Fri, 07 Jun 2013 00:17:45 -0700
add test annotations to css-fonts-3
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-7-june-2013>Editor's Draft 7
119 June 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-css3-fonts-20130607/">http://www.w3.org/TR/2013/ED-css3-fonts-20130607/</a> -->
129 <dt>Latest version:
131 <dd><a
132 href="http://www.w3.org/TR/css3-fonts/">http://www.w3.org/TR/css3-fonts/</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-css3-fonts-20130212/">http://www.w3.org/TR/2013/WD-css3-fonts-20130212/</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&product=CSS&component=Fonts&bug_status=NEW&bug_status=ASSIGNED&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
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180 href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
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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/css3-font-load-events/">CSS3 Font
199 Load 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-->
236 <!--
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:</p>
241 <ul>
242 </ul>
243 -->
245 <h2 class="no-num no-toc" id=contents>Table of contents</h2>
246 <!--begin-toc-->
248 <ul class=toc>
249 <li><a href="#introduction"><span class=secno>1 </span>Introduction</a>
251 <li><a href="#typography-background"><span class=secno>2 </span>Typography
252 Background</a>
254 <li><a href="#basic-font-props"><span class=secno>3 </span>Basic Font
255 Properties</a>
256 <ul class=toc>
257 <li><a href="#font-family-prop"><span class=secno>3.1 </span>Font
258 family: the font-family property</a>
259 <ul class=toc>
260 <li><a href="#generic-font-families"><span class=secno>3.1.1
261 </span>Generic font families</a>
262 </ul>
264 <li><a href="#font-weight-prop"><span class=secno>3.2 </span>Font
265 weight: the font-weight property</a>
267 <li><a href="#font-stretch-prop"><span class=secno>3.3 </span>Font
268 width: the font-stretch property</a>
270 <li><a href="#font-style-prop"><span class=secno>3.4 </span>Font style:
271 the font-style property</a>
273 <li><a href="#font-size-prop"><span class=secno>3.5 </span>Font size:
274 the font-size property</a>
276 <li><a href="#font-size-adjust-prop"><span class=secno>3.6
277 </span>Relative sizing: the font-size-adjust property</a>
279 <li><a href="#font-prop"><span class=secno>3.7 </span>Shorthand font
280 property: the font property</a>
282 <li><a href="#font-synthesis-prop"><span class=secno>3.8
283 </span>Controlling synthetic faces: the font-synthesis property</a>
284 </ul>
286 <li><a href="#font-resources"><span class=secno>4 </span>Font
287 Resources</a>
288 <ul class=toc>
289 <li><a href="#font-face-rule"><span class=secno>4.1 </span>The
290 <code>@font-face</code> rule</a>
292 <li><a href="#font-family-desc"><span class=secno>4.2 </span>Font
293 family: the font-family descriptor</a>
295 <li><a href="#src-desc"><span class=secno>4.3 </span>Font reference: the
296 src descriptor</a>
298 <li><a href="#font-prop-desc"><span class=secno>4.4 </span>Font property
299 descriptors: the font-style, font-weight, font-stretch descriptors</a>
301 <li><a href="#unicode-range-desc"><span class=secno>4.5 </span>Character
302 range: the unicode-range descriptor</a>
304 <li><a href="#composite-fonts"><span class=secno>4.6 </span>Using
305 character ranges to define composite fonts</a>
307 <li><a href="#font-rend-desc"><span class=secno>4.7 </span>Font
308 features: the font-variant and font-feature-settings descriptors</a>
310 <li><a href="#font-face-loading"><span class=secno>4.8 </span>Font
311 loading guidelines</a>
313 <li><a href="#same-origin-restriction"><span class=secno>4.9
314 </span>Same-origin restriction for fonts</a>
315 <ul class=toc>
316 <li><a href="#default-same-origin-restriction"><span class=secno>4.9.1
317 </span>Default same-origin restriction</a>
319 <li><a href="#allowing-cross-origin-font-loading"><span
320 class=secno>4.9.2 </span>Allowing cross-origin font loading</a>
321 </ul>
322 </ul>
324 <li><a href="#font-matching-algorithm"><span class=secno>5 </span>Font
325 Matching Algorithm</a>
326 <ul class=toc>
327 <li><a href="#font-family-casing"><span class=secno>5.1 </span>Case
328 sensitivity of font family names</a>
330 <li><a href="#font-style-matching"><span class=secno>5.2 </span>Matching
331 font styles</a>
333 <li><a href="#cluster-matching"><span class=secno>5.3 </span>Cluster
334 matching</a>
336 <li><a href="#char-handling-issues"><span class=secno>5.4
337 </span>Character handling issues</a>
339 <li><a href="#font-matching-changes"><span class=secno>5.5 </span>Font
340 matching changes since CSS 2.1</a>
342 <li><a href="#font-matching-examples"><span class=secno>5.6 </span>Font
343 matching examples</a>
344 </ul>
346 <li><a href="#font-rend-props"><span class=secno>6 </span>Font Feature
347 Properties</a>
348 <ul class=toc>
349 <li><a href="#glyph-selection-positioning"><span class=secno>6.1
350 </span>Glyph selection and positioning</a>
352 <li><a href="#language-specific-support"><span class=secno>6.2
353 </span>Language-specific display</a>
355 <li><a href="#font-kerning-prop"><span class=secno>6.3 </span>Kerning:
356 the font-kerning property</a>
358 <li><a href="#font-variant-ligatures-prop"><span class=secno>6.4
359 </span>Ligatures: the font-variant-ligatures property</a>
361 <li><a href="#font-variant-position-prop"><span class=secno>6.5
362 </span>Subscript and superscript forms: the font-variant-position
363 property</a>
365 <li><a href="#font-variant-caps-prop"><span class=secno>6.6
366 </span>Capitalization: the font-variant-caps property</a>
368 <li><a href="#font-variant-numeric-prop"><span class=secno>6.7
369 </span>Numerical formatting: the font-variant-numeric property</a>
371 <li><a href="#font-variant-alternates-prop"><span class=secno>6.8
372 </span>Alternates and swashes: the font-variant-alternates property</a>
375 <li><a href="#font-feature-values"><span class=secno>6.9 </span>Defining
376 font specific alternates: the <code>@font-feature-values</code>
377 rule</a>
378 <ul class=toc>
379 <li><a href="#basic-syntax"><span class=secno>6.9.1 </span>Basic
380 syntax</a>
382 <li><a href="#multi-valued-feature-value-definitions"><span
383 class=secno>6.9.2 </span>Multi-valued feature value definitions</a>
384 </ul>
386 <li><a href="#font-variant-east-asian-prop"><span class=secno>6.10
387 </span>East Asian text rendering: the font-variant-east-asian
388 property</a>
390 <li><a href="#font-variant-prop"><span class=secno>6.11 </span>Overall
391 shorthand for font rendering: the font-variant property</a>
393 <li><a href="#font-feature-settings-prop"><span class=secno>6.12
394 </span>Low-level font feature settings control: the
395 font-feature-settings property</a>
397 <li><a href="#font-language-override-prop"><span class=secno>6.13
398 </span>Font language override: the font-language-override property</a>
399 </ul>
401 <li><a href="#font-feature-resolution"><span class=secno>7 </span>Font
402 Feature Resolution </a>
403 <ul class=toc>
404 <li><a href="#default-features"><span class=secno>7.1 </span>Default
405 features</a>
407 <li><a href="#feature-precedence"><span class=secno>7.2 </span>Feature
408 precedence</a>
410 <li><a href="#feature-precedence-examples"><span class=secno>7.3
411 </span>Feature precedence examples</a>
412 </ul>
414 <li><a href="#object-model"><span class=secno>8 </span>Object Model</a>
415 <ul class=toc>
416 <li><a href="#om-fontface"><span class=secno>8.1 </span>The
417 <code>CSSFontFaceRule</code> interface</a>
419 <li><a href="#om-fontfeaturevalues"><span class=secno>8.2 </span>The
420 <code>CSSFontFeatureValuesRule</code> interface</a>
421 </ul>
423 <li class=no-num><a href="#platform-props-to-css">Appendix A: Mapping
424 platform font properties to CSS properties</a>
426 <li class=no-num><a href="#ch-ch-ch-changes">Changes</a>
427 <ul class=toc>
428 <li class=no-num><a href="#recent-changes"> Changes from the February
429 2013 CSS3 Fonts Working Draft</a>
430 </ul>
432 <li class=no-num><a href="#acknowledgments">Acknowledgments</a>
434 <li class=no-num><a href="#conformance"> Conformance</a>
435 <ul class=toc>
436 <li class=no-num><a href="#conventions"> Document Conventions</a>
438 <li class=no-num><a href="#conformance-classes"> Conformance Classes</a>
441 <li class=no-num><a href="#partial"> Partial Implementations</a>
443 <li class=no-num><a href="#experimental"> Experimental
444 Implementations</a>
446 <li class=no-num><a href="#testing"> Non-Experimental
447 Implementations</a>
448 </ul>
450 <li class=no-num><a href="#references">References</a>
451 <ul class=toc>
452 <li class=no-num><a href="#normative-references">Normative
453 References</a>
455 <li class=no-num><a href="#other-references">Other References</a>
456 </ul>
458 <li class=no-num><a href="#index">Index</a>
460 <li class=no-num><a href="#property-index">Property index</a>
461 </ul>
462 <!--end-toc-->
464 <h2 id=introduction><span class=secno>1 </span>Introduction</h2>
466 <p>A font provides a resource containing the visual representation of
467 characters. At the simplest level it contains information that maps
468 character codes to shapes (called glyphs) that represent these characters.
469 Fonts sharing a common design style are commonly grouped into font
470 families classified by a set of standard font properties. Within a family,
471 the shape displayed for a given character can vary by stroke weight, slant
472 or relative width, among others. An individual font face is described by a
473 unique combination of these properties. For a given range of text, CSS
474 font properties are used to select a font family and a specific font face
475 within that family to be used when rendering that text. As a simple
476 example, to use the bold form of Helvetica one could use:
478 <pre>body {
479 font-family: Helvetica;
480 font-weight: bold;
481 }</pre>
483 <p>Font resources may be installed locally on the system on which a user
484 agent is running or downloadable. For local font resources descriptive
485 information can be obtained directly from the font resource. For
486 downloadable font resources (sometimes referred to as web fonts), the
487 descriptive information is included with the reference to the font
488 resource.
490 <p>Families of fonts typically don't contain a single face for each
491 possible variation of font properties. The CSS font selection mechanism
492 describes how to match a given set of CSS font properties to a single font
493 face.
495 <h2 id=typography-background><span class=secno>2 </span>Typography
496 Background</h2>
498 <p><em>This section is non-normative.</em>
500 <p> Typographic traditions vary across the globe, so there is no unique way
501 to classify all fonts across languages and cultures. For even common Latin
502 letters, wide variations are possible:
504 <div class=figure><img alt="variations in glyphs for a single character"
505 src=aaaaaa.png>
506 <p class=caption>One character, many glyph variations
507 </div>
509 <p>Differences in the anatomy of letterforms is one way to distinguish
510 fonts. For Latin fonts, flourishes at the ends of a character's main
511 strokes, or serifs, can distinguish a font from those without. Similar
512 comparisons exist in non-Latin fonts between fonts with tapered strokes
513 and those using primarily uniform strokes:
515 <div class=figure><img alt="serif vs. non-serifs" src=serifvssansserif.png>
516 <p class=caption>Letterforms with and without serifs
517 </div>
519 <div class=figure><img alt="serif vs. non-serifs for japanese"
520 src=minchovsgothic.png>
521 <p class=caption>Similar groupings for Japanese typefaces
522 </div>
524 <p>Fonts contain letterforms and the data needed to map characters to these
525 letterforms. Often this may be a simple one-to-one mapping, but more
526 complex mappings are also possible. The use of combining diacritic marks
527 creates many variations for an underlying letterform:
529 <div class=figure><img alt="diacritic marks" src=aaaaaa-diacritics.png>
530 <p class=caption>Variations with diacritic marks
531 </div>
533 <p>A sequence of characters can be represented by a single glyph known as a
534 ligature:
536 <div class=figure><img alt="example of a fi ligature"
537 src=final-ligature.png>
538 <p class=caption>Ligature example
539 </div>
541 <p>Visual transformations based on textual context are often stylistic
542 option in European languages. They are required to correctly render
543 languages like Arabic, the lam and alef characters below <em>must</em> be
544 combined when they exist in sequence:
546 <div class=figure><img alt="lam alef ligature" src=lamaleflig.png>
547 <p class=caption>Required Arabic ligature
548 </div>
550 <p>The relative complexity of these shaping transformations requires
551 additional data within the font.
553 <p>Sets of font faces with various stylistic variations are often grouped
554 together into font families. In the simplest case a regular face is
555 supplemented with bold and italic faces, but much more extensive groupings
556 are possible. Variations in the thickness of letterform strokes, the <dfn
557 id=weight>weight</dfn>, and the overall proportions of the letterform, the
558 <dfn id=width>width</dfn>, are most common. In the example below, each
559 letter uses a different font face within the Univers font family. The
560 width used increases from top to bottom and the weight increases from left
561 to right:
563 <div class=figure><img alt="various width and weight variations within a
564 single family" src=weightwidthvariations.png>
565 <p class=caption>Weight and width variations within a single font family
566 </div>
568 <p>Creating fonts that support multiple scripts is a difficult task;
569 designers need to understand the cultural traditions surrounding the use
570 of type in different scripts and come up with letterforms that somehow
571 share a common theme. Many languages often share a common script and each
572 of these languages may have noticeable stylistic differences. For example,
573 the Arabic script is shared by Persian and Urdu and Cyrillic is used with
574 many languages, not just Russian.
576 <p>The <a href="#character-map"><em>character map</em></a> of a font
577 defines the mapping of characters to glyphs for that font. If a document
578 contains characters not supported by the <a href="#character-map"><em
579 title="character map">character maps</em></a> of the fonts contained in a
580 font family list, a user agent may use a <a
581 href="#system-font-fallback"><em>system font fallback</em></a> procedure
582 to locate an appropriate font that does. If no appropriate font can be
583 found, some form of "missing glyph" character will be rendered by the user
584 agent. System fallback can occur when the specified list of font families
585 does not include a font that supports a given character.
587 <p>Although the <a href="#character-map"><em>character map</em></a> of a
588 font maps a given character to a glyph for that character, modern font
589 technologies such as OpenType and AAT (Apple Advanced Typography) provide
590 ways of mapping a character to different glyphs based upon feature
591 settings. Fonts in these formats allow these features to be embedded in
592 the font itself and controlled by applications. Common typographic
593 features which can be specified this way include ligatures, swashes,
594 contextual alternates, proportional and tabular figures, and automatic
595 fractions, to list just a few. For a visual overview of OpenType features,
596 see the <a href="#OPENTYPE-FONT-GUIDE"
597 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
599 <h2 id=basic-font-props><span class=secno>3 </span>Basic Font Properties</h2>
601 <p>The particular font face used to render a character is determined by the
602 font family and other font properties that apply to a given element. This
603 structure allows settings to be varied independent of each other.</p>
604 <!-- prop: font-family -->
606 <h3 id=font-family-prop><span class=secno>3.1 </span>Font family: the <a
607 href="#propdef-font-family">font-family</a> property</h3>
609 <table class=propdef id=namefont-familyvalue-ltfamily-namegt-ltg>
610 <tbody>
611 <tr>
612 <td>Name:
614 <td><dfn id=propdef-font-family
615 title="font-family!!property">font-family</dfn>
617 <tr>
618 <td>Value:
620 <td>[ <a href="#family-name-value"><var><family-name></var></a> |
621 <a href="#generic-family-value"><var><generic-family></var></a> ]
622 #
624 <tr>
625 <td>Initial:
627 <td>depends on user agent
629 <tr>
630 <td>Applies to:
632 <td>all elements
634 <tr>
635 <td>Inherited:
637 <td>yes
639 <tr>
640 <td>Percentages:
642 <td>N/A
644 <tr>
645 <td>Media:
647 <td>visual
649 <tr>
650 <td>Computed value:
652 <td>as specified
654 <tr>
655 <td>Animatable:
657 <td>no
658 </table>
660 <p>This property specifies a prioritized list of font family names or
661 generic family names. A font family defines a set of faces that vary in
662 weight, width or slope. CSS uses the combination of a family name with
663 other style attributes to select an individual face. Using this selection
664 mechanism, rather than selecting a face via the style name as is often
665 done in design applications, allows some degree of regularity in textual
666 display when fallback occurs.
668 <p class=note>Designers should note that the CSS definition of font
669 attributes used for selection are explicitly not intended to define a font
670 taxonomy. A type designer's idea of a family may often extend to a set of
671 faces that vary along axes other than just the standard axes of weight,
672 width and slope. A family may extend to include both a set of serif faces
673 and a set of sans-serif faces or vary along axes that are unique to that
674 family. The CSS font selection mechanism merely provides a way to
675 determine the “closest” substitute when substitution is necessary.
677 <p>Unlike other CSS properties, component values are a comma-separated list
678 indicating alternatives. A user agent iterates through the list of family
679 names until it matches an available font that contains a glyph for the
680 character to be rendered. This allows for differences in available fonts
681 across platforms and for differences in the range of characters supported
682 by individual fonts.
684 <p>A font family name only specifies a name given to a set of font faces,
685 it does not specify an individual face. For example, given the
686 availability of the fonts below, Futura would match but Futura Medium
687 would not:
689 <div class=figure><img alt="family and face names"
690 src=familyvsfacename.png>
691 <p class=caption>Family and individual face names
692 </div>
694 <p>Consider the example below:
696 <div class=example>
697 <pre>body {
698 font-family: Helvetica, Verdana, sans-serif;
699 }</pre>
701 <p>If Helvetica is available it will be used when rendering. If neither
702 Helvetica nor Verdana is present, then the user-agent-defined sans serif
703 font will be used.</p>
704 </div>
706 <p>There are two types of font family names:
708 <dl>
709 <dt><dfn id=family-name-value><var><family-name></var></dfn>
711 <dd>The name of a font family of choice such as Helvetica or Verdana in
712 the previous example.
714 <dt><dfn id=generic-family-value><var><generic-family></var></dfn>
716 <dd> The following generic family keywords are defined: ‘<a
717 href="#serif"><code class=property>serif</code></a>’, ‘<a
718 href="#sans-serif"><code class=property>sans-serif</code></a>’, ‘<a
719 href="#cursive"><code class=property>cursive</code></a>’, ‘<a
720 href="#fantasy"><code class=property>fantasy</code></a>’, and ‘<a
721 href="#monospace"><code class=property>monospace</code></a>’. These
722 keywords can be used as a general fallback mechanism when an author's
723 desired font choices are not available. As keywords, they must not be
724 quoted. Authors are encouraged to append a generic font family as a last
725 alternative for improved robustness.
726 </dl>
728 <p>Font family names other than generic families must either be given
729 quoted as <a
730 href="//www.w3.org/TR/CSS21/syndata.html#strings">strings,</a> or unquoted
731 as a sequence of one or more <a
732 href="//www.w3.org/TR/CSS21/syndata.html#value-def-identifier">identifiers.</a>
733 This means most punctuation characters and digits at the start of each
734 token must be escaped in unquoted font family names.
736 <p>To illustrate this, the following declarations are invalid:
738 <pre>
739 font-family: Red/Black, sans-serif;
740 font-family: "Lucida" Grande, sans-serif;
741 font-family: Ahem!, sans-serif;
742 font-family: test@foo, sans-serif;
743 font-family: #POUND, sans-serif;
744 font-family: Hawaii 5-0, sans-serif;
745 </pre>
747 <p>If a sequence of identifiers is given as a font family name, the
748 computed value is the name converted to a string by joining all the
749 identifiers in the sequence by single spaces.
751 <p>To avoid mistakes in escaping, it is recommended to quote font family
752 names that contain white space, digits, or punctuation characters other
753 than hyphens:
755 <pre>
756 body { font-family: "New Century Schoolbook", serif }
758 <BODY STYLE="font-family: '21st Century', fantasy">
759 </pre>
761 <p>Font family <em>names</em> that happen to be the same as a keyword value
762 (‘<code class=property>inherit</code>’, ‘<a href="#serif"><code
763 class=property>serif</code></a>’, ‘<a href="#sans-serif"><code
764 class=property>sans-serif</code></a>’, ‘<a href="#monospace"><code
765 class=property>monospace</code></a>’, ‘<a href="#fantasy"><code
766 class=property>fantasy</code></a>’, and ‘<a href="#cursive"><code
767 class=property>cursive</code></a>’) must be quoted to prevent confusion
768 with the keywords with the same names. The keywords ‘<code
769 class=property>initial</code>’ and ‘<code
770 class=property>default</code>’ are reserved for future use and must also
771 be quoted when used as font names. UAs must not consider these keywords as
772 matching the <a
773 href="#family-name-value"><var><family-name></var></a> type.
775 <p>The precise way a set of fonts are grouped into font families varies
776 depending upon the platform font management API's. The Windows GDI API
777 only allows four faces to be grouped into a family while the DirectWrite
778 API and API's on OSX and other platforms support font families with a
779 variety of weights, widths and slopes (see <a
780 href="#platform-props-to-css">Appendix A</a> for more details).
782 <p>Some font formats allow fonts to carry multiple localizations of the
783 family name. User agents must recognize and correctly match all of these
784 names independent of the underlying platform localization, system API used
785 or document encoding:
787 <div class=figure><img alt="examples of localized family names"
788 src=localizedfamilynames.png>
789 <p class=caption>Localized family names
790 </div>
792 <h4 id=generic-font-families><span class=secno>3.1.1 </span>Generic font
793 families</h4>
795 <p>All five generic font families are defined to exist in all CSS
796 implementations (they need not necessarily map to five distinct actual
797 fonts). User agents should provide reasonable default choices for the
798 generic font families, which express the characteristics of each family as
799 well as possible within the limits allowed by the underlying technology.
800 User agents are encouraged to allow users to select alternative choices
801 for the generic fonts.
803 <h5 class="no-num no-toc"> <span class=index-def id=serif0 title="serif,
804 definition of"><a name=serif-def><dfn id=serif>serif</dfn></a></span></h5>
806 <p>Serif fonts represent the formal text style for a script. This often
807 means but is not limited to glyphs that have finishing strokes, flared or
808 tapering ends, or have actual serifed endings (including slab serifs).
809 Serif fonts are typically proportionately-spaced. They often display a
810 greater variation between thick and thin strokes than fonts from the ‘<a
811 href="#sans-serif"><code class=property>sans-serif</code></a>’ generic
812 font family. CSS uses the term ‘<a href="#serif"><code
813 class=property>serif</code></a>’ to apply to a font for any script,
814 although other names may be more familiar for particular scripts, such as
815 Mincho (Japanese), Sung, Song or Kai (Chinese), Batang (Korean). For
816 Arabic, the Naskh style would correspond to ‘<a href="#serif"><code
817 class=property>serif</code></a>’ more due to its typographic role rather
818 than its actual design style. Any font that is so described may be used to
819 represent the generic ‘<a href="#serif"><code
820 class=property>serif</code></a>’ family.
822 <div class=figure><img alt="sample serif fonts" src=serifexamples.png>
823 <p class=caption>Sample serif fonts
824 </div>
826 <h5 class="no-num no-toc"> <span class=index-def id=sans-serif0
827 title="sans-serif, definition of"> <a name=sans-serif-def><dfn
828 id=sans-serif>sans-serif</dfn></a></span></h5>
830 <p>Glyphs in sans-serif fonts, as the term is used in CSS, are generally
831 low contrast (vertical and horizontal stems have the close to the same
832 thickness) and have stroke endings that are plain -- without any flaring,
833 cross stroke, or other ornamentation. Sans-serif fonts are typically
834 proportionately-spaced. They often have little variation between thick and
835 thin strokes, compared to fonts from the ‘<a href="#serif"><code
836 class=property>serif</code></a>’ family. CSS uses the term ‘<a
837 href="#sans-serif"><code class=property>sans-serif</code></a>’ to apply
838 to a font for any script, although other names may be more familiar for
839 particular scripts, such as Gothic (Japanese), Hei (Chinese), or Gulim
840 (Korean). Any font that is so described may be used to represent the
841 generic ‘<a href="#sans-serif"><code
842 class=property>sans-serif</code></a>’ family.
844 <div class=figure><img alt="sample sans-serif fonts"
845 src=sansserifexamples.png>
846 <p class=caption>Sample sans-serif fonts
847 </div>
849 <h5 class="no-num no-toc"> <span class=index-def id=cursive0
850 title="cursive, definition of"> <a name=cursive-def><dfn
851 id=cursive>cursive</dfn></a></span></h5>
853 <p>Glyphs in cursive fonts generally use a more informal script style, and
854 the result looks more like handwritten pen or brush writing than printed
855 letterwork. CSS uses the term ‘<a href="#cursive"><code
856 class=property>cursive</code></a>’ to apply to a font for any script,
857 although other names such as Chancery, Brush, Swing and Script are also
858 used in font names.
860 <div class=figure><img alt="sample cursive fonts" src=cursiveexamples.png>
861 <p class=caption>Sample cursive fonts
862 </div>
864 <h5 class="no-num no-toc"> <span class=index-def id=fantasy0
865 title="fantasy, definition of"> <a name=fantasy-def><dfn
866 id=fantasy>fantasy</dfn></a></span></h5>
868 <p>Fantasy fonts are primarily decorative or expressive fonts that contain
869 playful representations of characters. These do not include Pi or Picture
870 fonts which do not represent actual characters.
872 <div class=figure><img alt="sample fantasy fonts" src=fantasyexamples.png>
873 <p class=caption>Sample fantasy fonts
874 </div>
876 <h5 class="no-num no-toc"> <span class=index-def id=monospace0
877 title="monospace, definition of"> <a name=monospace-def><dfn
878 id=monospace>monospace</dfn></a></span></h5>
880 <p>The sole criterion of a monospace font is that all glyphs have the same
881 fixed width. This is often used to render samples of computer code.
883 <div class=figure><img alt="sample monospace fonts"
884 src=monospaceexamples.png>
885 <p class=caption>Sample monospace fonts
886 </div>
887 <!-- prop: font-weight -->
889 <h3 id=font-weight-prop><span class=secno>3.2 </span>Font weight: the <a
890 href="#propdef-font-weight">font-weight</a> property</h3>
892 <table class=propdef id=namefont-weightvaluenormal-bold-bolder-l>
893 <tbody>
894 <tr>
895 <td>Name:
897 <td><dfn id=propdef-font-weight
898 title="font-weight!!property">font-weight</dfn>
900 <tr>
901 <td>Value:
903 <td><a href="#font-weight-normal-value"
904 title="normal!!font-weight">normal</a> | <a href="#bold">bold</a> | <a
905 href="#bolder">bolder</a> | <a href="#lighter">lighter</a> | <a
906 href="#font-weight-numeric-values" title="100...900 weight
907 values">100</a> | <a href="#font-weight-numeric-values"
908 title="100...900 weight values">200</a> | <a
909 href="#font-weight-numeric-values" title="100...900 weight
910 values">300</a> | <a href="#font-weight-numeric-values"
911 title="100...900 weight values">400</a> | <a
912 href="#font-weight-numeric-values" title="100...900 weight
913 values">500</a> | <a href="#font-weight-numeric-values"
914 title="100...900 weight values">600</a> | <a
915 href="#font-weight-numeric-values" title="100...900 weight
916 values">700</a> | <a href="#font-weight-numeric-values"
917 title="100...900 weight values">800</a> | <a
918 href="#font-weight-numeric-values" title="100...900 weight
919 values">900</a>
921 <tr>
922 <td>Initial:
924 <td>normal
926 <tr>
927 <td>Applies to:
929 <td>all elements
931 <tr>
932 <td>Inherited:
934 <td>yes
936 <tr>
937 <td>Percentages:
939 <td>N/A
941 <tr>
942 <td>Media:
944 <td>visual
946 <tr>
947 <td>Computed value:
949 <td>numeric weight value (see description)
951 <tr>
952 <td>Animatable:
954 <td>as <a
955 href="http://dev.w3.org/csswg/css3-transitions/#animtype-font-weight">font
956 weight</a>
957 </table>
959 <p>The <a href="#propdef-font-weight"
960 title="font-weight!!property">‘<code
961 class=property>font-weight</code>’</a> property specifies the weight of
962 glyphs in the font, their degree of blackness or stroke thickness.
964 <p>Values have the following meanings:
966 <dl>
967 <dt><dfn id=font-weight-numeric-values title="100...900 weight values">100
968 to 900</dfn>
970 <dd>These values form an ordered sequence, where each number indicates a
971 weight that is at least as dark as its predecessor. These roughly
972 correspond to the commonly used weight names below:
973 </dl>
975 <ul>
976 <li>100 - Thin
978 <li>200 - Extra Light (Ultra Light)
980 <li>300 - Light
982 <li>400 - Normal
984 <li>500 - Medium
986 <li>600 - Semi Bold (Demi Bold)
988 <li>700 - Bold
990 <li>800 - Extra Bold (Ultra Bold)
992 <li>900 - Black (Heavy)
993 </ul>
995 <dl>
996 <dt><dfn id=font-weight-normal-value
997 title="normal!!font-weight">normal</dfn>
999 <dd>Same as ‘<code class=css>400</code>’.
1001 <dt><dfn id=bold>bold</dfn>
1003 <dd>Same as ‘<code class=css>700</code>’.
1005 <dt><dfn id=bolder>bolder</dfn>
1007 <dd>Specifies a bolder weight than the inherited value.
1009 <dt><dfn id=lighter>lighter</dfn>
1011 <dd>Specifies a lighter weight than the inherited value.
1012 </dl>
1014 <p>Font formats that use a scale other than a nine-step scale should map
1015 their scale onto the CSS scale so that 400 roughly corresponds with a face
1016 that would be labeled as Regular, Book, Roman and 700 roughly matches a
1017 face that would be labeled as Bold. Or weights may be inferred from the
1018 style names, ones that correspond roughly with the scale above. The scale
1019 is relative, so a face with a larger weight value must never appear
1020 lighter. If style names are used to infer weights, care should be taken to
1021 handle variations in style names across locales.
1023 <p>Quite often there are only a few weights available for a particular font
1024 family. When a weight is specified for which no face exists, a face with a
1025 nearby weight is used. In general, bold weights map to faces with heavier
1026 weights and light weights map to faces with lighter weights (see the <a
1027 href="#font-matching-algorithm">font matching section below</a> for a
1028 precise definition). The examples here illustrate which face is used for
1029 different weights, grey indicates a face for that weight does not exist so
1030 a face with a nearby weight is used:
1032 <div class=figure><img alt="weight mappings for a family with 400, 700 and
1033 900 weights" src=optimaweights.png>
1034 <p class=caption>Weight mappings for a font family with 400, 700 and 900
1035 weight faces
1036 </div>
1038 <div class=figure><img alt="weight mappings for a family with 300, 600
1039 weights" src=hiraginoweights.png>
1040 <p class=caption>Weight mappings for a font family with 300 and 600 weight
1041 faces
1042 </div>
1044 <p>Although the practice is not well-loved by typographers, bold faces are
1045 often synthesized by user agents for faces that lack actual bold faces.
1046 For the purposes of style matching, these faces must be treated as if they
1047 exist within the family. Authors can explicitly avoid this behavior by
1048 using the ‘<a href="#propdef-font-synthesis"><code
1049 class=property>font-synthesis</code></a>’ property.
1051 <p>Specified values of ‘<a href="#bolder"><code
1052 class=property>bolder</code></a>’ and ‘<a href="#lighter"><code
1053 class=property>lighter</code></a>’ indicate weights relative to the
1054 weight of the parent element. The computed weight is calculated based on
1055 the inherited <a href="#propdef-font-weight"
1056 title="font-weight!!property">‘<code
1057 class=property>font-weight</code>’</a> value using the chart below.
1059 <table class=data id=bolderlighter summary="Bolder/lighter mappings">
1060 <thead>
1061 <tr>
1062 <th>Inherited value
1064 <th>bolder
1066 <th>lighter
1068 <tbody>
1069 <tr>
1070 <th>100
1072 <td>400
1074 <td>100
1076 <tr>
1077 <th>200
1079 <td>400
1081 <td>100
1083 <tr>
1084 <th>300
1086 <td>400
1088 <td>100
1090 <tr>
1091 <th>400
1093 <td>700
1095 <td>100
1097 <tr>
1098 <th>500
1100 <td>700
1102 <td>100
1104 <tr>
1105 <th>600
1107 <td>900
1109 <td>400
1111 <tr>
1112 <th>700
1114 <td>900
1116 <td>400
1118 <tr>
1119 <th>800
1121 <td>900
1123 <td>700
1125 <tr>
1126 <th>900
1128 <td>900
1130 <td>700
1131 </table>
1133 <p>The table above is equivalent to selecting the next relative bolder or
1134 lighter face, given a font family containing normal and bold faces along
1135 with a thin and a heavy face. Authors who desire finer control over the
1136 exact weight values used for a given element may use numerical values
1137 instead of relative weights.</p>
1138 <!-- prop: font-stretch -->
1140 <h3 id=font-stretch-prop><span class=secno>3.3 </span>Font width: the <a
1141 href="#propdef-font-stretch">font-stretch</a> property</h3>
1143 <table class=propdef id=namefont-stretchvalue-normal-ultra-conde>
1144 <tbody>
1145 <tr>
1146 <td>Name:
1148 <td><dfn id=propdef-font-stretch
1149 title="font-stretch!!property">font-stretch</dfn>
1151 <tr>
1152 <td>Value:
1154 <td> <a href="#font-stretch-normal-value"
1155 title="normal!!font-stretch">normal</a> | <a
1156 href="#ultra-condensed">ultra-condensed</a> | <a
1157 href="#extra-condensed">extra-condensed</a> | <a
1158 href="#condensed">condensed</a> | <a
1159 href="#semi-condensed-">semi-condensed</a> | <a
1160 href="#semi-expanded">semi-expanded</a> | <a
1161 href="#expanded">expanded</a> | <a
1162 href="#extra-expanded">extra-expanded</a> | <a
1163 href="#ultra-expanded">ultra-expanded</a>
1165 <tr>
1166 <td>Initial:
1168 <td>normal
1170 <tr>
1171 <td>Applies to:
1173 <td>all elements
1175 <tr>
1176 <td>Inherited:
1178 <td>yes
1180 <tr>
1181 <td>Percentages:
1183 <td>N/A
1185 <tr>
1186 <td>Media:
1188 <td>visual
1190 <tr>
1191 <td>Computed value:
1193 <td>as specified
1195 <tr>
1196 <td>Animatable:
1198 <td>as <a href="#font-stretch-animation">font stretch</a>
1199 </table>
1201 <p>The <a href="#propdef-font-stretch"
1202 title="font-stretch!!property">‘<code
1203 class=property>font-stretch</code>’</a> property selects a normal,
1204 condensed, or expanded face from a font family. Absolute keyword values
1205 have the following ordering, from narrowest to widest:
1207 <ul>
1208 <li><dfn id=ultra-condensed>ultra-condensed</dfn>
1210 <li><dfn id=extra-condensed>extra-condensed</dfn>
1212 <li><dfn id=condensed>condensed</dfn>
1214 <li><dfn id=semi-condensed->semi-condensed </dfn>
1216 <li><dfn id=font-stretch-normal-value
1217 title="normal!!font-stretch">normal</dfn>
1219 <li><dfn id=semi-expanded>semi-expanded</dfn>
1221 <li><dfn id=expanded>expanded</dfn>
1223 <li><dfn id=extra-expanded>extra-expanded</dfn>
1225 <li><dfn id=ultra-expanded>ultra-expanded</dfn>
1226 </ul>
1228 <p>When a face does not exist for a given width, normal or condensed values
1229 map to a narrower face, otherwise a wider face. Conversely, expanded
1230 values map to a wider face, otherwise a narrower face. The figure below
1231 shows how the nine font-stretch property settings affect font selection
1232 for font family containing a variety of widths, grey indicates a width for
1233 which no face exists and a different width is substituted:
1235 <div class=figure><img alt="width mappings for a family with condensed,
1236 normal and expanded faces" src=universwidths.png>
1237 <p class=caption>Width mappings for a font family with condensed, normal
1238 and expanded width faces
1239 </div>
1241 <p id=font-stretch-animation>Animation of font stretch: Font stretch is
1242 interpolated in discrete steps. The interpolation happens as though the
1243 ordered values are equally spaced real numbers. The interpolation result
1244 is rounded to the nearest value, with values exactly halfway between two
1245 values rounded towards the later value in the list above.</p>
1246 <!-- prop: font-style -->
1248 <h3 id=font-style-prop><span class=secno>3.4 </span>Font style: the <a
1249 href="#propdef-font-style">font-style</a> property</h3>
1251 <table class=propdef id=namefont-stylevaluenormal-italic-oblique>
1252 <tbody>
1253 <tr>
1254 <td>Name:
1256 <td><dfn id=propdef-font-style
1257 title="font-style!!property">font-style</dfn>
1259 <tr>
1260 <td>Value:
1262 <td><a href="#font-style-normal-value"
1263 title="normal!!font-style">normal</a> | <a href="#italic">italic</a> |
1264 <a href="#oblique">oblique</a>
1266 <tr>
1267 <td>Initial:
1269 <td>normal
1271 <tr>
1272 <td>Applies to:
1274 <td>all elements
1276 <tr>
1277 <td>Inherited:
1279 <td>yes
1281 <tr>
1282 <td>Percentages:
1284 <td>N/A
1286 <tr>
1287 <td>Media:
1289 <td>visual
1291 <tr>
1292 <td>Computed value:
1294 <td>as specified
1296 <tr>
1297 <td>Animatable:
1299 <td>no
1300 </table>
1302 <p>The <a href="#propdef-font-style" title="font-style!!property">‘<code
1303 class=property>font-style</code>’</a> property allows italic or oblique
1304 faces to be selected. Italic forms are generally cursive in nature while
1305 oblique faces are typically sloped versions of the regular face. Oblique
1306 faces can be simulated by artificially sloping the glyphs of the regular
1307 face. Compare the artificially sloped renderings of Palatino ‘<code
1308 class=property>a</code>’ and Baskerville ‘<code
1309 class=property>N</code>’ in grey with the actual italic versions:
1311 <div class=figure><img alt="artificial sloping vs. real italics"
1312 src=realvsfakeitalics.png>
1313 <p class=caption>Artificial sloping versus real italics
1314 </div>
1316 <p>Values have the following meanings:
1318 <dl>
1319 <dt><dfn id=font-style-normal-value
1320 title="normal!!font-style">normal</dfn>
1322 <dd>selects a face that is classified as a normal face, one that is
1323 neither italic or obliqued
1325 <dt><dfn id=italic>italic</dfn>
1327 <dd>selects a font that is labeled as an italic face, or an oblique face
1328 if one is not
1330 <dt><dfn id=oblique>oblique</dfn>
1332 <dd>selects a font that is labeled as an oblique face, or an italic face
1333 if one is not
1334 </dl>
1336 <p>If no italic or oblique face is available, oblique faces can be
1337 synthesized by rendering non-obliqued faces with an artificial obliquing
1338 operation. The use of these artificially obliqued faces can be disabled
1339 using the ‘<a href="#propdef-font-synthesis"><code
1340 class=property>font-synthesis</code></a>’ property. The details of the
1341 obliquing operation are not explicitly defined.</p>
1342 <!-- resolution on the "undefined" nature of synthetics: http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
1344 <p>Many scripts lack the tradition of mixing a cursive form within text
1345 rendered with a normal face. Chinese, Japanese and Korean fonts almost
1346 always lack italic or oblique faces. Fonts that support a mixture of
1347 scripts will sometimes omit specific scripts such as Arabic from the set
1348 of glyphs supported in the italic face. User agents should be careful
1349 about making <a href="#character-map"><em>character map</em></a>
1350 assumptions across faces when implementing support for <a
1351 href="#system-font-fallback"><em>system font fallback</em></a>.</p>
1352 <!-- prop: font-size -->
1354 <h3 id=font-size-prop><span class=secno>3.5 </span>Font size: the <a
1355 href="#propdef-font-size">font-size</a> property</h3>
1357 <table class=propdef id=namefont-sizevalueltabsolute-sizegt-ltre>
1358 <tbody>
1359 <tr>
1360 <td>Name:
1362 <td><dfn id=propdef-font-size>font-size</dfn>
1364 <tr>
1365 <td>Value:
1367 <td><a href="#absolute-size-value"><var><absolute-size></var></a>
1368 | <a href="#relative-size-value"><var><relative-size></var></a> |
1369 <a href="#length-size-value"><var><length></var></a> | <a
1370 href="#percentage-size-value"><var><percentage></var></a>
1372 <tr>
1373 <td>Initial:
1375 <td>medium
1377 <tr>
1378 <td>Applies to:
1380 <td>all elements
1382 <tr>
1383 <td>Inherited:
1385 <td>yes
1387 <tr>
1388 <td>Percentages:
1390 <td>refer to parent element's font size
1392 <tr>
1393 <td>Media:
1395 <td>visual
1397 <tr>
1398 <td>Computed value:
1400 <td>absolute length
1402 <tr>
1403 <td>Animatable:
1405 <td>as <a
1406 href="http://dev.w3.org/csswg/css3-transitions/#animtype-length">length</a>
1407 </table>
1409 <p>This property indicates the desired height of glyphs from the font. For
1410 scalable fonts, the font-size is a scale factor applied to the EM unit of
1411 the font. (Note that certain glyphs may bleed outside their EM box.) For
1412 non-scalable fonts, the font-size is converted into absolute units and
1413 matched against the declared font-size of the font, using the same
1414 absolute coordinate space for both of the matched values. Values have the
1415 following meanings:
1417 <dl>
1418 <dt><dfn id=absolute-size-value><var><absolute-size></var></dfn>
1420 <dd> An <a
1421 href="#absolute-size-value"><var><absolute-size></var></a> keyword
1422 refers to an entry in a table of font sizes computed and kept by the user
1423 agent. Possible values are:
1424 <p> [ xx-small | x-small | small | medium | large | x-large | xx-large ]</p>
1426 <dt><dfn id=relative-size-value><var><relative-size></var></dfn>
1428 <dd> A <a href="#relative-size-value"><var><relative-size></var></a>
1429 keyword is interpreted relative to the table of font sizes and the
1430 computed ‘<a href="#propdef-font-size"><code
1431 class=property>font-size</code></a>’ of the parent element. Possible
1432 values are:
1433 <p> [ larger | smaller ]
1435 <p> For example, if the parent element has a font size of ‘<code
1436 class=property>medium</code>’, a value of ‘<code
1437 class=property>larger</code>’ will make the font size of the current
1438 element be ‘<code class=property>large</code>’. If the parent
1439 element's size is not close to a table entry, the user agent is free to
1440 interpolate between table entries or round off to the closest one. The
1441 user agent may have to extrapolate table values if the numerical value
1442 goes beyond the keywords.
1444 <dt><dfn id=length-size-value><var><length></var></dfn>
1446 <dd>A length value specifies an absolute font size (independent of the
1447 user agent's font table). Negative lengths are illegal.
1449 <dt><dfn id=percentage-size-value><var><percentage></var></dfn>
1451 <dd>A percentage value specifies an absolute font size relative to the
1452 parent element's font size. Use of percentage values, or values in
1453 ‘<code class=property>em</code>’s, leads to more robust and
1454 cascadable style sheets.
1455 </dl>
1457 <p>The following table provides user agent guidelines for the absolute-size
1458 scaling factor and their mapping to HTML heading and absolute font-sizes.
1459 The ‘<code class=property>medium</code>’ value is used as the
1460 reference middle value. The user agent may fine-tune these values for
1461 different fonts or different types of display devices.
1463 <table class=data>
1464 <thead>
1465 <tr>
1466 <th>CSS absolute-size values
1468 <th>xx-small
1470 <th>x-small
1472 <th>small
1474 <th>medium
1476 <th>large
1478 <th>x-large
1480 <th>xx-large
1482 <th>
1484 <tbody>
1485 <tr>
1486 <th>scaling factor
1488 <td>3/5
1490 <td>3/4
1492 <td>8/9
1494 <td>1
1496 <td>6/5
1498 <td>3/2
1500 <td>2/1
1502 <td>3/1
1504 <tr>
1505 <th>HTML headings
1507 <td>h6
1509 <td>
1511 <td>h5
1513 <td>h4
1515 <td>h3
1517 <td>h2
1519 <td>h1
1521 <td>
1523 <tr>
1524 <th>HTML font sizes
1526 <td>1
1528 <td>
1530 <td>2
1532 <td>3
1534 <td>4
1536 <td>5
1538 <td>6
1540 <td>7
1541 </table>
1543 <p class=note><em><strong>Note 1.</strong> To preserve readability, an UA
1544 applying these guidelines should nevertheless avoid creating font-size
1545 resulting in less than 9 device pixels per EM unit on a computer
1546 display.</em>
1548 <p class=note><em><strong>Note 2.</strong> In CSS1, the suggested scaling
1549 factor between adjacent indexes was 1.5 which user experience proved to be
1550 too large. In CSS2, the suggested scaling factor for computer screen
1551 between adjacent indexes was 1.2 which still created issues for the small
1552 sizes. The new scaling factor varies between each index to provide a
1553 better readability.</em>
1555 <p>The actual value of this property may differ from the computed value due
1556 a numerical value on ‘<a href="#propdef-font-size-adjust"><code
1557 class=property>font-size-adjust</code></a>’ and the unavailability of
1558 certain font sizes.
1560 <p>Child elements inherit the computed <a class=noxref
1561 href="#font-size-prop"> <span class=property>‘<code
1562 class=property>font-size</code>’</span></a> value (otherwise, the effect
1563 of <a class=noxref href="#font-size-adjust-prop"><span
1564 class=property>‘<code
1565 class=property>font-size-adjust</code>’</span></a> would compound).
1567 <div class=example>
1568 <p style="display:none">Example(s):
1570 <p>
1572 <pre>p { font-size: 12pt; }
1573 blockquote { font-size: larger }
1574 em { font-size: 150% }
1575 em { font-size: 1.5em }
1576 </pre>
1577 </div>
1578 <!-- prop: font-size-adjust -->
1580 <h3 id=font-size-adjust-prop><span class=secno>3.6 </span>Relative sizing:
1581 the <a href="#propdef-font-size-adjust">font-size-adjust</a> property</h3>
1583 <table class=propdef id=namefont-size-adjustvaluenone-auto-ltnum>
1584 <tbody>
1585 <tr>
1586 <td>Name:
1588 <td><dfn id=propdef-font-size-adjust>font-size-adjust</dfn>
1590 <tr>
1591 <td>Value:
1593 <td><a href="#font-size-adjust-none-value"
1594 title="none!!font-size-adjust">none</a> | <a
1595 href="#font-size-adjust-auto-value"
1596 title="auto!!font-size-adjust">auto</a> | <a
1597 href="#aspect-ratio-value"><var><number></var></a>
1599 <tr>
1600 <td>Initial:
1602 <td>none
1604 <tr>
1605 <td>Applies to:
1607 <td>all elements
1609 <tr>
1610 <td>Inherited:
1612 <td>yes
1614 <tr>
1615 <td>Percentages:
1617 <td>N/A
1619 <tr>
1620 <td>Media:
1622 <td>visual
1624 <tr>
1625 <td>Computed value:
1627 <td>as specified
1629 <tr>
1630 <td>Animatable:
1632 <td>as <a
1633 href="http://dev.w3.org/csswg/css3-transitions/#animtype-number">number</a>
1634 </table>
1636 <p>For any given font size, the apparent size and legibility of text varies
1637 across fonts. For scripts such as Latin or Cyrillic that distinguish
1638 between upper and lowercase letters, the relative height of lowercase
1639 letters compared to their uppercase counterparts is a determining factor
1640 of legibility. This is commonly referred to as the <a class=index-def
1641 href="#aspect-value" id=aspect-value0 title="aspect value"><dfn
1642 id=aspect-value>aspect value</dfn></a>. Precisely defined, it is equal to
1643 the x-height of a font divided by the font size.
1645 <p>In situations where font fallback occurs, fallback fonts may not share
1646 the same aspect ratio as the desired font family and will thus appear less
1647 readable. The font-size-adjust property is a way to preserve the
1648 readability of text when font fallback occurs. It does this by adjusting
1649 the font-size so that the x-height is the same regardless of the font
1650 used.
1652 <div class=example>
1653 <p>The style defined below defines Verdana as the desired font family, but
1654 if Verdana is not available Futura or Times will be used.</p>
1656 <pre>p {
1657 font-family: Verdana, Futura, Times;
1658 }
1660 <p>Lorem ipsum dolor sit amet, ...</p>
1661 </pre>
1663 <p>Verdana has a relatively high aspect ratio, lowercase letters are
1664 relatively tall compared to uppercase letters, so at small sizes text
1665 appears legible. Times has a lower aspect ratio and so if fallback
1666 occurs, the text will be less legible at small sizes than Verdana.</p>
1667 </div>
1669 <p>How text rendered in each of these fonts compares is shown below, the
1670 columns show text rendered in Verdana, Futura and Times. The same
1671 font-size value is used across cells within each row and red lines are
1672 included to show the differences in x-height. In the upper half each row
1673 is rendered in the same font-size value. The same is true for the lower
1674 half but in this half the font-size-adjust property is also set so that
1675 the actual font size is adjusted to preserve the x-height across each row.
1676 Note how small text remains relatively legible across each row in the
1677 lower half.
1679 <div class=figure><img alt="text with and without font-size-adjust"
1680 src=fontsizeadjust.png>
1681 <p class=caption>Text with and without the use of font-size-adjust
1682 </div>
1684 <p>This property allows authors to specify an aspect value for an element
1685 that will effectively preserve the x-height of the first choice font,
1686 whether it is substituted or not. Values have the following meanings:
1688 <dl>
1689 <dt><dfn id=font-size-adjust-none-value
1690 title="none!!font-size-adjust">none</dfn>
1692 <dd>Do not preserve the font's x-height.
1694 <dt><dfn id=font-size-adjust-auto-value
1695 title="auto!!font-size-adjust">auto</dfn>
1697 <dd>Behaves just like <number>, except the number used is the aspect
1698 value calculated by user agents for the first font in the list of fonts
1699 defined for the initial value of the <a href="#propdef-font-family"
1700 title="font-family!!property">‘<code
1701 class=property>font-family</code>’</a> property. Effectively this is
1702 the default font used when <a href="#propdef-font-family"
1703 title="font-family!!property">‘<code
1704 class=property>font-family</code>’</a> is not otherwise specified.
1705 <p>Authors can use this value to specify that font size should be
1706 normalized across fonts based on the x-height without the need to
1707 specify the aspect ratio explicitly.</p>
1709 <dt><dfn id=aspect-ratio-value><var><number></var></dfn>
1711 <dd>Specifies the aspect value used in the calculation below to calculate
1712 the adjusted font size:
1713 <pre>c = ( a / a' ) s
1714 </pre>
1716 <p>where:</p>
1718 <pre>s = font-size value
1719 a = aspect value as specified by the font-size-adjust property
1720 a' = aspect value of actual font
1721 c = adjusted font-size to use
1722 </pre>
1724 <p>This value applies to any font that is selected but in typical usage
1725 it should be based on the aspect value of the first font in the
1726 font-family list. If this is specified accurately, the <tt>(a/a')</tt>
1727 term in the formula above is effectively 1 for the first font and no
1728 adjustment occurs. If the value is specified inaccurately, text rendered
1729 using the first font in the family list will display differently in
1730 older user agents that don't support font-size-adjust.</p>
1731 </dl>
1733 <p>Authors can calculate the aspect value for a given font by comparing
1734 spans with the same content but different font-size-adjust properties. If
1735 the same font-size is used, the spans will match when the font-size-adjust
1736 value is accurate for the given font.
1738 <div class=example>
1739 <p>Two spans with borders are used to determine the aspect value of a
1740 font. The font-size is the same for both spans but the font-size-adjust
1741 property is specified only for the right span. Starting with a value of
1742 0.5, the aspect value can be adjusted until the borders around the two
1743 letters line up.</p>
1745 <pre>p {
1746 font-family: Futura;
1747 font-size: 500px;
1748 }
1750 span {
1751 border: solid 1px red;
1752 }
1754 .adjust {
1755 font-size-adjust: 0.5;
1756 }
1758 <p><span>b</span><span class="adjust">b</span></p>
1759 </pre>
1761 <div class=figure><img alt="Futura with an aspect value of 0.5"
1762 src=beforefontsizeadjust.png>
1763 <p class=caption>Futura with an aspect value of 0.5
1764 </div>
1766 <p>The box on the right is a bit bigger than the one on the left, so the
1767 aspect value of this font is something less than 0.5. Adjust the value
1768 until the boxes align.</p>
1769 </div>
1770 <!-- prop: font -->
1772 <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
1773 <a href="#propdef-font">font</a> property</h3>
1775 <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
1776 <tbody>
1777 <tr>
1778 <td>Name:
1780 <td><dfn id=propdef-font>font</dfn>
1782 <tr>
1783 <td>Value:
1785 <td>[ [ <var><<a href="#propdef-font-style"
1786 title="font-style!!property">‘<code
1787 class=property>font-style</code>’</a>></var> || <a
1788 href="#font-variant-css21-values"><var><font-variant-css21></var></a>
1789 || <var><<a href="#propdef-font-weight"
1790 title="font-weight!!property">‘<code
1791 class=property>font-weight</code>’</a>></var> || <var><<a
1792 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
1793 class=property>font-stretch</code>’</a></var> ]? <var><‘<a
1794 href="#propdef-font-size"><code
1795 class=property>font-size</code></a>’></var> [ / <var><‘<code
1796 class=property>line-height</code>’></var> ]? <var><<a
1797 href="#propdef-font-family" title="font-family!!property">‘<code
1798 class=property>font-family</code>’</a>></var> ] | caption | icon |
1799 menu | message-box | small-caption | status-bar
1801 <tr>
1802 <td>Initial:
1804 <td>see individual properties
1806 <tr>
1807 <td>Applies to:
1809 <td>all elements
1811 <tr>
1812 <td>Inherited:
1814 <td>yes
1816 <tr>
1817 <td>Percentages:
1819 <td>see individual properties
1821 <tr>
1822 <td>Media:
1824 <td>visual
1826 <tr>
1827 <td>Computed value:
1829 <td>see individual properties
1831 <tr>
1832 <td>Animatable:
1834 <td>see individual properties
1835 </table>
1837 <p>The <span class=property>‘<a href="#propdef-font"><code
1838 class=property>font</code></a>’</span> property is, except as described
1839 below, a shorthand property for setting <a href="#propdef-font-style"
1840 title="font-style!!property">‘<code
1841 class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
1842 title="font-variant!!property">‘<code
1843 class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
1844 title="font-weight!!property">‘<code
1845 class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
1846 title="font-stretch!!property">‘<code
1847 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1848 href="#propdef-font-size"><code
1849 class=property>font-size</code></a>’</span>, <a class=property
1850 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1851 class=property>line-height</code>’</a>, <a href="#propdef-font-family"
1852 title="font-family!!property">‘<code
1853 class=property>font-family</code>’</a> at the same place in the
1854 stylesheet. Values for the <a href="#propdef-font-variant"
1855 title="font-variant!!property">‘<code
1856 class=property>font-variant</code>’</a> property may also be included
1857 but only those supported in CSS 2.1, none of the <a
1858 href="#propdef-font-variant" title="font-variant!!property">‘<code
1859 class=property>font-variant</code>’</a> values added in this
1860 specification can be used in the <span class=property>‘<a
1861 href="#propdef-font"><code class=property>font</code></a>’</span>
1862 shorthand:
1864 <pre
1865 class=prod><dfn id=font-variant-css21-values><var><font-variant-css21></var></dfn> = [normal | small-caps]</pre>
1867 <p>The syntax of this property is based on a traditional typographical
1868 shorthand notation to set multiple properties related to fonts.
1870 <p>All subproperties of the ‘<a href="#propdef-font"><code
1871 class=property>font</code></a>’ property are first reset to their
1872 initial values, including those listed above plus <span
1873 class=property>‘<a href="#propdef-font-size-adjust"><code
1874 class=property>font-size-adjust</code></a>’</span>, <span
1875 class=property>‘<a href="#propdef-font-kerning"><code
1876 class=property>font-kerning</code></a>’</span>, subproperties of <a
1877 href="#propdef-font-variant" title="font-variant!!property">‘<code
1878 class=property>font-variant</code>’</a> and and <span>‘<a
1879 href="#propdef-font-language-override"><code
1880 class=property>font-language-override</code></a>’</span>. Then, those
1881 properties that are given explicit values in the <span
1882 class=property>‘<a href="#propdef-font"><code
1883 class=property>font</code></a>’</span> shorthand are set to those
1884 values. For a definition of allowed and initial values, see the previously
1885 defined properties. For reasons of backwards compatibility, it is not
1886 possible to set <span class=property>‘<a
1887 href="#propdef-font-size-adjust"><code
1888 class=property>font-size-adjust</code></a>’</span> to anything other
1889 than its initial value using the <span class=property>‘<a
1890 href="#propdef-font"><code class=property>font</code></a>’</span>
1891 shorthand property; instead, use the individual property.
1893 <div class=example>
1894 <p style="display:none">Example(s):
1896 <p>
1898 <pre>p { font: 12pt/14pt sans-serif }
1899 p { font: 80% sans-serif }
1900 p { font: x-large/110% "new century schoolbook", serif }
1901 p { font: bold italic large Palatino, serif }
1902 p { font: normal small-caps 120%/120% fantasy }
1903 p { font: condensed oblique 12pt "Helvetica Neue", serif; }
1904 </pre>
1906 <p> In the second rule, the font size percentage value (‘<code
1907 class=css>80%</code>’) refers to the computed ‘<a
1908 href="#propdef-font-size"><code class=property>font-size</code></a>’ of
1909 the parent element. In the third rule, the line height percentage
1910 (‘<code class=css>110%</code>’) refers to the font size of the
1911 element itself.
1913 <p>The first three rules do not specify the <a
1914 href="#propdef-font-variant" title="font-variant!!property">‘<code
1915 class=property>font-variant</code>’</a> and <a
1916 href="#propdef-font-weight" title="font-weight!!property">‘<code
1917 class=property>font-weight</code>’</a> explicitly, so these properties
1918 receive their initial values (<span title="normal value">‘<code
1919 class=property>normal</code>’</span>). Notice that the font family name
1920 "new century schoolbook", which contains spaces, is enclosed in quotes.
1921 The fourth rule sets the <a href="#propdef-font-weight"
1922 title="font-weight!!property">‘<code
1923 class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
1924 class=property>bold</code></a>’, the <a href="#propdef-font-style"
1925 title="font-style!!property">‘<code
1926 class=property>font-style</code>’</a> to ‘<a href="#italic"><code
1927 class=property>italic</code></a>’, and implicitly sets <a
1928 href="#propdef-font-variant" title="font-variant!!property">‘<code
1929 class=property>font-variant</code>’</a> to <a
1930 href="#font-variant-normal-value" title="normal!!font-variant">‘<code
1931 class=property>normal</code>’</a>.
1933 <p> The fifth rule sets the <a href="#propdef-font-variant"
1934 title="font-variant!!property">‘<code
1935 class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
1936 class=property>small-caps</code></a>’), the <span class=property>‘<a
1937 href="#propdef-font-size"><code
1938 class=property>font-size</code></a>’</span> (120% of the parent's font
1939 size), the <a class=property
1940 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1941 class=property>line-height</code>’</a> (120% of the font size) and the
1942 <a href="#propdef-font-family" title="font-family!!property">‘<code
1943 class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
1944 class=property>fantasy</code></a>’). It follows that the keyword <span
1945 title="normal value">‘<code class=property>normal</code>’</span>
1946 applies to the two remaining properties: <a href="#propdef-font-style"
1947 title="font-style!!property">‘<code
1948 class=property>font-style</code>’</a> and <a
1949 href="#propdef-font-weight" title="font-weight!!property">‘<code
1950 class=property>font-weight</code>’</a>.
1952 <p>The sixth rule sets the <a href="#propdef-font-style"
1953 title="font-style!!property">‘<code
1954 class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
1955 title="font-stretch!!property">‘<code
1956 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1957 href="#propdef-font-size"><code
1958 class=property>font-size</code></a>’</span>, and <a
1959 href="#propdef-font-family" title="font-family!!property">‘<code
1960 class=property>font-family</code>’</a>, the other font properties being
1961 set to their initial values.
1962 </div>
1964 <p>Since the <a href="#propdef-font-stretch"
1965 title="font-stretch!!property">‘<code
1966 class=property>font-stretch</code>’</a> property was not defined in CSS
1967 2.1, when using <a href="#propdef-font-stretch"
1968 title="font-stretch!!property">‘<code
1969 class=property>font-stretch</code>’</a> values within ‘<a
1970 href="#propdef-font"><code class=property>font</code></a>’ rules,
1971 authors should include a extra version compatible with older user agents:
1973 <pre>p {
1974 font: 80% sans-serif; /* for older user agents */
1975 font: condensed 80% sans-serif;
1976 }</pre>
1978 <p>The following values refer to system fonts:
1980 <dl>
1981 <dt><strong>caption</strong>
1983 <dd>The font used for captioned controls (e.g., buttons, drop-downs,
1984 etc.).
1986 <dt><strong>icon</strong>
1988 <dd>The font used to label icons.
1990 <dt><strong>menu</strong>
1992 <dd>The font used in menus (e.g., dropdown menus and menu lists).
1994 <dt><strong>message-box</strong>
1996 <dd>The font used in dialog boxes.
1998 <dt><strong>small-caption</strong>
2000 <dd>The font used for labeling small controls.
2002 <dt><strong>status-bar</strong>
2004 <dd>The font used in window status bars.
2005 </dl>
2007 <p>System fonts may only be set as a whole; that is, the font family, size,
2008 weight, style, etc. are all set at the same time. These values may then be
2009 altered individually if desired. If no font with the indicated
2010 characteristics exists on a given platform, the user agent should either
2011 intelligently substitute (e.g., a smaller version of the ‘<code
2012 class=property>caption</code>’ font might be used for the ‘<code
2013 class=property>small-caption</code>’ font), or substitute a user agent
2014 default font. As for regular fonts, if, for a system font, any of the
2015 individual properties are not part of the operating system's available
2016 user preferences, those properties should be set to their initial values.
2018 <p>That is why this property is "almost" a shorthand property: system fonts
2019 can only be specified with this property, not with <a
2020 href="#propdef-font-family" title="font-family!!property">‘<code
2021 class=property>font-family</code>’</a> itself, so <span
2022 class=property>‘<a href="#propdef-font"><code
2023 class=property>font</code></a>’</span> allows authors to do more than
2024 the sum of its subproperties. However, the individual properties such as
2025 <a href="#propdef-font-weight" title="font-weight!!property">‘<code
2026 class=property>font-weight</code>’</a> are still given values taken from
2027 the system font, which can be independently varied.
2029 <p>Note that the keywords used for the system fonts listed above are only
2030 treated as keywords when they occur in the initial position, in other
2031 positions the same string is treated as part of the font family name:
2033 <pre> font: menu; /* use the font settings for system menus */
2034 font: large menu; /* use a font family named "menu" */</pre>
2036 <div class=example>
2037 <p style="display:none">Example(s):
2039 <p>
2041 <pre>button { font: 300 italic 1.3em/1.7em "FB Armada", sans-serif }
2042 button p { font: menu }
2043 button p em { font-weight: bolder }
2044 </pre>
2046 <p>If the font used for dropdown menus on a particular system happened to
2047 be, for example, 9-point Charcoal, with a weight of 600, then P elements
2048 that were descendants of BUTTON would be displayed as if this rule were
2049 in effect:
2051 <pre>button p { font: 600 9pt Charcoal }
2052 </pre>
2054 <p>Because the <span class=property>‘<a href="#propdef-font"><code
2055 class=property>font</code></a>’</span> shorthand resets to its initial
2056 value any property not explicitly given a value, this has the same effect
2057 as this declaration:
2059 <pre>button p {
2060 font-style: normal;
2061 font-variant: normal;
2062 font-weight: 600;
2063 font-size: 9pt;
2064 line-height: normal;
2065 font-family: Charcoal
2066 }
2067 </pre>
2068 </div>
2069 <!-- prop: font-synthesis -->
2071 <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
2072 synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
2073 property</h3>
2075 <table class=propdef id=namefont-synthesisvaluenone-weight-style>
2076 <tbody>
2077 <tr>
2078 <td>Name:
2080 <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
2082 <tr>
2083 <td>Value:
2085 <td>none | [ weight || style ]
2087 <tr>
2088 <td>Initial:
2090 <td>weight style
2092 <tr>
2093 <td>Applies to:
2095 <td>all elements
2097 <tr>
2098 <td>Inherited:
2100 <td>yes
2102 <tr>
2103 <td>Percentages:
2105 <td>N/A
2107 <tr>
2108 <td>Media:
2110 <td>visual
2112 <tr>
2113 <td>Computed value:
2115 <td>as specified
2117 <tr>
2118 <td>Animatable:
2120 <td>no
2121 </table>
2123 <p>This property controls whether user agents are allowed to synthesize
2124 bold or oblique font faces when a font family lacks bold or italic faces.
2125 If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
2126 specified, user agents must not synthesize bold faces and if ‘<code
2127 class=property>style</code>’ is not specified user agents must not
2128 synthesize italic faces. A value of ‘<code class=property>none</code>’
2129 disallows all synthetic faces.
2131 <div class=example>
2132 <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
2134 <pre>*:lang(ar) { font-synthesis: none; }
2135 </pre>
2136 </div>
2138 <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
2140 <h3 id=font-face-rule><span class=secno>4.1 </span>The <dfn
2141 id=at-font-face-rule style="font-weight: inherit; font-style:
2142 inherit"><code>@font-face</code></dfn> rule</h3>
2144 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule allows
2145 for linking to fonts that are automatically fetched and activated when
2146 needed. This allows authors to select a font that closely matches the
2147 design goals for a given page rather than limiting the font choice to a
2148 set of fonts available on all platforms. A set of font descriptors define
2149 the location of a font resource, either locally or externally, along with
2150 the style characteristics of an individual face. Multiple <a
2151 href="#at-font-face-rule"><code>@font-face</code></a> rules can be used to
2152 construct font families with a variety of faces. Using CSS font matching
2153 rules, a user agent can selectively download only those faces that are
2154 needed for a given piece of text.
2156 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2157 consists of the <a href="#at-font-face-rule"><code>@font-face</code></a>
2158 at-keyword followed by a block of descriptor declarations. In terms of the
2159 grammar, this specification defines the following productions:
2161 <pre><dfn id=fontfacerule>font_face_rule</dfn>
2162 : <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>*
2163 ;
2165 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
2166 : <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>
2167 ;</pre>
2169 <p>The following new definitions are introduced:
2171 <pre>- -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
2172 F f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
2174 <p>The following new token is introduced:
2176 <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
2178 <p>Each <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2179 specifies a value for every font descriptor, either implicitly or
2180 explicitly. Those not given explicit values in the rule take the initial
2181 value listed with each descriptor in this specification. These descriptors
2182 apply solely within the context of the <a
2183 href="#at-font-face-rule"><code>@font-face</code></a> rule in which they
2184 are defined, and do not apply to document language elements. There is no
2185 notion of which elements the descriptors apply to or whether the values
2186 are inherited by child elements. When a given descriptor occurs multiple
2187 times in a given <a href="#at-font-face-rule"><code>@font-face</code></a>
2188 rule, only the last descriptor declaration is used and all prior
2189 declarations for that descriptor are ignored.
2191 <div class=example>
2192 <p>To use a downloadable font called Gentium:</p>
2194 <pre>
2195 @font-face {
2196 font-family: Gentium;
2197 src: url(http://example.com/fonts/Gentium.ttf);
2198 }
2200 p { font-family: Gentium, serif; }
2201 </pre>
2203 <p>The user agent will download Gentium and use it when rendering text
2204 within paragraph elements. If for some reason the site serving the font
2205 is unavailable, the default serif font will be used.</p>
2206 </div>
2208 <p>A given set of <a href="#at-font-face-rule"><code>@font-face</code></a>
2209 rules define a set of fonts available for use within the documents that
2210 contain these rules. When font matching is done, fonts defined using these
2211 rules are considered before other available fonts on a system.
2213 <p>Downloaded fonts are only available to documents that reference them.
2214 The process of activating these fonts must not make them available to
2215 other applications or to documents that don't directly link to the same
2216 font. User agent implementers might consider it convenient to use
2217 downloaded fonts when rendering characters in other documents for which no
2218 other available font exists as part of the <a
2219 href="#system-font-fallback"><em>system font fallback</em></a> procedure.
2220 However, this would cause a security leak since the contents of one page
2221 would be able to affect other pages, something an attacker could use as an
2222 attack vector. These restrictions do not affect caching behavior, fonts
2223 are cached the same way other web resources are cached.
2225 <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
2226 properties in a declaration block, declarations of any descriptors that
2227 are not supported by the user agent must be ignored. <a
2228 href="#at-font-face-rule"><code>@font-face</code></a> rules require a
2229 font-family and src descriptor; if either of these are missing, the <a
2230 href="#at-font-face-rule"><code>@font-face</code></a> rule is invalid and
2231 must be ignored entirely.
2233 <p>In cases where user agents have limited platform resources or implement
2234 the ability to disable downloadable font resources, <a
2235 href="#at-font-face-rule"><code>@font-face</code></a> rules must simply be
2236 ignored; the behavior of individual descriptors as defined in this
2237 specification should not be altered.
2239 <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
2240 href="#descdef-font-family">font-family</a> descriptor</h3>
2242 <table class=descdef>
2243 <tbody>
2244 <tr>
2245 <td>Name:
2247 <td><dfn id=descdef-font-family
2248 title="font-family!!descriptor">font-family</dfn>
2250 <tr>
2251 <td>Value:
2253 <td><a href="#family-name-value"><var><family-name></var></a>
2255 <tr>
2256 <td><em>Initial:</em>
2258 <td>N/A
2259 </table>
2261 <p>This descriptor defines the font family name that will be used in all
2262 CSS font family name matching. It is required for the <a
2263 href="#at-font-face-rule"><code>@font-face</code></a> rule to be valid. It
2264 overrides the font family names contained in the underlying font data. If
2265 the font family name is the same as a font family available in a given
2266 user's environment, it effectively hides the underlying font for documents
2267 that use the stylesheet. This permits a web author to freely choose
2268 font-family names without worrying about conflicts with font family names
2269 present in a given user's environment. Likewise, platform substitutions
2270 for a given font family name must not be used.
2272 <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
2273 href="#descdef-src">src</a> descriptor</h3>
2275 <table class=descdef>
2276 <tbody>
2277 <tr>
2278 <td>Name:
2280 <td><dfn id=descdef-src>src</dfn>
2282 <tr>
2283 <td>Value:
2285 <td>[ <url> [format(<string> #)]? | <a
2286 href="#font-face-name-value"><var><font-face-name></var></a> ] #
2288 <tr>
2289 <td><em>Initial:</em>
2291 <td>N/A
2292 </table>
2294 <p>This descriptor specifies the resource containing font data. It is
2295 required for the <a href="#at-font-face-rule"><code>@font-face</code></a>
2296 rule to be valid. Its value is a prioritized, comma-separated list of
2297 external references or locally-installed font face names. When a font is
2298 needed the user agent iterates over the set of references listed, using
2299 the first one it can successfully activate. Fonts containing invalid data
2300 or local font faces that are not found are ignored and the user agent
2301 loads the next font in the list.
2303 <p>As with other URLs in CSS, the URL may be relative, in which case it is
2304 resolved relative to the location of the style sheet containing the <a
2305 href="#at-font-face-rule"><code>@font-face</code></a> rule. In the case of
2306 SVG fonts, the URL points to an element within a document containing SVG
2307 font definitions. If the element reference is omitted, a reference to the
2308 first defined font is implied. Similarly, font container formats that can
2309 contain more than one font must load one and only one of the fonts for a
2310 given <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
2311 Fragment identifiers are used to indicate which font to load. If a
2312 container format lacks a defined fragment identifier scheme,
2313 implementations should use a simple 1-based indexing scheme (e.g.
2314 "font-collection#1" for the first font, "font-collection#2" for the second
2315 font).
2317 <pre>
2318 src: url(fonts/simple.ttf); /* load simple.ttf relative to stylesheet location */
2319 src: url(/fonts/simple.ttf); /* load simple.ttf from absolute location */
2320 src: url(fonts.svg#simple); /* load SVG font with id 'simple' */
2321 </pre>
2323 <p>External references consist of a URL, followed by an optional hint
2324 describing the format of the font resource referenced by that URL. The
2325 format hint contains a comma-separated list of format strings that denote
2326 well-known font formats. Conformant user agents must skip downloading a
2327 font resource if the format hints indicate only unsupported or unknown
2328 font formats. If no format hints are supplied, the user agent should
2329 download the font resource.
2331 <pre>
2332 /* load WOFF font if possible, otherwise use OpenType font */
2333 @font-face {
2334 font-family: bodytext;
2335 src: url(ideal-sans-serif.woff) format("woff"),
2336 url(basic-sans-serif.ttf) format("opentype");
2337 }
2338 </pre>
2340 <p>Format strings defined by this specification:
2342 <table class=data id=fontformats>
2343 <thead>
2344 <tr>
2345 <th>String
2347 <th>Font Format
2349 <th>Common extensions
2351 <tbody>
2352 <tr>
2353 <th>"woff"
2355 <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
2357 <td>.woff
2359 <tr>
2360 <th>"truetype"
2362 <td><a
2363 href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
2365 <td>.ttf
2367 <tr>
2368 <th>"opentype"
2370 <td><a
2371 href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
2373 <td>.ttf, .otf
2375 <tr>
2376 <th>"embedded-opentype"
2378 <td><a
2379 href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
2380 OpenType</a>
2382 <td>.eot
2384 <tr>
2385 <th>"svg"
2387 <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
2389 <td>.svg, .svgz
2390 </table>
2392 <p>Given the overlap in common usage between TrueType and OpenType, the
2393 format hints "truetype" and "opentype" must be considered as synonymous; a
2394 format hint of "opentype" does not imply that the font contains Postscript
2395 CFF style glyph data or that it contains OpenType layout information (see
2396 <a href="#platform-props-to-css">Appendix A</a> for more background on
2397 this).
2399 <p>When authors would prefer to use a locally available copy of a given
2400 font and download it if it's not, <code>local()</code> can be used. The
2401 locally-installed <dfn
2402 id=font-face-name-value><var><font-face-name></var></dfn> argument
2403 to <code>local()</code> is a format-specific string that uniquely
2404 identifies a single font face within a larger family. The syntax for a <a
2405 href="#font-face-name-value"><var><font-face-name></var></a> is a
2406 unique font face name enclosed by "local(" and ")". The name can
2407 optionally be enclosed in quotes. If unquoted, the unquoted font family
2408 name processing conventions apply; the name must be a sequence of
2409 identifiers separated by whitespace which is converted to a string by
2410 joining the identifiers together separated by a single space.
2412 <pre>
2413 /* regular face of Gentium */
2414 @font-face {
2415 font-family: MyGentium;
2416 src: local(Gentium), /* use locally available Gentium */
2417 url(Gentium.ttf); /* otherwise, download it */
2418 }
2419 </pre>
2421 <p>For OpenType and TrueType fonts, this string is used to match only the
2422 Postscript name or the full font name in the name table of locally
2423 available fonts. Which type of name is used varies by platform and font,
2424 so authors should include both of these names to assure proper matching
2425 across platforms. Platform substitutions for a given font name must not be
2426 used.
2428 <pre>
2429 /* bold face of Gentium */
2430 @font-face {
2431 font-family: MyGentium;
2432 src: local(Gentium Bold), /* full font name */
2433 local(Gentium-Bold), /* Postscript name */
2434 url(GentiumBold.ttf); /* otherwise, download it */
2435 font-weight: bold;
2436 }
2437 </pre>
2439 <p>Just as a <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2440 specifies the characteristics of a single font within a family, the unique
2441 name used with <code>local()</code> specifies a single font, not an entire
2442 font family. Defined in terms of OpenType font data, the Postscript name
2443 is found in the font's <a
2444 href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
2445 in the name record with nameID = 6 (see <a href="#OPENTYPE"
2446 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
2447 Postscript name is the commonly used key for all fonts on OSX and for
2448 Postscript CFF fonts under Windows. The full font name (nameID = 4) is
2449 used as a unique key for fonts with TrueType glyphs on Windows.
2451 <p>For OpenType fonts with multiple localizations of the full font name,
2452 the US English version is used (language ID = 0x409 for Windows and
2453 language ID = 0 for Macintosh) or the first localization when a US English
2454 full font name is not available (the OpenType specification recommends
2455 that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
2456 fonts minimally include US English names</a>). User agents that also match
2457 other full font names, e.g. matching the Dutch name when the current
2458 system locale is set to Dutch, are considered non-conformant. This is done
2459 not to prefer English but to avoid matching inconsistencies across font
2460 versions and OS localizations, since font style names (e.g. "Bold") are
2461 frequently localized into many languages and the set of localizations
2462 available varies widely across platform and font version. User agents that
2463 match a concatenation of family name (nameID = 1) with style name (nameID
2464 = 2) are considered non-conformant.
2466 <p>This also allows for referencing faces that belong to larger families
2467 that cannot otherwise be referenced.
2469 <div class=example>
2470 <p>Use a local font or reference an SVG font in another document:</p>
2472 <pre>
2473 @font-face {
2474 font-family: Headline;
2475 src: local(Futura-Medium),
2476 url(fonts.svg#MyGeometricModern) format("svg");
2477 }
2478 </pre>
2480 <p>Create an alias for local Japanese fonts on different platforms:</p>
2482 <pre>
2483 @font-face {
2484 font-family: jpgothic;
2485 src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
2486 }
2487 </pre>
2489 <p>Reference a font face that cannot be matched within a larger family:</p>
2491 <pre>
2492 @font-face {
2493 font-family: Hoefler Text Ornaments;
2494 /* has the same font properties as Hoefler Text Regular */
2495 src: local(HoeflerText-Ornaments);
2496 }
2497 </pre>
2499 <p>Since localized fullnames never match, a document with the header style
2500 rules below would always render using the default serif font, regardless
2501 whether a particular system locale parameter is set to Finnish or not:</p>
2503 <pre>
2504 @font-face {
2505 font-family: SectionHeader;
2506 src: local("Arial Lihavoitu"); /* Finnish fullname for Arial Bold, should fail */
2507 font-weight: bold;
2508 }
2510 h2 { font-family: SectionHeader, serif; }
2511 </pre>
2513 <p>A conformant user agent would never load the font ‘<code
2514 class=css>gentium.eot</code>’ in the example below, since it is
2515 included in the first definition of the ‘<a href="#descdef-src"><code
2516 class=property>src</code></a>’ descriptor which is overridden by the
2517 second definition in the same <a
2518 href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
2520 <pre>
2521 @font-face {
2522 font-family: MainText;
2523 src: url(gentium.eot); /* for use with older non-conformant user agents */
2524 src: local("Gentium"), url(gentium.ttf); /* Overrides src definition */
2525 }
2526 </pre>
2527 </div>
2529 <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
2530 descriptors: the <a href="#descdef-font-style">font-style</a>, <a
2531 href="#descdef-font-weight">font-weight</a>, <a
2532 href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
2534 <table class=descdef>
2535 <tbody>
2536 <tr>
2537 <td>Name:
2539 <td><dfn id=descdef-font-style
2540 title="font-style!!descriptor">font-style</dfn>
2542 <tr>
2543 <td>Value:
2545 <td>normal | italic | oblique
2547 <tr>
2548 <td><em>Initial:</em>
2550 <td>normal
2551 </table>
2553 <table class=descdef>
2554 <tbody>
2555 <tr>
2556 <td>Name:
2558 <td><dfn id=descdef-font-weight
2559 title="font-weight!!descriptor">font-weight</dfn>
2561 <tr>
2562 <td>Value:
2564 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
2566 <tr>
2567 <td><em>Initial:</em>
2569 <td>normal
2570 </table>
2572 <table class=descdef>
2573 <tbody>
2574 <tr>
2575 <td>Name:
2577 <td><dfn id=descdef-font-stretch
2578 title="font-stretch!!descriptor">font-stretch</dfn>
2580 <tr>
2581 <td>Value:
2583 <td>normal | ultra-condensed | extra-condensed | condensed |
2584 semi-condensed | semi-expanded | expanded | extra-expanded |
2585 ultra-expanded
2587 <tr>
2588 <td><em>Initial:</em>
2590 <td>normal
2591 </table>
2593 <p>These descriptors define the characteristics of a font face and are used
2594 in the process of matching styles to specific faces. For a font family
2595 defined with several <a
2596 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
2597 can either download all faces in the family or use these descriptors to
2598 selectively download font faces that match actual styles used in document.
2599 The values for these descriptors are the same as those for the
2600 corresponding font properties except that relative keywords are not
2601 allowed, ‘<a href="#bolder"><code class=property>bolder</code></a>’
2602 and ‘<a href="#lighter"><code class=property>lighter</code></a>’. If
2603 these descriptors are omitted, initial values are assumed.
2605 <p>The value for these font face style attributes is used in place of the
2606 style implied by the underlying font data. This allows authors to combine
2607 faces in flexible combinations, even in situations where the original font
2608 data was arranged differently. User agents that implement synthetic
2609 bolding and obliquing must only apply synthetic styling in cases where the
2610 font descriptors imply this is needed, rather than based on the style
2611 attributes implied by the font data.
2613 <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
2614 <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
2616 <table class=descdef>
2617 <tbody>
2618 <tr>
2619 <td>Name:
2621 <td><dfn id=descdef-unicode-range>unicode-range</dfn>
2623 <tr>
2624 <td>Value:
2626 <td><a href="#urange-value"><var><urange></var></a> #
2628 <tr>
2629 <td><em>Initial:</em>
2631 <td>U+0-10FFFF
2632 </table>
2634 <p>This descriptor defines the set of Unicode codepoints that may be
2635 supported by the font face for which it is declared. The descriptor value
2636 is a comma-delimited list of Unicode range (<a
2637 href="#urange-value"><var><urange></var></a>) values. The union of
2638 these ranges defines the set of codepoints that serves as a hint for user
2639 agents when deciding whether or not to download a font resource for a
2640 given text run.
2642 <p>Each <dfn id=urange-value><var><urange></var></dfn> value is a <a
2643 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2644 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
2645 "U+" or "u+" prefix followed by a codepoint range in one of the three
2646 forms listed below. Ranges that do not fit one of the these forms are
2647 invalid and cause the declaration to be ignored.
2649 <dl>
2650 <dt>single codepoint (e.g. U+416)
2652 <dd>a valid Unicode codepoint, represented as one to six hexadecimal
2653 digits
2655 <dt>interval range (e.g. U+400-4ff)
2657 <dd>represented as two hyphen-separated valid Unicode codepoints
2658 indicating the inclusive start and end codepoints of a range
2660 <dt>wildcard range (e.g. U+4??)
2662 <dd>defined by the set of codepoints implied when trailing ‘<code
2663 class=css>?</code>’ characters signify any hexadeximal digit
2664 </dl>
2666 <p>Individual codepoints are written using hexadecimal values that
2667 correspond to <a href="http://www.unicode.org/charts/">Unicode character
2668 codepoints</a>. Valid Unicode codepoint values vary between 0 and 10FFFF
2669 inclusive. Digit values of codepoints are ASCII case-insensitive. For
2670 interval ranges, the start and end codepoints are valid Unicode values and
2671 the end codepoint is greater than or equal to the start codepoint.
2673 <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
2674 "U+???") are valid and equivalent to a wildcard range with an initial zero
2675 digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
2676 the range of valid Unicode codepoints are invalid. Because of this, the
2677 maximum number of trailing ‘<code class=css>?</code>’ wildcard
2678 characters is five, even though the <a
2679 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2680 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
2682 <p>Within the comma-delimited list of Unicode ranges in a ‘<a
2683 href="#descdef-unicode-range"><code
2684 class=property>unicode-range</code></a>’ descriptor declaration, ranges
2685 may overlap. The union of these ranges defines the set of codepoints for
2686 which the corresponding font may be used. User agents must not download or
2687 use the font for codepoints outside this set. User agents may normalize
2688 the list of ranges into a list that is different but represents the same
2689 set of codepoints.
2691 <p>The associated font might not contain glyphs for the entire set of
2692 codepoints defined by the ‘<a href="#descdef-unicode-range"><code
2693 class=property>unicode-range</code></a>’ descriptor. When the font is
2694 used the effective <a href="#character-map"><em>character map</em></a> is
2695 the intersection of the codepoints defined by ‘<a
2696 href="#descdef-unicode-range"><code
2697 class=property>unicode-range</code></a>’ with the font's <a
2698 href="#character-map"><em>character map</em></a>. This allows authors to
2699 define supported ranges in terms of broad ranges without worrying about
2700 the precise codepoint ranges supported by the underlying font.
2702 <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
2703 to define composite fonts</h3>
2705 <p>Multiple <a href="#at-font-face-rule"><code>@font-face</code></a> rules
2706 with different unicode ranges for the same family and style descriptor
2707 values can be used to create composite fonts that mix the glyphs from
2708 different fonts for different scripts. This can be used to combine fonts
2709 that only contain glyphs for a single script (e.g. Latin, Greek, Cyrillic)
2710 or it can be used by authors as a way of segmenting a font into fonts for
2711 commonly used characters and less frequently used characters. Since the
2712 user agent will only pull down the fonts it needs this helps reduce page
2713 bandwidth.
2715 <p>If the unicode ranges overlap for a set of <a
2716 href="#at-font-face-rule"><code>@font-face</code></a> rules with the same
2717 family and style descriptor values, the rules are ordered in the reverse
2718 order they were defined; the last rule defined is the first to be checked
2719 for a given character.
2721 <p>Example ranges for specific languages or characters:
2723 <dl>
2724 <dt>unicode-range: U+A5;
2726 <dd>a single code point, the yen/yuan symbol
2728 <dt>unicode-range: U+0-7F;
2730 <dd>code range for basic ASCII characters
2732 <dt>unicode-range: U+590-5ff;
2734 <dd>code range for Hebrew characters
2736 <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
2738 <dd>code range for Japanese kanji, hiragana and katakana characters plus
2739 yen/yuan symbol
2740 </dl>
2742 <div class=example>
2743 <p>The BBC provides news services in a wide variety of languages, many
2744 that are not well supported across all platforms. Using an <a
2745 href="#at-font-face-rule"><code>@font-face</code></a> rule, the BBC could
2746 provide a font for any of these languages, as it already does via a
2747 manual font download.</p>
2749 <pre>
2750 @font-face {
2751 font-family: BBCBengali;
2752 src: url(fonts/BBCBengali.ttf) format("opentype");
2753 unicode-range: U+00-FF, U+980-9FF;
2754 }
2755 </pre>
2756 </div>
2758 <div class=example>
2759 <p>Technical documents often require a wide range of symbols. The STIX
2760 Fonts project is one project aimed at providing fonts to support a wide
2761 range of technical typesetting in a standardized way. The example below
2762 shows the use of a font that provides glyphs for many of the mathematical
2763 and technical symbol ranges within Unicode:</p>
2765 <pre>
2766 @font-face {
2767 font-family: STIXGeneral;
2768 src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
2769 unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
2770 }
2771 </pre>
2772 </div>
2774 <div class=example>
2775 <p>This example shows how an author can override the glyphs used for Latin
2776 characters in a Japanese font with glyphs from a different font. The
2777 first rule specifies no range so it defaults to the entire range. The
2778 range specified in the second rule overlaps but takes precedence because
2779 it is defined later.</p>
2781 <pre>
2782 @font-face {
2783 font-family: JapaneseWithGentium;
2784 src: local(MSMincho);
2785 /* no range specified, defaults to entire range */
2786 }
2788 @font-face {
2789 font-family: JapaneseWithGentium;
2790 src: url(../fonts/Gentium.ttf);
2791 unicode-range: U+0-2FF;
2792 }
2793 </pre>
2794 </div>
2796 <div class=example>
2797 <p>Consider a family constructed to optimize bandwidth by separating out
2798 Latin, Japanese and other characters into different font files:</p>
2800 <pre>
2801 /* fallback font - size: 4.5MB */
2802 @font-face {
2803 font-family: DroidSans;
2804 src: url(DroidSansFallback.ttf);
2805 /* no range specified, defaults to entire range */
2806 }
2808 /* Japanese glyphs - size: 1.2MB */
2809 @font-face {
2810 font-family: DroidSans;
2811 src: url(DroidSansJapanese.ttf);
2812 unicode-range: U+3000-9FFF, U+ff??;
2813 }
2815 /* Latin, Greek, Cyrillic along with some
2816 punctuation and symbols - size: 190KB */
2817 @font-face {
2818 font-family: DroidSans;
2819 src: url(DroidSans.ttf);
2820 unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
2821 }
2822 </pre>
2824 <p>For simple Latin text, only the font for Latin characters is
2825 downloaded:</p>
2827 <pre>
2828 body { font-family: DroidSans; }
2830 <p>This is that</p>
2831 </pre>
2833 <p>In this case the user agent first checks the unicode-range for the font
2834 containing Latin characters (DroidSans.ttf). Since all the characters
2835 above are in the range U+0-5FF, the user agent downloads the font and
2836 renders the text with that font.</p>
2838 <p>Next, consider text that makes use of an arrow character (⇨):</p>
2840 <pre>
2841 <p>This &#x21e8; that<p>
2842 </pre>
2844 <p>The user agent again first checks the unicode-range of the font
2845 containing Latin characters. Since U+2000-2300 includes the arrow code
2846 point (U+21E8), the user agent downloads the font. For this character
2847 however the Latin font does not have a matching glyph, so the effective
2848 unicode-range used for font matching excludes this code point. Next, the
2849 user agent evaluates the Japanese font. The unicode-range for the
2850 Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
2851 user agent does not download the Japanese font. Next the fallback font is
2852 considered. The <a href="#at-font-face-rule"><code>@font-face</code></a>
2853 rule for the fallback font does not define unicode-range so its value
2854 defaults to the range of all Unicode code points. The fallback font is
2855 downloaded and used to render the arrow character.</p>
2856 </div>
2858 <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
2859 href="#descdef-font-variant">font-variant</a> and <a
2860 href="#descdef-font-feature-settings">font-feature-settings</a>
2861 descriptors</h3>
2863 <table class=descdef>
2864 <tbody>
2865 <tr>
2866 <td>Name:
2868 <td><dfn id=descdef-font-variant
2869 title="font-variant!!descriptor">font-variant</dfn>
2871 <tr>
2872 <td>Value:
2874 <td><a href="#font-variant-normal-value"
2875 title="normal!!font-variant">normal</a> | <a
2876 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
2877 <a href="#common-lig-values"><var><common-lig-values></var></a>
2878 || <a
2879 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
2880 || <a
2881 href="#historical-lig-values"><var><historical-lig-values></var></a>
2882 || <a
2883 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
2884 || <a href="#stylistic"><var
2885 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
2886 href="#historical-forms"><var>historical-forms</var></a> || <a
2887 href="#styleset"><var
2888 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
2889 href="#character-variant"><var
2890 title=character-variant>character-variant(<feature-value-name>
2891 #)</var></a> || <a href="#swash"><var
2892 title=swash>swash(<feature-value-name>)</var></a> || <a
2893 href="#ornaments"><var
2894 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
2895 href="#annotation"><var
2896 title=annotation>annotation(<feature-value-name>)</var></a> || [
2897 <a href="#small-caps"><i>small-caps</i></a> | <a
2898 href="#all-small-caps"><i>all-small-caps</i></a> | <a
2899 href="#petite-caps"><i>petite-caps</i></a> | <a
2900 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
2901 href="#unicase"><i>unicase</i></a> | <a
2902 href="#titling-caps"><i>titling-caps</i></a> ] || <a
2903 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
2904 || <a
2905 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
2906 || <a
2907 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
2908 || <a href="#ordinal"><i>ordinal</i></a> || <a
2909 href="#slashed-zero"><i>slashed-zero</i></a> || <a
2910 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
2911 || <a
2912 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
2913 || <a href="#ruby"><i>ruby</i></a> ]
2915 <tr>
2916 <td><em>Initial:</em>
2918 <td>normal
2919 </table>
2921 <table class=descdef>
2922 <tbody>
2923 <tr>
2924 <td>Name:
2926 <td><dfn id=descdef-font-feature-settings
2927 title="font-feature-settings!!descriptor">font-feature-settings</dfn>
2929 <tr>
2930 <td>Value:
2932 <td><a href="#font-feature-settings-normal-value"
2933 title="normal!!font-feature-settings">normal</a> | <a
2934 href="#feature-tag-value"><var><feature-tag-value></var></a> #
2936 <tr>
2937 <td><em>Initial:</em>
2939 <td>normal
2940 </table>
2942 <p>These descriptors define initial settings that apply when the font
2943 defined by an <a href="#at-font-face-rule"><code>@font-face</code></a>
2944 rule is rendered. They do not affect font selection. Values are identical
2945 to those defined for the corresponding <a href="#propdef-font-variant"
2946 title="font-variant!!property">‘<code
2947 class=property>font-variant</code>’</a> and <a
2948 href="#propdef-font-feature-settings"
2949 title="font-feature-settings!!property">‘<code
2950 class=property>font-feature-settings</code>’</a> properties defined
2951 below except that the value ‘<code class=property>inherit</code>’ is
2952 omitted. When multiple font feature descriptors or properties are used,
2953 the cumulative effect on text rendering is detailed in the section <a
2954 href="#font-feature-resolution">Font Feature Resolution</a> below. In
2955 cases where specific values define synthesized fallback for certain <a
2956 href="#propdef-font-variant" title="font-variant!!property">‘<code
2957 class=property>font-variant</code>’</a> subproperties, the same
2958 synthesized fallback applies when used within those values are used with
2959 the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
2960 class=property>font-variant</code>’</a> descriptor.
2962 <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
2963 guidelines</h3>
2965 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule is
2966 designed to allow lazy loading of font resources that are only downloaded
2967 when used within a document. A stylesheet can include <a
2968 href="#at-font-face-rule"><code>@font-face</code></a> rules for a library
2969 of fonts of which only a select set are used; user agents must only
2970 download those fonts that are referred to within the style rules
2971 applicable to a given page. User agents that download all fonts defined in
2972 <a href="#at-font-face-rule"><code>@font-face</code></a> rules without
2973 considering whether those fonts are in fact used within a page are
2974 considered non-conformant. In cases where a font might be downloaded in
2975 character fallback cases, user agents may download a font if it's
2976 contained within the computed value of <a href="#propdef-font-family"
2977 title="font-family!!property">‘<code
2978 class=property>font-family</code>’</a> for a given text run.
2980 <pre>
2981 @font-face {
2982 font-family: GeometricModern;
2983 src: url(font.ttf);
2984 }
2986 p {
2987 /* font will be downloaded for pages with p elements */
2988 font-family: GeometricModern, sans-serif;
2989 }
2991 h2 {
2992 /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
2993 font-family: Futura, GeometricModern, sans-serif;
2994 }
2995 </pre>
2997 <p>In cases where textual content is loaded before downloadable fonts are
2998 available, user agents may render text as it would be rendered if
2999 downloadable font resources are not available or they may render text
3000 transparently with fallback fonts to avoid a flash of text using a
3001 fallback font. In cases where the font download fails user agents must
3002 display text, simply leaving transparent text is considered non-conformant
3003 behavior. Authors are advised to use fallback fonts in their font lists
3004 that closely match the vertical metrics of the downloadable fonts to avoid
3005 large page reflows where possible.
3007 <h3 id=same-origin-restriction><span class=secno>4.9 </span>Same-origin
3008 restriction for fonts</h3>
3010 <h4 id=default-same-origin-restriction><span class=secno>4.9.1
3011 </span>Default same-origin restriction</h4>
3012 <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
3013 http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
3014 http://www.w3.org/2011/10/31-webapps-minutes.html#item02
3015 -->
3017 <p>User agents must implement a same-origin restriction when loading fonts
3018 via the <a href="#at-font-face-rule"><code>@font-face</code></a>
3019 mechanism. This restriction limits the loading of fonts for a given
3020 document to fonts loaded from the same origin. Fonts can only be loaded
3021 via the same host, port, and method combination as the containing
3022 document, using the <a
3023 href="http://www.w3.org/TR/html5/browsers.html#origin">origin matching
3024 algorithm</a> described in the <a href="#HTML5"
3025 rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification. The origin of
3026 the stylesheet containing <a
3027 href="#at-font-face-rule"><code>@font-face</code></a> rules is not used
3028 when deciding whether a font is same origin or not, only the origin of the
3029 containing document is used. The restriction applies to all font types.
3031 <p>Given a document located at http://example.com/page.html, fonts defined
3032 with ‘<a href="#descdef-src"><code class=property>src</code></a>’
3033 definitions considered cross origin must not be loaded:
3035 <pre>
3036 /* same origin (i.e. domain, protocol, port match document) */
3037 src: url(fonts/simple.ttf);
3038 src: url(//fonts/simple.ttf);
3040 /* cross origin, different protocol */
3041 src: url(https://example.com/fonts/simple.ttf);
3043 /* cross origin, different domain */
3044 src: url(http://another.example.com/fonts/simple.ttf);
3045 </pre>
3047 <h4 id=allowing-cross-origin-font-loading><span class=secno>4.9.2
3048 </span>Allowing cross-origin font loading</h4>
3050 <p>User agents must also implement the ability to relax this restriction
3051 using cross-site origin controls <a href="#CORS"
3052 rel=biblioentry>[CORS]<!--{{!CORS}}--></a> for fonts loaded via HTTP.
3053 Sites can explicitly allow cross-site downloading of font data using the
3054 <code>Access-Control-Allow-Origin</code> HTTP header. For other protocols,
3055 no explicit relaxation mechanism is defined or required.
3057 <p>For font loads over HTTP, cross-origin requests must be made with the
3058 following parameter settings which are used in conjunction with the <a
3059 href="http://www.w3.org/TR/cors/#cross-origin-request-0"> <em>cross-origin
3060 request algorithm</em></a> <a href="#CORS"
3061 rel=biblioentry>[CORS]<!--{{!CORS}}--></a>:
3063 <ul>
3064 <li><em>request URL</em> — the URL of the font resource in the <a
3065 href="#descdef-src"><code>src</code></a> descriptor
3067 <li><em>request method</em> — GET
3069 <li><em>author request headers</em> — none
3071 <li><em>request entity body</em> — empty
3073 <li><em>source origin</em> — the origin of the page which linked to the
3074 stylesheet
3076 <li><em>manual redirect flag</em> — false
3078 <li><em>omit credentials flag</em> — true
3080 <li><em>force preflight flag</em> — false
3081 </ul>
3083 <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
3084 Algorithm</h2>
3086 <p>The algorithm below describes how fonts are associated with individual
3087 runs of text. For each character in the run a font family is chosen and a
3088 particular font face is selected containing a glyph for that character.
3090 <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
3091 font family names</h3>
3093 <p>As part of the font matching algorithm outlined below, user agents must
3094 match font family names used in style rules with actual font family names
3095 contained in fonts available in a given environment or defined via <a
3096 href="#at-font-face-rule"><code>@font-face</code></a> rules. User agents
3097 must match these names case insensitively, using the "Default Caseless
3098 Matching" algorithm outlined in the Unicode specification <a
3099 href="#UNICODE6" rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This
3100 algorithm is detailed in section 3.13 entitled "Default Case Algorithms".
3101 Specifically, the algorithm must be applied without normalizing the
3102 strings involved and without applying any language-specific tailorings.
3103 The case folding method specified by this algorithm uses the case mappings
3104 with status field ‘<code class=property>C</code>’ or ‘<code
3105 class=property>F</code>’ in the CaseFolding.txt file of the Unicode
3106 Character Database.
3108 <p class=note> Implementors should take care to verify that a given
3109 caseless string comparison implementation uses this precise algorithm and
3110 not assume that a given platform string matching routine follows it, as
3111 many of these have locale-specific behavior or use some level of string
3112 normalization.
3114 <p class=note> For authors this means that font family names are matched
3115 case insensitively, whether those names exist in a platform font or in the
3116 <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
3117 in a stylesheet. Authors should take care to ensure that names use a
3118 character sequence consistent with the actual font family name,
3119 particularly when using combining characters such as diacritical marks.
3120 For example, a family name that contains an uppercase A (U+0041) followed
3121 by a combining ring (U+030A) will <strong>not</strong> match a name that
3122 looks identical but which uses the precomposed lowercase a-ring character
3123 (U+00E5) instead of the combining sequence.
3125 <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
3126 styles</h3>
3128 <p>The procedure for choosing fonts consists of iterating over the font
3129 families determined by the font-family property, selecting a font face
3130 with the appropriate style based on other font properties and then
3131 determining whether a glyph exists for a given character. This is done
3132 using the <dfn id=character-map>character map</dfn> of the font, data
3133 which maps characters to the default glyph for that character. Codepoint
3134 sequences consisting of a base character followed by a sequence of
3135 combining characters are treated slightly differently, see the section on
3136 <a href="#cluster-matching">cluster matching</a> below.
3138 <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
3139 given font family is defined to be the face that would be selected if all
3140 font style properties were set to their initial value.
3142 <ol id=fontmatchingalg>
3143 <li>Using the computed font property values for a given element, the user
3144 agent starts with the first family name in the fontlist specified by the
3145 <a href="#propdef-font-family" title="font-family!!property">‘<code
3146 class=property>font-family</code>’</a> property.
3148 <li>If the family name is unquoted and is a generic family name, the user
3149 agent looks up the appropriate font family name to be used. User agents
3150 may choose the generic font family to use based on the language of the
3151 containing element or the Unicode range of the character.
3153 <li>For other family names, the user agent attempts to find the family
3154 name among fonts defined via <a
3155 href="#at-font-face-rule"><code>@font-face</code></a> rules and then
3156 among available system fonts, matching names with a case-insensitive
3157 comparison as outlined <a href="#font-family-casing">in the section
3158 above</a>. On systems containing fonts with multiple localized font
3159 family names, user agents must match any of these names independent of
3160 the underlying system locale or platform API used. If the font resources
3161 defined for a given face in an <a
3162 href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
3163 available or contain invalid font data, then the face should be treated
3164 as not present in the family. If no faces are present for a family
3165 defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
3166 rules, the family should be treated as missing; matching a platform font
3167 with the same name must not occur in this case.
3169 <li>If a font family match occurs, the user agent assembles the set of
3170 font faces in that family and then narrows the set to a single face using
3171 other font properties in the order given below:
3172 <ol id=fontstylematchingalg>
3173 <li><a href="#propdef-font-stretch"
3174 title="font-stretch!!property">‘<code
3175 class=property>font-stretch</code>’</a> is tried first. If the
3176 matching set contains faces with width values matching the <a
3177 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
3178 class=property>font-stretch</code>’</a> value, faces with other width
3179 values are removed from the matching set. If there is no face that
3180 exactly matches the width value the nearest width is used instead. If
3181 the value of <a href="#propdef-font-stretch"
3182 title="font-stretch!!property">‘<code
3183 class=property>font-stretch</code>’</a> is <a
3184 href="#font-stretch-normal-value" title="normal!!font-stretch">‘<code
3185 class=property>normal</code>’</a> or one of the condensed values,
3186 narrower width values are checked first, then wider values. If the
3187 value of <a href="#propdef-font-stretch"
3188 title="font-stretch!!property">‘<code
3189 class=property>font-stretch</code>’</a> is one of the expanded
3190 values, wider values are checked first, followed by narrower values.
3191 Once the closest matching width has been determined by this process,
3192 faces with other widths are removed from the matching set.
3194 <li><a href="#propdef-font-style" title="font-style!!property">‘<code
3195 class=property>font-style</code>’</a> is tried next. If the value of
3196 <a href="#propdef-font-style" title="font-style!!property">‘<code
3197 class=property>font-style</code>’</a> is ‘<a href="#italic"><code
3198 class=property>italic</code></a>’, italic faces are checked first,
3199 then oblique, then normal faces. If the value is ‘<a
3200 href="#oblique"><code class=property>oblique</code></a>’, oblique
3201 faces are checked first, then italic faces and then normal faces. If
3202 the value is <a href="#font-style-normal-value"
3203 title="normal!!font-style">‘<code
3204 class=property>normal</code>’</a>, normal faces are checked first,
3205 then oblique faces, then italic faces. Faces with other style values
3206 are excluded from the matching set. User agents are permitted to
3207 distinguish between italic and oblique faces within platform font
3208 families but this is not required, they may treat all italic or oblique
3209 faces as italic faces. However, within font families defined via <a
3210 href="#at-font-face-rule"><code>@font-face</code></a> rules, italic and
3211 oblique faces must be distinguished using the value of the <a
3212 href="#descdef-font-style" title="font-style!!descriptor">‘<code
3213 class=property>font-style</code>’</a> descriptor.
3215 <li><a href="#propdef-font-weight"
3216 title="font-weight!!property">‘<code
3217 class=property>font-weight</code>’</a> is matched next, it will
3218 always reduce the matching set to a single font face. If bolder/lighter
3219 relative weights are used, the effective weight is calculated based on
3220 the inherited weight value, as described in the definition of the <a
3221 href="#propdef-font-weight" title="font-weight!!property">‘<code
3222 class=property>font-weight</code>’</a> property. Given the desired
3223 weight and the weights of faces in the matching set after the steps
3224 above, if the desired weight is available that face matches. Otherwise,
3225 a weight is chosen using the rules below:
3226 <ul>
3227 <li>If the desired weight is less than 400, weights below the desired
3228 weight are checked in descending order followed by weights above the
3229 desired weight in ascending order until a match is found.
3231 <li>If the desired weight is greater than 500, weights above the
3232 desired weight are checked in ascending order followed by weights
3233 below the desired weight in descending order until a match is found.
3235 <li>If the desired weight is 400, 500 is checked first and then the
3236 rule for desired weights less than 400 is used.
3238 <li>If the desired weight is 500, 400 is checked first and then the
3239 rule for desired weights less than 400 is used.
3240 </ul>
3242 <li><span class=property>‘<a href="#propdef-font-size"><code
3243 class=property>font-size</code></a>’</span> must be matched within a
3244 UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
3245 are rounded to the nearest whole pixel, while the tolerance for
3246 bitmapped fonts could be as large as 20%.) Further computations, e.g.,
3247 by ‘<code class=property>em</code>’ values in other properties, are
3248 based on the <span class=property>‘<a href="#propdef-font-size"><code
3249 class=property>font-size</code></a>’</span> value that is used, not
3250 the one that is specified.
3251 </ol>
3253 <li>
3254 <p>If no matching face exists or the matched face does not contain a
3255 glyph for the character to be rendered, the next family name is selected
3256 and the previous two steps repeated. Glyphs from other faces in the
3257 family are not considered. The only exception is that user agents may
3258 optionally substitute a synthetic version of the <a
3259 href="#default-face"><em>default face</em></a> if that face supports a
3260 given glyph (e.g. a synthetic italic version of the regular face may be
3261 used if the italic face doesn't support glyphs for Arabic).</p>
3262 <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
3264 <p>If the matched font is defined via an <a
3265 href="#at-font-face-rule"><code>@font-face</code></a> rule and needs to
3266 be downloaded, the font resource is downloaded. While the download
3267 occurs, the user agent can either wait until the font is downloaded or
3268 render once with substituted font metrics and render again once the font
3269 is downloaded.</p>
3271 <li>If there are no more font families to be evaluated and no matching
3272 face has been found, then the user agent performs a <dfn
3273 id=system-font-fallback>system font fallback</dfn> procedure to find the
3274 best match for the character to be rendered. The result of this procedure
3275 may vary across user agents.
3277 <li>If a particular character cannot be displayed using any font, the user
3278 agent should indicate by some means that a character is not being
3279 displayed, displaying either a symbolic representation of the missing
3280 glyph (e.g. using a <a
3281 href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
3282 Font</a>) or using the missing character glyph from a default font.
3283 </ol>
3285 <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
3287 <p>When text contains characters such as combining diacritics, ideally the
3288 base character should be rendered using the same font as the diacritic,
3289 this assures proper placement of the diacritic. For this reason, the font
3290 matching algorithm for clusters is more specialized than the general case
3291 of matching a single character by itself. For sequences containing
3292 variation selectors, which indicate the precise glyph to be used for a
3293 given character, user agents always attempt <a
3294 href="#system-font-fallback"><em>system font fallback</em></a> to find the
3295 appropriate glyph before using the default glyph of the base character.
3297 <p>A font is considered to <em>support</em> a given character if (1) the
3298 character is contained in the font's <a
3299 href="#character-map"><em>character map</em></a> and (2) if required by
3300 the containing script, shaping information is available for that
3301 character. Some legacy fonts may include a given character in the <a
3302 href="#character-map"><em>character map</em></a> but lack the shaping
3303 information (e.g. <a
3304 href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
3305 layout tables</a> or <a
3306 href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&item_id=graphite_techAbout">Graphite
3307 tables</a>) necessary for correctly rendering text runs containing that
3308 character.
3310 <p>A sequence of codepoints containing combining diacritics or other
3311 modifiers is termed a grapheme cluster (see <a href="#CSS3TEXT"
3312 rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
3313 description). For a given cluster containing a base character, <em>b</em>
3314 and a sequence of combining characters <em>c1, c2…</em>, the entire
3315 cluster is matched using these steps:
3317 <ol>
3318 <li>For each family in the font list, a face is chosen using the style
3319 selection rules defined in the previous section.
3320 <ol>
3321 <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
3322 completely supported by the font, select this font for the sequence.
3324 <li>If a sequence of multiple codepoints is canonically equivalent to a
3325 single character and the font supports that character, select this font
3326 for the sequence.
3327 </ol>
3329 <li>If no font was found in the font list in step 1:
3330 <ol>
3331 <li>If <em>c1</em> is a variation selector, system fallback must be used
3332 to find a font that supports the full sequence of <em>b + c1</em>. If
3333 no font on the system supports the full sequence, match the single
3334 character <em>b</em> using the normal procedure for matching single
3335 characters and ignore the variation selector. Note: a sequence with
3336 more than one variation selector is treated as an encoding error and
3337 the trailing selectors are ignored.
3339 <li>Otherwise, the user agent may optionally use system font fallback to
3340 match a font that supports the entire cluster.
3341 </ol>
3343 <li>If no font is found in step 2, use the matching sequence from step 1
3344 to determine the longest sequence that is completely matched by a font in
3345 the font list and attempt to match the remaining combining characters
3346 separately using the rules for single characters.
3347 </ol>
3349 <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
3350 issues</h3>
3352 <p>The procedure above is always performed on text runs containing Unicode
3353 characters, documents using legacy encodings are assumed to have been
3354 transcoded before matching fonts. For fonts containing <a
3355 href="#character-map"><em title="character map">character maps</em></a>
3356 for both legacy encodings and Unicode, the contents of the legacy encoding
3357 <a href="#character-map"><em>character map</em></a> must have no effect on
3358 the results of the font matching process.
3360 <p>The font matching process does not assume that text runs are in either
3361 normalized or denormalized form (see <a href="#CHARMOD-NORM"
3362 rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
3363 details). Layout engines often convert base character plus combining
3364 character sequences into precomposed characters if they exist. The font
3365 matching algorithm outlined here supports both ways and fonts can
3366 generally support either but variations can occur. Authors should always
3367 tailor their choice of fonts to their content, including whether that
3368 content contains normalized or denormalized character streams.
3370 <p>If a given character is a Private-Use Area Unicode codepoint and none of
3371 the fonts in the fontlist contain a glyph for that codepoint, user agents
3372 must display some form of missing glyph symbol for that character rather
3373 than attempting <a href="#system-font-fallback"><em>system font
3374 fallback</em></a> for that codepoint. When matching the replacement
3375 character U+FFFD, user agents may skip the font matching process and
3376 immediately display some form of missing glyph symbol, they are not
3377 required to display the glyph from the font that would be selected by the
3378 font matching process.
3380 <p>In general, the fonts for a given family will all have the same or
3381 similar <a href="#character-map"><em title="character map">character
3382 maps</em></a>. The process outlined here is designed to handle even font
3383 families containing faces with widely variant <a href="#character-map"><em
3384 title="character map">character maps</em></a>. However, authors are
3385 cautioned that the use of such families can lead to unexpected results.
3387 <p>Optimizations of this process are allowed provided that an
3388 implementation behaves as if the algorithm had been followed exactly.
3389 Matching occurs in a well-defined order to insure that the results are as
3390 consistent as possible across user agents, given an identical set of
3391 available fonts and rendering technology.
3393 <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
3394 changes since CSS 2.1</h3>
3396 <p>The algorithm above is different from CSS 2.1 in a number of key places.
3397 These changes were made to better reflect actual font matching behavior
3398 across user agent implementations.
3400 <p>Differences compared to the font matching algorithm in CSS 2.1:
3402 <ul>
3403 <li>The algorithm includes font-stretch matching.
3405 <li>All possible font-style matching scenarios are delineated.
3407 <li>Small-caps fonts are not matched as part of the font matching process,
3408 they are now handled via font features.
3410 <li>Unicode variation selector matching is required.
3412 <li>Cluster sequences are matched as a unit.
3413 </ul>
3415 <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
3416 examples</h3>
3418 <div class=example>
3419 <p>It's useful to note that the CSS selector syntax may be used to create
3420 language-sensitive typography. For example, some Chinese and Japanese
3421 characters are unified to have the same Unicode code point, although the
3422 abstract glyphs are not the same in the two languages.
3424 <pre>*:lang(ja-jp) { font: 900 14pt/16pt "Heisei Mincho W9", serif; }
3425 *:lang(zh-tw) { font: 800 14pt/16.5pt "Li Sung", serif; }
3426 </pre>
3428 <p>This selects any element that has the given language - Japanese or
3429 Traditional Chinese - and uses the appropriate font.
3430 </div>
3432 <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
3434 <p>Modern font technologies support a variety of advanced typographic and
3435 language-specific font features. Using these features, a single font can
3436 provide glyphs for a wide range of ligatures, contextual and stylistic
3437 alternates, tabular and old-style figures, small capitals, automatic
3438 fractions, swashes, and alternates specific to a given language. To allow
3439 authors control over these font capabilities, the ‘<code
3440 class=property>font-variant</code>’ property has been expanded for CSS3.
3441 It now functions as a shorthand for a set of properties that provide
3442 control over stylistic font features.
3444 <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
3445 selection and positioning</h3>
3447 <p>Simple fonts used for displaying Latin text use a very basic processing
3448 model. Fonts contain a <a href="#character-map"><em>character map</em></a>
3449 which maps each character to a glyph for that character. Glyphs for
3450 subsequent characters are simply placed one after the other along a run of
3451 text. Modern font formats such as OpenType and AAT (Apple Advanced
3452 Typography) use a richer processing model. The glyph for a given character
3453 can be chosen and positioned not just based on the codepoint of the
3454 character itself, but also on adjacent characters as well as the language,
3455 script, and features enabled for the text. Font features may be required
3456 for specific scripts, or recommended as enabled by default or they might
3457 be stylistic features meant to be used under author control.
3459 <p>For a good visual overview of these features, see the <a
3460 href="#OPENTYPE-FONT-GUIDE"
3461 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
3462 For a detailed description of glyph processing for OpenType fonts, see <a
3463 href="#WINDOWS-GLYPH-PROC"
3464 rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
3466 <p>Stylistic font features can be classified into two broad categories:
3467 ones that affect the harmonization of glyph shapes with the surrounding
3468 context, such as kerning and ligature features, and ones such as the
3469 small-caps, subscript/superscript and alternate features that affect shape
3470 selection.
3472 <p>The subproperties of <a href="#propdef-font-variant"
3473 title="font-variant!!property">‘<code
3474 class=property>font-variant</code>’</a> listed below are used to control
3475 these stylistic font features. They do not control features that are
3476 required for displaying certain scripts, such as the OpenType features
3477 used when displaying Arabic or Indic language text. They affect glyph
3478 selection and positioning, but do not affect font selection as described
3479 in the font matching section (except in cases required for compatibility
3480 with CSS 2.1).
3482 <p>To assure consistent behavior across user agents, the equivalent
3483 OpenType property settings are listed for individual properties and are
3484 normative. When using other font formats these should be used as a
3485 guideline to map CSS font feature property values to specific font
3486 features.
3488 <h3 id=language-specific-support><span class=secno>6.2
3489 </span>Language-specific display</h3>
3491 <p>OpenType also supports language-specific glyph selection and
3492 positioning, so that text can be displayed correctly in cases where the
3493 language dictates a specific display behavior. Many languages share a
3494 common script, but the shape of certain letters can vary across those
3495 languages. For example, certain Cyrillic letters have different shapes in
3496 Russian text than in Bulgarian. In Latin text, it's common to render "fi"
3497 with an explicit fi-ligature that lacks a dot on the "i". However, in
3498 languages such as Turkish which uses both a dotted-i and a dotless-i, it's
3499 important to not use this ligature or use a specialized version that
3500 contains a dot over the "i". The example below shows language-specific
3501 variations based on stylistic traditions found in Spanish, Italian and
3502 French orthography:
3504 <div class=featex><img alt="language specific forms, spanish"
3505 src=locl-1.png></div>
3507 <div class=featex><img alt="language specific forms, italian"
3508 src=locl-2.png></div>
3510 <div class=featex><img alt="language specific forms, french"
3511 src=locl-3.png></div>
3513 <p>If the content language of the element is known according to the rules
3514 of the <a
3515 href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
3516 language</a>, user agents are required to infer the OpenType language
3517 system from the content language and use that when selecting and
3518 positioning glyphs using an OpenType font.
3520 <p>For OpenType fonts, in some cases it may be necessary to explicitly
3521 declare the OpenType language to be used, for example when displaying text
3522 in a given language that uses the typographic conventions of another
3523 language or when the font does not explicitly support a given language but
3524 supports a language that shares common typographic conventions. The ‘<a
3525 href="#propdef-font-language-override"><code
3526 class=property>font-language-override</code></a>’ property is used for
3527 this purpose.</p>
3528 <!-- prop: font-kerning -->
3530 <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
3531 href="#propdef-font-kerning">font-kerning</a> property</h3>
3533 <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
3534 <tbody>
3535 <tr>
3536 <td>Name:
3538 <td><dfn id=propdef-font-kerning>font-kerning</dfn>
3540 <tr>
3541 <td>Value:
3543 <td><a href="#font-kerning-auto-value"
3544 title="auto!!font-kerning">auto</a> | <a
3545 href="#font-kerning-normal-value"
3546 title="normal!!font-kerning">normal</a> | <a
3547 href="#font-kerning-none-value" title="none!!font-kerning">none</a>
3549 <tr>
3550 <td>Initial:
3552 <td>auto
3554 <tr>
3555 <td>Applies to:
3557 <td>all elements
3559 <tr>
3560 <td>Inherited:
3562 <td>yes
3564 <tr>
3565 <td>Percentages:
3567 <td>N/A
3569 <tr>
3570 <td>Media:
3572 <td>visual
3574 <tr>
3575 <td>Computed value:
3577 <td>as specified
3579 <tr>
3580 <td>Animatable:
3582 <td>no
3583 </table>
3585 <p>Kerning is the contextual adjustment of inter-glyph spacing. This
3586 property controls metric kerning, kerning that utilizes adjustment data
3587 contained in the font.
3589 <dl>
3590 <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
3592 <dd>Specifies that kerning is applied at the discretion of the user agent
3594 <dt><dfn id=font-kerning-normal-value
3595 title="normal!!font-kerning">normal</dfn>
3597 <dd>Specifies that kerning is applied
3599 <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
3601 <dd>Specifies that kerning is not applied
3602 </dl>
3604 <p>For fonts that do not include kerning data this property will have no
3605 visible effect. When rendering with OpenType fonts, the <a
3606 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
3607 specification suggests that kerning be enabled by default. When kerning is
3608 enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
3609 vertical text runs the <span class=tag>vkrn</span> feature is enabled
3610 instead). User agents must also support fonts that only support kerning
3611 via data contained in a <span class=tag>kern</span> font table, as
3612 detailed in the OpenType specification. If the ‘<code
3613 class=property>letter-spacing</code>’ property is defined, kerning
3614 adjustments are considered part of the default spacing and letter spacing
3615 adjustments are made after kerning has been applied.
3617 <p>When set to ‘<code class=property>auto</code>’, user agents can
3618 determine whether to apply kerning or not based on a number of factors:
3619 text size, script, or other factors that influence text processing speed.
3620 Authors who want proper kerning should use <a
3621 href="#font-kerning-normal-value" title="normal!!font-kerning">‘<code
3622 class=property>normal</code>’</a> to explicitly enable kerning.
3623 Likewise, some authors may prefer to disable kerning in situations where
3624 performance is more important than precise appearance. However, in
3625 well-designed modern implementations the use of kerning generally does not
3626 have a large impact on text rendering speed.</p>
3627 <!-- prop: font-variant-ligatures -->
3629 <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
3630 the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
3631 property</h3>
3633 <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
3634 <tbody>
3635 <tr>
3636 <td>Name:
3638 <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
3640 <tr>
3641 <td>Value:
3643 <td><a href="#font-variant-ligatures-normal-value"
3644 title="normal!!font-variant-ligatures">normal</a> | <a
3645 href="#font-variant-ligatures-none-value"
3646 title="none!!font-variant-ligatures">none</a> | [ <a
3647 href="#common-lig-values"><var><common-lig-values></var></a> ||
3648 <a
3649 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
3650 || <a
3651 href="#historical-lig-values"><var><historical-lig-values></var></a>
3652 || <a
3653 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
3654 ]
3656 <tr>
3657 <td>Initial:
3659 <td>normal
3661 <tr>
3662 <td>Applies to:
3664 <td>all elements
3666 <tr>
3667 <td>Inherited:
3669 <td>yes
3671 <tr>
3672 <td>Percentages:
3674 <td>N/A
3676 <tr>
3677 <td>Media:
3679 <td>visual
3681 <tr>
3682 <td>Computed value:
3684 <td>as specified
3686 <tr>
3687 <td>Animatable:
3689 <td>no
3690 </table>
3692 <p>Ligatures and contextual forms are ways of combining glyphs to produce
3693 more harmonized forms.
3695 <pre
3696 class=prod><dfn id=common-lig-values><var><common-lig-values></var></dfn> = [ <a href="#common-ligatures">common-ligatures</a> | <a href="#no-common-ligatures">no-common-ligatures</a> ]</pre>
3698 <pre
3699 class=prod><dfn id=discretionary-lig-values><var><discretionary-lig-values></var></dfn> = [ <a href="#discretionary-ligatures">discretionary-ligatures</a> | <a href="#no-discretionary-ligatures">no-discretionary-ligatures</a> ]</pre>
3701 <pre
3702 class=prod><dfn id=historical-lig-values><var><historical-lig-values></var></dfn> = [ <a href="#historical-ligatures">historical-ligatures</a> | <a href="#no-historical-ligatures">no-historical-ligatures</a> ]</pre>
3704 <pre
3705 class=prod><dfn id=contextual-alt-values><var><contextual-alt-values></var></dfn> = [ <a href="#contextual">contextual</a> | <a href="#no-contextual">no-contextual</a> ]</pre>
3707 <p>Individual values have the following meanings:
3709 <dl>
3710 <dt><dfn id=font-variant-ligatures-normal-value
3711 title="normal!!font-variant-ligatures">normal</dfn>
3713 <dd>A value of <a href="#font-variant-ligatures-normal-value"
3714 title="normal!!font-variant-ligatures">‘<code
3715 class=property>normal</code>’</a> specifies that common default
3716 features are enabled, <a href="#font-feature-resolution">as described in
3717 detail in the next section</a>. For OpenType fonts, common ligatures and
3718 contextual forms are on by default, discretionary and historical
3719 ligatures are not.
3721 <dt><dfn id=font-variant-ligatures-none-value
3722 title="none!!font-variant-ligatures">none</dfn>
3724 <dd>Specifies that all types of ligatures and contextual forms covered by
3725 this property are explicitly disabled. In situations where ligatures are
3726 not considered necessary, this may improve the speed of text rendering.
3728 <dt><dfn id=common-ligatures>common-ligatures</dfn>
3730 <dd>Enables display of common ligatures (OpenType features: <span
3731 class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
3732 enabled by default.
3733 </dl>
3735 <div class=featex><img alt="common ligature example" src=liga.png></div>
3737 <dl>
3738 <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
3740 <dd>Disables display of common ligatures (OpenType features: <span
3741 class=tag>liga, clig</span>).
3743 <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
3745 <dd>Enables display of discretionary ligatures (OpenType feature: <span
3746 class=tag>dlig</span>). Which ligatures are discretionary or optional is
3747 decided by the type designer, so authors will need to refer to the
3748 documentation of a given font to understand which ligatures are
3749 considered discretionary.
3750 </dl>
3752 <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
3754 <dl>
3755 <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
3757 <dd>Disables display of discretionary ligatures (OpenType feature: <span
3758 class=tag>dlig</span>).
3760 <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
3762 <dd>Enables display of historical ligatures (OpenType feature: <span
3763 class=tag>hlig</span>).
3764 </dl>
3766 <div class=featex><img alt="historical ligature example" src=hlig.png></div>
3768 <dl>
3769 <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
3771 <dd>Disables display of historical ligatures (OpenType feature: <span
3772 class=tag>hlig</span>).
3774 <dt><dfn id=contextual>contextual</dfn>
3776 <dd>Enables display of contextual alternates (OpenType feature: <span
3777 class=tag>calt</span>). Although not strictly a ligature feature, like
3778 ligatures this feature is commonly used to harmonize the shapes of glyphs
3779 with the surrounding context. For OpenType fonts, this feature is on by
3780 default.
3781 </dl>
3783 <div class=featex><img alt="contextual alternate example" src=calt.png></div>
3785 <dl>
3786 <dt><dfn id=no-contextual>no-contextual</dfn>
3788 <dd>Disables display of contextual alternates (OpenType feature: <span
3789 class=tag>calt</span>).
3790 </dl>
3792 <p>Required ligatures, needed for correctly rendering complex scripts, are
3793 not affected by the settings above, including ‘<code
3794 class=property>none</code>’ (OpenType feature: <span
3795 class=tag>rlig</span>).</p>
3796 <!-- prop: font-variant-position -->
3798 <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
3799 and superscript forms: the <a
3800 href="#propdef-font-variant-position">font-variant-position</a> property</h3>
3802 <table class=propdef id=namefont-variant-positionvaluenormal-sub>
3803 <tbody>
3804 <tr>
3805 <td>Name:
3807 <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
3809 <tr>
3810 <td>Value:
3812 <td><a href="#font-variant-position-normal-value"
3813 title="normal!!font-variant-position">normal</a> | <a
3814 href="#sub">sub</a> | <a href="#super">super</a>
3816 <tr>
3817 <td>Initial:
3819 <td>normal
3821 <tr>
3822 <td>Applies to:
3824 <td>all elements
3826 <tr>
3827 <td>Inherited:
3829 <td>yes
3831 <tr>
3832 <td>Percentages:
3834 <td>N/A
3836 <tr>
3837 <td>Media:
3839 <td>visual
3841 <tr>
3842 <td>Computed value:
3844 <td>as specified
3846 <tr>
3847 <td>Animatable:
3849 <td>no
3850 </table>
3852 <p>This property is used to enable typographic subscript and superscript
3853 glyphs. These are alternate glyphs designed within the same em-box as
3854 default glyphs and are intended to be laid out on the same baseline as the
3855 default glyphs, with no resizing or repositioning of the baseline. They
3856 are explicitly designed to match the surrounding text and to be more
3857 readable without affecting the line height.
3859 <div class=figure><img alt="comparison between real subscript glyphs and
3860 synthesized ones" src=realsubscripts.png>
3861 <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
3862 (bottom)
3863 </div>
3865 <p>Individual values have the following meanings:
3867 <dl>
3868 <dt><dfn id=font-variant-position-normal-value
3869 title="normal!!font-variant-position">normal</dfn>
3871 <dd>None of the features listed below are enabled.
3873 <dt><dfn id=sub>sub</dfn>
3875 <dd>Enables display of subscript variants (OpenType feature: <span
3876 class=tag>subs</span>).
3878 <dt><dfn id=super>super</dfn>
3880 <dd>Enables display of superscript variants (OpenType feature: <span
3881 class=tag>sups</span>).
3882 </dl>
3884 <p>Because of the semantic nature of subscripts and superscripts, when the
3885 value is either ‘<a href="#sub"><code class=property>sub</code></a>’
3886 or ‘<a href="#super"><code class=property>super</code></a>’ for a
3887 given contiguous run of text, if a variant glyph is not available for all
3888 the characters in the run, simulated glyphs must be synthesized for all
3889 characters using reduced forms of the glyphs that would be used without
3890 this feature applied. This is done per run to avoid a mixture of variant
3891 glyphs and synthesized ones that would not align correctly. In the case of
3892 OpenType fonts that lack subscript or superscript glyphs for a given
3893 character, user agents must use the appropriate subscript and superscript
3894 metrics specified in the selected font's <a
3895 href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
3896 table</a> <a href="#OPENTYPE"
3897 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
3898 and offset of the synthesized substitutes.
3900 <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
3901 using superscript metrics" src=superscript-alt-synth.png>
3902 <p class=caption>Superscript alternate glyph (left), synthesized
3903 superscript glyphs (middle), and incorrect mixture of the two (right)
3904 </div>
3906 <p>In the past, user agents have used font-size and vertical-align to
3907 simulate subscripts and superscripts for the <code title="HTML sub
3908 element">sub</code> and <code title="HTML sup element">sup</code>
3909 elements. To allow a backwards compatible way of defining subscripts and
3910 superscripts, it is recommended that authors use conditional rules <a
3911 href="#CSS3-CONDITIONAL"
3912 rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
3913 older user agents will still render subscripts and superscripts via the
3914 older mechanism.
3916 <p>Authors should note that fonts typically only provide subscript and
3917 superscript glyphs for a subset of all characters supported by the font.
3918 For example, while subscript and superscript glyphs are often available
3919 for Latin numbers, glyphs for punctuation and letter characters are less
3920 frequently provided. The synthetic fallback rules defined for this
3921 property assure that subscripts and superscripts will always appear but
3922 the appearance may not match author expectations if the font used does not
3923 provide the appropriate alternate glyph for all characters contained in a
3924 subscript or superscript.
3926 <p>This property is not cumulative. Applying it to elements within a
3927 subscript or superscript won't nest the placement of a subscript or
3928 superscript glyph. Images contained within text runs where the value of
3929 this property is ‘<a href="#sub"><code class=property>sub</code></a>’
3930 or ‘<a href="#super"><code class=property>super</code></a>’ will be
3931 drawn just as they would if the value was <a
3932 href="#font-variant-position-normal-value"
3933 title="normal!!font-variant-position">‘<code
3934 class=property>normal</code>’</a>.</p>
3935 <!-- due to lack of consensus, couldn't resolve on exact positioning of text decorations:
3936 http://www.w3.org/2013/06/06-css-minutes.html#item03 -->
3938 <p>Because of these limitations, ‘<a
3939 href="#propdef-font-variant-position"><code
3940 class=property>font-variant-position</code></a>’ is not recommended for
3941 use in user agent stylesheets. Authors should use it in cases where
3942 subscripts or superscripts will only contain the narrow range of
3943 characters supported by the fonts specified.
3945 <p class=note>The variant glyphs use the same baseline as the default
3946 glyphs would use. There is no shift in the placement along the baseline,
3947 so the use of variant glyphs doesn't affect the height of the inline box
3948 or alter the height of the linebox. This makes superscript and subscript
3949 variants ideal for situations where it's important that leading remain
3950 constant, such as in multi-column layout.
3952 <div class=example>
3953 <p>A typical user agent default style for the <a class=tag
3954 href="#sub">sub</a> element:</p>
3956 <pre>sub {
3957 vertical-align: sub;
3958 font-size: smaller;
3959 line-height: normal;
3960 }
3961 </pre>
3963 <p>Using font-variant-position to specify typographic subscripts in a way
3964 that will still show subscripts in older user agents:</p>
3966 <pre>@supports ( font-variant-position: sub ) {
3968 sub {
3969 vertical-align: baseline;
3970 font-size: 100%;
3971 line-height: inherit;
3972 font-variant-position: sub;
3973 }
3975 }
3976 </pre>
3978 <p>User agents that support the ‘<a
3979 href="#propdef-font-variant-position"><code
3980 class=property>font-variant-position</code></a>’ property will select a
3981 subscript variant glyph and render this without adjusting the baseline or
3982 font-size. Older user agents will ignore the ‘<a
3983 href="#propdef-font-variant-position"><code
3984 class=property>font-variant-position</code></a>’ property definition
3985 and use the standard defaults for subscripts.</p>
3986 </div>
3987 <!-- prop: font-variant-caps -->
3989 <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
3990 the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
3992 <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
3993 <tbody>
3994 <tr>
3995 <td>Name:
3997 <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
3999 <tr>
4000 <td>Value:
4002 <td><a href="#font-variant-caps-normal-value"
4003 title="normal!!font-variant-caps">normal</a> | <a
4004 href="#small-caps">small-caps</a> | <a
4005 href="#all-small-caps">all-small-caps</a> | <a
4006 href="#petite-caps">petite-caps</a> | <a
4007 href="#all-petite-caps">all-petite-caps</a> | <a
4008 href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
4010 <tr>
4011 <td>Initial:
4013 <td>normal
4015 <tr>
4016 <td>Applies to:
4018 <td>all elements
4020 <tr>
4021 <td>Inherited:
4023 <td>yes
4025 <tr>
4026 <td>Percentages:
4028 <td>N/A
4030 <tr>
4031 <td>Media:
4033 <td>visual
4035 <tr>
4036 <td>Computed value:
4038 <td>as specified
4040 <tr>
4041 <td>Animatable:
4043 <td>no
4044 </table>
4046 <p>This property allows the selection of alternate glyphs used for small or
4047 petite capitals or for titling. These glyphs are specifically designed to
4048 blend well with the surrounding normal glyphs, to maintain the weight and
4049 readability which suffers when text is simply resized to fit this purpose.
4051 <p>Individual values have the following meanings:
4053 <dl>
4054 <dt><dfn id=font-variant-caps-normal-value
4055 title="normal!!font-variant-caps">normal</dfn>
4057 <dd>None of the features listed below are enabled.
4059 <dt><dfn id=small-caps>small-caps</dfn>
4061 <dd>Enables display of small capitals (OpenType feature: <span
4062 class=tag>smcp</span>). Small-caps glyphs typically use the form of
4063 uppercase letters but are reduced to the size of lowercase letters.
4064 </dl>
4066 <div class=featex><img alt="small-caps example" src=smcp.png></div>
4068 <dl>
4069 <dt><dfn id=all-small-caps>all-small-caps</dfn>
4071 <dd>Enables display of small capitals for both upper and lowercase letters
4072 (OpenType features: <span class=tag>c2sc, smcp</span>).
4074 <dt><dfn id=petite-caps>petite-caps</dfn>
4076 <dd>Enables display of petite capitals (OpenType feature: <span
4077 class=tag>pcap</span>).
4079 <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
4081 <dd>Enables display of petite capitals for both upper and lowercase
4082 letters (OpenType features: <span class=tag>c2pc, pcap</span>).
4084 <dt><dfn id=unicase>unicase</dfn>
4086 <dd>Enables display of mixture of small capitals for uppercase letters
4087 with normal lowercase letters (OpenType feature: <span
4088 class=tag>unic</span>).
4090 <dt><dfn id=titling-caps>titling-caps</dfn>
4092 <dd>Enables display of titling capitals (OpenType feature: <span
4093 class=tag>titl</span>). Uppercase letter glyphs are often designed for
4094 use with lowercase letters. When used in all uppercase titling sequences
4095 they can appear too strong. Titling capitals are designed specifically
4096 for this situation.
4097 </dl>
4099 <p>The availability of these glyphs is based on whether a given feature is
4100 defined or not in the feature list of the font. User agents can optionally
4101 decide this on a per-script basis but should explicitly not decide this on
4102 a per-character basis.
4104 <p>Some fonts may only support a subset or none of the features described
4105 for this property. For backwards compatibility with CSS 2.1, if ‘<a
4106 href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
4107 href="#all-small-caps"><code class=property>all-small-caps</code></a>’
4108 is specified but small-caps glyphs are not available for a given font,
4109 user agents should simulate a small-caps font, for example by taking a
4110 normal font and replacing the glyphs for lowercase letters with scaled
4111 versions of the glyphs for uppercase characters (replacing the glyphs for
4112 both upper and lowercase letters in the case of ‘<a
4113 href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
4115 <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
4116 real small-caps" class=hires src=synthetic-vs-real-small-caps.png
4117 width=512px>
4118 <p class=caption>Synthetic vs. real small-caps
4119 </div>
4121 <p>To match the surrounding text, a font may provide alternate glyphs for
4122 caseless characters when these features are enabled but when a user agent
4123 simulates small capitals, it must not attempt to simulate alternates for
4124 codepoints which are considered caseless.
4126 <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
4127 characters with small-caps, all-small-caps enabled" class=hires
4128 src=small-capitals-variations.png width=418px>
4129 <p class=caption>Caseless characters with small-caps, all-small-caps
4130 enabled
4131 </div>
4133 <p>If either ‘<a href="#petite-caps"><code
4134 class=property>petite-caps</code></a>’ or ‘<a
4135 href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
4136 is specified for a font that doesn't support these features, the property
4137 behaves as if ‘<a href="#small-caps"><code
4138 class=property>small-caps</code></a>’ or ‘<a
4139 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4140 respectively, had been specified. If ‘<a href="#unicase"><code
4141 class=property>unicase</code></a>’ is specified for a font that doesn't
4142 support that feature, the property behaves as if ‘<a
4143 href="#small-caps"><code class=property>small-caps</code></a>’ was
4144 applied only to lowercased uppercase letters. If ‘<a
4145 href="#titling-caps"><code class=property>titling-caps</code></a>’ is
4146 specified with a font that does not support this feature, this property
4147 has no visible effect. When simulated small capital glyphs are used, for
4148 scripts that lack uppercase and lowercase letters, ‘<a
4149 href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
4150 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4151 ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
4152 ‘<a href="#all-petite-caps"><code
4153 class=property>all-petite-caps</code></a>’ and ‘<a
4154 href="#unicase"><code class=property>unicase</code></a>’ have no visible
4155 effect.
4157 <p>When casing transforms are used to simulate small capitals, the casing
4158 transformations must match those used for the <span
4159 class=property>‘<code class=property>text-transform</code>’</span>
4160 property.
4162 <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
4163 replace glyphs in a small-caps font so that the text appears in all
4164 uppercase letters.
4166 <div class=figure style="padding: 0; margin: auto;"><img alt="using
4167 all-small-caps in acronym-laden text" class=hires
4168 src=acronym-laden-text.png width=596px>
4169 <p class=caption>Using small capitals to improve readability in
4170 acronym-laden text
4171 </div>
4173 <div class=example>
4174 <p>Quotes rendered italicised, with small-caps on the first line:</p>
4176 <pre>blockquote { font-style: italic; }
4177 blockquote:first-line { font-variant: small-caps; }
4179 <blockquote><a href="http://lists.w3.org/Archives/Public/www-style/2009Dec/0036.html" style="text-decoration: none">I'll be honor-bound to slap them like a haddock.</a></blockquote>
4180 </pre>
4181 </div>
4182 <!-- prop: font-variant-numeric -->
4184 <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
4185 formatting: the <a
4186 href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
4188 <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
4189 <tbody>
4190 <tr>
4191 <td>Name:
4193 <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
4195 <tr>
4196 <td>Value:
4198 <td><a href="#font-variant-numeric-normal-value"
4199 title="normal!!font-variant-numeric">normal</a> | [ <a
4200 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
4201 || <a
4202 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
4203 || <a
4204 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
4205 || <a href="#ordinal">ordinal</a> || <a
4206 href="#slashed-zero">slashed-zero</a> ]
4208 <tr>
4209 <td>Initial:
4211 <td>normal
4213 <tr>
4214 <td>Applies to:
4216 <td>all elements
4218 <tr>
4219 <td>Inherited:
4221 <td>yes
4223 <tr>
4224 <td>Percentages:
4226 <td>N/A
4228 <tr>
4229 <td>Media:
4231 <td>visual
4233 <tr>
4234 <td>Computed value:
4236 <td>as specified
4238 <tr>
4239 <td>Animatable:
4241 <td>no
4242 </table>
4244 <p>Specifies control over numerical forms. The example below shows how some
4245 of these values can be combined to influence the rendering of tabular data
4246 with fonts that support these features. Within normal paragraph text,
4247 proportional numbers are used while tabular numbers are used so that
4248 columns of numbers line up properly:
4250 <div class=figure style="padding: 0; margin: auto;"><img alt="combining
4251 number styles" src=numberstyles.png>
4252 <p class=caption>Using number styles
4253 </div>
4255 <p>Possible combinations:
4257 <pre
4258 class=prod><dfn id=numeric-figure-values><var><numeric-figure-values></var></dfn> = [ <a href="#lining-nums">lining-nums</a> | <a href="#oldstyle-nums">oldstyle-nums</a> ]</pre>
4260 <pre
4261 class=prod><dfn id=numeric-spacing-values><var><numeric-spacing-values></var></dfn> = [ <a href="#proportional-nums">proportional-nums</a> | <a href="#tabular-nums">tabular-nums</a> ]</pre>
4263 <pre
4264 class=prod><dfn id=numeric-fraction-values><var><numeric-fraction-values></var></dfn> = [ <a href="#diagonal-fractions">diagonal-fractions</a> | <a href="#stacked-fractions">stacked-fractions</a> ]</pre>
4266 <p>Individual values have the following meanings:
4268 <dl>
4269 <dt><dfn id=font-variant-numeric-normal-value
4270 title="normal!!font-variant-numeric">normal</dfn>
4272 <dd>None of the features listed below are enabled.
4274 <dt><dfn id=lining-nums>lining-nums</dfn>
4276 <dd>Enables display of lining numerals (OpenType feature: <span
4277 class=tag>lnum</span>).
4279 <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
4281 <dd>Enables display of old-style numerals (OpenType feature: <span
4282 class=tag>onum</span>).
4284 <dt><dfn id=proportional-nums>proportional-nums</dfn>
4286 <dd>Enables display of proportional numerals (OpenType feature: <span
4287 class=tag>pnum</span>).
4289 <dt><dfn id=tabular-nums>tabular-nums</dfn>
4291 <dd>Enables display of tabular numerals (OpenType feature: <span
4292 class=tag>tnum</span>).
4294 <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
4296 <dd>Enables display of lining diagonal fractions (OpenType feature: <span
4297 class=tag>frac</span>).
4298 </dl>
4300 <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
4302 <dl>
4303 <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
4305 <dd>Enables display of lining stacked fractions (OpenType feature: <span
4306 class=tag>afrc</span>).
4307 </dl>
4309 <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
4311 <dl>
4312 <dt><dfn id=ordinal>ordinal</dfn>
4314 <dd>Enables display of forms used with ordinal numbers (OpenType feature:
4315 <span class=tag>ordn</span>).
4317 <dt><dfn id=slashed-zero>slashed-zero</dfn>
4319 <dd>Enables display of slashed zeros (OpenType feature: <span
4320 class=tag>zero</span>).
4321 </dl>
4323 <div class=featex><img alt="slashed zero example" src=zero.png></div>
4325 <div class=example id=steak-marinade>
4326 <p>A simple flank steak marinade recipe, rendered with automatic fractions
4327 and old-style numerals:</p>
4329 <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
4331 <h4>Steak marinade:</h4>
4332 <ul>
4333 <li><span class="amount">2</span> tbsp olive oil</li>
4334 <li><span class="amount">1</span> tbsp lemon juice</li>
4335 <li><span class="amount">1</span> tbsp soy sauce</li>
4336 <li><span class="amount">1 1/2</span> tbsp dry minced onion</li>
4337 <li><span class="amount">2 1/2</span> tsp italian seasoning</li>
4338 <li>Salt &amp; pepper</li>
4339 </ul>
4341 <p>Mix the meat with the marinade and let it sit covered in the refrigerator
4342 for a few hours or overnight.</p>
4343 </pre>
4345 <p>Note that the fraction feature is only applied to values not the entire
4346 paragraph. Fonts often implement this feature using contextual rules
4347 based on the use of the slash (‘<code class=css>/</code>’) character.
4348 As such, it's not suitable for use as a paragraph-level style.</p>
4349 </div>
4350 <!-- prop: font-variant-alternates -->
4352 <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
4353 and swashes: the <a
4354 href="#propdef-font-variant-alternates">font-variant-alternates</a>
4355 property</h3>
4357 <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
4358 <tbody>
4359 <tr>
4360 <td>Name:
4362 <td><dfn
4363 id=propdef-font-variant-alternates>font-variant-alternates</dfn>
4365 <tr>
4366 <td>Value:
4368 <td>normal | [ <a href="#stylistic"
4369 title=stylistic>stylistic(<feature-value-name>)</a> || <a
4370 href="#historical-forms">historical-forms</a> || <a href="#styleset"
4371 title=styleset>styleset(<feature-value-name> #)</a> || <a
4372 href="#character-variant"
4373 title=character-variant>character-variant(<feature-value-name>
4374 #)</a> || <a href="#swash"
4375 title=swash>swash(<feature-value-name>)</a> || <a
4376 href="#ornaments"
4377 title=ornaments>ornaments(<feature-value-name>)</a> || <a
4378 href="#annotation"
4379 title=annotation>annotation(<feature-value-name>)</a> ]
4381 <tr>
4382 <td>Initial:
4384 <td>normal
4386 <tr>
4387 <td>Applies to:
4389 <td>all elements
4391 <tr>
4392 <td>Inherited:
4394 <td>yes
4396 <tr>
4397 <td>Percentages:
4399 <td>N/A
4401 <tr>
4402 <td>Media:
4404 <td>visual
4406 <tr>
4407 <td>Computed value:
4409 <td>as specified
4411 <tr>
4412 <td>Animatable:
4414 <td>no
4415 </table>
4417 <p>For any given character, fonts can provide a variety of alternate glyphs
4418 in addition to the default glyph for that character. This property
4419 provides control over the selection of these alternate glyphs.
4421 <p>For many of the property values listed below, several different
4422 alternate glyphs are available. How many alternates are available and what
4423 they represent is font-specific, so these are each marked <dfn
4424 id=font-specific>font specific</dfn> in the value definitions below.
4425 Because the nature of these alternates is font-specific, the <a
4426 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4427 rule is used to define values for a specific font family or set of
4428 families that associate a font-specific numeric
4429 <code><feature-index></code> with a custom
4430 <code><feature-value-name></code>, which is then used in this
4431 property to select specific alternates:
4433 <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
4435 p {
4436 font-family: Noble Script;
4437 font-variant-alternates: swash(flowing); /* use swash alternate #2 */
4438 }</pre>
4440 <p>When a particular <code><feature-value-name></code> has not been
4441 defined for a given family or for a particular feature type, the computed
4442 value must be the same as if it had been defined. However, property values
4443 that contain these undefined <code><feature-value-name></code>
4444 identifiers must be ignored when choosing glyphs.
4446 <pre>/* these two style rules are effectively the same */
4447 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
4448 p { font-variant-alternates: normal; }
4449 </pre>
4451 <p>This allows values to be defined and used for a given set of font
4452 families but ignored if fallback occurs, since the font family name would
4453 be different. If a given value is outside the range supported by a given
4454 font, the value is ignored. These values never apply to generic font
4455 families.
4457 <p>Individual values have the following meanings:
4459 <dl>
4460 <dt><dfn id=font-variant-alternates-normal-value
4461 title="normal!!font-variant-alternates">normal</dfn>
4463 <dd>None of the features listed below are enabled.
4465 <dt><dfn id=historical-forms>historical-forms</dfn>
4467 <dd>Enables display of historical forms (OpenType feature: <span
4468 class=tag>hist</span>).
4469 </dl>
4471 <div class=featex><img alt="historical form example" src=hist.png></div>
4473 <dl>
4474 <dt><dfn id=stylistic
4475 title=stylistic>stylistic(<feature-value-name>)</dfn>
4477 <dd>Enables display of stylistic alternates (<a
4478 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4479 class=tag>salt <feature-index></span>).
4480 </dl>
4482 <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
4484 <dl>
4485 <dt><dfn id=styleset title=styleset>styleset(<feature-value-name>
4486 #)</dfn>
4488 <dd>Enables display with stylistic sets (<a href="#font-specific"><em>font
4489 specific</em></a>, OpenType feature: <span
4490 class=tag>ss<feature-index></span> OpenType currently defines <span
4491 class=tag>ss01</span> through <span class=tag>ss20</span>).
4492 </dl>
4494 <div class=featex><img alt="styleset example" src=ssnn.png></div>
4496 <dl>
4497 <dt><dfn id=character-variant
4498 title=character-variant>character-variant(<feature-value-name>
4499 #)</dfn>
4501 <dd>Enables display of specific character variants (<a
4502 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4503 class=tag>cv<feature-index></span> OpenType currently defines <span
4504 class=tag>cv01</span> through <span class=tag>cv99</span>).
4506 <dt><dfn id=swash title=swash>swash(<feature-value-name>)</dfn>
4508 <dd>Enables display of swash glyphs (<a href="#font-specific"><em>font
4509 specific</em></a>, OpenType feature: <span class=tag>swsh
4510 <feature-index>, cswh <feature-index></span>).
4511 </dl>
4513 <div class=featex><img alt="swash example" src=swsh.png></div>
4515 <dl>
4516 <dt><dfn id=ornaments
4517 title=ornaments>ornaments(<feature-value-name>)</dfn>
4519 <dd>Enables replacement of default glyphs with ornaments, if provided in
4520 the font (<a href="#font-specific"><em>font specific</em></a>, OpenType
4521 feature: <span class=tag>ornm <feature-index></span>). Some fonts
4522 may offer ornament glyphs as alternates for a wide collection of
4523 characters; however, displaying arbitrary characters (e.g.,
4524 alphanumerics) as ornaments is poor practice as it distorts the semantics
4525 of the data. Font designers are encouraged to encode all ornaments
4526 (except those explicitly encoded in the Unicode Dingbats blocks, etc.) as
4527 alternates for the bullet character (U+2022) to allow authors to select
4528 the desired glyph using ‘<a href="#ornaments"><code
4529 class=property>ornaments</code></a>’.
4530 </dl>
4532 <div class=featex><img alt="ornaments example" src=ornm.png></div>
4534 <dl>
4535 <dt><dfn id=annotation
4536 title=annotation>annotation(<feature-value-name>)</dfn>
4538 <dd>Enables display of alternate annotation forms (<a
4539 href="#font-specific"><em>font specific</em></a>, OpenType feature: <span
4540 class=tag>nalt <feature-index></span>).
4541 </dl>
4543 <div class=featex><img alt="alternate annotation form example"
4544 src=nalt.png></div>
4546 <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
4547 specific alternates: the <dfn id=at-font-feature-values-rule
4548 style="font-weight: inherit; font-style:
4549 inherit"><code>@font-feature-values</code></dfn> rule</h3>
4551 <p>Several of the possible values of ‘<a
4552 href="#propdef-font-variant-alternates"><code
4553 class=property>font-variant-alternates</code></a>’ listed above are
4554 labeled as <a href="#font-specific"><em>font specific</em></a>. For these
4555 features fonts may define not just a single glyph but a set of alternate
4556 glyphs with an index to select a given alternate. Since these are font
4557 family specific, the <a
4558 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4559 rule is used to define named values for these indices for a given family.
4561 <p class=note>See the <a href="#om-fontfeaturevalues">object model
4562 reference section</a> for a description of the interfaces used to modify
4563 these rules via the CSS Object Model.
4565 <div class=example>
4566 <p>In the case of the swash Q in the example shown above, the swash could
4567 be specified using these style rules:</p>
4569 <pre>
4571 @font-feature-values Jupiter Sans {
4572 @swash {
4573 delicate: 1;
4574 flowing: 2;
4575 }
4576 }
4578 h2 { font-family: Jupiter Sans, sans-serif; }
4580 /* show the second swash variant in h2 headings */
4581 h2:first-letter { font-variant-alternates: swash(flowing); }
4583 <h2>Quick</h2></pre>
4585 <p>When Jupiter Sans is present, the second alternate swash alternate will
4586 be displayed. When not present, no swash character will be shown, since
4587 the specific named value "flowing" is only defined for the Jupiter Sans
4588 family. The @-mark indicates the name of the property value for which a
4589 named value can be used. The name "flowing" is chosen by the author. The
4590 index that represents each alternate is defined within a given font's
4591 data.</p>
4592 </div>
4594 <h4 id=basic-syntax><span class=secno>6.9.1 </span>Basic syntax</h4>
4596 <p>An <a
4597 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4598 rule is composed of a list of font families followed by a block containing
4599 individual <a href="#featurevalueblock"><i
4600 title="feature_value_block">feature value blocks</i></a> that take the
4601 form of @-rules. Each block defines a set of named values for a specific
4602 font feature when a given set of font families is used. Effectively, they
4603 define a mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
4604 ⟨values⟩ are the numeric indices used for specific features defined
4605 for a given font.
4607 <p>In terms of the grammar, this specification defines the following
4608 productions:
4610 <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
4611 : <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>*
4612 '{' <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>*
4613 ;
4615 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
4616 : <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> ]*
4617 ;
4619 <dfn id=fontfamilyname>font_family_name</dfn>
4620 : <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> ]* ]
4621 ;
4623 <dfn id=featurevalueblock>feature_value_block</dfn>
4624 : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4625 '{' <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>*
4626 ;
4628 <dfn id=featuretype>feature_type</dfn>:
4629 <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
4630 ;
4632 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
4633 : <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> ]*
4634 ;
4635 </pre>
4637 <p>The following new token is introduced:
4639 <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>;}
4640 </pre>
4642 <p><a href="#featurevalueblock"><i title="feature_value_block">Feature
4643 value blocks</i></a> are handled as <a
4644 href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">at-rules</a>, they
4645 consist of everything up to the next block or semi-colon, whichever comes
4646 first.
4648 <p>The <a href="#fontfamilynamelist"><i title="font_family_name_list">font
4649 family list</i></a> is a comma-delimited list of <a
4650 href="#fontfamilyname"><i title="font_family_name">font family
4651 names</i></a> that match the definition of <a
4652 href="#family-name-value"><var><family-name></var></a> for the <a
4653 href="#propdef-font-family" title="font-family!!property">‘<code
4654 class=property>font-family</code>’</a> property. This means that only
4655 named font families are allowed, rules that include generic or system
4656 fonts in the list of font families are syntax errors. However, if a user
4657 agent defines a generic font to be a specific named font (e.g. Helvetica),
4658 the settings associated with that family name will be used. If syntax
4659 errors occur within the font family list, the entire rule must be ignored.
4661 <p>Within <a href="#featurevalueblock"><i
4662 title="feature_value_block">feature value blocks</i></a>, the <a
4663 href="#featuretype"><i title="feature_type">feature type</i></a> is
4664 ‘<code class=css>@</code>’ followed by the name of one of the <a
4665 href="#font-specific"><em>font specific</em></a> property values of ‘<a
4666 href="#propdef-font-variant-alternates"><code
4667 class=property>font-variant-alternates</code></a>’ (e.g. <a
4668 href="#swash"><code>@swash</code></a>). The identifiers used within
4669 feature value definitions follow the rules of CSS user identifiers and are
4670 case-sensitive. They are unique only for a given set of font families and
4671 <a href="#featuretype"><i title="feature_type">feature type</i></a>. The
4672 same identifier used with a different <a href="#featuretype"><i
4673 title="feature_type">feature type</i></a> is treated as a separate and
4674 distinct value. If the same identifier is defined mulitple times for a
4675 given <a href="#featuretype"><i title="feature_type">feature type</i></a>
4676 and font family, the last defined value is used. Values associated with a
4677 given identifier are limited to integer values 0 or greater.
4679 <p>When syntax errors occur within a <a href="#featurevaluedefinition"><i
4680 title="feature_value_definition">feature value definition</i></a>, such as
4681 invalid identifiers or values, the entire <a
4682 href="#featurevaluedefinition"><i title="feature_value_definition">feature
4683 value definition</i></a> must be omitted, just as syntax errors in style
4684 declarations are handled. When the <a href="#featuretype"><i
4685 title="feature_type">feature type</i></a> is invalid, the entire
4686 associated <a href="#featurevalueblock"><i
4687 title="feature_value_block">feature value block</i></a> must be ignored.
4689 <div class=example>
4690 <p>Rules that are equivalent given syntax error handling:</p>
4692 <pre>@font-feature-values Bongo {
4693 @swash { ornate: 1; }
4694 annotation { boxed: 4; } /* should be @annotation! */
4695 @swash { double-loops: 1; flowing: -1; } /* negative value */
4696 @ornaments ; /* incomplete definition */
4697 @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
4698 <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none; border: none;">redrum</a> /* random editing mistake */
4699 }</pre>
4701 <p>The example above is equivalent to:</p>
4703 <pre>@font-feature-values Bongo {
4704 @swash { ornate: 1; }
4705 @swash { double-loops: 1; }
4706 @styleset { double-W: 14; sharp-terminals: 16 1; }
4707 }</pre>
4708 </div>
4710 <p>If multiple <a
4711 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4712 rules are defined for a given family, the resulting values definitions are
4713 the union of the definitions contained within these rules. This allows a
4714 set of named values to be defined for a given font family globally for a
4715 site and specific additions made per-page.
4717 <div class=example>
4718 <p>Using both site-wide and per-page feature values:</p>
4720 <pre>
4721 site.css:
4723 @font-feature-values Mercury Serif {
4724 @styleset {
4725 stacked-g: 3; /* "two-storey" versions of g, a */
4726 stacked-a: 4;
4727 }
4728 }
4730 page.css:
4732 @font-feature-values Mercury Serif {
4733 @styleset {
4734 geometric-m: 7; /* alternate version of m */
4735 }
4736 }
4738 body {
4739 font-family: Mercury Serif, serif;
4741 /* enable both the use of stacked g and alternate m */
4742 font-variant-alternates: styleset(stacked-g, geometric-m);
4743 }</pre>
4744 </div>
4746 <div class=example>
4747 <p>Using a commonly named value allows authors to use a single style rule
4748 to cover a set of fonts for which the underlying selector is different
4749 for each font. If either font in the example below is found, a circled
4750 number glyph will be used:</p>
4752 <pre>@font-feature-values Taisho Gothic {
4753 @annotation { boxed: 1; circled: 4; }
4754 }
4756 @font-feature-values Otaru Kisa {
4757 @annotation { circled: 1; black-boxed: 3; }
4758 }
4760 h3.title {
4761 /* circled form defined for both fonts */
4762 font-family: Taisho Gothic, Otaru Kisa;
4763 font-variant: annotation(circled);
4764 }</pre>
4765 </div>
4767 <h4 id=multi-valued-feature-value-definitions><span class=secno>6.9.2
4768 </span>Multi-valued feature value definitions</h4>
4770 <p>Most <a href="#font-specific"><em>font specific</em></a> ‘<a
4771 href="#propdef-font-variant-alternates"><code
4772 class=property>font-variant-alternates</code></a>’ property values take
4773 a single value (e.g. ‘<a href="#swash"><code
4774 class=property>swash</code></a>’). The ‘<a
4775 href="#character-variant"><code
4776 class=property>character-variant</code></a>’ property value allows two
4777 values and ‘<a href="#styleset"><code
4778 class=property>styleset</code></a>’ allows an unlimited number.
4780 <p>For the styleset property value, multiple values indicate the style sets
4781 to be enabled. Values between 1 and 99 enable OpenType features <span
4782 class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
4783 OpenType standard only officially defines <span class=tag>ss01</span>
4784 through <span class=tag>ss20</span>. For OpenType fonts, values greater
4785 than 99 or equal to 0 do not generate a syntax error when parsed but
4786 enable no OpenType features.
4788 <pre>@font-feature-values Mars Serif {
4789 @styleset {
4790 alt-g: 1; /* implies ss01 = 1 */
4791 curly-quotes: 3; /* implies ss03 = 1 */
4792 code: 4 5; /* implies ss04 = 1, ss05 = 1 */
4793 }
4795 @styleset {
4796 dumb: 125; /* >99, ignored */
4797 }
4799 @swash {
4800 swishy: 3 5; /* more than 1 value for swash, syntax error */
4801 }
4802 }
4804 p.codeblock {
4805 /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
4806 font-variant-alternates: styleset(curly-quotes, code);
4807 }</pre>
4809 <p>For character-variant, a single value between 1 and 99 indicates the
4810 enabling of OpenType feature <span class=tag>cv01</span> through <span
4811 class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
4812 to 0 are ignored but do not generate a syntax error when parsed but enable
4813 no OpenType features. When two values are listed, the first value
4814 indicates the feature used and the second the value passed for that
4815 feature. If more than two values are assigned to a given name, a syntax
4816 error occurs and the entire <a href="#featurevaluedefinition"><i
4817 title="feature_value_definition">feature value definition</i></a> is
4818 ignored.
4820 <pre>@font-feature-values MM Greek {
4821 @character-variant { alpha-2: 1 2; } /* implies cv01 = 2 */
4822 @character-variant { beta-3: 2 3; } /* implies cv02 = 3 */
4823 @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, definition ignored */
4824 @character-variant { gamma: 12; } /* implies cv12 = 1 */
4825 @character-variant { zeta: 20 3; } /* implies cv20 = 3 */
4826 @character-variant { zeta-2: 20 2; } /* implies cv20 = 2 */
4827 @character-variant { silly: 105; } /* >99, ignored */
4828 @character-variant { dumb: 323 3; } /* >99, ignored */
4829 }
4831 #title {
4832 /* use the third alternate beta, first alternate gamma */
4833 font-variant-alternates: character-variant(beta-3, gamma);
4834 }
4836 p {
4837 /* zeta-2 follows zeta, implies cv20 = 2 */
4838 font-variant-alternates: character-variant(zeta, zeta-2);
4839 }
4841 .special {
4842 /* zeta follows zeta-2, implies cv20 = 3 */
4843 font-variant-alternates: character-variant(zeta-2, zeta);
4844 }</pre>
4846 <div class=figure><img alt="Matching text on Byzantine seals using
4847 character variants" src=byzantineseal.png>
4848 <p class=caption>Byzantine seal text displayed with character variants
4849 </div>
4851 <div class=example>
4852 <p>In the figure above, the text in red is rendered using a font
4853 containing character variants that mimic the character forms found on a
4854 Byzantine seal from the 8th century A.D. Two lines below is the same text
4855 displayed in a font without variants. Note the two variants for U and N
4856 used on the seal.</p>
4858 <pre>@font-feature-values Athena Ruby {
4859 @character-variant {
4860 leo-B: 2 1;
4861 leo-M: 13 3;
4862 leo-alt-N: 14 1;
4863 leo-N: 14 2;
4864 leo-T: 20 1;
4865 leo-U: 21 2;
4866 leo-alt-U: 21 4;
4867 }
4868 }
4870 p {
4871 font-variant: discretionary-ligatures,
4872 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
4873 }
4875 span.alt-N {
4876 font-variant-alternates: character-variant(leo-alt-N);
4877 }
4879 span.alt-U {
4880 font-variant-alternates: character-variant(leo-alt-U);
4881 }
4883 <p>ENO....UP͞RSTU<span class="alt-U">U</span>͞<span class="alt-U">U</span>ΚΑΙTỤẠG̣IUPNS</p>
4885 <p>LEON|ΚΑΙCONSTA|NTI<span class="alt-N">N</span>OS..|STOIBAṢ.|LIṢROM|AIO<span class="alt-N">N</span></p>
4886 </pre>
4887 </div>
4889 <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
4890 Asian text rendering: the <a
4891 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
4892 property</h3>
4894 <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
4895 <tbody>
4896 <tr>
4897 <td>Name:
4899 <td><dfn
4900 id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
4902 <tr>
4903 <td>Value:
4905 <td><a href="#font-variant-east-asian-normal-value"
4906 title="normal!!font-variant-east-asian">normal</a> | [ <a
4907 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
4908 || <a
4909 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
4910 || <a href="#ruby">ruby</a> ]
4912 <tr>
4913 <td>Initial:
4915 <td>normal
4917 <tr>
4918 <td>Applies to:
4920 <td>all elements
4922 <tr>
4923 <td>Inherited:
4925 <td>yes
4927 <tr>
4928 <td>Percentages:
4930 <td>N/A
4932 <tr>
4933 <td>Media:
4935 <td>visual
4937 <tr>
4938 <td>Computed value:
4940 <td>as specified
4942 <tr>
4943 <td>Animatable:
4945 <td>no
4946 </table>
4948 <p>Allows control of glyph substitution and sizing in East Asian text.
4950 <pre
4951 class=prod><dfn id=east-asian-variant-values><var><east-asian-variant-values></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>
4953 <pre
4954 class=prod><dfn id=east-asian-width-values><var><east-asian-width-values></var></dfn> = [ <a href="#full-width">full-width</a> | <a href="#proportional-width">proportional-width</a> ]</pre>
4956 <p>Individual values have the following meanings:
4958 <dl>
4959 <dt><dfn id=font-variant-east-asian-normal-value
4960 title="normal!!font-variant-east-asian">normal</dfn>
4962 <dd>None of the features listed below are enabled.
4964 <dt><dfn id=jis78>jis78</dfn>
4966 <dd>Enables rendering of JIS78 forms (OpenType feature: <span
4967 class=tag>jp78</span>).
4968 </dl>
4970 <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
4972 <dl>
4973 <dt><dfn id=jis83>jis83</dfn>
4975 <dd>Enables rendering of JIS83 forms (OpenType feature: <span
4976 class=tag>jp83</span>).
4978 <dt><dfn id=jis90>jis90</dfn>
4980 <dd>Enables rendering of JIS90 forms (OpenType feature: <span
4981 class=tag>jp90</span>).
4983 <dt><dfn id=jis04>jis04</dfn>
4985 <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
4986 class=tag>jp04</span>).
4987 <p>The various JIS variants reflect the glyph forms defined in different
4988 Japanese national standards. Fonts generally include glyphs defined by
4989 the most recent national standard but it's sometimes necessary to use
4990 older variants, to match signage for example.</p>
4992 <dt><dfn id=simplified>simplified</dfn>
4994 <dd>Enables rendering of simplified forms (OpenType feature: <span
4995 class=tag>smpl</span>).
4997 <dt><dfn id=traditional>traditional</dfn>
4999 <dd>Enables rendering of traditional forms (OpenType feature: <span
5000 class=tag>trad</span>).
5001 </dl>
5003 <p>The ‘<a href="#simplified"><code
5004 class=property>simplified</code></a>’ and ‘<a
5005 href="#traditional"><code class=property>traditional</code></a>’ values
5006 allow control over the glyph forms for characters which have been
5007 simplified over time but for which the older, traditional form is still
5008 used in some contexts. The exact set of characters and glyph forms will
5009 vary to some degree by context for which a given font was designed.
5011 <div class=featex><img alt="tradtional form example" src=trad.png></div>
5013 <dl>
5014 <dt><dfn id=full-width>full-width</dfn>
5016 <dd>Enables rendering of full-width variants (OpenType feature: <span
5017 class=tag>fwid</span>).
5019 <dt><dfn id=proportional-width>proportional-width</dfn>
5021 <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
5022 <span class=tag>pwid</span>).
5023 </dl>
5025 <div class=featex><img alt="proportionally spaced Japanese example"
5026 src=pwid.png></div>
5028 <dl>
5029 <dt><dfn id=ruby>ruby</dfn>
5031 <dd>Enables display of ruby variant glyphs (OpenType feature: <span
5032 class=tag>ruby</span>). Since ruby text is generally smaller than the
5033 associated body text, font designers can design special glyphs for use
5034 with ruby that are more readable than scaled down versions of the default
5035 glyphs. Only glyph selection is affected, there is no associated font
5036 scaling or other change that affects line layout. The red ruby text below
5037 is shown with default glyphs (top) and with ruby variant glyphs (bottom).
5038 Note the slight difference in stroke thickness.
5039 </dl>
5041 <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
5043 <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
5044 for font rendering: the <a href="#propdef-font-variant">font-variant</a>
5045 property</h3>
5047 <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
5048 <tbody>
5049 <tr>
5050 <td>Name:
5052 <td><dfn id=propdef-font-variant
5053 title="font-variant!!property">font-variant</dfn>
5055 <tr>
5056 <td>Value:
5058 <td><a href="#font-variant-normal-value"
5059 title="normal!!font-variant">normal</a> | <a
5060 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
5061 <a href="#common-lig-values"><var><common-lig-values></var></a>
5062 || <a
5063 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
5064 || <a
5065 href="#historical-lig-values"><var><historical-lig-values></var></a>
5066 || <a
5067 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
5068 || <a href="#stylistic"><var
5069 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
5070 href="#historical-forms"><var>historical-forms</var></a> || <a
5071 href="#styleset"><var
5072 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
5073 href="#character-variant"><var
5074 title=character-variant>character-variant(<feature-value-name>
5075 #)</var></a> || <a href="#swash"><var
5076 title=swash>swash(<feature-value-name>)</var></a> || <a
5077 href="#ornaments"><var
5078 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
5079 href="#annotation"><var
5080 title=annotation>annotation(<feature-value-name>)</var></a> || [
5081 <a href="#small-caps"><i>small-caps</i></a> | <a
5082 href="#all-small-caps"><i>all-small-caps</i></a> | <a
5083 href="#petite-caps"><i>petite-caps</i></a> | <a
5084 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
5085 href="#unicase"><i>unicase</i></a> | <a
5086 href="#titling-caps"><i>titling-caps</i></a> ] || <a
5087 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
5088 || <a
5089 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
5090 || <a
5091 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
5092 || <a href="#ordinal"><i>ordinal</i></a> || <a
5093 href="#slashed-zero"><i>slashed-zero</i></a> || <a
5094 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
5095 || <a
5096 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
5097 || <a href="#ruby"><i>ruby</i></a> ]
5099 <tr>
5100 <td>Initial:
5102 <td>normal
5104 <tr>
5105 <td>Applies to:
5107 <td>all elements
5109 <tr>
5110 <td>Inherited:
5112 <td>yes
5114 <tr>
5115 <td>Percentages:
5117 <td>see individual properties
5119 <tr>
5120 <td>Media:
5122 <td>visual
5124 <tr>
5125 <td>Computed value:
5127 <td>see individual properties
5129 <tr>
5130 <td>Animatable:
5132 <td>see individual properties
5133 </table>
5135 <p>The <a href="#propdef-font-variant"
5136 title="font-variant!!property">‘<code
5137 class=property>font-variant</code>’</a> property is a shorthand for all
5138 font-variant subproperties. The value <dfn id=font-variant-normal-value
5139 title="normal!!font-variant">‘<code
5140 class=property>normal</code>’</dfn> resets all subproperties of <a
5141 href="#propdef-font-variant" title="font-variant!!property">‘<code
5142 class=property>font-variant</code>’</a> to their inital value. The <dfn
5143 id=font-variant-none-value title="none!!font-variant">‘<code
5144 class=property>none</code>’</dfn> value sets ‘<a
5145 href="#propdef-font-variant-ligatures"><code
5146 class=property>font-variant-ligatures</code></a>’ to ‘<code
5147 class=property>none</code>’ and resets all other font feature properties
5148 to their initial value. Like other shorthands, using <a
5149 href="#propdef-font-variant" title="font-variant!!property">‘<code
5150 class=property>font-variant</code>’</a> resets unspecified <a
5151 href="#propdef-font-variant" title="font-variant!!property">‘<code
5152 class=property>font-variant</code>’</a> subproperties to their initial
5153 values. It does not reset the values of either ‘<a
5154 href="#propdef-font-language-override"><code
5155 class=property>font-language-override</code></a>’ or <a
5156 href="#propdef-font-feature-settings"
5157 title="font-feature-settings!!property">‘<code
5158 class=property>font-feature-settings</code>’</a>.
5160 <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
5161 font feature settings control: the <a
5162 href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
5164 <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
5165 <tbody>
5166 <tr>
5167 <td>Name:
5169 <td><dfn id=propdef-font-feature-settings
5170 title="font-feature-settings!!property">font-feature-settings</dfn>
5172 <tr>
5173 <td>Value:
5175 <td><a href="#font-feature-settings-normal-value"
5176 title="normal!!font-feature-settings">normal</a> | <a
5177 href="#feature-tag-value"><var><feature-tag-value></var></a> #
5179 <tr>
5180 <td>Initial:
5182 <td>normal
5184 <tr>
5185 <td>Applies to:
5187 <td>all elements
5189 <tr>
5190 <td>Inherited:
5192 <td>yes
5194 <tr>
5195 <td>Percentages:
5197 <td>N/A
5199 <tr>
5200 <td>Media:
5202 <td>visual
5204 <tr>
5205 <td>Computed value:
5207 <td>as specified
5209 <tr>
5210 <td>Animatable:
5212 <td>no
5213 </table>
5215 <p>This property provides low-level control over OpenType font features. It
5216 is intended as a way of providing access to font features that are not
5217 widely used but are needed for a particular use case.
5219 <p>Authors should generally use <a href="#propdef-font-variant"
5220 title="font-variant!!property">‘<code
5221 class=property>font-variant</code>’</a> and its related subproperties
5222 whenever possible and only use this property for special cases where its
5223 use is the only way of accessing a particular infrequently used font
5224 feature.
5226 <pre>/* enable small caps and use second swash alternate */
5227 font-feature-settings: "smcp", "swsh" 2;</pre>
5229 <p>A value of <dfn id=font-feature-settings-normal-value
5230 title="normal!!font-feature-settings">‘<code
5231 class=property>normal</code>’</dfn> means that no change in glyph
5232 selection or positioning occurs due to this property.
5234 <p>Feature tag values have the following syntax:
5236 <pre
5237 class=prod><dfn id=feature-tag-value><var><feature-tag-value></var></dfn> = <string> [ <integer> | on | off ]?</pre>
5239 <p>The <string> is a case-sensitive OpenType feature tag. As
5240 specified in the OpenType specification, feature tags contain four ASCII
5241 characters. Tag strings longer or shorter than four characters, or
5242 containing characters outside the U+20–7E codepoint range are invalid.
5243 Feature tags need only match a feature tag defined in the font, so they
5244 are not limited to explicitly registered OpenType features. Fonts defining
5245 custom feature tags should follow the <a
5246 href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
5247 rules</a> defined in the OpenType specification <a
5248 href="#OPENTYPE-FEATURES"
5249 rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
5250 Feature tags not present in the font are ignored; a user agent must not
5251 attempt to synthesize fallback behavior based on these feature tags.
5253 <p>This means that explicitly disabling the <span class=tag>kern</span>
5254 feature will not affect the application of kerning data found in the
5255 ‘<code class=property>kern</code>’ table (as opposed to kerning data
5256 associated with the <span class=tag>kern</span> feature in the ‘<code
5257 class=property>GPOS</code>’ table). Authors should use the ‘<a
5258 href="#propdef-font-kerning"><code
5259 class=property>font-kerning</code></a>’ property to explictly enable or
5260 disable kerning since this property affects both types of kerning.
5262 <p>If present, a value indicates an index used for glyph selection. An
5263 <integer> value must be 0 or greater. A value of 0 indicates that
5264 the feature is disabled. For boolean features, a value of 1 enables the
5265 feature. For non-boolean features, a value of 1 or greater enables the
5266 feature and indicates the feature selection index. A value of ‘<code
5267 class=property>on</code>’ is synonymous with 1 and ‘<code
5268 class=property>off</code>’ is synonymous with 0. If the value is
5269 omitted, a value of 1 is assumed.
5271 <pre>
5272 font-feature-settings: "dlig" 1; /* dlig=1 enable discretionary ligatures */
5273 font-feature-settings: "smcp" on; /* smcp=1 enable small caps */
5274 font-feature-settings: 'c2sc'; /* c2sc=1 enable caps to small caps */
5275 font-feature-settings: "liga" off; /* liga=0 no common ligatures */
5276 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
5277 font-feature-settings: "tnum" "hist"; /* invalid, need a comma-delimited list */
5278 font-feature-settings: "palin" off; /* good idea but invalid tagname */
5279 font-feature-settings: "PKRN"; /* PKRN=1 enable custom feature */
5280 font-feature-settings: dlig; /* invalid, tag must be a string */
5281 </pre>
5283 <p>When values greater than the range supported by the font are specified,
5284 the behavior is explicitly undefined. For boolean features, in general
5285 these will enable the feature. For non-boolean features, out of range
5286 values will in general be equivalent to a 0 value. However, in both cases
5287 the exact behavior will depend upon the way the font is designed
5288 (specifically, which type of lookup is used to define the feature).
5290 <p>Although specifically defined for OpenType feature tags, feature tags
5291 for other modern font formats that support font features may be added in
5292 the future. Where possible, features defined for other font formats should
5293 attempt to follow the pattern of registered OpenType tags.
5295 <div class=example>
5296 <p>The Japanese text below will be rendered with half-width kana
5297 characters:</p>
5299 <pre lang=ja>
5300 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
5302 <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</p>
5303 </pre>
5304 </div>
5306 <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
5307 language override: the <a
5308 href="#propdef-font-language-override">font-language-override</a> property</h3>
5310 <table class=propdef id=namefont-language-overridevaluenormal-lt>
5311 <tbody>
5312 <tr>
5313 <td>Name:
5315 <td><dfn id=propdef-font-language-override>font-language-override</dfn>
5317 <tr>
5318 <td>Value:
5320 <td><a href="#font-language-override-normal-value"
5321 title="normal!!font-language-override">normal</a> | <a
5322 href="#font-language-override-string-value"><var><string></var></a>
5324 <tr>
5325 <td>Initial:
5327 <td><a href="#font-language-override-normal-value"
5328 title="normal!!font-language-override">normal</a>
5330 <tr>
5331 <td>Applies to:
5333 <td>all elements
5335 <tr>
5336 <td>Inherited:
5338 <td>yes
5340 <tr>
5341 <td>Percentages:
5343 <td>N/A
5345 <tr>
5346 <td>Media:
5348 <td>visual
5350 <tr>
5351 <td>Computed value:
5353 <td>as specified
5355 <tr>
5356 <td>Animatable:
5358 <td>no
5359 </table>
5361 <p>Normally, authors can control the use of language-specific glyph
5362 substitutions and positioning by setting the content language of an
5363 element, as <a href="#language-specific-support">described above</a>:
5365 <pre><!-- Display text using S'gaw Karen specific features -->
5366 <p lang="ksw">...</p></pre>
5368 <p>In some cases, authors may need to specify a language system that
5369 differs from the content language, for example due to the need to mimic
5370 another language's typographic traditions. The ‘<a
5371 href="#propdef-font-language-override"><code
5372 class=property>font-language-override</code></a>’ property allows
5373 authors to explicitly specify the language system of the font, overriding
5374 the language system implied by the content language.
5376 <p>Values have the following meanings:
5378 <dl>
5379 <dt><dfn id=font-language-override-normal-value
5380 title="normal!!font-language-override">normal</dfn>
5382 <dd>specifies that when rendering with OpenType fonts, the content
5383 language of the element is used to infer the OpenType language system
5385 <dt><dfn
5386 id=font-language-override-string-value><var><string></var></dfn>
5388 <dd>single three-letter case-sensitive OpenType <a
5389 href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
5390 system tag</a>, specifies the OpenType language system to be used instead
5391 of the language system implied by the language of the element
5392 </dl>
5394 <p>Use of invalid OpenType language system tags must not generate a parse
5395 error but must be ignored when doing glyph selection and placement.
5397 <div class=example>
5398 <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
5399 Declaration of Human Rights</a> has been translated into a wide variety
5400 of languages. In Turkish, Article 9 of this document might be marked up
5401 as below:</p>
5403 <pre lang=tr><body lang="tr">
5405 <h4>Madde 9</h4>
5406 <p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.</p>
5407 </pre>
5409 <p>Here the user agent uses the value of the ‘<code
5410 class=property>lang</code>’ attribute when rendering text and
5411 appropriately renders this text without ‘<code
5412 class=property>fi</code>’ ligatures. There is no need to use the ‘<a
5413 href="#propdef-font-language-override"><code
5414 class=property>font-language-override</code></a>’ property.</p>
5416 <p>However, a given font may lack support for a specific language. In this
5417 situation authors may need to use the typographic conventions of a
5418 related language that are supported by that font:</p>
5420 <pre lang=mk><body lang="mk"> <!-- Macedonian lang code -->
5422 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
5424 <h4>Члeн 9</h4>
5425 <p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.</p>
5427 </pre>
5429 <p>The Macedonian text here will be rendered using Serbian typographic
5430 conventions, with the assumption that the font specified supports
5431 Serbian.</p>
5432 </div>
5434 <p><a id=rendering-considerations></a>
5436 <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
5437 Resolution</h2>
5439 <p>As described in the previous section, font features can be enabled in a
5440 variety of ways, either via the use of <a href="#propdef-font-variant"
5441 title="font-variant!!property">‘<code
5442 class=property>font-variant</code>’</a> or <a
5443 href="#propdef-font-feature-settings"
5444 title="font-feature-settings!!property">‘<code
5445 class=property>font-feature-settings</code>’</a> in a style rule or
5446 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5447 The resolution order for the union of these settings is defined below.
5448 Features defined via CSS properties are applied on top of layout engine
5449 default features.
5451 <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
5453 <p>For OpenType fonts, user agents must enable the default features defined
5454 in the OpenType documentation for a given script and writing mode.
5455 Required ligatures, common ligatures and contextual forms must be enabled
5456 by default (OpenType features: <span class=tag>rlig, liga, clig,
5457 calt</span>), along with localized forms (OpenType feature: <span
5458 class=tag>locl</span>), and features required for proper display of
5459 composed characters and marks (OpenType features: <span class=tag>ccmp,
5460 mark, mkmk</span>). These features must always be enabled, even when the
5461 value of the <a href="#propdef-font-variant"
5462 title="font-variant!!property">‘<code
5463 class=property>font-variant</code>’</a> and <a
5464 href="#propdef-font-feature-settings"
5465 title="font-feature-settings!!property">‘<code
5466 class=property>font-feature-settings</code>’</a> properties is <span
5467 title="normal value">‘<code class=property>normal</code>’</span>.
5468 Individual features are only disabled when explicitly overridden by the
5469 author, as when ‘<a href="#propdef-font-variant-ligatures"><code
5470 class=property>font-variant-ligatures</code></a>’ is set to ‘<a
5471 href="#no-common-ligatures"><code
5472 class=property>no-common-ligatures</code></a>’. For handling complex
5473 scripts such as <a
5474 href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
5475 <a
5476 href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
5477 or <a
5478 href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
5479 additional features are required. For upright text within vertical text
5480 runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
5481 must be enabled.
5483 <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
5485 <p>General and <a href="#font-specific"><em>font specific</em></a> font
5486 feature property settings are resolved in the order below, in ascending
5487 order of precedence. This ordering is used to construct a combined list of
5488 font features that affect a given text run.
5490 <ol>
5491 <li>Font features enabled by default, including features required for a
5492 given script.
5494 <li>If the font is defined via an <a
5495 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5496 features implied by the font-variant descriptor in the <a
5497 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5499 <li>If the font is defined via an <a
5500 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5501 features implied by the font-feature-settings descriptor in the <a
5502 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5504 <li>Feature settings determined by properties other than <a
5505 href="#propdef-font-variant" title="font-variant!!property">‘<code
5506 class=property>font-variant</code>’</a> or <a
5507 href="#propdef-font-feature-settings"
5508 title="font-feature-settings!!property">‘<code
5509 class=property>font-feature-settings</code>’</a>. For example, setting
5510 a non-default value for the ‘<code
5511 class=property>letter-spacing</code>’ property disables common
5512 ligatures.
5514 <li>Font features implied by the value of the <a
5515 href="#propdef-font-variant" title="font-variant!!property">‘<code
5516 class=property>font-variant</code>’</a> property, the related <a
5517 href="#propdef-font-variant" title="font-variant!!property">‘<code
5518 class=property>font-variant</code>’</a> subproperties and any other CSS
5519 property that uses OpenType features (e.g. the ‘<a
5520 href="#propdef-font-kerning"><code
5521 class=property>font-kerning</code></a>’ property).
5523 <li>Font features implied by the value of <a
5524 href="#propdef-font-feature-settings"
5525 title="font-feature-settings!!property">‘<code
5526 class=property>font-feature-settings</code>’</a> property.
5527 </ol>
5529 <p>This ordering allows authors to set up a general set of defaults for
5530 fonts within their <a
5531 href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
5532 them with property settings for specific elements. General property
5533 settings override the settings in <a
5534 href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
5535 font feature settings override <a href="#propdef-font-variant"
5536 title="font-variant!!property">‘<code
5537 class=property>font-variant</code>’</a> property settings.
5539 <p>For situations where the combined list of font feature settings contains
5540 more than one value for the same feature, the last value is used. When a
5541 font lacks support for a given underlying font feature, text is simply
5542 rendered as if that font feature was not enabled; font fallback does not
5543 occur and no attempt is made to synthesize the feature except where
5544 explicitly defined for specific properties.
5546 <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
5547 precedence examples</h3>
5549 <div class=example>
5550 <p>With the styles below, numbers are rendered proportionally when used
5551 within a paragraph but are shown in tabular form within tables of prices:</p>
5553 <pre>body {
5554 font-variant-numeric: proportional-nums;
5555 }
5557 table.prices td {
5558 font-variant-numeric: tabular-nums;
5559 }
5560 </pre>
5561 </div>
5563 <div class=example>
5564 <p>When the <a href="#descdef-font-variant"
5565 title="font-variant!!descriptor">font-variant</a> descriptor is used
5566 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule,
5567 it only applies to the font defined by that rule.</p>
5569 <pre>@font-face {
5570 font-family: MainText;
5571 src: url(http://example.com/font.ttf);
5572 font-variant: oldstyle-nums proportional-nums styleset(1,3);
5573 }
5575 body {
5576 font-family: MainText, Helvetica;
5577 }
5579 table.prices td {
5580 font-variant-numeric: tabular-nums;
5581 }
5582 </pre>
5584 <p>In this case, old-style numerals will be used throughout but only where
5585 the font "MainText" is used. Just as in the previous example, tabular
5586 values will be used in price tables since ‘<a
5587 href="#tabular-nums"><code class=property>tabular-nums</code></a>’
5588 appears in a general style rule and its use is mutually exclusive with
5589 ‘<a href="#proportional-nums"><code
5590 class=property>proportional-nums</code></a>’. Stylistic alternate sets
5591 will only be used where MainText is used.</p>
5592 </div>
5594 <div class=example>
5595 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
5596 also be used to access font features in locally available fonts via the
5597 use of <code>local()</code> in the ‘<a href="#descdef-src"><code
5598 class=property>src</code></a>’ descriptor of the <a
5599 href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
5601 <pre>@font-face {
5602 font-family: BodyText;
5603 src: local("HiraMaruPro-W4");
5604 font-variant: proportional-width;
5605 font-feature-settings: "ital"; /* Latin italics within CJK text feature */
5606 }
5608 body { font-family: BodyText, serif; }
5609 </pre>
5611 <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
5612 text rendering occurs, Japanese kana will be proportionally spaced and
5613 Latin text will be italicised. Text rendered with the fallback serif font
5614 will use default rendering properties.</p>
5615 </div>
5617 <div class=example>
5618 <p>In the example below, discretionary ligatures are enabled only for a
5619 downloadable font but are disabled within spans of class "special":</p>
5621 <pre>@font-face {
5622 font-family: main;
5623 src: url(fonts/ffmeta.woff) format("woff");
5624 font-variant: discretionary-ligatures;
5625 }
5627 body { font-family: main, Helvetica; }
5628 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5629 </pre>
5631 <p>Suppose one adds a rule using ‘<code
5632 class=property>font-feature-settings</code>’ to enable discretionary
5633 ligatures:</p>
5635 <pre>body { font-family: main, Helvetica; }
5636 span { font-feature-settings: "dlig"; }
5637 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5638 </pre>
5640 <p>In this case, discretionary ligatures <em>will</em> be rendered within
5641 spans of class "special". This is because both the <a
5642 href="#propdef-font-feature-settings"
5643 title="font-feature-settings!!property">‘<code
5644 class=property>font-feature-settings</code>’</a> and ‘<a
5645 href="#propdef-font-variant-ligatures"><code
5646 class=property>font-variant-ligatures</code></a>’ properties apply to
5647 these spans. Although the ‘<code class=css>no-discretionary
5648 ligatures</code>’ setting of ‘<a
5649 href="#propdef-font-variant-ligatures"><code
5650 class=property>font-variant-ligatures</code></a>’ effectively disables
5651 the OpenType <span class=tag>dlig</span> feature, because the <a
5652 href="#propdef-font-feature-settings"
5653 title="font-feature-settings!!property">‘<code
5654 class=property>font-feature-settings</code>’</a> is resolved after
5655 that, the ‘<code class=property>dlig</code>’ value reenables
5656 discretionary ligatures.</p>
5657 </div>
5659 <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
5661 <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
5662 and <a
5663 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5664 rules can be accessed via the following extensions to the CSS Object
5665 Model.
5667 <h3 id=om-fontface><span class=secno>8.1 </span>The <a
5668 href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
5670 <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
5671 <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5673 <pre class=idl>
5674 interface CSSFontFaceRule : CSSRule {
5675 attribute DOMString family;
5676 attribute DOMString src;
5677 attribute DOMString style;
5678 attribute DOMString weight;
5679 attribute DOMString stretch;
5680 attribute DOMString unicodeRange;
5681 attribute DOMString variant;
5682 attribute DOMString featureSettings;
5683 }</pre>
5685 <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
5686 rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
5687 defined a different variant of this rule. This definition supercedes that
5688 one.
5690 <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
5691 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5692 interface</h3>
5694 <p>The <code>CSSRule</code> interface is extended as follows:
5696 <pre class=idl>partial interface CSSRule {
5697 const unsigned short FONT_FEATURE_VALUES_RULE = 14;
5698 }</pre>
5700 <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
5701 interface represents a <a
5702 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5703 rule.
5705 <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
5706 readonly attribute DOMString familyList;
5707 readonly attribute DOMString valueText;
5708 };</pre>
5710 <dl class=idl-attributes>
5711 <dt><var>familyList</var> of type <code>DOMString</code>, readonly
5713 <dd>The list of one or more font families for which a given set of feature
5714 values is defined.
5716 <dt><var>valueText</var> of type <code>DOMString</code>, readonly
5718 <dd>Serialized set of feature values.
5719 </dl>
5721 <p class=issue>This needs to be reworked along the lines of <a
5722 href="http://lists.w3.org/Archives/Public/www-style/2013May/0781.html">Tab's
5723 proposal</a> for a rule containing a family list and map objects for each
5724 of the feature types.
5726 <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
5727 properties to CSS properties</h2>
5729 <p><em>This appendix is included as background for some of the problems and
5730 situations that are described in other sections. It should be viewed as
5731 informative only.</em>
5733 <p>Font properties in CSS are designed to be independent of the underlying
5734 font formats used; they can be used to specify bitmap fonts, Type1 fonts,
5735 SVG fonts in addition to the common TrueType and OpenType fonts. But there
5736 are facets of the TrueType and OpenType formats that often cause confusion
5737 for authors and present challenges to implementers on different platforms.
5739 <p>Originally developed at Apple, TrueType was designed as an outline font
5740 format for both screen and print. Microsoft joined Apple in developing the
5741 TrueType format and both platforms have supported TrueType fonts since
5742 then. Font data in the TrueType format consists of a set of tables
5743 distinguished with common four-letter tag names, each containing a
5744 specific type of data. For example, naming information, including
5745 copyright and license information, is stored in the ‘<code
5746 class=property>name</code>’ table. The <a
5747 href="#character-map"><em>character map</em></a> (‘<code
5748 class=property>cmap</code>’) table contains a mapping of character
5749 encodings to glyphs. Apple later added additional tables for supporting
5750 enhanced typographic functionality; these are now called Apple Advanced
5751 Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
5752 tables for advanced typography and called their format OpenType <a
5753 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
5755 <p>In many cases the font data used under Microsoft Windows or Linux is
5756 slightly different from the data used under Apple's Mac OS X because the
5757 TrueType format allowed for explicit variation across platforms. This
5758 includes font metrics, names and <a href="#character-map"><em>character
5759 map</em></a> data.
5761 <p>Specifically, font family name data is handled differently across
5762 platforms. For TrueType and OpenType fonts these names are contained in
5763 the ‘<code class=property>name</code>’ table, in name records with
5764 name ID 1. Mulitple names can be stored for different locales, but
5765 Microsoft recommends fonts always include at least a US English version of
5766 the name. On Windows, Microsoft made the decision for backwards
5767 compatibility to limit this family name to a maximum of four faces; for
5768 larger groupings the "preferred family" (name ID 16) or "WWS family" (name
5769 ID 21) can be used. Other platforms such as OSX don't have this
5770 limitation, so the family name is used to define all possible groupings.
5772 <p>Other name table data provides names used to uniquely identify a
5773 specific face within a family. The full font name (name ID 4) and the
5774 Postscript name (name ID 6) describe a single face uniquely. For example,
5775 the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
5776 and a Postscript name of "GillSans-Bold". There can be multiple localized
5777 versions of the fullname for a given face, but the Postscript name is
5778 always a unique name made from a limited set of ASCII characters.
5780 <p>On various platforms, different names are used to search for a font. For
5781 example, with the Windows GDI CreateIndirectFont API, either a family or
5782 fullname can be used to lookup a face, while on Mac OS X the
5783 CTFontCreateWithName API call is used to lookup a given face using the
5784 fullname and Postscript name. Under Linux, the fontconfig API allows fonts
5785 to be searched using any of these names. In situations where platform
5786 API's automatically substitute other font choices, it may be necessary to
5787 verify a returned font matches a given name.
5789 <p>The weight of a given face can be determined via the usWeightClass field
5790 of the OS/2 table or inferred from the style name (name ID 2). Likewise,
5791 the width can be determined via the usWidthClass of the OS/2 table or
5792 inferred from the style name. For historical reasons related to synthetic
5793 bolding at weights 200 or lower with the Windows GDI API, font designers
5794 have sometimes skewed values in the OS/2 table to avoid these weights.
5796 <p>Rendering complex scripts that use contextual shaping such as Thai,
5797 Arabic and Devanagari requires features present only in OpenType or AAT
5798 fonts. Currently, complex script rendering is supported on Windows and
5799 Linux using OpenType font features while both OpenType and AAT font
5800 features are used under Mac OS X.
5802 <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
5804 <h3 class=no-num id=recent-changes> Changes from the <a
5805 href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">February 2013
5806 CSS3 Fonts Working Draft</a></h3>
5808 <p>Major changes include:
5810 <ul>
5811 <li>Moved font load events into a separate <a
5812 href="http://dev.w3.org/csswg/css3-font-load-events/">spec</a>
5814 <li>Tightened syntax rules for <a
5815 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5816 rules
5818 <li>Added grammar productions for <a
5819 href="#at-font-face-rule"><code>@font-face</code></a> and <a
5820 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5821 rules
5823 <li>Tightened definition of synthetic oblique
5825 <li>Revised definition of ‘<a href="#descdef-unicode-range"><code
5826 class=property>unicode-range</code></a>’ descriptor
5827 </ul>
5829 <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
5831 <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
5832 their help and feedback. John Hudson was kind enough to take the time to
5833 explain the subtleties of OpenType language tags and provided the example
5834 of character variant usage for displaying text on Byzantine seals. Ken
5835 Lunde and Eric Muller provided valuable feedback on CJK OpenType features
5836 and Unicode variation selectors. The idea for supporting font features by
5837 using <a href="#propdef-font-variant"
5838 title="font-variant!!property">‘<code
5839 class=property>font-variant</code>’</a> subproperties originated with
5840 Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
5841 of the initial design ideas for the <a
5842 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5843 rule. Thanks also to House Industries for allowing the use of Ed Interlock
5844 in the discretionary ligatures example.
5846 <p>A special thanks to Robert Bringhurst for the sublime mind expansion
5847 that is <em>The Elements of Typographic Style</em>.
5849 <h2 class=no-num id=conformance> Conformance</h2>
5851 <h3 class=no-num id=conventions> Document Conventions</h3>
5853 <p>Conformance requirements are expressed with a combination of descriptive
5854 assertions and RFC 2119 terminology. The key words “MUST”, “MUST
5855 NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
5856 “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
5857 normative parts of this document are to be interpreted as described in RFC
5858 2119. However, for readability, these words do not appear in all uppercase
5859 letters in this specification.
5861 <p>All of the text of this specification is normative except sections
5862 explicitly marked as non-normative, examples, and notes. <a
5863 href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
5865 <p>Examples in this specification are introduced with the words “for
5866 example” or are set apart from the normative text with
5867 <code>class="example"</code>, like this:
5869 <div class=example>
5870 <p>This is an example of an informative example.
5871 </div>
5873 <p>Informative notes begin with the word “Note” and are set apart from
5874 the normative text with <code>class="note"</code>, like this:
5876 <p class=note>Note, this is an informative note.
5878 <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
5880 <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
5881 classes:
5883 <dl>
5884 <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
5885 sheet</dfn>
5887 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
5888 style sheet</a>.
5890 <dt><dfn id=renderer>renderer</dfn>
5892 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5893 that interprets the semantics of a style sheet and renders documents that
5894 use them.
5896 <dt><dfn id=authoring-tool>authoring tool</dfn>
5898 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5899 that writes a style sheet.
5900 </dl>
5902 <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
5903 declarations that use properties defined in this module have values that
5904 are valid according to the generic CSS grammar and the individual grammars
5905 of each property as given in this module.
5907 <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
5908 interpreting the style sheet as defined by the appropriate specifications,
5909 it supports all the features defined by CSS Fonts Level 3 Module by
5910 parsing them correctly and rendering the document accordingly. However,
5911 the inability of a UA to correctly render a document due to limitations of
5912 the device does not make the UA non-conformant. (For example, a UA is not
5913 required to render color on a monochrome monitor.)
5915 <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
5916 style sheets that are syntactically correct according to the generic CSS
5917 grammar and the individual grammars of each feature in this module, and
5918 meet all other conformance requirements of style sheets as described in
5919 this module.
5921 <h3 class=no-num id=partial> Partial Implementations</h3>
5923 <p>So that authors can exploit the forward-compatible parsing rules to
5924 assign fallback values, CSS renderers <strong>must</strong> treat as
5925 invalid (and <a
5926 href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
5927 appropriate</a>) any at-rules, properties, property values, keywords, and
5928 other syntactic constructs for which they have no usable level of support.
5929 In particular, user agents <strong>must not</strong> selectively ignore
5930 unsupported component values and honor supported values in a single
5931 multi-value property declaration: if any value is considered invalid (as
5932 unsupported values must be), CSS requires that the entire declaration be
5933 ignored.
5935 <h3 class=no-num id=experimental> Experimental Implementations</h3>
5937 <p>To avoid clashes with future CSS features, the CSS2.1 specification
5938 reserves a <a
5939 href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
5940 syntax</a> for proprietary and experimental extensions to CSS.
5942 <p>Prior to a specification reaching the Candidate Recommendation stage in
5943 the W3C process, all implementations of a CSS feature are considered
5944 experimental. The CSS Working Group recommends that implementations use a
5945 vendor-prefixed syntax for such features, including those in W3C Working
5946 Drafts. This avoids incompatibilities with future changes in the draft.
5948 <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
5950 <p>Once a specification reaches the Candidate Recommendation stage,
5951 non-experimental implementations are possible, and implementors should
5952 release an unprefixed implementation of any CR-level feature they can
5953 demonstrate to be correctly implemented according to spec.
5955 <p>To establish and maintain the interoperability of CSS across
5956 implementations, the CSS Working Group requests that non-experimental CSS
5957 renderers submit an implementation report (and, if necessary, the
5958 testcases used for that implementation report) to the W3C before releasing
5959 an unprefixed implementation of any CSS features. Testcases submitted to
5960 W3C are subject to review and correction by the CSS Working Group.
5962 <p>Further information on submitting testcases and implementation reports
5963 can be found from on the CSS Working Group's website at <a
5964 href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
5965 Questions should be directed to the <a
5966 href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
5967 mailing list.
5969 <h2 class=no-num id=references>References</h2>
5971 <h3 class=no-num id=normative-references>Normative References</h3>
5972 <!--begin-normative-->
5973 <!-- Sorted by label -->
5975 <dl class=bibliography>
5976 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
5977 <!---->
5979 <dt id=CHARMOD>[CHARMOD]
5981 <dd>Martin J. Dürst; et al. <a
5982 href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
5983 Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
5984 2005. W3C Recommendation. URL: <a
5985 href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
5986 </dd>
5987 <!---->
5989 <dt id=CORS>[CORS]
5991 <dd>Anne van Kesteren. <a
5992 href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
5993 Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
5994 Recommendation. (Work in progress.) URL: <a
5995 href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
5996 </dd>
5997 <!---->
5999 <dt id=CSS21>[CSS21]
6001 <dd>Bert Bos; et al. <a
6002 href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
6003 Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
6004 2011. W3C Recommendation. URL: <a
6005 href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
6006 </dd>
6007 <!---->
6009 <dt id=CSS3VAL>[CSS3VAL]
6011 <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
6012 href="http://www.w3.org/TR/2012/CR-css3-values-20120828/"><cite>CSS
6013 Values and Units Module Level 3.</cite></a> 28 August 2012. W3C Candidate
6014 Recommendation. (Work in progress.) URL: <a
6015 href="http://www.w3.org/TR/2012/CR-css3-values-20120828/">http://www.w3.org/TR/2012/CR-css3-values-20120828/</a>
6016 </dd>
6017 <!---->
6019 <dt id=HTML5>[HTML5]
6021 <dd>Ian Hickson. <a
6022 href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
6023 17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
6024 <a
6025 href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
6026 </dd>
6027 <!---->
6029 <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
6031 <dd><a
6032 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip"><cite>Information
6033 technology — Coding of audio-visual objects — Part 22: Open Font
6034 Format.</cite></a> International Organization for Standardization.
6035 ISO/IEC 14496-22:2009. URL: <a
6036 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip">http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip</a>
6037 </dd>
6038 <!---->
6040 <dt id=OPENTYPE>[OPENTYPE]
6042 <dd><a
6043 href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
6044 specification.</cite></a> Microsoft. URL: <a
6045 href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
6046 </dd>
6047 <!---->
6049 <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
6051 <dd><a
6052 href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
6053 feature registry.</cite></a> Microsoft. URL: <a
6054 href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
6055 </dd>
6056 <!---->
6058 <dt id=RFC2119>[RFC2119]
6060 <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
6061 words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
6062 RFC 2119. URL: <a
6063 href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
6064 </dd>
6065 <!---->
6067 <dt id=UAX15>[UAX15]
6069 <dd>Mark Davis; Ken Whistler. <a
6070 href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
6071 Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
6072 href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
6073 </dd>
6074 <!---->
6076 <dt id=UAX29>[UAX29]
6078 <dd>Mark Davis. <a
6079 href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
6080 Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
6081 URL: <a
6082 href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
6083 </dd>
6084 <!---->
6086 <dt id=UNICODE6>[UNICODE6]
6088 <dd>The Unicode Consortium. <a
6089 href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
6090 Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
6091 Version 6.2.0 URL: <a
6092 href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
6093 </dd>
6094 <!---->
6095 </dl>
6096 <!--end-normative-->
6097 <!--{{!CSS21}}-->
6098 <!--{{!CSS3VAL}}-->
6099 <!--{{!OPENTYPE}}-->
6100 <!--{{!OPENTYPE-FEATURES}}-->
6101 <!--{{!OPEN-FONT-FORMAT}}-->
6102 <!--{{!UNICODE6}}-->
6103 <!--{{!UAX15}}-->
6104 <!--{{!UAX29}}-->
6105 <!--{{!CORS}}-->
6106 <!--{{!HTML5}}-->
6107 <!--{{!CHARMOD}}-->
6109 <h3 class=no-num id=other-references>Other References</h3>
6110 <!--begin-informative-->
6111 <!-- Sorted by label -->
6113 <dl class=bibliography>
6114 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6115 <!---->
6117 <dt id=AAT-FEATURES>[AAT-FEATURES]
6119 <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
6120 Advanced Typography font feature registry.</cite></a> Apple. URL: <a
6121 href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
6122 </dd>
6123 <!---->
6125 <dt id=ARABIC-TYPO>[ARABIC-TYPO]
6127 <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
6128 Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
6129 <!---->
6131 <dt id=CHARMOD-NORM>[CHARMOD-NORM]
6133 <dd>François Yergeau; et al. <a
6134 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
6135 Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
6136 W3C Working Draft. (Work in progress.) URL: <a
6137 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
6138 </dd>
6139 <!---->
6141 <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
6143 <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
6144 O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
6145 <!---->
6147 <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
6149 <dd>L. David Baron. <a
6150 href="http://www.w3.org/TR/2012/WD-css3-conditional-20121213/"><cite>CSS
6151 Conditional Rules Module Level 3.</cite></a> 13 December 2012. W3C
6152 Working Draft. (Work in progress.) URL: <a
6153 href="http://www.w3.org/TR/2012/WD-css3-conditional-20121213/">http://www.w3.org/TR/2012/WD-css3-conditional-20121213/</a>
6154 </dd>
6155 <!---->
6157 <dt id=CSS3TEXT>[CSS3TEXT]
6159 <dd>Elika J. Etemad; Koji Ishii. <a
6160 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
6161 Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
6162 progress.) URL: <a
6163 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
6164 </dd>
6165 <!---->
6167 <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
6169 <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
6170 and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
6171 ISBN 0-201-17633-5.</dd>
6172 <!---->
6174 <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
6176 <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
6177 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
6178 Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
6179 2000. W3C Recommendation. URL: <a
6180 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>
6181 </dd>
6182 <!---->
6184 <dt id=ELEMTYPO>[ELEMTYPO]
6186 <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
6187 4.</cite> Hartley & Marks. 2013. ISBN 0-88179-212-8.</dd>
6188 <!---->
6190 <dt id=LANGCULTTYPE>[LANGCULTTYPE]
6192 <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
6193 ISBN 1-932026-01-0.</dd>
6194 <!---->
6196 <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
6198 <dd><a
6199 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
6200 User Guide.</cite></a> FontShop International. URL: <a
6201 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
6202 </dd>
6203 <!---->
6205 <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
6207 <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
6208 Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
6209 href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
6210 <!---->
6212 <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
6214 <dd>John Hudson. <a
6215 href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
6216 Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
6217 href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
6218 </dd>
6219 <!---->
6220 </dl>
6221 <!--end-informative-->
6222 <!--{{ARABIC-TYPO}}-->
6223 <!--{{CJKV-INFO-PROCESSING}}-->
6224 <!--{{DIGITAL-TYPOGRAPHY}}-->
6225 <!--{{DOM-LEVEL-2-STYLE}}-->
6226 <!--{{ELEMTYPO}}-->
6227 <!--{{LANGCULTTYPE}}-->
6228 <!--{{OPENTYPE-FONT-GUIDE}}-->
6229 <!--{{RASTER-TRAGEDY}}-->
6230 <!--{{WINDOWS-GLYPH-PROC}}-->
6231 <!--{{CHARMOD-NORM}}-->
6232 <!--{{AAT-FEATURES}}-->
6233 <!--{{CSS3-CONDITIONAL}}-->
6234 <!--{{CSS3TEXT}}-->
6236 <h2 class=no-num id=index>Index</h2>
6237 <!--begin-index-->
6239 <ul class=indexlist>
6240 <li>100...900 weight values, <a href="#font-weight-numeric-values"
6241 title="100...900 weight values"><strong>3.2</strong></a>
6243 <li><var><absolute-size></var>, <a href="#absolute-size-value"
6244 title="<absolute-size>"><strong>3.5</strong></a>
6246 <li><var><common-lig-values></var>, <a href="#common-lig-values"
6247 title="<common-lig-values>"><strong>6.4</strong></a>
6249 <li><var><contextual-alt-values></var>, <a
6250 href="#contextual-alt-values"
6251 title="<contextual-alt-values>"><strong>6.4</strong></a>
6253 <li><var><discretionary-lig-values></var>, <a
6254 href="#discretionary-lig-values"
6255 title="<discretionary-lig-values>"><strong>6.4</strong></a>
6257 <li><var><east-asian-variant-values></var>, <a
6258 href="#east-asian-variant-values"
6259 title="<east-asian-variant-values>"><strong>6.10</strong></a>
6261 <li><var><east-asian-width-values></var>, <a
6262 href="#east-asian-width-values"
6263 title="<east-asian-width-values>"><strong>6.10</strong></a>
6265 <li><var><family-name></var>, <a href="#family-name-value"
6266 title="<family-name>"><strong>3.1</strong></a>
6268 <li><var><feature-tag-value></var>, <a href="#feature-tag-value"
6269 title="<feature-tag-value>"><strong>6.12</strong></a>
6271 <li><var><font-face-name></var>, <a href="#font-face-name-value"
6272 title="<font-face-name>"><strong>4.3</strong></a>
6274 <li><var><font-variant-css21></var>, <a
6275 href="#font-variant-css21-values"
6276 title="<font-variant-css21>"><strong>3.7</strong></a>
6278 <li><var><generic-family></var>, <a href="#generic-family-value"
6279 title="<generic-family>"><strong>3.1</strong></a>
6281 <li><var><historical-lig-values></var>, <a
6282 href="#historical-lig-values"
6283 title="<historical-lig-values>"><strong>6.4</strong></a>
6285 <li><var><length></var>, <a href="#length-size-value"
6286 title="<length>"><strong>3.5</strong></a>
6288 <li><var><number></var>, <a href="#aspect-ratio-value"
6289 title="<number>"><strong>3.6</strong></a>
6291 <li><var><numeric-figure-values></var>, <a
6292 href="#numeric-figure-values"
6293 title="<numeric-figure-values>"><strong>6.7</strong></a>
6295 <li><var><numeric-fraction-values></var>, <a
6296 href="#numeric-fraction-values"
6297 title="<numeric-fraction-values>"><strong>6.7</strong></a>
6299 <li><var><numeric-spacing-values></var>, <a
6300 href="#numeric-spacing-values"
6301 title="<numeric-spacing-values>"><strong>6.7</strong></a>
6303 <li><var><percentage></var>, <a href="#percentage-size-value"
6304 title="<percentage>"><strong>3.5</strong></a>
6306 <li><var><relative-size></var>, <a href="#relative-size-value"
6307 title="<relative-size>"><strong>3.5</strong></a>
6309 <li><var><string></var>, <a
6310 href="#font-language-override-string-value"
6311 title="<string>"><strong>6.13</strong></a>
6313 <li><var><urange></var>, <a href="#urange-value"
6314 title="<urange>"><strong>4.5</strong></a>
6316 <li><code>@font-face</code>, <a href="#at-font-face-rule"
6317 title="@font-face"><strong>4.1</strong></a>
6319 <li><code>@font-feature-values</code>, <a
6320 href="#at-font-feature-values-rule"
6321 title="@font-feature-values"><strong>6.9</strong></a>
6323 <li>all-petite-caps, <a href="#all-petite-caps"
6324 title=all-petite-caps><strong>6.6</strong></a>
6326 <li>all-small-caps, <a href="#all-small-caps"
6327 title=all-small-caps><strong>6.6</strong></a>
6329 <li>annotation, <a href="#annotation"
6330 title=annotation><strong>6.8</strong></a>
6332 <li>aspect value, <a href="#aspect-value0" title="aspect
6333 value"><strong>3.6</strong></a>
6335 <li>authoring tool, <a href="#authoring-tool" title="authoring
6336 tool"><strong>#</strong></a>
6338 <li>auto
6339 <ul>
6340 <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
6341 font-kerning"><strong>6.3</strong></a>
6343 <li>font-size-adjust, <a href="#font-size-adjust-auto-value"
6344 title="auto, font-size-adjust"><strong>3.6</strong></a>
6345 </ul>
6347 <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
6349 <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
6351 <li>character map, <a href="#character-map" title="character
6352 map"><strong>5.2</strong></a>
6354 <li>character-variant, <a href="#character-variant"
6355 title=character-variant><strong>6.8</strong></a>
6357 <li>common-ligatures, <a href="#common-ligatures"
6358 title=common-ligatures><strong>6.4</strong></a>
6360 <li>condensed, <a href="#condensed"
6361 title=condensed><strong>3.3</strong></a>
6363 <li>contextual, <a href="#contextual"
6364 title=contextual><strong>6.4</strong></a>
6366 <li>CSSFontFaceRule, <a href="#cssfontfacerule"
6367 title=CSSFontFaceRule><strong>8.1</strong></a>
6369 <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
6370 title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
6372 <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
6373 of"><strong>#</strong></a>
6375 <li>default face, <a href="#default-face" title="default
6376 face"><strong>5.2</strong></a>
6378 <li>descriptor_declaration, <a href="#descriptordeclaration"
6379 title="descriptor_declaration"><strong>4.1</strong></a>
6381 <li>diagonal-fractions, <a href="#diagonal-fractions"
6382 title=diagonal-fractions><strong>6.7</strong></a>
6384 <li>discretionary-ligatures, <a href="#discretionary-ligatures"
6385 title=discretionary-ligatures><strong>6.4</strong></a>
6387 <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
6389 <li>extra-condensed, <a href="#extra-condensed"
6390 title=extra-condensed><strong>3.3</strong></a>
6392 <li>extra-expanded, <a href="#extra-expanded"
6393 title=extra-expanded><strong>3.3</strong></a>
6395 <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
6396 of"><strong>#</strong></a>
6398 <li>feature_type, <a href="#featuretype"
6399 title="feature_type"><strong>6.9.1</strong></a>
6401 <li>feature_value_block, <a href="#featurevalueblock"
6402 title="feature_value_block"><strong>6.9.1</strong></a>
6404 <li>feature_value_definition, <a href="#featurevaluedefinition"
6405 title="feature_value_definition"><strong>6.9.1</strong></a>
6407 <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
6409 <li>font specific, <a href="#font-specific" title="font
6410 specific"><strong>6.8</strong></a>
6412 <li>font-family
6413 <ul>
6414 <li>descriptor, <a href="#descdef-font-family" title="font-family,
6415 descriptor"><strong>4.2</strong></a>
6417 <li>property, <a href="#propdef-font-family" title="font-family,
6418 property"><strong>3.1</strong></a>
6419 </ul>
6421 <li>font-feature-settings
6422 <ul>
6423 <li>descriptor, <a href="#descdef-font-feature-settings"
6424 title="font-feature-settings, descriptor"><strong>4.7</strong></a>
6426 <li>property, <a href="#propdef-font-feature-settings"
6427 title="font-feature-settings, property"><strong>6.12</strong></a>
6428 </ul>
6430 <li>font-kerning, <a href="#propdef-font-kerning"
6431 title=font-kerning><strong>6.3</strong></a>
6433 <li>font-language-override, <a href="#propdef-font-language-override"
6434 title=font-language-override><strong>6.13</strong></a>
6436 <li>font-size, <a href="#propdef-font-size"
6437 title=font-size><strong>3.5</strong></a>
6439 <li>font-size-adjust, <a href="#propdef-font-size-adjust"
6440 title=font-size-adjust><strong>3.6</strong></a>
6442 <li>font-stretch
6443 <ul>
6444 <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
6445 descriptor"><strong>4.4</strong></a>
6447 <li>property, <a href="#propdef-font-stretch" title="font-stretch,
6448 property"><strong>3.3</strong></a>
6449 </ul>
6451 <li>font-style
6452 <ul>
6453 <li>descriptor, <a href="#descdef-font-style" title="font-style,
6454 descriptor"><strong>4.4</strong></a>
6456 <li>property, <a href="#propdef-font-style" title="font-style,
6457 property"><strong>3.4</strong></a>
6458 </ul>
6460 <li>font-synthesis, <a href="#propdef-font-synthesis"
6461 title=font-synthesis><strong>3.8</strong></a>
6463 <li>font-variant
6464 <ul>
6465 <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
6466 descriptor"><strong>4.7</strong></a>
6468 <li>property, <a href="#propdef-font-variant" title="font-variant,
6469 property"><strong>6.11</strong></a>
6470 </ul>
6472 <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
6473 title=font-variant-alternates><strong>6.8</strong></a>
6475 <li>font-variant-caps, <a href="#propdef-font-variant-caps"
6476 title=font-variant-caps><strong>6.6</strong></a>
6478 <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
6479 title=font-variant-east-asian><strong>6.10</strong></a>
6481 <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
6482 title=font-variant-ligatures><strong>6.4</strong></a>
6484 <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
6485 title=font-variant-numeric><strong>6.7</strong></a>
6487 <li>font-variant-position, <a href="#propdef-font-variant-position"
6488 title=font-variant-position><strong>6.5</strong></a>
6490 <li>font-weight
6491 <ul>
6492 <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
6493 descriptor"><strong>4.4</strong></a>
6495 <li>property, <a href="#propdef-font-weight" title="font-weight,
6496 property"><strong>3.2</strong></a>
6497 </ul>
6499 <li>font_face_rule, <a href="#fontfacerule"
6500 title="font_face_rule"><strong>4.1</strong></a>
6502 <li>FONT_FACE_SYM, <a href="#fontfacesym"
6503 title="FONT_FACE_SYM"><strong>4.1</strong></a>
6505 <li>font_family_name, <a href="#fontfamilyname"
6506 title="font_family_name"><strong>6.9.1</strong></a>
6508 <li>font_family_name_list, <a href="#fontfamilynamelist"
6509 title="font_family_name_list"><strong>6.9.1</strong></a>
6511 <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
6512 title="font_feature_values_rule"><strong>6.9.1</strong></a>
6514 <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
6515 title="FONT_FEATURE_VALUES_SYM"><strong>6.9.1</strong></a>
6517 <li>full-width, <a href="#full-width"
6518 title=full-width><strong>6.10</strong></a>
6520 <li>historical-forms, <a href="#historical-forms"
6521 title=historical-forms><strong>6.8</strong></a>
6523 <li>historical-ligatures, <a href="#historical-ligatures"
6524 title=historical-ligatures><strong>6.4</strong></a>
6526 <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
6528 <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
6530 <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
6532 <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
6534 <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
6536 <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
6538 <li>lining-nums, <a href="#lining-nums"
6539 title=lining-nums><strong>6.7</strong></a>
6541 <li>monospace, definition of, <a href="#monospace0" title="monospace,
6542 definition of"><strong>#</strong></a>
6544 <li>no-common-ligatures, <a href="#no-common-ligatures"
6545 title=no-common-ligatures><strong>6.4</strong></a>
6547 <li>no-contextual, <a href="#no-contextual"
6548 title=no-contextual><strong>6.4</strong></a>
6550 <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
6551 title=no-discretionary-ligatures><strong>6.4</strong></a>
6553 <li>no-historical-ligatures, <a href="#no-historical-ligatures"
6554 title=no-historical-ligatures><strong>6.4</strong></a>
6556 <li>none
6557 <ul>
6558 <li>font-kerning, <a href="#font-kerning-none-value" title="none,
6559 font-kerning"><strong>6.3</strong></a>
6561 <li>font-size-adjust, <a href="#font-size-adjust-none-value"
6562 title="none, font-size-adjust"><strong>3.6</strong></a>
6564 <li>font-variant, <a href="#font-variant-none-value" title="none,
6565 font-variant"><strong>6.11</strong></a>
6567 <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
6568 title="none, font-variant-ligatures"><strong>6.4</strong></a>
6569 </ul>
6571 <li>normal
6572 <ul>
6573 <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
6574 title="normal, font-feature-settings"><strong>6.12</strong></a>
6576 <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
6577 font-kerning"><strong>6.3</strong></a>
6579 <li>font-language-override, <a
6580 href="#font-language-override-normal-value" title="normal,
6581 font-language-override"><strong>6.13</strong></a>
6583 <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
6584 font-stretch"><strong>3.3</strong></a>
6586 <li>font-style, <a href="#font-style-normal-value" title="normal,
6587 font-style"><strong>3.4</strong></a>
6589 <li>font-variant, <a href="#font-variant-normal-value" title="normal,
6590 font-variant"><strong>6.11</strong></a>
6592 <li>font-variant-alternates, <a
6593 href="#font-variant-alternates-normal-value" title="normal,
6594 font-variant-alternates"><strong>6.8</strong></a>
6596 <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
6597 title="normal, font-variant-caps"><strong>6.6</strong></a>
6599 <li>font-variant-east-asian, <a
6600 href="#font-variant-east-asian-normal-value" title="normal,
6601 font-variant-east-asian"><strong>6.10</strong></a>
6603 <li>font-variant-ligatures, <a
6604 href="#font-variant-ligatures-normal-value" title="normal,
6605 font-variant-ligatures"><strong>6.4</strong></a>
6607 <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
6608 title="normal, font-variant-numeric"><strong>6.7</strong></a>
6610 <li>font-variant-position, <a href="#font-variant-position-normal-value"
6611 title="normal, font-variant-position"><strong>6.5</strong></a>
6613 <li>font-weight, <a href="#font-weight-normal-value" title="normal,
6614 font-weight"><strong>3.2</strong></a>
6615 </ul>
6617 <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
6619 <li>oldstyle-nums, <a href="#oldstyle-nums"
6620 title=oldstyle-nums><strong>6.7</strong></a>
6622 <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
6624 <li>ornaments, <a href="#ornaments"
6625 title=ornaments><strong>6.8</strong></a>
6627 <li>petite-caps, <a href="#petite-caps"
6628 title=petite-caps><strong>6.6</strong></a>
6630 <li>proportional-nums, <a href="#proportional-nums"
6631 title=proportional-nums><strong>6.7</strong></a>
6633 <li>proportional-width, <a href="#proportional-width"
6634 title=proportional-width><strong>6.10</strong></a>
6636 <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
6638 <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
6640 <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
6641 definition of"><strong>#</strong></a>
6643 <li>semi-condensed, <a href="#semi-condensed-"
6644 title=semi-condensed><strong>3.3</strong></a>
6646 <li>semi-expanded, <a href="#semi-expanded"
6647 title=semi-expanded><strong>3.3</strong></a>
6649 <li>serif, definition of, <a href="#serif0" title="serif, definition
6650 of"><strong>#</strong></a>
6652 <li>simplified, <a href="#simplified"
6653 title=simplified><strong>6.10</strong></a>
6655 <li>slashed-zero, <a href="#slashed-zero"
6656 title=slashed-zero><strong>6.7</strong></a>
6658 <li>small-caps, <a href="#small-caps"
6659 title=small-caps><strong>6.6</strong></a>
6661 <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
6663 <li>stacked-fractions, <a href="#stacked-fractions"
6664 title=stacked-fractions><strong>6.7</strong></a>
6666 <li>style sheet
6667 <ul>
6668 <li>as conformance class, <a href="#style-sheet" title="style sheet, as
6669 conformance class"><strong>#</strong></a>
6670 </ul>
6672 <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
6674 <li>stylistic, <a href="#stylistic"
6675 title=stylistic><strong>6.8</strong></a>
6677 <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
6679 <li>super, <a href="#super" title=super><strong>6.5</strong></a>
6681 <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
6683 <li>system font fallback, <a href="#system-font-fallback" title="system
6684 font fallback"><strong>5.2</strong></a>
6686 <li>tabular-nums, <a href="#tabular-nums"
6687 title=tabular-nums><strong>6.7</strong></a>
6689 <li>titling-caps, <a href="#titling-caps"
6690 title=titling-caps><strong>6.6</strong></a>
6692 <li>traditional, <a href="#traditional"
6693 title=traditional><strong>6.10</strong></a>
6695 <li>ultra-condensed, <a href="#ultra-condensed"
6696 title=ultra-condensed><strong>3.3</strong></a>
6698 <li>ultra-expanded, <a href="#ultra-expanded"
6699 title=ultra-expanded><strong>3.3</strong></a>
6701 <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
6703 <li>unicode-range, <a href="#descdef-unicode-range"
6704 title=unicode-range><strong>4.5</strong></a>
6706 <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
6708 <li>width, <a href="#width" title=width><strong>2</strong></a>
6709 </ul>
6710 <!--end-index-->
6712 <h2 class=no-num id=property-index>Property index</h2>
6713 <!--begin-properties-->
6715 <table class=proptable>
6716 <thead>
6717 <tr>
6718 <th>Property
6720 <th>Values
6722 <th>Initial
6724 <th>Applies to
6726 <th>Inh.
6728 <th>Percentages
6730 <th>Media
6732 <tbody>
6733 <tr>
6734 <th><a class=property href="#propdef-font">font</a>
6736 <td>[ [ <‘font-style’> || <font-variant-css21> ||
6737 <‘font-weight’> || <‘font-stretch’ ]?
6738 <‘font-size’> [ / <‘line-height’> ]?
6739 <‘font-family’> ] | caption | icon | menu | message-box |
6740 small-caption | status-bar
6742 <td>see individual properties
6744 <td>all elements
6746 <td>yes
6748 <td>see individual properties
6750 <td>visual
6752 <tr>
6753 <th><span class=property>font-family</span>
6755 <td>[ <family-name> | <generic-family> ] #
6757 <td>depends on user agent
6759 <td>all elements
6761 <td>yes
6763 <td>N/A
6765 <td>visual
6767 <tr>
6768 <th><span class=property>font-feature-settings</span>
6770 <td>normal | <feature-tag-value> #
6772 <td>normal
6774 <td>all elements
6776 <td>yes
6778 <td>N/A
6780 <td>visual
6782 <tr>
6783 <th><a class=property href="#propdef-font-kerning">font-kerning</a>
6785 <td>auto | normal | none
6787 <td>auto
6789 <td>all elements
6791 <td>yes
6793 <td>N/A
6795 <td>visual
6797 <tr>
6798 <th><a class=property
6799 href="#propdef-font-language-override">font-language-override</a>
6801 <td>normal | <string>
6803 <td>normal
6805 <td>all elements
6807 <td>yes
6809 <td>N/A
6811 <td>visual
6813 <tr>
6814 <th><a class=property href="#propdef-font-size">font-size</a>
6816 <td><absolute-size> | <relative-size> | <length> |
6817 <percentage>
6819 <td>medium
6821 <td>all elements
6823 <td>yes
6825 <td>refer to parent element's font size
6827 <td>visual
6829 <tr>
6830 <th><a class=property
6831 href="#propdef-font-size-adjust">font-size-adjust</a>
6833 <td>none | auto | <number>
6835 <td>none
6837 <td>all elements
6839 <td>yes
6841 <td>N/A
6843 <td>visual
6845 <tr>
6846 <th><span class=property>font-stretch</span>
6848 <td>normal | ultra-condensed | extra-condensed | condensed |
6849 semi-condensed | semi-expanded | expanded | extra-expanded |
6850 ultra-expanded
6852 <td>normal
6854 <td>all elements
6856 <td>yes
6858 <td>N/A
6860 <td>visual
6862 <tr>
6863 <th><span class=property>font-style</span>
6865 <td>normal | italic | oblique
6867 <td>normal
6869 <td>all elements
6871 <td>yes
6873 <td>N/A
6875 <td>visual
6877 <tr>
6878 <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
6880 <td>none | [ weight || style ]
6882 <td>weight style
6884 <td>all elements
6886 <td>yes
6888 <td>N/A
6890 <td>visual
6892 <tr>
6893 <th><span class=property>font-variant</span>
6895 <td>normal | none | [ <common-lig-values> ||
6896 <discretionary-lig-values> || <historical-lig-values> ||
6897 <contextual-alt-values> || stylistic(<feature-value-name>)
6898 || historical-forms || styleset(<feature-value-name> #) ||
6899 character-variant(<feature-value-name> #) ||
6900 swash(<feature-value-name>) ||
6901 ornaments(<feature-value-name>) ||
6902 annotation(<feature-value-name>) || [ small-caps | all-small-caps
6903 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
6904 <numeric-figure-values> || <numeric-spacing-values> ||
6905 <numeric-fraction-values> || ordinal || slashed-zero ||
6906 <east-asian-variant-values> || <east-asian-width-values> ||
6907 ruby ]
6909 <td>normal
6911 <td>all elements
6913 <td>yes
6915 <td>see individual properties
6917 <td>visual
6919 <tr>
6920 <th><a class=property
6921 href="#propdef-font-variant-alternates">font-variant-alternates</a>
6923 <td>normal | [ stylistic(<feature-value-name>) || historical-forms
6924 || styleset(<feature-value-name> #) ||
6925 character-variant(<feature-value-name> #) ||
6926 swash(<feature-value-name>) ||
6927 ornaments(<feature-value-name>) ||
6928 annotation(<feature-value-name>) ]
6930 <td>normal
6932 <td>all elements
6934 <td>yes
6936 <td>N/A
6938 <td>visual
6940 <tr>
6941 <th><a class=property
6942 href="#propdef-font-variant-caps">font-variant-caps</a>
6944 <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
6945 | unicase | titling-caps
6947 <td>normal
6949 <td>all elements
6951 <td>yes
6953 <td>N/A
6955 <td>visual
6957 <tr>
6958 <th><a class=property
6959 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
6961 <td>normal | [ <east-asian-variant-values> ||
6962 <east-asian-width-values> || ruby ]
6964 <td>normal
6966 <td>all elements
6968 <td>yes
6970 <td>N/A
6972 <td>visual
6974 <tr>
6975 <th><a class=property
6976 href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
6978 <td>normal | none | [ <common-lig-values> ||
6979 <discretionary-lig-values> || <historical-lig-values> ||
6980 <contextual-alt-values> ]
6982 <td>normal
6984 <td>all elements
6986 <td>yes
6988 <td>N/A
6990 <td>visual
6992 <tr>
6993 <th><a class=property
6994 href="#propdef-font-variant-numeric">font-variant-numeric</a>
6996 <td>normal | [ <numeric-figure-values> ||
6997 <numeric-spacing-values> || <numeric-fraction-values> ||
6998 ordinal || slashed-zero ]
7000 <td>normal
7002 <td>all elements
7004 <td>yes
7006 <td>N/A
7008 <td>visual
7010 <tr>
7011 <th><a class=property
7012 href="#propdef-font-variant-position">font-variant-position</a>
7014 <td>normal | sub | super
7016 <td>normal
7018 <td>all elements
7020 <td>yes
7022 <td>N/A
7024 <td>visual
7026 <tr>
7027 <th><span class=property>font-weight</span>
7029 <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
7030 | 700 | 800 | 900
7032 <td>normal
7034 <td>all elements
7036 <td>yes
7038 <td>N/A
7040 <td>visual
7041 </table>
7042 <!--end-properties-->
7043 <!--begin-descriptors-->
7045 <table class=proptable>
7046 <thead>
7047 <tr>
7048 <th>Descriptor
7050 <th>Value
7052 <th>Initial
7054 <th>Percentages
7056 <th>Media
7058 <tbody>
7059 <tr>
7060 <th><span class=property>font-family</span>
7062 <td><family-name>
7064 <td>N/A
7066 <tr>
7067 <th><span class=property>font-feature-settings</span>
7069 <td>normal | <feature-tag-value> #
7071 <td>normal
7073 <tr>
7074 <th><span class=property>font-stretch</span>
7076 <td>normal | ultra-condensed | extra-condensed | condensed |
7077 semi-condensed | semi-expanded | expanded | extra-expanded |
7078 ultra-expanded
7080 <td>normal
7082 <tr>
7083 <th><span class=property>font-style</span>
7085 <td>normal | italic | oblique
7087 <td>normal
7089 <tr>
7090 <th><span class=property>font-variant</span>
7092 <td>normal | none | [ <common-lig-values> ||
7093 <discretionary-lig-values> || <historical-lig-values> ||
7094 <contextual-alt-values> || stylistic(<feature-value-name>)
7095 || historical-forms || styleset(<feature-value-name> #) ||
7096 character-variant(<feature-value-name> #) ||
7097 swash(<feature-value-name>) ||
7098 ornaments(<feature-value-name>) ||
7099 annotation(<feature-value-name>) || [ small-caps | all-small-caps
7100 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
7101 <numeric-figure-values> || <numeric-spacing-values> ||
7102 <numeric-fraction-values> || ordinal || slashed-zero ||
7103 <east-asian-variant-values> || <east-asian-width-values> ||
7104 ruby ]
7106 <td>normal
7108 <tr>
7109 <th><span class=property>font-weight</span>
7111 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
7113 <td>normal
7115 <tr>
7116 <th><a class=property href="#descdef-src">src</a>
7118 <td>[ <url> [format(<string> #)]? | <font-face-name> ] #
7120 <td>N/A
7122 <tr>
7123 <th><a class=property href="#descdef-unicode-range">unicode-range</a>
7125 <td><urange> #
7127 <td>U+0-10FFFF
7128 </table>
7129 <!--end-descriptors-->
7130 <script type="text/javascript">
7131 window.onload = function () {
7132 if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
7133 var i, hiresElements = document.getElementsByClassName("hires");
7134 for (i = 0; i < hiresElements.length; i++) {
7135 var h = hiresElements[i];
7136 if (h.tagName != "IMG") continue;
7137 var src = h.getAttribute("src");
7138 var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
7139 h.src = src2x;
7140 }
7141 }
7142 </script>
7143 </html>
7144 <!-- Keep this comment at the end of the file
7145 Local variables:
7146 mode: sgml
7147 sgml-declaration:"~/SGML/HTML4.decl"
7148 sgml-default-doctype-name:"html"
7149 sgml-minimize-attributes:t
7150 sgml-nofill-elements:("pre" "style" "br")
7151 sgml-live-element-indicator:t
7152 sgml-omittag:nil
7153 sgml-shorttag:nil
7154 sgml-namecase-general:t
7155 sgml-general-insert-case:lower
7156 sgml-always-quote-attributes:t
7157 sgml-indent-step:nil
7158 sgml-indent-data:t
7159 sgml-parent-document:nil
7160 sgml-exposed-tags:nil
7161 sgml-local-catalogs:nil
7162 sgml-local-ecat-files:nil
7163 End:
7164 -->
7165 <!--
7167 to do:
7169 - wording of OpenType family name handling
7170 - handling combining sequences in the font matching algorithm
7171 - fix-up fi ligature example
7173 -->