, <a href="#featuretype"
  6492     title="feature_type"><strong>6.9.1</strong></a>
  6494    <li>feature_value_block, <a href="#featurevalueblock"
  6495     title="feature_value_block"><strong>6.9.1</strong></a>
  6497    <li>feature_value_definition, <a href="#featurevaluedefinition"
  6498     title="feature_value_definition"><strong>6.9.1</strong></a>
  6500    <li>first available font, <a href="#first-available-font" title="first
  6501     available font"><strong>5.2</strong></a>
  6503    <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
  6505    <li>font specific, <a href="#font-specific" title="font
  6506     specific"><strong>6.8</strong></a>
  6508    <li>font-family
  6509     <ul>
  6510      <li>descriptor, <a href="#descdef-font-family" title="font-family,
  6511       descriptor"><strong>4.2</strong></a>
  6513      <li>property, <a href="#propdef-font-family" title="font-family,
  6514       property"><strong>3.1</strong></a>
  6515     </ul>
  6517    <li>font-feature-settings
  6518     <ul>
  6519      <li>descriptor, <a href="#descdef-font-feature-settings"
  6520       title="font-feature-settings, descriptor"><strong>4.7</strong></a>
  6522      <li>property, <a href="#propdef-font-feature-settings"
  6523       title="font-feature-settings, property"><strong>6.12</strong></a>
  6524     </ul>
  6526    <li>font-kerning, <a href="#propdef-font-kerning"
  6527     title=font-kerning><strong>6.3</strong></a>
  6529    <li>font-language-override, <a href="#propdef-font-language-override"
  6530     title=font-language-override><strong>6.13</strong></a>
  6532    <li>font-size, <a href="#propdef-font-size"
  6533     title=font-size><strong>3.5</strong></a>
  6535    <li>font-size-adjust, <a href="#propdef-font-size-adjust"
  6536     title=font-size-adjust><strong>3.6</strong></a>
  6538    <li>font-stretch
  6539     <ul>
  6540      <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
  6541       descriptor"><strong>4.4</strong></a>
  6543      <li>property, <a href="#propdef-font-stretch" title="font-stretch,
  6544       property"><strong>3.3</strong></a>
  6545     </ul>
  6547    <li>font-style
  6548     <ul>
  6549      <li>descriptor, <a href="#descdef-font-style" title="font-style,
  6550       descriptor"><strong>4.4</strong></a>
  6552      <li>property, <a href="#propdef-font-style" title="font-style,
  6553       property"><strong>3.4</strong></a>
  6554     </ul>
  6556    <li>font-synthesis, <a href="#propdef-font-synthesis"
  6557     title=font-synthesis><strong>3.8</strong></a>
  6559    <li>font-variant
  6560     <ul>
  6561      <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
  6562       descriptor"><strong>4.7</strong></a>
  6564      <li>property, <a href="#propdef-font-variant" title="font-variant,
  6565       property"><strong>6.11</strong></a>
  6566     </ul>
  6568    <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
  6569     title=font-variant-alternates><strong>6.8</strong></a>
  6571    <li>font-variant-caps, <a href="#propdef-font-variant-caps"
  6572     title=font-variant-caps><strong>6.6</strong></a>
  6574    <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
  6575     title=font-variant-east-asian><strong>6.10</strong></a>
  6577    <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
  6578     title=font-variant-ligatures><strong>6.4</strong></a>
  6580    <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
  6581     title=font-variant-numeric><strong>6.7</strong></a>
  6583    <li>font-variant-position, <a href="#propdef-font-variant-position"
  6584     title=font-variant-position><strong>6.5</strong></a>
  6586    <li>font-weight
  6587     <ul>
  6588      <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
  6589       descriptor"><strong>4.4</strong></a>
  6591      <li>property, <a href="#propdef-font-weight" title="font-weight,
  6592       property"><strong>3.2</strong></a>
  6593     </ul>
  6595    <li>font_face_rule, <a href="#fontfacerule"
  6596     title="font_face_rule"><strong>4.1</strong></a>
  6598    <li>FONT_FACE_SYM, <a href="#fontfacesym"
  6599     title="FONT_FACE_SYM"><strong>4.1</strong></a>
  6601    <li>font_family_name, <a href="#fontfamilyname"
  6602     title="font_family_name"><strong>6.9.1</strong></a>
  6604    <li>font_family_name_list, <a href="#fontfamilynamelist"
  6605     title="font_family_name_list"><strong>6.9.1</strong></a>
  6607    <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
  6608     title="font_feature_values_rule"><strong>6.9.1</strong></a>
  6610    <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
  6611     title="FONT_FEATURE_VALUES_SYM"><strong>6.9.1</strong></a>
  6613    <li>full-width, <a href="#full-width"
  6614     title=full-width><strong>6.10</strong></a>
  6616    <li>historical-forms, <a href="#historical-forms"
  6617     title=historical-forms><strong>6.8</strong></a>
  6619    <li>historical-ligatures, <a href="#historical-ligatures"
  6620     title=historical-ligatures><strong>6.4</strong></a>
  6622    <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
  6624    <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
  6626    <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
  6628    <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
  6630    <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
  6632    <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
  6634    <li>lining-nums, <a href="#lining-nums"
  6635     title=lining-nums><strong>6.7</strong></a>
  6637    <li>monospace, definition of, <a href="#monospace0" title="monospace,
  6638     definition of"><strong>#</strong></a>
  6640    <li>no-common-ligatures, <a href="#no-common-ligatures"
  6641     title=no-common-ligatures><strong>6.4</strong></a>
  6643    <li>no-contextual, <a href="#no-contextual"
  6644     title=no-contextual><strong>6.4</strong></a>
  6646    <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
  6647     title=no-discretionary-ligatures><strong>6.4</strong></a>
  6649    <li>no-historical-ligatures, <a href="#no-historical-ligatures"
  6650     title=no-historical-ligatures><strong>6.4</strong></a>
  6652    <li>none
  6653     <ul>
  6654      <li>font-kerning, <a href="#font-kerning-none-value" title="none,
  6655       font-kerning"><strong>6.3</strong></a>
  6657      <li>font-size-adjust, <a href="#font-size-adjust-none-value"
  6658       title="none, font-size-adjust"><strong>3.6</strong></a>
  6660      <li>font-variant, <a href="#font-variant-none-value" title="none,
  6661       font-variant"><strong>6.11</strong></a>
  6663      <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
  6664       title="none, font-variant-ligatures"><strong>6.4</strong></a>
  6665     </ul>
  6667    <li>normal
  6668     <ul>
  6669      <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
  6670       title="normal, font-feature-settings"><strong>6.12</strong></a>
  6672      <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
  6673       font-kerning"><strong>6.3</strong></a>
  6675      <li>font-language-override, <a
  6676       href="#font-language-override-normal-value" title="normal,
  6677       font-language-override"><strong>6.13</strong></a>
  6679      <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
  6680       font-stretch"><strong>3.3</strong></a>
  6682      <li>font-style, <a href="#font-style-normal-value" title="normal,
  6683       font-style"><strong>3.4</strong></a>
  6685      <li>font-variant, <a href="#font-variant-normal-value" title="normal,
  6686       font-variant"><strong>6.11</strong></a>
  6688      <li>font-variant-alternates, <a
  6689       href="#font-variant-alternates-normal-value" title="normal,
  6690       font-variant-alternates"><strong>6.8</strong></a>
  6692      <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
  6693       title="normal, font-variant-caps"><strong>6.6</strong></a>
  6695      <li>font-variant-east-asian, <a
  6696       href="#font-variant-east-asian-normal-value" title="normal,
  6697       font-variant-east-asian"><strong>6.10</strong></a>
  6699      <li>font-variant-ligatures, <a
  6700       href="#font-variant-ligatures-normal-value" title="normal,
  6701       font-variant-ligatures"><strong>6.4</strong></a>
  6703      <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
  6704       title="normal, font-variant-numeric"><strong>6.7</strong></a>
  6706      <li>font-variant-position, <a href="#font-variant-position-normal-value"
  6707       title="normal, font-variant-position"><strong>6.5</strong></a>
  6709      <li>font-weight, <a href="#font-weight-normal-value" title="normal,
  6710       font-weight"><strong>3.2</strong></a>
  6711     </ul>
  6713    <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
  6715    <li>oldstyle-nums, <a href="#oldstyle-nums"
  6716     title=oldstyle-nums><strong>6.7</strong></a>
  6718    <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
  6720    <li>ornaments, <a href="#ornaments"
  6721     title=ornaments><strong>6.8</strong></a>
  6723    <li>petite-caps, <a href="#petite-caps"
  6724     title=petite-caps><strong>6.6</strong></a>
  6726    <li>proportional-nums, <a href="#proportional-nums"
  6727     title=proportional-nums><strong>6.7</strong></a>
  6729    <li>proportional-width, <a href="#proportional-width"
  6730     title=proportional-width><strong>6.10</strong></a>
  6732    <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
  6734    <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
  6736    <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
  6737     definition of"><strong>#</strong></a>
  6739    <li>semi-condensed, <a href="#semi-condensed-"
  6740     title=semi-condensed><strong>3.3</strong></a>
  6742    <li>semi-expanded, <a href="#semi-expanded"
  6743     title=semi-expanded><strong>3.3</strong></a>
  6745    <li>serif, definition of, <a href="#serif0" title="serif, definition
  6746     of"><strong>#</strong></a>
  6748    <li>simplified, <a href="#simplified"
  6749     title=simplified><strong>6.10</strong></a>
  6751    <li>slashed-zero, <a href="#slashed-zero"
  6752     title=slashed-zero><strong>6.7</strong></a>
  6754    <li>small-caps, <a href="#small-caps"
  6755     title=small-caps><strong>6.6</strong></a>
  6757    <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
  6759    <li>stacked-fractions, <a href="#stacked-fractions"
  6760     title=stacked-fractions><strong>6.7</strong></a>
  6762    <li>style sheet
  6763     <ul>
  6764      <li>as conformance class, <a href="#style-sheet" title="style sheet, as
  6765       conformance class"><strong>#</strong></a>
  6766     </ul>
  6768    <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
  6770    <li>stylistic, <a href="#stylistic"
  6771     title=stylistic><strong>6.8</strong></a>
  6773    <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
  6775    <li>super, <a href="#super" title=super><strong>6.5</strong></a>
  6777    <li>support, <a href="#support" title=support><strong>5.2</strong></a>
  6779    <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
  6781    <li>system font fallback, <a href="#system-font-fallback" title="system
  6782     font fallback"><strong>5.2</strong></a>
  6784    <li>tabular-nums, <a href="#tabular-nums"
  6785     title=tabular-nums><strong>6.7</strong></a>
  6787    <li>titling-caps, <a href="#titling-caps"
  6788     title=titling-caps><strong>6.6</strong></a>
  6790    <li>traditional, <a href="#traditional"
  6791     title=traditional><strong>6.10</strong></a>
  6793    <li>ultra-condensed, <a href="#ultra-condensed"
  6794     title=ultra-condensed><strong>3.3</strong></a>
  6796    <li>ultra-expanded, <a href="#ultra-expanded"
  6797     title=ultra-expanded><strong>3.3</strong></a>
  6799    <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
  6801    <li>unicode-range, <a href="#descdef-unicode-range"
  6802     title=unicode-range><strong>4.5</strong></a>
  6804    <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
  6806    <li>width, <a href="#width" title=width><strong>2</strong></a>
  6807   </ul>
  6808   <!--end-index-->
  6810   <h2 class=no-num id=property-index>Property index</h2>
  6811   <!--begin-properties-->
  6813   <table class=proptable>
  6814    <thead>
  6815     <tr>
  6816      <th>Property
  6818      <th>Values
  6820      <th>Initial
  6822      <th>Applies to
  6824      <th>Inh.
  6826      <th>Percentages
  6828      <th>Media
  6830    <tbody>
  6831     <tr>
  6832      <th><a class=property href="#propdef-font">font</a>
  6834      <td>[ [ &lt;‘font-style’&gt; || &lt;font-variant-css21&gt; ||
  6835       &lt;‘font-weight’&gt; || &lt;‘font-stretch’ ]?
  6836       &lt;‘font-size’&gt; [ / &lt;‘line-height’&gt; ]?
  6837       &lt;‘font-family’&gt; ] | caption | icon | menu | message-box |
  6838       small-caption | status-bar
  6840      <td>see individual properties
  6842      <td>all elements
  6844      <td>yes
  6846      <td>see individual properties
  6848      <td>visual
  6850     <tr>
  6851      <th><span class=property>font-family</span>
  6853      <td>[ &lt;family-name&gt; | &lt;generic-family&gt; ] #
  6855      <td>depends on user agent
  6857      <td>all elements
  6859      <td>yes
  6861      <td>N/A
  6863      <td>visual
  6865     <tr>
  6866      <th><span class=property>font-feature-settings</span>
  6868      <td>normal | &lt;feature-tag-value&gt; #
  6870      <td>normal
  6872      <td>all elements
  6874      <td>yes
  6876      <td>N/A
  6878      <td>visual
  6880     <tr>
  6881      <th><a class=property href="#propdef-font-kerning">font-kerning</a>
  6883      <td>auto | normal | none
  6885      <td>auto
  6887      <td>all elements
  6889      <td>yes
  6891      <td>N/A
  6893      <td>visual
  6895     <tr>
  6896      <th><a class=property
  6897       href="#propdef-font-language-override">font-language-override</a>
  6899      <td>normal | &lt;string&gt;
  6901      <td>normal
  6903      <td>all elements
  6905      <td>yes
  6907      <td>N/A
  6909      <td>visual
  6911     <tr>
  6912      <th><a class=property href="#propdef-font-size">font-size</a>
  6914      <td>&lt;absolute-size&gt; | &lt;relative-size&gt; | &lt;length&gt; |
  6915       &lt;percentage&gt;
  6917      <td>medium
  6919      <td>all elements
  6921      <td>yes
  6923      <td>refer to parent element's font size
  6925      <td>visual
  6927     <tr>
  6928      <th><a class=property
  6929       href="#propdef-font-size-adjust">font-size-adjust</a>
  6931      <td>none | auto | &lt;number&gt;
  6933      <td>none
  6935      <td>all elements
  6937      <td>yes
  6939      <td>N/A
  6941      <td>visual
  6943     <tr>
  6944      <th><span class=property>font-stretch</span>
  6946      <td>normal | ultra-condensed | extra-condensed | condensed |
  6947       semi-condensed | semi-expanded | expanded | extra-expanded |
  6948       ultra-expanded
  6950      <td>normal
  6952      <td>all elements
  6954      <td>yes
  6956      <td>N/A
  6958      <td>visual
  6960     <tr>
  6961      <th><span class=property>font-style</span>
  6963      <td>normal | italic | oblique
  6965      <td>normal
  6967      <td>all elements
  6969      <td>yes
  6971      <td>N/A
  6973      <td>visual
  6975     <tr>
  6976      <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
  6978      <td>none | [ weight || style ]
  6980      <td>weight style
  6982      <td>all elements
  6984      <td>yes
  6986      <td>N/A
  6988      <td>visual
  6990     <tr>
  6991      <th><span class=property>font-variant</span>
  6993      <td>normal | none | [ &lt;common-lig-values&gt; ||
  6994       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  6995       &lt;contextual-alt-values&gt; || stylistic(&lt;feature-value-name&gt;)
  6996       || historical-forms || styleset(&lt;feature-value-name&gt; #) ||
  6997       character-variant(&lt;feature-value-name&gt; #) ||
  6998       swash(&lt;feature-value-name&gt;) ||
  6999       ornaments(&lt;feature-value-name&gt;) ||
  7000       annotation(&lt;feature-value-name&gt;) || [ small-caps | all-small-caps
  7001       | petite-caps | all-petite-caps | unicase | titling-caps ] ||
  7002       &lt;numeric-figure-values&gt; || &lt;numeric-spacing-values&gt; ||
  7003       &lt;numeric-fraction-values&gt; || ordinal || slashed-zero ||
  7004       &lt;east-asian-variant-values&gt; || &lt;east-asian-width-values&gt; ||
  7005       ruby ]
  7007      <td>normal
  7009      <td>all elements
  7011      <td>yes
  7013      <td>see individual properties
  7015      <td>visual
  7017     <tr>
  7018      <th><a class=property
  7019       href="#propdef-font-variant-alternates">font-variant-alternates</a>
  7021      <td>normal | [ stylistic(&lt;feature-value-name&gt;) || historical-forms
  7022       || styleset(&lt;feature-value-name&gt; #) ||
  7023       character-variant(&lt;feature-value-name&gt; #) ||
  7024       swash(&lt;feature-value-name&gt;) ||
  7025       ornaments(&lt;feature-value-name&gt;) ||
  7026       annotation(&lt;feature-value-name&gt;) ]
  7028      <td>normal
  7030      <td>all elements
  7032      <td>yes
  7034      <td>N/A
  7036      <td>visual
  7038     <tr>
  7039      <th><a class=property
  7040       href="#propdef-font-variant-caps">font-variant-caps</a>
  7042      <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
  7043       | unicase | titling-caps
  7045      <td>normal
  7047      <td>all elements
  7049      <td>yes
  7051      <td>N/A
  7053      <td>visual
  7055     <tr>
  7056      <th><a class=property
  7057       href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
  7059      <td>normal | [ &lt;east-asian-variant-values&gt; ||
  7060       &lt;east-asian-width-values&gt; || ruby ]
  7062      <td>normal
  7064      <td>all elements
  7066      <td>yes
  7068      <td>N/A
  7070      <td>visual
  7072     <tr>
  7073      <th><a class=property
  7074       href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
  7076      <td>normal | none | [ &lt;common-lig-values&gt; ||
  7077       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  7078       &lt;contextual-alt-values&gt; ]
  7080      <td>normal
  7082      <td>all elements
  7084      <td>yes
  7086      <td>N/A
  7088      <td>visual
  7090     <tr>
  7091      <th><a class=property
  7092       href="#propdef-font-variant-numeric">font-variant-numeric</a>
  7094      <td>normal | [ &lt;numeric-figure-values&gt; ||
  7095       &lt;numeric-spacing-values&gt; || &lt;numeric-fraction-values&gt; ||
  7096       ordinal || slashed-zero ]
  7098      <td>normal
  7100      <td>all elements
  7102      <td>yes
  7104      <td>N/A
  7106      <td>visual
  7108     <tr>
  7109      <th><a class=property
  7110       href="#propdef-font-variant-position">font-variant-position</a>
  7112      <td>normal | sub | super
  7114      <td>normal
  7116      <td>all elements
  7118      <td>yes
  7120      <td>N/A
  7122      <td>visual
  7124     <tr>
  7125      <th><span class=property>font-weight</span>
  7127      <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
  7128       | 700 | 800 | 900
  7130      <td>normal
  7132      <td>all elements
  7134      <td>yes
  7136      <td>N/A
  7138      <td>visual
  7139   </table>
  7140   <!--end-properties-->
  7141   <!--begin-descriptors-->
  7143   <table class=proptable>
  7144    <thead>
  7145     <tr>
  7146      <th>Descriptor
  7148      <th>Value
  7150      <th>Initial
  7152      <th>Percentages
  7154      <th>Media
  7156    <tbody>
  7157     <tr>
  7158      <th><span class=property>font-family</span>
  7160      <td>&lt;family-name&gt;
  7162      <td>N/A
  7164     <tr>
  7165      <th><span class=property>font-feature-settings</span>
  7167      <td>normal | &lt;feature-tag-value&gt; #
  7169      <td>normal
  7171     <tr>
  7172      <th><span class=property>font-stretch</span>
  7174      <td>normal | ultra-condensed | extra-condensed | condensed |
  7175       semi-condensed | semi-expanded | expanded | extra-expanded |
  7176       ultra-expanded
  7178      <td>normal
  7180     <tr>
  7181      <th><span class=property>font-style</span>
  7183      <td>normal | italic | oblique
  7185      <td>normal
  7187     <tr>
  7188      <th><span class=property>font-variant</span>
  7190      <td>normal | none | [ &lt;common-lig-values&gt; ||
  7191       &lt;discretionary-lig-values&gt; || &lt;historical-lig-values&gt; ||
  7192       &lt;contextual-alt-values&gt; || stylistic(&lt;feature-value-name&gt;)
  7193       || historical-forms || styleset(&lt;feature-value-name&gt; #) ||
  7194       character-variant(&lt;feature-value-name&gt; #) ||
  7195       swash(&lt;feature-value-name&gt;) ||
  7196       ornaments(&lt;feature-value-name&gt;) ||
  7197       annotation(&lt;feature-value-name&gt;) || [ small-caps | all-small-caps
  7198       | petite-caps | all-petite-caps | unicase | titling-caps ] ||
  7199       &lt;numeric-figure-values&gt; || &lt;numeric-spacing-values&gt; ||
  7200       &lt;numeric-fraction-values&gt; || ordinal || slashed-zero ||
  7201       &lt;east-asian-variant-values&gt; || &lt;east-asian-width-values&gt; ||
  7202       ruby ]
  7204      <td>normal
  7206     <tr>
  7207      <th><span class=property>font-weight</span>
  7209      <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
  7211      <td>normal
  7213     <tr>
  7214      <th><a class=property href="#descdef-src">src</a>
  7216      <td>[ &lt;url> [format(&lt;string> #)]? | &lt;font-face-name&gt; ] #
  7218      <td>N/A
  7220     <tr>
  7221      <th><a class=property href="#descdef-unicode-range">unicode-range</a>
  7223      <td>&lt;urange&gt; #
  7225      <td>U+0-10FFFF
  7226   </table>
  7227   <!--end-descriptors-->
  7228   <script type="text/javascript">
  7229 window.onload = function () {
  7230   if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
  7231   var i, hiresElements = document.getElementsByClassName("hires");
  7232   for (i = 0; i < hiresElements.length; i++) {
  7233     var h = hiresElements[i];
  7234     if (h.tagName != "IMG") continue;
  7235     var src = h.getAttribute("src");
  7236     var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
  7237     h.src = src2x;
  7240 </script>
  7241 </html>
  7242 <!-- Keep this comment at the end of the file
  7243 Local variables:
  7244 mode: sgml
  7245 sgml-declaration:"~/SGML/HTML4.decl"
  7246 sgml-default-doctype-name:"html"
  7247 sgml-minimize-attributes:t
  7248 sgml-nofill-elements:("pre" "style" "br")
  7249 sgml-live-element-indicator:t
  7250 sgml-omittag:nil
  7251 sgml-shorttag:nil
  7252 sgml-namecase-general:t
  7253 sgml-general-insert-case:lower
  7254 sgml-always-quote-attributes:t
  7255 sgml-indent-step:nil
  7256 sgml-indent-data:t
  7257 sgml-parent-document:nil
  7258 sgml-exposed-tags:nil
  7259 sgml-local-catalogs:nil
  7260 sgml-local-ecat-files:nil
  7261 End:
  7262 -->
  7263 <!--
  7265 to do:
  7267 - wording of OpenType family name handling
  7268 - handling combining sequences in the font matching algorithm
  7269 - fix-up fi ligature example
  7271 -->

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