css-fonts/Fonts.html@5e29c9d80cca
css-fonts/Fonts.html
Wed, 29 May 2013 09:58:56 +0900
- author
- John Daggett <jdaggett@mozilla.com>
- date
- Wed, 29 May 2013 09:58:56 +0900
- changeset 8272
- 5e29c9d80cca
- parent 8246
- fd72a8d4ecfd
- child 8276
- bf52664a49ae
- permissions
- -rw-r--r--
[css-fonts] fixes based on comments
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">
108 <body>
109 <div class=head> <!--begin-logo-->
110 <p><a href="http://www.w3.org/"><img alt=W3C height=48
111 src="http://www.w3.org/Icons/w3c_home" width=72></a> <!--end-logo-->
113 <h1>CSS Fonts Module Level 3</h1>
115 <h2 class="no-num no-toc" id=editors-draft-29-may-2013>Editor's Draft 29
116 May 2013</h2>
118 <dl id=authors>
119 <dt>This version:
121 <dd><a
122 href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
123 <!-- <dd><a href="http://www.w3.org/TR/2013/ED-css3-fonts-20130529/">http://www.w3.org/TR/2013/ED-css3-fonts-20130529/</a> -->
126 <dt>Latest version:
128 <dd><a
129 href="http://www.w3.org/TR/css3-fonts/">http://www.w3.org/TR/css3-fonts/</a>
131 <dt>Latest editor's draft:
133 <dd><a
134 href="http://dev.w3.org/csswg/css-fonts/">http://dev.w3.org/csswg/css-fonts/</a>
135 (<a
136 href="https://dvcs.w3.org/hg/csswg/log/tip/css-fonts/Fonts.html">change
137 log</a>)
139 <dt>Previous version:
141 <dd><a
142 href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">http://www.w3.org/TR/2013/WD-css3-fonts-20130212/</a>
144 <dt>Issues List:
146 <dd><a href="http://www.w3.org/Style/CSS/Tracker/products/18">CSS3 Fonts
147 issues in Tracker</a>
149 <dd><a
150 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
151 Fonts issues in Bugzilla</a>
153 <dt>Discussion:
155 <dd><a
156 href="mailto:www-style@w3.org?subject=%5Bcss-fonts%5D%20feedback">www-style@w3.org</a>
157 with subject line “<kbd>[css-fonts] <var>… message topic
158 …</var></kbd>” (<a
159 href="http://lists.w3.org/Archives/Public/www-style/"
160 rel=discussion>archives</a>)
162 <dt>Editor:
164 <dd><a href="mailto:jdaggett@mozilla.com">John Daggett (Mozilla)</a>
165 </dl>
166 <!--begin-copyright-->
167 <p class=copyright><a
168 href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright"
169 rel=license>Copyright</a> © 2013 <a href="http://www.w3.org/"><abbr
170 title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a
171 href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of
172 Technology">MIT</abbr></a>, <a href="http://www.ercim.eu/"><abbr
173 title="European Research Consortium for Informatics and
174 Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>,
175 <a href="http://ev.buaa.edu.cn/">Beihang</a>), All Rights Reserved. W3C
176 <a
177 href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
178 <a
179 href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>
180 and <a
181 href="http://www.w3.org/Consortium/Legal/copyright-documents">document
182 use</a> rules apply.</p>
183 <!--end-copyright-->
184 <hr title="Separator for header">
185 </div>
187 <h2 class="no-num no-toc" id=abstract>Abstract</h2>
189 <p>This CSS3 module describes how font properties are specified and how
190 font resources are loaded dynamically. The contents of this specification
191 are a consolidation of content previously divided into <a
192 href="http://www.w3.org/TR/2002/WD-css3-fonts-20020802/">CSS3 Fonts</a>
193 and <a href="http://www.w3.org/TR/2002/WD-css3-webfonts-20020802/">CSS3
194 Web Fonts</a> modules. The description of font load events was moved into
195 the <a href="http://dev.w3.org/csswg/css3-font-load-events/">CSS3 Font
196 Load Events</a> module.
198 <h2 class="no-num no-toc" id=status>Status of this document</h2>
199 <!--begin-status-->
201 <p>This is a public copy of the editors' draft. It is provided for
202 discussion only and may change at any moment. Its publication here does
203 not imply endorsement of its contents by W3C. Don't cite this document
204 other than as work in progress.
206 <p>The (<a
207 href="http://lists.w3.org/Archives/Public/www-style/">archived</a>) public
208 mailing list <a
209 href="mailto:www-style@w3.org?Subject=%5Bcss3-fonts%5D%20PUT%20SUBJECT%20HERE">
210 www-style@w3.org</a> (see <a
211 href="http://www.w3.org/Mail/Request">instructions</a>) is preferred for
212 discussion of this specification. When sending e-mail, please put the text
213 “css3-fonts” in the subject, preferably like this:
214 “[<!---->css3-fonts<!---->] <em>…summary of comment…</em>”
216 <p>This document was produced by the <a
217 href="http://www.w3.org/Style/CSS/members">CSS Working Group</a> (part of
218 the <a href="http://www.w3.org/Style/">Style Activity</a>).
220 <p>This document was produced by a group operating under the <a
221 href="http://www.w3.org/Consortium/Patent-Policy-20040205/">5 February
222 2004 W3C Patent Policy</a>. W3C maintains a <a
223 href="http://www.w3.org/2004/01/pp-impl/32061/status"
224 rel=disclosure>public list of any patent disclosures</a> made in
225 connection with the deliverables of the group; that page also includes
226 instructions for disclosing a patent. An individual who has actual
227 knowledge of a patent which the individual believes contains <a
228 href="http://www.w3.org/Consortium/Patent-Policy-20040205/#def-essential">Essential
229 Claim(s)</a> must disclose the information in accordance with <a
230 href="http://www.w3.org/Consortium/Patent-Policy-20040205/#sec-Disclosure">section
231 6 of the W3C Patent Policy</a>.</p>
232 <!--end-status-->
233 <!--
234 <h3 class="no-num no-toc" id="atrisk">Features at risk</h3>
236 <p>The following features are at risk and may be removed when exiting CR:</p>
238 <ul>
239 </ul>
240 -->
242 <h2 class="no-num no-toc" id=contents>Table of contents</h2>
243 <!--begin-toc-->
245 <ul class=toc>
246 <li><a href="#introduction"><span class=secno>1 </span>Introduction</a>
248 <li><a href="#typography-background"><span class=secno>2 </span>Typography
249 Background</a>
251 <li><a href="#basic-font-props"><span class=secno>3 </span>Basic Font
252 Properties</a>
253 <ul class=toc>
254 <li><a href="#font-family-prop"><span class=secno>3.1 </span>Font
255 family: the font-family property</a>
256 <ul class=toc>
257 <li><a href="#generic-font-families"><span class=secno>3.1.1
258 </span>Generic font families</a>
259 </ul>
261 <li><a href="#font-weight-prop"><span class=secno>3.2 </span>Font
262 weight: the font-weight property</a>
264 <li><a href="#font-stretch-prop"><span class=secno>3.3 </span>Font
265 width: the font-stretch property</a>
267 <li><a href="#font-style-prop"><span class=secno>3.4 </span>Font style:
268 the font-style property</a>
270 <li><a href="#font-size-prop"><span class=secno>3.5 </span>Font size:
271 the font-size property</a>
273 <li><a href="#font-size-adjust-prop"><span class=secno>3.6
274 </span>Relative sizing: the font-size-adjust property</a>
276 <li><a href="#font-prop"><span class=secno>3.7 </span>Shorthand font
277 property: the font property</a>
279 <li><a href="#font-synthesis-prop"><span class=secno>3.8
280 </span>Controlling synthetic faces: the font-synthesis property</a>
281 </ul>
283 <li><a href="#font-resources"><span class=secno>4 </span>Font
284 Resources</a>
285 <ul class=toc>
286 <li><a href="#font-face-rule"><span class=secno>4.1 </span>The
287 <code>@font-face</code> rule</a>
289 <li><a href="#font-family-desc"><span class=secno>4.2 </span>Font
290 family: the font-family descriptor</a>
292 <li><a href="#src-desc"><span class=secno>4.3 </span>Font reference: the
293 src descriptor</a>
295 <li><a href="#font-prop-desc"><span class=secno>4.4 </span>Font property
296 descriptors: the font-style, font-weight, font-stretch descriptors</a>
298 <li><a href="#unicode-range-desc"><span class=secno>4.5 </span>Character
299 range: the unicode-range descriptor</a>
301 <li><a href="#composite-fonts"><span class=secno>4.6 </span>Using
302 character ranges to define composite fonts</a>
304 <li><a href="#font-rend-desc"><span class=secno>4.7 </span>Font
305 features: the font-variant and font-feature-settings descriptors</a>
307 <li><a href="#font-face-loading"><span class=secno>4.8 </span>Font
308 loading guidelines</a>
310 <li><a href="#same-origin-restriction"><span class=secno>4.9
311 </span>Same-origin restriction for fonts</a>
312 <ul class=toc>
313 <li><a href="#default-same-origin-restriction"><span class=secno>4.9.1
314 </span>Default same-origin restriction</a>
316 <li><a href="#allowing-cross-origin-font-loading"><span
317 class=secno>4.9.2 </span>Allowing cross-origin font loading</a>
318 </ul>
319 </ul>
321 <li><a href="#font-matching-algorithm"><span class=secno>5 </span>Font
322 Matching Algorithm</a>
323 <ul class=toc>
324 <li><a href="#font-family-casing"><span class=secno>5.1 </span>Case
325 sensitivity of font family names</a>
327 <li><a href="#font-style-matching"><span class=secno>5.2 </span>Matching
328 font styles</a>
330 <li><a href="#cluster-matching"><span class=secno>5.3 </span>Cluster
331 matching</a>
333 <li><a href="#char-handling-issues"><span class=secno>5.4
334 </span>Character handling issues</a>
336 <li><a href="#font-matching-changes"><span class=secno>5.5 </span>Font
337 matching changes since CSS 2.1</a>
339 <li><a href="#font-matching-examples"><span class=secno>5.6 </span>Font
340 matching examples</a>
341 </ul>
343 <li><a href="#font-rend-props"><span class=secno>6 </span>Font Feature
344 Properties</a>
345 <ul class=toc>
346 <li><a href="#glyph-selection-positioning"><span class=secno>6.1
347 </span>Glyph selection and positioning</a>
349 <li><a href="#language-specific-support"><span class=secno>6.2
350 </span>Language-specific display</a>
352 <li><a href="#font-kerning-prop"><span class=secno>6.3 </span>Kerning:
353 the font-kerning property</a>
355 <li><a href="#font-variant-ligatures-prop"><span class=secno>6.4
356 </span>Ligatures: the font-variant-ligatures property</a>
358 <li><a href="#font-variant-position-prop"><span class=secno>6.5
359 </span>Subscript and superscript forms: the font-variant-position
360 property</a>
362 <li><a href="#font-variant-caps-prop"><span class=secno>6.6
363 </span>Capitalization: the font-variant-caps property</a>
365 <li><a href="#font-variant-numeric-prop"><span class=secno>6.7
366 </span>Numerical formatting: the font-variant-numeric property</a>
368 <li><a href="#font-variant-alternates-prop"><span class=secno>6.8
369 </span>Alternates and swashes: the font-variant-alternates property</a>
372 <li><a href="#font-feature-values"><span class=secno>6.9 </span>Defining
373 font specific alternates: the <code>@font-feature-values</code>
374 rule</a>
376 <li><a href="#font-variant-east-asian-prop"><span class=secno>6.10
377 </span>East Asian text rendering: the font-variant-east-asian
378 property</a>
380 <li><a href="#font-variant-prop"><span class=secno>6.11 </span>Overall
381 shorthand for font rendering: the font-variant property</a>
383 <li><a href="#font-feature-settings-prop"><span class=secno>6.12
384 </span>Low-level font feature settings control: the
385 font-feature-settings property</a>
387 <li><a href="#font-language-override-prop"><span class=secno>6.13
388 </span>Font language override: the font-language-override property</a>
389 </ul>
391 <li><a href="#font-feature-resolution"><span class=secno>7 </span>Font
392 Feature Resolution </a>
393 <ul class=toc>
394 <li><a href="#default-features"><span class=secno>7.1 </span>Default
395 features</a>
397 <li><a href="#feature-precedence"><span class=secno>7.2 </span>Feature
398 precedence</a>
400 <li><a href="#feature-precedence-examples"><span class=secno>7.3
401 </span>Feature precedence examples</a>
402 </ul>
404 <li><a href="#object-model"><span class=secno>8 </span>Object Model</a>
405 <ul class=toc>
406 <li><a href="#om-fontface"><span class=secno>8.1 </span>The
407 <code>CSSFontFaceRule</code> interface</a>
409 <li><a href="#om-fontfeaturevalues"><span class=secno>8.2 </span>The
410 <code>CSSFontFeatureValuesRule</code> interface</a>
411 </ul>
413 <li class=no-num><a href="#platform-props-to-css">Appendix A: Mapping
414 platform font properties to CSS properties</a>
416 <li class=no-num><a href="#ch-ch-ch-changes">Changes</a>
417 <ul class=toc>
418 <li class=no-num><a href="#recent-changes"> Changes from the February
419 2013 CSS3 Fonts Working Draft</a>
420 </ul>
422 <li class=no-num><a href="#acknowledgments">Acknowledgments</a>
424 <li class=no-num><a href="#conformance"> Conformance</a>
425 <ul class=toc>
426 <li class=no-num><a href="#conventions"> Document Conventions</a>
428 <li class=no-num><a href="#conformance-classes"> Conformance Classes</a>
431 <li class=no-num><a href="#partial"> Partial Implementations</a>
433 <li class=no-num><a href="#experimental"> Experimental
434 Implementations</a>
436 <li class=no-num><a href="#testing"> Non-Experimental
437 Implementations</a>
438 </ul>
440 <li class=no-num><a href="#references">References</a>
441 <ul class=toc>
442 <li class=no-num><a href="#normative-references">Normative
443 References</a>
445 <li class=no-num><a href="#other-references">Other References</a>
446 </ul>
448 <li class=no-num><a href="#index">Index</a>
450 <li class=no-num><a href="#property-index">Property index</a>
451 </ul>
452 <!--end-toc-->
454 <h2 id=introduction><span class=secno>1 </span>Introduction</h2>
456 <p>A font provides a resource containing the visual representation of
457 characters. At the simplest level it contains information that maps
458 character codes to shapes (called glyphs) that represent these characters.
459 Fonts sharing a common design style are commonly grouped into font
460 families classified by a set of standard font properties. Within a family,
461 the shape displayed for a given character can vary by stroke weight, slant
462 or relative width, among others. An individual font face is described by a
463 unique combination of these properties. For a given range of text, CSS
464 font properties are used to select a font family and a specific font face
465 within that family to be used when rendering that text. As a simple
466 example, to use the bold form of Helvetica one could use:
468 <pre>body {
469 font-family: Helvetica;
470 font-weight: bold;
471 }</pre>
473 <p>Font resources may be installed locally on the system on which a user
474 agent is running or downloadable. For local font resources descriptive
475 information can be obtained directly from the font resource. For
476 downloadable font resources (sometimes referred to as web fonts), the
477 descriptive information is included with the reference to the font
478 resource.
480 <p>Families of fonts typically don't contain a single face for each
481 possible variation of font properties. The CSS font selection mechanism
482 describes how to match a given set of CSS font properties to a single font
483 face.
485 <h2 id=typography-background><span class=secno>2 </span>Typography
486 Background</h2>
488 <p><em>This section is non-normative.</em>
490 <p> Typographic traditions vary across the globe, so there is no unique way
491 to classify all fonts across languages and cultures. For even common Latin
492 letters, wide variations are possible:
494 <div class=figure><img alt="variations in glyphs for a single character"
495 src=aaaaaa.png>
496 <p class=caption>One character, many glyph variations
497 </div>
499 <p>Differences in the anatomy of letterforms is one way to distinguish
500 fonts. For Latin fonts, flourishes at the ends of a character's main
501 strokes, or serifs, can distinguish a font from those without. Similar
502 comparisons exist in non-Latin fonts between fonts with tapered strokes
503 and those using primarily uniform strokes:
505 <div class=figure><img alt="serif vs. non-serifs" src=serifvssansserif.png>
506 <p class=caption>Letterforms with and without serifs
507 </div>
509 <div class=figure><img alt="serif vs. non-serifs for japanese"
510 src=minchovsgothic.png>
511 <p class=caption>Similar groupings for Japanese typefaces
512 </div>
514 <p>Fonts contain letterforms and the data needed to map characters to these
515 letterforms. Often this may be a simple one-to-one mapping, but more
516 complex mappings are also possible. The use of combining diacritic marks
517 creates many variations for an underlying letterform:
519 <div class=figure><img alt="diacritic marks" src=aaaaaa-diacritics.png>
520 <p class=caption>Variations with diacritic marks
521 </div>
523 <p>A sequence of characters can be represented by a single glyph known as a
524 ligature:
526 <div class=figure><img alt="example of a fi ligature"
527 src=final-ligature.png>
528 <p class=caption>Ligature example
529 </div>
531 <p>Visual transformations based on textual context are often stylistic
532 option in European languages. They are required to correctly render
533 languages like Arabic, the lam and alef characters below <em>must</em> be
534 combined when they exist in sequence:
536 <div class=figure><img alt="lam alef ligature" src=lamaleflig.png>
537 <p class=caption>Required Arabic ligature
538 </div>
540 <p>The relative complexity of these shaping transformations requires
541 additional data within the font.
543 <p>Sets of font faces with various stylistic variations are often grouped
544 together into font families. In the simplest case a regular face is
545 supplemented with bold and italic faces, but much more extensive groupings
546 are possible. Variations in the thickness of letterform strokes, the <dfn
547 id=weight>weight</dfn>, and the overall proportions of the letterform, the
548 <dfn id=width>width</dfn>, are most common. In the example below, each
549 letter uses a different font face within the Univers font family. The
550 width used increases from top to bottom and the weight increases from left
551 to right:
553 <div class=figure><img alt="various width and weight variations within a
554 single family" src=weightwidthvariations.png>
555 <p class=caption>Weight and width variations within a single font family
556 </div>
558 <p>Creating fonts that support multiple scripts is a difficult task;
559 designers need to understand the cultural traditions surrounding the use
560 of type in different scripts and come up with letterforms that somehow
561 share a common theme. Many languages often share a common script and each
562 of these languages may have noticeable stylistic differences. For example,
563 the Arabic script is shared by Persian and Urdu and Cyrillic is used with
564 many languages, not just Russian.
566 <p>The <a href="#character-map"><em>character map</em></a> of a font
567 defines the mapping of characters to glyphs for that font. If a document
568 contains characters not supported by the <a href="#character-map"><em
569 title="character map">character maps</em></a> of the fonts contained in a
570 font family list, a user agent may use a system font fallback procedure to
571 locate an appropriate font that does. If no appropriate font can be found,
572 some form of "missing glyph" character will be rendered by the user agent.
573 System fallback can occur when the specified list of font families does
574 not include a font that supports a given character.
576 <p>Although the <a href="#character-map"><em>character map</em></a> of a
577 font maps a given character to a glyph for that character, modern font
578 technologies such as OpenType and AAT (Apple Advanced Typography) provide
579 ways of mapping a character to different glyphs based upon feature
580 settings. Fonts in these formats allow these features to be embedded in
581 the font itself and controlled by applications. Common typographic
582 features which can be specified this way include ligatures, swashes,
583 contextual alternates, proportional and tabular figures, and automatic
584 fractions, to list just a few. For a visual overview of OpenType features,
585 see the <a href="#OPENTYPE-FONT-GUIDE"
586 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
588 <h2 id=basic-font-props><span class=secno>3 </span>Basic Font Properties</h2>
590 <p>The particular font face used to render a character is determined by the
591 font family and other font properties that apply to a given element. This
592 structure allows settings to be varied independent of each other.</p>
593 <!-- prop: font-family -->
595 <h3 id=font-family-prop><span class=secno>3.1 </span>Font family: the <a
596 href="#propdef-font-family">font-family</a> property</h3>
598 <table class=propdef id=namefont-familyvalue-ltfamily-namegt-ltg>
599 <tbody>
600 <tr>
601 <td>Name:
603 <td><dfn id=propdef-font-family>font-family</dfn>
605 <tr>
606 <td>Value:
608 <td>[ <a href="#family-name-value"><var><family-name></var></a> |
609 <a href="#generic-family-value"><var><generic-family></var></a> ]
610 #
612 <tr>
613 <td>Initial:
615 <td>depends on user agent
617 <tr>
618 <td>Applies to:
620 <td>all elements
622 <tr>
623 <td>Inherited:
625 <td>yes
627 <tr>
628 <td>Percentages:
630 <td>N/A
632 <tr>
633 <td>Media:
635 <td>visual
637 <tr>
638 <td>Computed value:
640 <td>as specified
642 <tr>
643 <td>Animatable:
645 <td>no
646 </table>
648 <p>This property specifies a prioritized list of font family names or
649 generic family names. A font family defines a set of faces that vary in
650 weight, width or slope. CSS uses the combination of a family name with
651 other style attributes to select an individual face. Using this selection
652 mechanism, rather than selecting a face via the style name as is often
653 done in design applications, allows some degree of regularity in textual
654 display when fallback occurs.
656 <p class=note>Designers should note that the CSS definition of font
657 attributes used for selection are explicitly not intended to define a font
658 taxonomy. A type designer's idea of a family may often extend to a set of
659 faces that vary along axes other than just the standard axes of weight,
660 width and slope. A family may extend to include both a set of serif faces
661 and a set of sans-serif faces or vary along axes that are unique to that
662 family. The CSS font selection mechanism merely provides a way to
663 determine the “closest” substitute when substitution is necessary.
665 <p>Unlike other CSS properties, component values are a comma-separated list
666 indicating alternatives. A user agent iterates through the list of family
667 names until it matches an available font that contains a glyph for the
668 character to be rendered. This allows for differences in available fonts
669 across platforms and for differences in the range of characters supported
670 by individual fonts.
672 <p>A font family name only specifies a name given to a set of font faces,
673 it does not specify an individual face. For example, given the
674 availability of the fonts below, Futura would match but Futura Medium
675 would not:
677 <div class=figure><img alt="family and face names"
678 src=familyvsfacename.png>
679 <p class=caption>Family and individual face names
680 </div>
682 <p>Consider the example below:
684 <div class=example>
685 <pre>body {
686 font-family: Helvetica, Verdana, sans-serif;
687 }</pre>
689 <p>If Helvetica is available it will be used when rendering. If neither
690 Helvetica nor Verdana is present, then the user-agent-defined sans serif
691 font will be used.</p>
692 </div>
694 <p>There are two types of font family names:
696 <dl>
697 <dt><dfn id=family-name-value><var><family-name></var></dfn>
699 <dd>The name of a font family of choice such as Helvetica or Verdana in
700 the previous example.
702 <dt><dfn id=generic-family-value><var><generic-family></var></dfn>
704 <dd> The following generic family keywords are defined: ‘<a
705 href="#serif"><code class=property>serif</code></a>’, ‘<a
706 href="#sans-serif"><code class=property>sans-serif</code></a>’, ‘<a
707 href="#cursive"><code class=property>cursive</code></a>’, ‘<a
708 href="#fantasy"><code class=property>fantasy</code></a>’, and ‘<a
709 href="#monospace"><code class=property>monospace</code></a>’. These
710 keywords can be used as a general fallback mechanism when an author's
711 desired font choices are not available. As keywords, they must not be
712 quoted. Authors are encouraged to append a generic font family as a last
713 alternative for improved robustness.
714 </dl>
716 <p>Font family names other than generic families must either be given
717 quoted as <a
718 href="//www.w3.org/TR/CSS21/syndata.html#strings">strings,</a> or unquoted
719 as a sequence of one or more <a
720 href="//www.w3.org/TR/CSS21/syndata.html#value-def-identifier">identifiers.</a>
721 This means most punctuation characters and digits at the start of each
722 token must be escaped in unquoted font family names.
724 <p>To illustrate this, the following declarations are invalid:
726 <pre>
727 font-family: Red/Black, sans-serif;
728 font-family: "Lucida" Grande, sans-serif;
729 font-family: Ahem!, sans-serif;
730 font-family: test@foo, sans-serif;
731 font-family: #POUND, sans-serif;
732 font-family: Hawaii 5-0, sans-serif;
733 </pre>
735 <p>If a sequence of identifiers is given as a font family name, the
736 computed value is the name converted to a string by joining all the
737 identifiers in the sequence by single spaces.
739 <p>To avoid mistakes in escaping, it is recommended to quote font family
740 names that contain white space, digits, or punctuation characters other
741 than hyphens:
743 <pre>
744 body { font-family: "New Century Schoolbook", serif }
746 <BODY STYLE="font-family: '21st Century', fantasy">
747 </pre>
749 <p>Font family <em>names</em> that happen to be the same as a keyword value
750 (‘<code class=property>inherit</code>’, ‘<a href="#serif"><code
751 class=property>serif</code></a>’, ‘<a href="#sans-serif"><code
752 class=property>sans-serif</code></a>’, ‘<a href="#monospace"><code
753 class=property>monospace</code></a>’, ‘<a href="#fantasy"><code
754 class=property>fantasy</code></a>’, and ‘<a href="#cursive"><code
755 class=property>cursive</code></a>’) must be quoted to prevent confusion
756 with the keywords with the same names. The keywords ‘<code
757 class=property>initial</code>’ and ‘<code
758 class=property>default</code>’ are reserved for future use and must also
759 be quoted when used as font names. UAs must not consider these keywords as
760 matching the <a
761 href="#family-name-value"><var><family-name></var></a> type.
763 <p>The precise way a set of fonts are grouped into font families varies
764 depending upon the platform font management API's. The Windows GDI API
765 only allows four faces to be grouped into a family while the DirectWrite
766 API and API's on OSX and other platforms support font families with a
767 variety of weights, widths and slopes (see <a
768 href="#platform-props-to-css">Appendix A</a> for more details).
770 <p>Some font formats allow fonts to carry multiple localizations of the
771 family name. User agents must recognize and correctly match all of these
772 names independent of the underlying platform localization, system API used
773 or document encoding:
775 <div class=figure><img alt="examples of localized family names"
776 src=localizedfamilynames.png>
777 <p class=caption>Localized family names
778 </div>
780 <h4 id=generic-font-families><span class=secno>3.1.1 </span>Generic font
781 families</h4>
783 <p>All five generic font families are defined to exist in all CSS
784 implementations (they need not necessarily map to five distinct actual
785 fonts). User agents should provide reasonable default choices for the
786 generic font families, which express the characteristics of each family as
787 well as possible within the limits allowed by the underlying technology.
788 User agents are encouraged to allow users to select alternative choices
789 for the generic fonts.
791 <h5 class="no-num no-toc"> <span class=index-def id=serif0 title="serif,
792 definition of"><a name=serif-def><dfn id=serif>serif</dfn></a></span></h5>
794 <p>Serif fonts represent the formal text style for a script. This often
795 means but is not limited to glyphs that have finishing strokes, flared or
796 tapering ends, or have actual serifed endings (including slab serifs).
797 Serif fonts are typically proportionately-spaced. They often display a
798 greater variation between thick and thin strokes than fonts from the ‘<a
799 href="#sans-serif"><code class=property>sans-serif</code></a>’ generic
800 font family. CSS uses the term ‘<a href="#serif"><code
801 class=property>serif</code></a>’ to apply to a font for any script,
802 although other names may be more familiar for particular scripts, such as
803 Mincho (Japanese), Sung, Song or Kai (Chinese), Batang (Korean). For
804 Arabic, the Naskh style would correspond to ‘<a href="#serif"><code
805 class=property>serif</code></a>’ more due to its typographic role rather
806 than its actual design style. Any font that is so described may be used to
807 represent the generic ‘<a href="#serif"><code
808 class=property>serif</code></a>’ family.
810 <div class=figure><img alt="sample serif fonts" src=serifexamples.png>
811 <p class=caption>Sample serif fonts
812 </div>
814 <h5 class="no-num no-toc"> <span class=index-def id=sans-serif0
815 title="sans-serif, definition of"> <a name=sans-serif-def><dfn
816 id=sans-serif>sans-serif</dfn></a></span></h5>
818 <p>Glyphs in sans-serif fonts, as the term is used in CSS, are generally
819 low contrast (vertical and horizontal stems have the close to the same
820 thickness) and have stroke endings that are plain -- without any flaring,
821 cross stroke, or other ornamentation. Sans-serif fonts are typically
822 proportionately-spaced. They often have little variation between thick and
823 thin strokes, compared to fonts from the ‘<a href="#serif"><code
824 class=property>serif</code></a>’ family. CSS uses the term ‘<a
825 href="#sans-serif"><code class=property>sans-serif</code></a>’ to apply
826 to a font for any script, although other names may be more familiar for
827 particular scripts, such as Gothic (Japanese), Hei (Chinese), or Gulim
828 (Korean). Any font that is so described may be used to represent the
829 generic ‘<a href="#sans-serif"><code
830 class=property>sans-serif</code></a>’ family.
832 <div class=figure><img alt="sample sans-serif fonts"
833 src=sansserifexamples.png>
834 <p class=caption>Sample sans-serif fonts
835 </div>
837 <h5 class="no-num no-toc"> <span class=index-def id=cursive0
838 title="cursive, definition of"> <a name=cursive-def><dfn
839 id=cursive>cursive</dfn></a></span></h5>
841 <p>Glyphs in cursive fonts generally use a more informal script style, and
842 the result looks more like handwritten pen or brush writing than printed
843 letterwork. CSS uses the term ‘<a href="#cursive"><code
844 class=property>cursive</code></a>’ to apply to a font for any script,
845 although other names such as Chancery, Brush, Swing and Script are also
846 used in font names.
848 <div class=figure><img alt="sample cursive fonts" src=cursiveexamples.png>
849 <p class=caption>Sample cursive fonts
850 </div>
852 <h5 class="no-num no-toc"> <span class=index-def id=fantasy0
853 title="fantasy, definition of"> <a name=fantasy-def><dfn
854 id=fantasy>fantasy</dfn></a></span></h5>
856 <p>Fantasy fonts are primarily decorative or expressive fonts that contain
857 playful representations of characters. These do not include Pi or Picture
858 fonts which do not represent actual characters.
860 <div class=figure><img alt="sample fantasy fonts" src=fantasyexamples.png>
861 <p class=caption>Sample fantasy fonts
862 </div>
864 <h5 class="no-num no-toc"> <span class=index-def id=monospace0
865 title="monospace, definition of"> <a name=monospace-def><dfn
866 id=monospace>monospace</dfn></a></span></h5>
868 <p>The sole criterion of a monospace font is that all glyphs have the same
869 fixed width. This is often used to render samples of computer code.
871 <div class=figure><img alt="sample monospace fonts"
872 src=monospaceexamples.png>
873 <p class=caption>Sample monospace fonts
874 </div>
875 <!-- prop: font-weight -->
877 <h3 id=font-weight-prop><span class=secno>3.2 </span>Font weight: the <a
878 href="#propdef-font-weight">font-weight</a> property</h3>
880 <table class=propdef id=namefont-weightvaluenormal-bold-bolder-l>
881 <tbody>
882 <tr>
883 <td>Name:
885 <td><dfn id=propdef-font-weight>font-weight</dfn>
887 <tr>
888 <td>Value:
890 <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
891 | 700 | 800 | 900
893 <tr>
894 <td>Initial:
896 <td>normal
898 <tr>
899 <td>Applies to:
901 <td>all elements
903 <tr>
904 <td>Inherited:
906 <td>yes
908 <tr>
909 <td>Percentages:
911 <td>N/A
913 <tr>
914 <td>Media:
916 <td>visual
918 <tr>
919 <td>Computed value:
921 <td>numeric weight value (see description)
923 <tr>
924 <td>Animatable:
926 <td>as <a
927 href="http://dev.w3.org/csswg/css3-transitions/#animtype-font-weight">font
928 weight</a>
929 </table>
931 <p>The <a class=noxref href="#font-weight-prop"><span
932 class=property>‘<code class=property>font-weight</code>’</span></a>
933 property specifies the weight of glyphs in the font, their degree of
934 blackness or stroke thickness.
936 <p>Values have the following meanings:
938 <dl>
939 <dt>100 to 900
941 <dd>These values form an ordered sequence, where each number indicates a
942 weight that is at least as dark as its predecessor. These roughly
943 correspond to the commonly used weight names below:
944 </dl>
946 <ul>
947 <li>100 - Thin
949 <li>200 - Extra Light (Ultra Light)
951 <li>300 - Light
953 <li>400 - Normal
955 <li>500 - Medium
957 <li>600 - Semi Bold (Demi Bold)
959 <li>700 - Bold
961 <li>800 - Extra Bold (Ultra Bold)
963 <li>900 - Black (Heavy)
964 </ul>
966 <dl>
967 <dt><a href="#normal2"><strong>normal</strong></a>
969 <dd>Same as ‘<code class=css>400</code>’.
971 <dt><strong>bold</strong>
973 <dd>Same as ‘<code class=css>700</code>’.
975 <dt><strong>bolder</strong>
977 <dd>Specifies a bolder weight than the inherited value.
979 <dt><strong>lighter</strong>
981 <dd>Specifies a lighter weight than the inherited value.
982 </dl>
984 <p>Font formats that use a scale other than a nine-step scale should map
985 their scale onto the CSS scale so that 400 roughly corresponds with a face
986 that would be labeled as Regular, Book, Roman and 700 roughly matches a
987 face that would be labeled as Bold. Or weights may be inferred from the
988 style names, ones that correspond roughly with the scale above. The scale
989 is relative, so a face with a larger weight value must never appear
990 lighter. If style names are used to infer weights, care should be taken to
991 handle variations in style names across locales.
993 <p>Quite often there are only a few weights available for a particular font
994 family. When a weight is specified for which no face exists, a face with a
995 nearby weight is used. In general, bold weights map to faces with heavier
996 weights and light weights map to faces with lighter weights (see the <a
997 href="#font-matching-algorithm">font matching section below</a> for a
998 precise definition). The examples here illustrate which face is used for
999 different weights, grey indicates a face for that weight does not exist so
1000 a face with a nearby weight is used:
1002 <div class=figure><img alt="weight mappings for a family with 400, 700 and
1003 900 weights" src=optimaweights.png>
1004 <p class=caption>Weight mappings for a font family with 400, 700 and 900
1005 weight faces
1006 </div>
1008 <div class=figure><img alt="weight mappings for a family with 300, 600
1009 weights" src=hiraginoweights.png>
1010 <p class=caption>Weight mappings for a font family with 300 and 600 weight
1011 faces
1012 </div>
1014 <p>Although the practice is not well-loved by typographers, bold faces are
1015 often synthesized by user agents for faces that lack actual bold faces.
1016 For the purposes of style matching, these faces must be treated as if they
1017 exist within the family. Authors can explicitly avoid this behavior by
1018 using the ‘<a href="#propdef-font-synthesis"><code
1019 class=property>font-synthesis</code></a>’ property.
1021 <p>Specified values of ‘<code class=property>bolder</code>’ and
1022 ‘<code class=property>lighter</code>’ indicate weights relative to the
1023 weight of the parent element. The computed weight is calculated based on
1024 the inherited ‘<a href="#propdef-font-weight"><code
1025 class=property>font-weight</code></a>’ value using the chart below.
1027 <table class=data id=bolderlighter summary="Bolder/lighter mappings">
1028 <thead>
1029 <tr>
1030 <th>Inherited value
1032 <th>bolder
1034 <th>lighter
1036 <tbody>
1037 <tr>
1038 <th>100
1040 <td>400
1042 <td>100
1044 <tr>
1045 <th>200
1047 <td>400
1049 <td>100
1051 <tr>
1052 <th>300
1054 <td>400
1056 <td>100
1058 <tr>
1059 <th>400
1061 <td>700
1063 <td>100
1065 <tr>
1066 <th>500
1068 <td>700
1070 <td>100
1072 <tr>
1073 <th>600
1075 <td>900
1077 <td>400
1079 <tr>
1080 <th>700
1082 <td>900
1084 <td>400
1086 <tr>
1087 <th>800
1089 <td>900
1091 <td>700
1093 <tr>
1094 <th>900
1096 <td>900
1098 <td>700
1099 </table>
1101 <p>The table above is equivalent to selecting the next relative bolder or
1102 lighter face, given a font family containing normal and bold faces along
1103 with a thin and a heavy face. Authors who desire finer control over the
1104 exact weight values used for a given element may use numerical values
1105 instead of relative weights.</p>
1106 <!-- prop: font-stretch -->
1108 <h3 id=font-stretch-prop><span class=secno>3.3 </span>Font width: the <a
1109 href="#propdef-font-stretch">font-stretch</a> property</h3>
1111 <table class=propdef id=namefont-stretchvaluenormal-ultra-conden>
1112 <tbody>
1113 <tr>
1114 <td>Name:
1116 <td><dfn id=propdef-font-stretch>font-stretch</dfn>
1118 <tr>
1119 <td>Value:
1121 <td>normal | ultra-condensed | extra-condensed | condensed |
1122 semi-condensed | semi-expanded | expanded | extra-expanded |
1123 ultra-expanded
1125 <tr>
1126 <td>Initial:
1128 <td>normal
1130 <tr>
1131 <td>Applies to:
1133 <td>all elements
1135 <tr>
1136 <td>Inherited:
1138 <td>yes
1140 <tr>
1141 <td>Percentages:
1143 <td>N/A
1145 <tr>
1146 <td>Media:
1148 <td>visual
1150 <tr>
1151 <td>Computed value:
1153 <td>as specified
1155 <tr>
1156 <td>Animatable:
1158 <td>as <a href="#font-stretch-animation">font stretch</a>
1159 </table>
1161 <p>The <a class=noxref href="#font-stretch-prop"><span
1162 class=property>‘<code class=property>font-stretch</code>’</span></a>
1163 property selects a normal, condensed, or expanded face from a font family.
1164 Absolute keyword values have the following ordering, from narrowest to
1165 widest:
1167 <ul>
1168 <li><code>ultra-condensed</code>
1170 <li><code>extra-condensed</code>
1172 <li><code>condensed</code>
1174 <li><code>semi-condensed </code>
1176 <li><code>normal</code>
1178 <li><code>semi-expanded</code>
1180 <li><code>expanded</code>
1182 <li><code>extra-expanded</code>
1184 <li><code>ultra-expanded</code>
1185 </ul>
1187 <p>When a face does not exist for a given width, normal or condensed values
1188 map to a narrower face, otherwise a wider face. Conversely, expanded
1189 values map to a wider face, otherwise a narrower face. The figure below
1190 shows how the nine font-stretch property settings affect font selection
1191 for font family containing a variety of widths, grey indicates a width for
1192 which no face exists and a different width is substituted:
1194 <div class=figure><img alt="width mappings for a family with condensed,
1195 normal and expanded faces" src=universwidths.png>
1196 <p class=caption>Width mappings for a font family with condensed, normal
1197 and expanded width faces
1198 </div>
1200 <p id=font-stretch-animation>Animation of font stretch: Font stretch is
1201 interpolated in discrete steps. The interpolation happens as though the
1202 ordered values are equally spaced real numbers. The interpolation result
1203 is rounded to the nearest value, with values exactly halfway between two
1204 values rounded towards the later value in the list above.</p>
1205 <!-- prop: font-style -->
1207 <h3 id=font-style-prop><span class=secno>3.4 </span>Font style: the <a
1208 href="#propdef-font-style">font-style</a> property</h3>
1210 <table class=propdef id=namefont-stylevaluenormal-italic-oblique>
1211 <tbody>
1212 <tr>
1213 <td>Name:
1215 <td><dfn id=propdef-font-style>font-style</dfn>
1217 <tr>
1218 <td>Value:
1220 <td>normal | italic | oblique
1222 <tr>
1223 <td>Initial:
1225 <td>normal
1227 <tr>
1228 <td>Applies to:
1230 <td>all elements
1232 <tr>
1233 <td>Inherited:
1235 <td>yes
1237 <tr>
1238 <td>Percentages:
1240 <td>N/A
1242 <tr>
1243 <td>Media:
1245 <td>visual
1247 <tr>
1248 <td>Computed value:
1250 <td>as specified
1252 <tr>
1253 <td>Animatable:
1255 <td>no
1256 </table>
1258 <p>The <a class=noxref href="#font-style-prop"><span
1259 class=property>‘<code class=property>font-style</code>’</span></a>
1260 property allows italic or oblique faces to be selected. Italic forms are
1261 generally cursive in nature while oblique faces are typically sloped
1262 versions of the regular face. Oblique faces can be simulated by
1263 artificially sloping the glyphs of the regular face. Compare the
1264 artificially sloped renderings of Palatino ‘<code
1265 class=property>a</code>’ and Baskerville ‘<code
1266 class=property>N</code>’ in grey with the actual italic versions:
1268 <div class=figure><img alt="artificial sloping vs. real italics"
1269 src=realvsfakeitalics.png>
1270 <p class=caption>Artificial sloping versus real italics
1271 </div>
1273 <p>A value of ‘<a href="#normal2"><code
1274 class=property>normal</code></a>’ selects a face that is classified as
1275 ‘<a href="#normal2"><code class=property>normal</code></a>’, while
1276 ‘<code class=property>oblique</code>’ selects a font that is labeled
1277 ‘<code class=property>oblique</code>’. A value of ‘<code
1278 class=property>italic</code>’ selects a font that is labeled ‘<code
1279 class=property>italic</code>’, or, if that is not available, one labeled
1280 ‘<code class=property>oblique</code>’. If no italic or oblique face is
1281 available, oblique faces can be synthesized by rendering non-obliqued
1282 faces with a right sloping transformation applied. When synthesizing these
1283 faces, the transformation should apply to all glyphs in the same way and
1284 not vary based on codepoint or due to horizontal or vertical line
1285 orientation.
1287 <p>Many scripts lack the tradition of mixing a cursive form within text
1288 rendered with a normal face. Chinese, Japanese and Korean fonts almost
1289 always lack italic or oblique faces. Fonts that support a mixture of
1290 scripts will sometimes omit specific scripts such as Arabic from the set
1291 of glyphs supported in the italic face. User agents should be careful
1292 about making <a href="#character-map"><em>character map</em></a>
1293 assumptions across faces.
1295 <p class=issue>For synthetic italics in vertical runs of Chinese, Japanese,
1296 or Korean text, is there a need to define explicitly the direction of the
1297 faux oblique for runs that include a mixture of ideographic and Latin
1298 text?</p>
1299 <!-- prop: font-size -->
1301 <h3 id=font-size-prop><span class=secno>3.5 </span>Font size: the <a
1302 href="#propdef-font-size">font-size</a> property</h3>
1304 <table class=propdef id=namefont-sizevalueltabsolute-sizegt-ltre>
1305 <tbody>
1306 <tr>
1307 <td>Name:
1309 <td><dfn id=propdef-font-size>font-size</dfn>
1311 <tr>
1312 <td>Value:
1314 <td><a href="#absolute-size-value"><var><absolute-size></var></a>
1315 | <a href="#relative-size-value"><var><relative-size></var></a> |
1316 <a href="#length-size-value"><var><length></var></a> | <a
1317 href="#percentage-size-value"><var><percentage></var></a>
1319 <tr>
1320 <td>Initial:
1322 <td>medium
1324 <tr>
1325 <td>Applies to:
1327 <td>all elements
1329 <tr>
1330 <td>Inherited:
1332 <td>yes
1334 <tr>
1335 <td>Percentages:
1337 <td>refer to parent element's font size
1339 <tr>
1340 <td>Media:
1342 <td>visual
1344 <tr>
1345 <td>Computed value:
1347 <td>absolute length
1349 <tr>
1350 <td>Animatable:
1352 <td>as <a
1353 href="http://dev.w3.org/csswg/css3-transitions/#animtype-length">length</a>
1354 </table>
1356 <p>This property indicates the desired height of glyphs from the font. For
1357 scalable fonts, the font-size is a scale factor applied to the EM unit of
1358 the font. (Note that certain glyphs may bleed outside their EM box.) For
1359 non-scalable fonts, the font-size is converted into absolute units and
1360 matched against the declared font-size of the font, using the same
1361 absolute coordinate space for both of the matched values. Values have the
1362 following meanings:
1364 <dl>
1365 <dt><dfn id=absolute-size-value><var><absolute-size></var></dfn>
1367 <dd> An <a
1368 href="#absolute-size-value"><var><absolute-size></var></a> keyword
1369 refers to an entry in a table of font sizes computed and kept by the user
1370 agent. Possible values are:
1371 <p> [ xx-small | x-small | small | medium | large | x-large | xx-large ]</p>
1373 <dt><dfn id=relative-size-value><var><relative-size></var></dfn>
1375 <dd> A <a href="#relative-size-value"><var><relative-size></var></a>
1376 keyword is interpreted relative to the table of font sizes and the
1377 computed ‘<a href="#propdef-font-size"><code
1378 class=property>font-size</code></a>’ of the parent element. Possible
1379 values are:
1380 <p> [ larger | smaller ]
1382 <p> For example, if the parent element has a font size of ‘<code
1383 class=property>medium</code>’, a value of ‘<code
1384 class=property>larger</code>’ will make the font size of the current
1385 element be ‘<code class=property>large</code>’. If the parent
1386 element's size is not close to a table entry, the user agent is free to
1387 interpolate between table entries or round off to the closest one. The
1388 user agent may have to extrapolate table values if the numerical value
1389 goes beyond the keywords.
1391 <dt><dfn id=length-size-value><var><length></var></dfn>
1393 <dd>A length value specifies an absolute font size (independent of the
1394 user agent's font table). Negative lengths are illegal.
1396 <dt><dfn id=percentage-size-value><var><percentage></var></dfn>
1398 <dd>A percentage value specifies an absolute font size relative to the
1399 parent element's font size. Use of percentage values, or values in
1400 ‘<code class=property>em</code>’s, leads to more robust and
1401 cascadable style sheets.
1402 </dl>
1404 <p>The following table provides user agent guidelines for the absolute-size
1405 scaling factor and their mapping to HTML heading and absolute font-sizes.
1406 The ‘<code class=property>medium</code>’ value is used as the
1407 reference middle value. The user agent may fine-tune these values for
1408 different fonts or different types of display devices.
1410 <table class=data>
1411 <thead>
1412 <tr>
1413 <th>CSS absolute-size values
1415 <th>xx-small
1417 <th>x-small
1419 <th>small
1421 <th>medium
1423 <th>large
1425 <th>x-large
1427 <th>xx-large
1429 <th>
1431 <tbody>
1432 <tr>
1433 <th>scaling factor
1435 <td>3/5
1437 <td>3/4
1439 <td>8/9
1441 <td>1
1443 <td>6/5
1445 <td>3/2
1447 <td>2/1
1449 <td>3/1
1451 <tr>
1452 <th>HTML headings
1454 <td>h6
1456 <td>
1458 <td>h5
1460 <td>h4
1462 <td>h3
1464 <td>h2
1466 <td>h1
1468 <td>
1470 <tr>
1471 <th>HTML font sizes
1473 <td>1
1475 <td>
1477 <td>2
1479 <td>3
1481 <td>4
1483 <td>5
1485 <td>6
1487 <td>7
1488 </table>
1490 <p class=note><em><strong>Note 1.</strong> To preserve readability, an UA
1491 applying these guidelines should nevertheless avoid creating font-size
1492 resulting in less than 9 device pixels per EM unit on a computer
1493 display.</em>
1495 <p class=note><em><strong>Note 2.</strong> In CSS1, the suggested scaling
1496 factor between adjacent indexes was 1.5 which user experience proved to be
1497 too large. In CSS2, the suggested scaling factor for computer screen
1498 between adjacent indexes was 1.2 which still created issues for the small
1499 sizes. The new scaling factor varies between each index to provide a
1500 better readability.</em>
1502 <p>The actual value of this property may differ from the computed value due
1503 a numerical value on ‘<a href="#propdef-font-size-adjust"><code
1504 class=property>font-size-adjust</code></a>’ and the unavailability of
1505 certain font sizes.
1507 <p>Child elements inherit the computed <a class=noxref
1508 href="#font-size-prop"> <span class=property>‘<code
1509 class=property>font-size</code>’</span></a> value (otherwise, the effect
1510 of <a class=noxref href="#font-size-adjust-prop"><span
1511 class=property>‘<code
1512 class=property>font-size-adjust</code>’</span></a> would compound).
1514 <div class=example>
1515 <p style="display:none">Example(s):
1517 <p>
1519 <pre>p { font-size: 12pt; }
1520 blockquote { font-size: larger }
1521 em { font-size: 150% }
1522 em { font-size: 1.5em }
1523 </pre>
1524 </div>
1525 <!-- prop: font-size-adjust -->
1527 <h3 id=font-size-adjust-prop><span class=secno>3.6 </span>Relative sizing:
1528 the <a href="#propdef-font-size-adjust">font-size-adjust</a> property</h3>
1530 <table class=propdef id=namefont-size-adjustvaluenone-auto-ltnum>
1531 <tbody>
1532 <tr>
1533 <td>Name:
1535 <td><dfn id=propdef-font-size-adjust>font-size-adjust</dfn>
1537 <tr>
1538 <td>Value:
1540 <td>none | auto | <a
1541 href="#aspect-ratio-value"><var><number></var></a>
1543 <tr>
1544 <td>Initial:
1546 <td>none
1548 <tr>
1549 <td>Applies to:
1551 <td>all elements
1553 <tr>
1554 <td>Inherited:
1556 <td>yes
1558 <tr>
1559 <td>Percentages:
1561 <td>N/A
1563 <tr>
1564 <td>Media:
1566 <td>visual
1568 <tr>
1569 <td>Computed value:
1571 <td>as specified
1573 <tr>
1574 <td>Animatable:
1576 <td>as <a
1577 href="http://dev.w3.org/csswg/css3-transitions/#animtype-number">number</a>
1578 </table>
1580 <p>For any given font size, the apparent size and legibility of text varies
1581 across fonts. For scripts such as Latin or Cyrillic that distinguish
1582 between upper and lowercase letters, the relative height of lowercase
1583 letters compared to their uppercase counterparts is a determining factor
1584 of legibility. This is commonly referred to as the <a class=index-def
1585 href="#aspect-value" id=aspect-value0 title="aspect value"><dfn
1586 id=aspect-value>aspect value</dfn></a>. Precisely defined, it is equal to
1587 the x-height of a font divided by the font size.
1589 <p>In situations where font fallback occurs, fallback fonts may not share
1590 the same aspect ratio as the desired font family and will thus appear less
1591 readable. The font-size-adjust property is a way to preserve the
1592 readability of text when font fallback occurs. It does this by adjusting
1593 the font-size so that the x-height is the same regardless of the font
1594 used.
1596 <div class=example>
1597 <p>The style defined below defines Verdana as the desired font family, but
1598 if Verdana is not available Futura or Times will be used.</p>
1600 <pre>p {
1601 font-family: Verdana, Futura, Times;
1602 }
1604 <p>Lorem ipsum dolor sit amet, ...</p>
1605 </pre>
1607 <p>Verdana has a relatively high aspect ratio, lowercase letters are
1608 relatively tall compared to uppercase letters, so at small sizes text
1609 appears legible. Times has a lower aspect ratio and so if fallback
1610 occurs, the text will be less legible at small sizes than Verdana.</p>
1611 </div>
1613 <p>How text rendered in each of these fonts compares is shown below, the
1614 columns show text rendered in Verdana, Futura and Times. The same
1615 font-size value is used across cells within each row and red lines are
1616 included to show the differences in x-height. In the upper half each row
1617 is rendered in the same font-size value. The same is true for the lower
1618 half but in this half the font-size-adjust property is also set so that
1619 the actual font size is adjusted to preserve the x-height across each row.
1620 Note how small text remains relatively legible across each row in the
1621 lower half.
1623 <div class=figure><img alt="text with and without font-size-adjust"
1624 src=fontsizeadjust.png>
1625 <p class=caption>Text with and without the use of font-size-adjust
1626 </div>
1628 <p>This property allows authors to specify an aspect value for an element
1629 that will effectively preserve the x-height of the first choice font,
1630 whether it is substituted or not. Values have the following meanings:
1632 <dl>
1633 <dt><strong>none</strong>
1635 <dd>Do not preserve the font's x-height.
1637 <dt><strong>auto</strong>
1639 <dd>Behaves just like <number>, except the number used is the aspect
1640 value calculated by user agents for the first font in the list of fonts
1641 defined for the initial value of the ‘<a
1642 href="#descdef-font-family"><code
1643 class=property>font-family</code></a>’ property. Effectively this is
1644 the default font used when ‘<a href="#descdef-font-family"><code
1645 class=property>font-family</code></a>’ is not otherwise specified.
1646 <p>Authors can use this value to specify that font size should be
1647 normalized across fonts based on the x-height without the need to
1648 specify the aspect ratio explicitly.</p>
1650 <dt><dfn id=aspect-ratio-value><var><number></var></dfn>
1652 <dd>Specifies the aspect value used in the calculation below to calculate
1653 the adjusted font size:
1654 <pre>c = ( a / a' ) s
1655 </pre>
1657 <p>where:</p>
1659 <pre>s = font-size value
1660 a = aspect value as specified by the font-size-adjust property
1661 a' = aspect value of actual font
1662 c = adjusted font-size to use
1663 </pre>
1665 <p>This value applies to any font that is selected but in typical usage
1666 it should be based on the aspect value of the first font in the
1667 font-family list. If this is specified accurately, the <tt>(a/a')</tt>
1668 term in the formula above is effectively 1 for the first font and no
1669 adjustment occurs. If the value is specified inaccurately, text rendered
1670 using the first font in the family list will display differently in
1671 older user agents that don't support font-size-adjust.</p>
1672 </dl>
1674 <p>Authors can calculate the aspect value for a given font by comparing
1675 spans with the same content but different font-size-adjust properties. If
1676 the same font-size is used, the spans will match when the font-size-adjust
1677 value is accurate for the given font.
1679 <div class=example>
1680 <p>Two spans with borders are used to determine the aspect value of a
1681 font. The font-size is the same for both spans but the font-size-adjust
1682 property is specified only for the right span. Starting with a value of
1683 0.5, the aspect value can be adjusted until the borders around the two
1684 letters line up.</p>
1686 <pre>p {
1687 font-family: Futura;
1688 font-size: 500px;
1689 }
1691 span {
1692 border: solid 1px red;
1693 }
1695 .adjust {
1696 font-size-adjust: 0.5;
1697 }
1699 <p><span>b</span><span class="adjust">b</span></p>
1700 </pre>
1702 <div class=figure><img alt="Futura with an aspect value of 0.5"
1703 src=beforefontsizeadjust.png>
1704 <p class=caption>Futura with an aspect value of 0.5
1705 </div>
1707 <p>The box on the right is a bit bigger than the one on the left, so the
1708 aspect value of this font is something less than 0.5. Adjust the value
1709 until the boxes align.</p>
1710 </div>
1711 <!-- prop: font -->
1712 <!-- jtdfix, crap, preprocessor is inserting links to descriptors rather than properties. bert, make it stop... -->
1713 <!-- <a href="#font-stretch-prop" class="noxref"><span class="property">'font-stretch'</span></a> -->
1715 <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
1716 <a href="#propdef-font">font</a> property</h3>
1718 <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
1719 <tbody>
1720 <tr>
1721 <td>Name:
1723 <td><dfn id=propdef-font>font</dfn>
1725 <tr>
1726 <td>Value:
1728 <td>[ [ <var><‘<a href="#propdef-font-style"><code
1729 class=property>font-style</code></a>’></var> || <a
1730 href="#font-variant-css21-values"><var><font-variant-css21></var></a>
1731 || <var><‘<a href="#propdef-font-weight"><code
1732 class=property>font-weight</code></a>’></var> || <var><‘<a
1733 href="#propdef-font-stretch"><code
1734 class=property>font-stretch</code></a>’</var> ]? <var><‘<a
1735 href="#propdef-font-size"><code
1736 class=property>font-size</code></a>’></var> [ / <var><‘<code
1737 class=property>line-height</code>’></var> ]? <var><‘<a
1738 href="#descdef-font-family"><code
1739 class=property>font-family</code></a>’></var> ] | caption | icon |
1740 menu | message-box | small-caption | status-bar
1742 <tr>
1743 <td>Initial:
1745 <td>see individual properties
1747 <tr>
1748 <td>Applies to:
1750 <td>all elements
1752 <tr>
1753 <td>Inherited:
1755 <td>yes
1757 <tr>
1758 <td>Percentages:
1760 <td>see individual properties
1762 <tr>
1763 <td>Media:
1765 <td>visual
1767 <tr>
1768 <td>Computed value:
1770 <td>see individual properties
1772 <tr>
1773 <td>Animatable:
1775 <td>see individual properties
1776 </table>
1778 <p>The <span class=property>‘<a href="#propdef-font"><code
1779 class=property>font</code></a>’</span> property is, except as described
1780 below, a shorthand property for setting ‘<a
1781 href="#propdef-font-style"><code class=property>font-style</code></a>’,
1782 <span class=property>‘<a href="#propdef-font-variant"><code
1783 class=property>font-variant</code></a>’</span>, <span
1784 class=property>‘<a href="#propdef-font-weight"><code
1785 class=property>font-weight</code></a>’</span>, <span
1786 class=property>‘<a href="#propdef-font-stretch"><code
1787 class=property>font-stretch</code></a>’</span>, <span
1788 class=property>‘<a href="#propdef-font-size"><code
1789 class=property>font-size</code></a>’</span>, ‘<code
1790 class=property>line-height</code>’, <span class=property>‘<a
1791 href="#descdef-font-family"><code
1792 class=property>font-family</code></a>’</span> at the same place in the
1793 stylesheet. Values for the <span class=property>‘<a
1794 href="#propdef-font-variant"><code
1795 class=property>font-variant</code></a>’</span> property may also be
1796 included but only those supported in CSS 2.1, none of the font-variant
1797 values added in this specification can be used in the <span
1798 class=property>‘<a href="#propdef-font"><code
1799 class=property>font</code></a>’</span> shorthand:
1801 <pre
1802 class=prod><dfn id=font-variant-css21-values><var><font-variant-css21></var></dfn> = [normal | small-caps]</pre>
1804 <p>The syntax of this property is based on a traditional typographical
1805 shorthand notation to set multiple properties related to fonts.
1807 <p>All subproperties of the ‘<a href="#propdef-font"><code
1808 class=property>font</code></a>’ property are first reset to their
1809 initial values, including those listed above plus <span
1810 class=property>‘<a href="#propdef-font-size-adjust"><code
1811 class=property>font-size-adjust</code></a>’</span>, <span
1812 class=property>‘<a href="#propdef-font-kerning"><code
1813 class=property>font-kerning</code></a>’</span>, subproperties of <span
1814 class=property>‘<a href="#propdef-font-variant"><code
1815 class=property>font-variant</code></a>’</span> and and <span
1816 class=property>‘<a href="#propdef-font-language-override"><code
1817 class=property>font-language-override</code></a>’</span>. Then, those
1818 properties that are given explicit values in the <span
1819 class=property>‘<a href="#propdef-font"><code
1820 class=property>font</code></a>’</span> shorthand are set to those
1821 values. For a definition of allowed and initial values, see the previously
1822 defined properties. For reasons of backwards compatibility, it is not
1823 possible to set <span class=property>‘<a
1824 href="#propdef-font-size-adjust"><code
1825 class=property>font-size-adjust</code></a>’</span> to anything other
1826 than its initial value using the <span class=property>‘<a
1827 href="#propdef-font"><code class=property>font</code></a>’</span>
1828 shorthand property; instead, use the individual property.
1830 <div class=example>
1831 <p style="display:none">Example(s):
1833 <p>
1835 <pre>p { font: 12pt/14pt sans-serif }
1836 p { font: 80% sans-serif }
1837 p { font: x-large/110% "new century schoolbook", serif }
1838 p { font: bold italic large Palatino, serif }
1839 p { font: normal small-caps 120%/120% fantasy }
1840 p { font: condensed oblique 12pt "Helvetica Neue", serif; }
1841 </pre>
1843 <p> In the second rule, the font size percentage value (‘<code
1844 class=css>80%</code>’) refers to the computed ‘<a
1845 href="#propdef-font-size"><code class=property>font-size</code></a>’ of
1846 the parent element. In the third rule, the line height percentage
1847 (‘<code class=css>110%</code>’) refers to the font size of the
1848 element itself.
1850 <p>The first three rules do not specify the <span class=property>‘<a
1851 href="#propdef-font-variant"><code
1852 class=property>font-variant</code></a>’</span> and <span
1853 class=property>‘<a href="#propdef-font-weight"><code
1854 class=property>font-weight</code></a>’</span> explicitly, so these
1855 properties receive their initial values (‘<a href="#normal2"><code
1856 class=property>normal</code></a>’). Notice that the font family name
1857 "new century schoolbook", which contains spaces, is enclosed in quotes.
1858 The fourth rule sets the <span class=property>‘<a
1859 href="#propdef-font-weight"><code
1860 class=property>font-weight</code></a>’</span> to ‘<code
1861 class=property>bold</code>’, the <span class=property>‘<a
1862 href="#propdef-font-style"><code
1863 class=property>font-style</code></a>’</span> to ‘<code
1864 class=property>italic</code>’, and implicitly sets <span
1865 class=property>‘<a href="#propdef-font-variant"><code
1866 class=property>font-variant</code></a>’</span> to ‘<a
1867 href="#normal2"><code class=property>normal</code></a>’.
1869 <p> The fifth rule sets the <span class=property>‘<a
1870 href="#propdef-font-variant"><code
1871 class=property>font-variant</code></a>’</span> (‘<a
1872 href="#small-caps"><code class=property>small-caps</code></a>’), the
1873 <span class=property>‘<a href="#propdef-font-size"><code
1874 class=property>font-size</code></a>’</span> (120% of the parent's font
1875 size), the <span class=property>‘<code
1876 class=property>line-height</code>’</span> (120% of the font size) and
1877 the <span class=property>‘<a href="#descdef-font-family"><code
1878 class=property>font-family</code></a>’</span> (‘<a
1879 href="#fantasy"><code class=property>fantasy</code></a>’). It follows
1880 that the keyword ‘<a href="#normal2"><code
1881 class=property>normal</code></a>’ applies to the two remaining
1882 properties: <span class=property>‘<a href="#propdef-font-style"><code
1883 class=property>font-style</code></a>’</span> and <span
1884 class=property>‘<a href="#propdef-font-weight"><code
1885 class=property>font-weight</code></a>’</span>.
1887 <p>The sixth rule sets the <span class=property>‘<a
1888 href="#propdef-font-style"><code
1889 class=property>font-style</code></a>’</span>, <span
1890 class=property>‘<a href="#propdef-font-stretch"><code
1891 class=property>font-stretch</code></a>’</span>, <span
1892 class=property>‘<a href="#propdef-font-size"><code
1893 class=property>font-size</code></a>’</span>, and <span
1894 class=property>‘<a href="#descdef-font-family"><code
1895 class=property>font-family</code></a>’</span>, the other font
1896 properties being set to their initial values.
1897 </div>
1899 <p>Since the ‘<a href="#propdef-font-stretch"><code
1900 class=property>font-stretch</code></a>’ property was not defined in CSS
1901 2.1, when using ‘<a href="#propdef-font-stretch"><code
1902 class=property>font-stretch</code></a>’ values within ‘<a
1903 href="#propdef-font"><code class=property>font</code></a>’ rules,
1904 authors should include a extra version compatible with older user agents:
1906 <pre>p {
1907 font: 80% sans-serif; /* for older user agents */
1908 font: condensed 80% sans-serif;
1909 }</pre>
1911 <p>The following values refer to system fonts:
1913 <dl>
1914 <dt><strong>caption</strong>
1916 <dd>The font used for captioned controls (e.g., buttons, drop-downs,
1917 etc.).
1919 <dt><strong>icon</strong>
1921 <dd>The font used to label icons.
1923 <dt><strong>menu</strong>
1925 <dd>The font used in menus (e.g., dropdown menus and menu lists).
1927 <dt><strong>message-box</strong>
1929 <dd>The font used in dialog boxes.
1931 <dt><strong>small-caption</strong>
1933 <dd>The font used for labeling small controls.
1935 <dt><strong>status-bar</strong>
1937 <dd>The font used in window status bars.
1938 </dl>
1940 <p>System fonts may only be set as a whole; that is, the font family, size,
1941 weight, style, etc. are all set at the same time. These values may then be
1942 altered individually if desired. If no font with the indicated
1943 characteristics exists on a given platform, the user agent should either
1944 intelligently substitute (e.g., a smaller version of the ‘<code
1945 class=property>caption</code>’ font might be used for the ‘<code
1946 class=property>small-caption</code>’ font), or substitute a user agent
1947 default font. As for regular fonts, if, for a system font, any of the
1948 individual properties are not part of the operating system's available
1949 user preferences, those properties should be set to their initial values.
1951 <p>That is why this property is "almost" a shorthand property: system fonts
1952 can only be specified with this property, not with <span
1953 class=property>‘<a href="#descdef-font-family"><code
1954 class=property>font-family</code></a>’</span> itself, so <span
1955 class=property>‘<a href="#propdef-font"><code
1956 class=property>font</code></a>’</span> allows authors to do more than
1957 the sum of its subproperties. However, the individual properties such as
1958 <span class=property>‘<a href="#propdef-font-weight"><code
1959 class=property>font-weight</code></a>’</span> are still given values
1960 taken from the system font, which can be independently varied.
1962 <p>Note that the keywords used for the system fonts listed above are only
1963 treated as keywords when they occur in the initial position, in other
1964 positions the same string is treated as part of the font family name:
1966 <pre> font: menu; /* use the font settings for system menus */
1967 font: large menu; /* use a font family named "menu" */</pre>
1969 <div class=example>
1970 <p style="display:none">Example(s):
1972 <p>
1974 <pre>button { font: 300 italic 1.3em/1.7em "FB Armada", sans-serif }
1975 button p { font: menu }
1976 button p em { font-weight: bolder }
1977 </pre>
1979 <p>If the font used for dropdown menus on a particular system happened to
1980 be, for example, 9-point Charcoal, with a weight of 600, then P elements
1981 that were descendants of BUTTON would be displayed as if this rule were
1982 in effect:
1984 <pre>button p { font: 600 9pt Charcoal }
1985 </pre>
1987 <p>Because the <span class=property>‘<a href="#propdef-font"><code
1988 class=property>font</code></a>’</span> shorthand resets to its initial
1989 value any property not explicitly given a value, this has the same effect
1990 as this declaration:
1992 <pre>button p {
1993 font-style: normal;
1994 font-variant: normal;
1995 font-weight: 600;
1996 font-size: 9pt;
1997 line-height: normal;
1998 font-family: Charcoal
1999 }
2000 </pre>
2001 </div>
2002 <!-- prop: font-synthesis -->
2004 <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
2005 synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
2006 property</h3>
2008 <table class=propdef id=namefont-synthesisvaluenone-weight-style>
2009 <tbody>
2010 <tr>
2011 <td>Name:
2013 <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
2015 <tr>
2016 <td>Value:
2018 <td>none | [ weight || style ]
2020 <tr>
2021 <td>Initial:
2023 <td>weight style
2025 <tr>
2026 <td>Applies to:
2028 <td>all elements
2030 <tr>
2031 <td>Inherited:
2033 <td>yes
2035 <tr>
2036 <td>Percentages:
2038 <td>N/A
2040 <tr>
2041 <td>Media:
2043 <td>visual
2045 <tr>
2046 <td>Computed value:
2048 <td>as specified
2050 <tr>
2051 <td>Animatable:
2053 <td>no
2054 </table>
2056 <p>This property controls whether user agents are allowed to synthesize
2057 bold or oblique font faces when a font family lacks bold or italic faces.
2058 If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
2059 specified, user agents must not synthesize bold faces and if ‘<code
2060 class=property>style</code>’ is not specified user agents must not
2061 synthesize italic faces. A value of ‘<code class=property>none</code>’
2062 disallows all synthetic faces.
2064 <div class=example>
2065 <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
2067 <pre>*:lang(ar) { font-synthesis: none; }
2068 </pre>
2069 </div>
2071 <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
2073 <h3 id=font-face-rule><span class=secno>4.1 </span>The
2074 <code>@font-face</code> rule</h3>
2076 <p>The <code>@font-face</code> rule allows for linking to fonts that are
2077 automatically fetched and activated when needed. This allows authors to
2078 select a font that closely matches the design goals for a given page
2079 rather than limiting the font choice to a set of fonts available on all
2080 platforms. A set of font descriptors define the location of a font
2081 resource, either locally or externally, along with the style
2082 characteristics of an individual face. Multiple <code>@font-face</code>
2083 rules can be used to construct font families with a variety of faces.
2084 Using CSS font matching rules, a user agent can selectively download only
2085 those faces that are needed for a given piece of text.
2087 <p>The @font-face rule consists of the @font-face at-keyword followed by a
2088 block of descriptor declarations. In terms of the grammar, this
2089 specification defines the following productions:
2091 <pre><dfn id=fontfacerule>font_face_rule</dfn>
2092 : <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>*
2093 ;
2095 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
2096 : <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>
2097 ;</pre>
2099 <p>The following new definitions are introduced:
2101 <pre>- -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
2102 F f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
2104 <p>The following new token is introduced:
2106 <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
2108 <p>Each <span class=index-inst id=font-face
2109 title="@font-face"><code>@font-face</code></span> rule specifies a value
2110 for every font descriptor, either implicitly or explicitly. Those not
2111 given explicit values in the rule take the initial value listed with each
2112 descriptor in this specification. These descriptors apply solely within
2113 the context of the <code>@font-face</code> rule in which they are defined,
2114 and do not apply to document language elements. There is no notion of
2115 which elements the descriptors apply to or whether the values are
2116 inherited by child elements. When a given descriptor occurs multiple times
2117 in a given <code>@font-face</code> rule, only the last descriptor
2118 declaration is used and all prior declarations for that descriptor are
2119 ignored.
2121 <div class=example>
2122 <p>To use a downloadable font called Gentium:</p>
2124 <pre>
2125 @font-face {
2126 font-family: Gentium;
2127 src: url(http://example.com/fonts/Gentium.ttf);
2128 }
2130 p { font-family: Gentium, serif; }
2131 </pre>
2133 <p>The user agent will download Gentium and use it when rendering text
2134 within paragraph elements. If for some reason the site serving the font
2135 is unavailable, the default serif font will be used.</p>
2136 </div>
2138 <p>A given set of <code>@font-face</code> rules define a set of fonts
2139 available for use within the documents that contain these rules. When font
2140 matching is done, fonts defined using these rules are considered before
2141 other available fonts on a system.
2143 <p>Downloaded fonts are only available to documents that reference them.
2144 The process of activating these fonts must not make them available to
2145 other applications or to documents that don't directly link to the same
2146 font. User agent implementers might consider it convenient to use
2147 downloaded fonts when rendering characters in other documents for which no
2148 other available font exists as part of the system font fallback procedure.
2149 However, this would cause a security leak since the contents of one page
2150 would be able to affect other pages, something an attacker could use as an
2151 attack vector. These restrictions do not affect caching behavior, fonts
2152 are cached the same way other web resources are cached.
2154 <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
2155 properties in a declaration block, declarations of any descriptors that
2156 are not supported by the user agent must be ignored.
2157 <code>@font-face</code> rules require a font-family and src descriptor; if
2158 either of these are missing, the <code>@font-face</code> rule is invalid
2159 and must be ignored entirely.
2161 <p>In cases where user agents have limited platform resources or implement
2162 the ability to disable downloadable font resources,
2163 <code>@font-face</code> rules must simply be ignored; the behavior of
2164 individual descriptors as defined in this specification should not be
2165 altered.
2167 <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
2168 href="#descdef-font-family">font-family</a> descriptor</h3>
2170 <table class=descdef>
2171 <tbody>
2172 <tr>
2173 <td>Name:
2175 <td><dfn id=descdef-font-family>font-family</dfn>
2177 <tr>
2178 <td>Value:
2180 <td><a href="#family-name-value"><var><family-name></var></a>
2182 <tr>
2183 <td><em>Initial:</em>
2185 <td>N/A
2186 </table>
2188 <p>This descriptor defines the font family name that will be used in all
2189 CSS font family name matching. It is required for the @font-face rule to
2190 be valid. It overrides the font family names contained in the underlying
2191 font data. If the font family name is the same as a font family available
2192 in a given user's environment, it effectively hides the underlying font
2193 for documents that use the stylesheet. This permits a web author to freely
2194 choose font-family names without worrying about conflicts with font family
2195 names present in a given user's environment. Likewise, platform
2196 substitutions for a given font family name must not be used.
2198 <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
2199 href="#descdef-src">src</a> descriptor</h3>
2201 <table class=descdef>
2202 <tbody>
2203 <tr>
2204 <td>Name:
2206 <td><dfn id=descdef-src>src</dfn>
2208 <tr>
2209 <td>Value:
2211 <td>[ <url> [format(<string> #)]? | <a
2212 href="#font-face-name-value"><var><font-face-name></var></a> ] #
2214 <tr>
2215 <td><em>Initial:</em>
2217 <td>N/A
2218 </table>
2220 <p>This descriptor specifies the resource containing font data. It is
2221 required for the <code>@font-face</code> rule to be valid. Its value is a
2222 prioritized, comma-separated list of external references or
2223 locally-installed font face names. When a font is needed the user agent
2224 iterates over the set of references listed, using the first one it can
2225 successfully activate. Fonts containing invalid data or local font faces
2226 that are not found are ignored and the user agent loads the next font in
2227 the list.
2229 <p>As with other URLs in CSS, the URL may be relative, in which case it is
2230 resolved relative to the location of the style sheet containing the <span
2231 class=index-inst id=font-face0
2232 title="@font-face"><code>@font-face</code></span> rule. In the case of SVG
2233 fonts, the URL points to an element within a document containing SVG font
2234 definitions. If the element reference is omitted, a reference to the first
2235 defined font is implied. Similarly, font container formats that can
2236 contain more than one font must load one and only one of the fonts for a
2237 given <code>@font-face</code> rule. Fragment identifiers are used to
2238 indicate which font to load. If a container format lacks a defined
2239 fragment identifier scheme, implementations should use a simple 1-based
2240 indexing scheme (e.g. "font-collection#1" for the first font,
2241 "font-collection#2" for the second font).
2243 <pre>
2244 src: url(fonts/simple.ttf); /* load simple.ttf relative to stylesheet location */
2245 src: url(/fonts/simple.ttf); /* load simple.ttf from absolute location */
2246 src: url(fonts.svg#simple); /* load SVG font with id 'simple' */
2247 </pre>
2249 <p>External references consist of a URL, followed by an optional hint
2250 describing the format of the font resource referenced by that URL. The
2251 format hint contains a comma-separated list of format strings that denote
2252 well-known font formats. Conformant user agents must skip downloading a
2253 font resource if the format hints indicate only unsupported or unknown
2254 font formats. If no format hints are supplied, the user agent should
2255 download the font resource.
2257 <pre>
2258 /* load WOFF font if possible, otherwise use OpenType font */
2259 @font-face {
2260 font-family: bodytext;
2261 src: url(ideal-sans-serif.woff) format("woff"),
2262 url(basic-sans-serif.ttf) format("opentype");
2263 }
2264 </pre>
2266 <p>Format strings defined by this specification:
2268 <table class=data id=fontformats>
2269 <thead>
2270 <tr>
2271 <th>String
2273 <th>Font Format
2275 <th>Common extensions
2277 <tbody>
2278 <tr>
2279 <th>"woff"
2281 <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
2283 <td>.woff
2285 <tr>
2286 <th>"truetype"
2288 <td><a
2289 href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
2291 <td>.ttf
2293 <tr>
2294 <th>"opentype"
2296 <td><a
2297 href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
2299 <td>.ttf, .otf
2301 <tr>
2302 <th>"embedded-opentype"
2304 <td><a
2305 href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
2306 OpenType</a>
2308 <td>.eot
2310 <tr>
2311 <th>"svg"
2313 <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
2315 <td>.svg, .svgz
2316 </table>
2318 <p>Given the overlap in common usage between TrueType and OpenType, the
2319 format hints "truetype" and "opentype" must be considered as synonymous; a
2320 format hint of "opentype" does not imply that the font contains Postscript
2321 CFF style glyph data or that it contains OpenType layout information (see
2322 <a href="#platform-props-to-css">Appendix A</a> for more background on
2323 this).
2325 <p>When authors would prefer to use a locally available copy of a given
2326 font and download it if it's not, <code>local()</code> can be used. The
2327 locally-installed <dfn
2328 id=font-face-name-value><var><font-face-name></var></dfn> argument
2329 to <code>local()</code> is a format-specific string that uniquely
2330 identifies a single font face within a larger family. The syntax for a <a
2331 href="#font-face-name-value"><var><font-face-name></var></a> is a
2332 unique font face name enclosed by "local(" and ")". The name can
2333 optionally be enclosed in quotes. If unquoted, the unquoted font family
2334 name processing conventions apply; the name must be a sequence of
2335 identifiers separated by whitespace which is converted to a string by
2336 joining the identifiers together separated by a single space.
2338 <pre>
2339 /* regular face of Gentium */
2340 @font-face {
2341 font-family: MyGentium;
2342 src: local(Gentium), /* use locally available Gentium */
2343 url(Gentium.ttf); /* otherwise, download it */
2344 }
2345 </pre>
2347 <p>For OpenType and TrueType fonts, this string is used to match only the
2348 Postscript name or the full font name in the name table of locally
2349 available fonts. Which type of name is used varies by platform and font,
2350 so authors should include both of these names to assure proper matching
2351 across platforms. Platform substitutions for a given font name must not be
2352 used.
2354 <pre>
2355 /* bold face of Gentium */
2356 @font-face {
2357 font-family: MyGentium;
2358 src: local(Gentium Bold), /* full font name */
2359 local(Gentium-Bold), /* Postscript name */
2360 url(GentiumBold.ttf); /* otherwise, download it */
2361 font-weight: bold;
2362 }
2363 </pre>
2365 <p>Just as a <code>@font-face</code> rule specifies the characteristics of
2366 a single font within a family, the unique name used with
2367 <code>local()</code> specifies a single font, not an entire font family.
2368 Defined in terms of OpenType font data, the Postscript name is found in
2369 the font's <a
2370 href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
2371 in the name record with nameID = 6 (see <a href="#OPENTYPE"
2372 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
2373 Postscript name is the commonly used key for all fonts on OSX and for
2374 Postscript CFF fonts under Windows. The full font name (nameID = 4) is
2375 used as a unique key for fonts with TrueType glyphs on Windows.
2377 <p>For OpenType fonts with multiple localizations of the full font name,
2378 the US English version is used (language ID = 0x409 for Windows and
2379 language ID = 0 for Macintosh) or the first localization when a US English
2380 full font name is not available (the OpenType specification recommends
2381 that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
2382 fonts minimally include US English names</a>). User agents that also match
2383 other full font names, e.g. matching the Dutch name when the current
2384 system locale is set to Dutch, are considered non-conformant. This is done
2385 not to prefer English but to avoid matching inconsistencies across font
2386 versions and OS localizations, since font style names (e.g. "Bold") are
2387 frequently localized into many languages and the set of localizations
2388 available varies widely across platform and font version. User agents that
2389 match a concatenation of family name (nameID = 1) with style name (nameID
2390 = 2) are considered non-conformant.
2392 <p>This also allows for referencing faces that belong to larger families
2393 that cannot otherwise be referenced.
2395 <div class=example>
2396 <p>Use a local font or reference an SVG font in another document:</p>
2398 <pre>
2399 @font-face {
2400 font-family: Headline;
2401 src: local(Futura-Medium),
2402 url(fonts.svg#MyGeometricModern) format("svg");
2403 }
2404 </pre>
2406 <p>Create an alias for local Japanese fonts on different platforms:</p>
2408 <pre>
2409 @font-face {
2410 font-family: jpgothic;
2411 src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
2412 }
2413 </pre>
2415 <p>Reference a font face that cannot be matched within a larger family:</p>
2417 <pre>
2418 @font-face {
2419 font-family: Hoefler Text Ornaments;
2420 /* has the same font properties as Hoefler Text Regular */
2421 src: local(HoeflerText-Ornaments);
2422 }
2423 </pre>
2425 <p>Since localized fullnames never match, a document with the header style
2426 rules below would always render using the default serif font, regardless
2427 whether a particular system locale parameter is set to Finnish or not:</p>
2429 <pre>
2430 @font-face {
2431 font-family: SectionHeader;
2432 src: local("Arial Lihavoitu"); /* Finnish fullname for Arial Bold, should fail */
2433 font-weight: bold;
2434 }
2436 h2 { font-family: SectionHeader, serif; }
2437 </pre>
2439 <p>A conformant user agent would never load the font ‘<code
2440 class=css>gentium.eot</code>’ in the example below, since it is
2441 included in the first definition of the ‘<a href="#descdef-src"><code
2442 class=property>src</code></a>’ descriptor which is overridden by the
2443 second definition in the same <code>@font-face</code> rule:</p>
2445 <pre>
2446 @font-face {
2447 font-family: MainText;
2448 src: url(gentium.eot); /* for use with older non-conformant user agents */
2449 src: local("Gentium"), url(gentium.ttf); /* Overrides src definition */
2450 }
2451 </pre>
2452 </div>
2454 <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
2455 descriptors: the <a href="#descdef-font-style">font-style</a>, <a
2456 href="#descdef-font-weight">font-weight</a>, <a
2457 href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
2459 <table class=descdef>
2460 <tbody>
2461 <tr>
2462 <td>Name:
2464 <td><dfn id=descdef-font-style title="font-style
2465 (descriptor)">font-style</dfn>
2467 <tr>
2468 <td>Value:
2470 <td>normal | italic | oblique
2472 <tr>
2473 <td><em>Initial:</em>
2475 <td>normal
2476 </table>
2478 <table class=descdef>
2479 <tbody>
2480 <tr>
2481 <td>Name:
2483 <td><dfn id=descdef-font-weight title="font-weight
2484 (descriptor)">font-weight</dfn>
2486 <tr>
2487 <td>Value:
2489 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
2491 <tr>
2492 <td><em>Initial:</em>
2494 <td>normal
2495 </table>
2497 <table class=descdef>
2498 <tbody>
2499 <tr>
2500 <td>Name:
2502 <td><dfn id=descdef-font-stretch title="font-stretch
2503 (descriptor)">font-stretch</dfn>
2505 <tr>
2506 <td>Value:
2508 <td>normal | ultra-condensed | extra-condensed | condensed |
2509 semi-condensed | semi-expanded | expanded | extra-expanded |
2510 ultra-expanded
2512 <tr>
2513 <td><em>Initial:</em>
2515 <td>normal
2516 </table>
2518 <p>These descriptors define the characteristics of a font face and are used
2519 in the process of matching styles to specific faces. For a font family
2520 defined with several <code>@font-face</code> rules, user agents can either
2521 download all faces in the family or use these descriptors to selectively
2522 download font faces that match actual styles used in document. The values
2523 for these descriptors are the same as those for the corresponding font
2524 properties except that relative keywords are not allowed, ‘<code
2525 class=property>bolder</code>’ and ‘<code
2526 class=property>lighter</code>’. If these descriptors are omitted,
2527 initial values are assumed.
2529 <p>The value for these font face style attributes is used in place of the
2530 style implied by the underlying font data. This allows authors to combine
2531 faces in flexible combinations, even in situations where the original font
2532 data was arranged differently. User agents that implement synthetic
2533 bolding and obliquing must only apply synthetic styling in cases where the
2534 font descriptors imply this is needed, rather than based on the style
2535 attributes implied by the font data.
2537 <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
2538 <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
2540 <table class=descdef>
2541 <tbody>
2542 <tr>
2543 <td>Name:
2545 <td><dfn id=descdef-unicode-range>unicode-range</dfn>
2547 <tr>
2548 <td>Value:
2550 <td><a href="#urange-value"><var><urange></var></a> #
2552 <tr>
2553 <td><em>Initial:</em>
2555 <td>U+0-10FFFF
2556 </table>
2558 <p>This descriptor defines the set of Unicode codepoints that may be
2559 supported by the font face for which it is declared. The descriptor value
2560 is a comma-delimited list of Unicode range (<a
2561 href="#urange-value"><var><urange></var></a>) values. The union of
2562 these ranges defines the set of codepoints that serves as a hint for user
2563 agents when deciding whether or not to download a font resource for a
2564 given text run.
2566 <p>Each <dfn id=urange-value><var><urange></var></dfn> value is a <a
2567 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2568 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
2569 "U+" or "u+" prefix followed by a codepoint range in one of the three
2570 forms listed below. Ranges that do not fit one of the these forms are
2571 invalid and cause the declaration to be ignored.
2573 <dl>
2574 <dt>single codepoint (e.g. U+416)
2576 <dd>a valid Unicode codepoint, represented as one to six hexadecimal
2577 digits
2579 <dt>interval range (e.g. U+400-4ff)
2581 <dd>represented as two hyphen-separated valid Unicode codepoints
2582 indicating the inclusive start and end codepoints of a range
2584 <dt>wildcard range (e.g. U+4??)
2586 <dd>defined by the set of codepoints implied when trailing ‘<code
2587 class=css>?</code>’ characters signify any hexadeximal digit
2588 </dl>
2590 <p>Individual codepoints are written using hexadecimal values that
2591 correspond to <a href="http://www.unicode.org/charts/">Unicode character
2592 codepoints</a>. Valid Unicode codepoint values vary between 0 and 10FFFF
2593 inclusive. Digit values of codepoints are ASCII case-insensitive. For
2594 interval ranges, the start and end codepoints must be valid Unicode values
2595 and the end codepoint must be greater than or equal to the start
2596 codepoint.
2598 <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
2599 "U+???") are valid and equivalent to a wildcard range with an initial zero
2600 digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
2601 the range of valid Unicode codepoints are invalid. Because of this, the
2602 maximum number of trailing ‘<code class=css>?</code>’ wildcard
2603 characters is five, even though the <a
2604 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2605 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
2607 <p>Within the comma-delimited list of Unicode ranges in a ‘<a
2608 href="#descdef-unicode-range"><code
2609 class=property>unicode-range</code></a>’ descriptor declaration, ranges
2610 may overlap. The union of these ranges defines the set of codepoints for
2611 which the corresponding font may be used. User agents must not download or
2612 use the font for codepoints outside this set. User agents may normalize
2613 the list of ranges into a list that is different but represents the same
2614 set of codepoints.
2616 <p>The associated font might not contain glyphs for the entire set of
2617 codepoints defined by the ‘<a href="#descdef-unicode-range"><code
2618 class=property>unicode-range</code></a>’ descriptor. When the font is
2619 used the effective <a href="#character-map"><em>character map</em></a> is
2620 the intersection of the codepoints defined by ‘<a
2621 href="#descdef-unicode-range"><code
2622 class=property>unicode-range</code></a>’ with the font's <a
2623 href="#character-map"><em>character map</em></a>. This allows authors to
2624 define supported ranges in terms of broad ranges without worrying about
2625 the precise codepoint ranges supported by the underlying font.
2627 <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
2628 to define composite fonts</h3>
2630 <p>Multiple <code>@font-face</code> rules with different unicode ranges for
2631 the same family and style descriptor values can be used to create
2632 composite fonts that mix the glyphs from different fonts for different
2633 scripts. This can be used to combine fonts that only contain glyphs for a
2634 single script (e.g. Latin, Greek, Cyrillic) or it can be used by authors
2635 as a way of segmenting a font into fonts for commonly used characters and
2636 less frequently used characters. Since the user agent will only pull down
2637 the fonts it needs this helps reduce page bandwidth.
2639 <p>If the unicode ranges overlap for a set of <code>@font-face</code> rules
2640 with the same family and style descriptor values, the rules are ordered in
2641 the reverse order they were defined; the last rule defined is the first to
2642 be checked for a given character.
2644 <p>Example ranges for specific languages or characters:
2646 <dl>
2647 <dt>unicode-range: U+A5;
2649 <dd>a single code point, the yen/yuan symbol
2651 <dt>unicode-range: U+0-7F;
2653 <dd>code range for basic ASCII characters
2655 <dt>unicode-range: U+590-5ff;
2657 <dd>code range for Hebrew characters
2659 <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
2661 <dd>code range for Japanese kanji, hiragana and katakana characters plus
2662 yen/yuan symbol
2663 </dl>
2665 <div class=example>
2666 <p>The BBC provides news services in a wide variety of languages, many
2667 that are not well supported across all platforms. Using an
2668 <code>@font-face</code> rule, the BBC could provide a font for any of
2669 these languages, as it already does via a manual font download.</p>
2671 <pre>
2672 @font-face {
2673 font-family: BBCBengali;
2674 src: url(fonts/BBCBengali.ttf) format("opentype");
2675 unicode-range: U+00-FF, U+980-9FF;
2676 }
2677 </pre>
2678 </div>
2680 <div class=example>
2681 <p>Technical documents often require a wide range of symbols. The STIX
2682 Fonts project is one project aimed at providing fonts to support a wide
2683 range of technical typesetting in a standardized way. The example below
2684 shows the use of a font that provides glyphs for many of the mathematical
2685 and technical symbol ranges within Unicode:</p>
2687 <pre>
2688 @font-face {
2689 font-family: STIXGeneral;
2690 src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
2691 unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
2692 }
2693 </pre>
2694 </div>
2696 <div class=example>
2697 <p>This example shows how an author can override the glyphs used for Latin
2698 characters in a Japanese font with glyphs from a different font. The
2699 first rule specifies no range so it defaults to the entire range. The
2700 range specified in the second rule overlaps but takes precedence because
2701 it is defined later.</p>
2703 <pre>
2704 @font-face {
2705 font-family: JapaneseWithGentium;
2706 src: local(MSMincho);
2707 /* no range specified, defaults to entire range */
2708 }
2710 @font-face {
2711 font-family: JapaneseWithGentium;
2712 src: url(../fonts/Gentium.ttf);
2713 unicode-range: U+0-2FF;
2714 }
2715 </pre>
2716 </div>
2718 <div class=example>
2719 <p>Consider a family constructed to optimize bandwidth by separating out
2720 Latin, Japanese and other characters into different font files:</p>
2722 <pre>
2723 /* fallback font - size: 4.5MB */
2724 @font-face {
2725 font-family: DroidSans;
2726 src: url(DroidSansFallback.ttf);
2727 /* no range specified, defaults to entire range */
2728 }
2730 /* Japanese glyphs - size: 1.2MB */
2731 @font-face {
2732 font-family: DroidSans;
2733 src: url(DroidSansJapanese.ttf);
2734 unicode-range: U+3000-9FFF, U+ff??;
2735 }
2737 /* Latin, Greek, Cyrillic along with some
2738 punctuation and symbols - size: 190KB */
2739 @font-face {
2740 font-family: DroidSans;
2741 src: url(DroidSans.ttf);
2742 unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
2743 }
2744 </pre>
2746 <p>For simple Latin text, only the font for Latin characters is
2747 downloaded:</p>
2749 <pre>
2750 body { font-family: DroidSans; }
2752 <p>This is that</p>
2753 </pre>
2755 <p>In this case the user agent first checks the unicode-range for the font
2756 containing Latin characters (DroidSans.ttf). Since all the characters
2757 above are in the range U+0-5FF, the user agent downloads the font and
2758 renders the text with that font.</p>
2760 <p>Next, consider text that makes use of an arrow character (⇨):</p>
2762 <pre>
2763 <p>This &#x21e8; that<p>
2764 </pre>
2766 <p>The user agent again first checks the unicode-range of the font
2767 containing Latin characters. Since U+2000-2300 includes the arrow code
2768 point (U+21E8), the user agent downloads the font. For this character
2769 however the Latin font does not have a matching glyph, so the effective
2770 unicode-range used for font matching excludes this code point. Next, the
2771 user agent evaluates the Japanese font. The unicode-range for the
2772 Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
2773 user agent does not download the Japanese font. Next the fallback font is
2774 considered. The <code>@font-face</code> rule for the fallback font does
2775 not define unicode-range so its value defaults to the range of all
2776 Unicode code points. The fallback font is downloaded and used to render
2777 the arrow character.</p>
2778 </div>
2780 <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
2781 href="#descdef-font-variant">font-variant</a> and <a
2782 href="#descdef-font-feature-settings">font-feature-settings</a>
2783 descriptors</h3>
2785 <table class=descdef>
2786 <tbody>
2787 <tr>
2788 <td>Name:
2790 <td><dfn id=descdef-font-variant title="font-variant
2791 (descriptor)">font-variant</dfn>
2793 <tr>
2794 <td>Value:
2796 <td>normal | none | [ <a
2797 href="#common-lig-values"><var><common-lig-values></var></a> ||
2798 <a
2799 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
2800 || <a
2801 href="#historical-lig-values"><var><historical-lig-values></var></a>
2802 || <a
2803 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
2804 || <a href="#stylistic"><var
2805 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
2806 href="#historical-forms"><var>historical-forms</var></a> || <a
2807 href="#styleset"><var
2808 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
2809 href="#character-variant"><var
2810 title=character-variant>character-variant(<feature-value-name>
2811 #)</var></a> || <a href="#swash"><var
2812 title=swash>swash(<feature-value-name>)</var></a> || <a
2813 href="#ornaments"><var
2814 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
2815 href="#annotation"><var
2816 title=annotation>annotation(<feature-value-name>)</var></a> || [
2817 <a href="#small-caps"><i>small-caps</i></a> | <a
2818 href="#all-small-caps"><i>all-small-caps</i></a> | <a
2819 href="#petite-caps"><i>petite-caps</i></a> | <a
2820 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
2821 href="#unicase"><i>unicase</i></a> | <a
2822 href="#titling-caps"><i>titling-caps</i></a> ] || <a
2823 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
2824 || <a
2825 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
2826 || <a
2827 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
2828 || <a href="#ordinal"><i>ordinal</i></a> || <a
2829 href="#slashed-zero"><i>slashed-zero</i></a> || <a
2830 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
2831 || <a
2832 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
2833 || <a href="#ruby"><i>ruby</i></a> ]
2835 <tr>
2836 <td><em>Initial:</em>
2838 <td>normal
2839 </table>
2841 <table class=descdef>
2842 <tbody>
2843 <tr>
2844 <td>Name:
2846 <td><dfn id=descdef-font-feature-settings title="font-feature-settings
2847 (descriptor)">font-feature-settings</dfn>
2849 <tr>
2850 <td>Value:
2852 <td>normal | <a
2853 href="#feature-tag-value"><var><feature-tag-value></var></a> #
2855 <tr>
2856 <td><em>Initial:</em>
2858 <td>normal
2859 </table>
2861 <p>These descriptors define initial settings that apply when the font
2862 defined by an <code>@font-face</code> rule is rendered. They do not affect
2863 font selection. Values are identical to those defined for the
2864 corresponding ‘<a href="#propdef-font-variant"><code
2865 class=property>font-variant</code></a>’ and ‘<a
2866 href="#propdef-font-feature-settings"><code
2867 class=property>font-feature-settings</code></a>’ properties defined
2868 below except that the value ‘<code class=property>inherit</code>’ is
2869 omitted. When multiple font feature descriptors or properties are used,
2870 the cumulative effect on text rendering is detailed in the section <a
2871 href="#font-feature-resolution">Font Feature Resolution</a> below. In
2872 cases where specific values define synthesized fallback for certain ‘<a
2873 href="#propdef-font-variant"><code
2874 class=property>font-variant</code></a>’ subproperties, the same
2875 synthesized fallback applies when used within those values are used with
2876 the <a href="#descdef-font-variant">‘<code
2877 class=property>font-variant</code>’</a> descriptor.
2879 <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
2880 guidelines</h3>
2882 <p>The <code>@font-face</code> rule is designed to allow lazy loading of
2883 font resources that are only downloaded when used within a document. A
2884 stylesheet can include <code>@font-face</code> rules for a library of
2885 fonts of which only a select set are used; user agents must only download
2886 those fonts that are referred to within the style rules applicable to a
2887 given page. User agents that download all fonts defined in
2888 <code>@font-face</code> rules without considering whether those fonts are
2889 in fact used within a page are considered non-conformant. In cases where a
2890 font might be downloaded in character fallback cases, user agents may
2891 download a font if it's listed in a font list but is not actually used for
2892 a given text run.
2894 <pre>
2895 @font-face {
2896 font-family: GeometricModern;
2897 src: url(font.ttf);
2898 }
2900 p {
2901 /* font will be downloaded for pages with p elements */
2902 font-family: GeometricModern, sans-serif;
2903 }
2905 h2 {
2906 /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
2907 font-family: Futura, GeometricModern, sans-serif;
2908 }
2909 </pre>
2911 <p>In cases where textual content is loaded before downloadable fonts are
2912 available, user agents may render text as it would be rendered if
2913 downloadable font resources are not available or they may render text
2914 transparently with fallback fonts to avoid a flash of text using a
2915 fallback font. In cases where the font download fails user agents must
2916 display text, simply leaving transparent text is considered non-conformant
2917 behavior. Authors are advised to use fallback fonts in their font lists
2918 that closely match the vertical metrics of the downloadable fonts to avoid
2919 large page reflows where possible.
2921 <h3 id=same-origin-restriction><span class=secno>4.9 </span>Same-origin
2922 restriction for fonts</h3>
2924 <h4 id=default-same-origin-restriction><span class=secno>4.9.1
2925 </span>Default same-origin restriction</h4>
2926 <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
2927 http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
2928 http://www.w3.org/2011/10/31-webapps-minutes.html#item02
2929 -->
2931 <p>User agents must implement a same-origin restriction when loading fonts
2932 via the <code>@font-face</code> mechanism. This restriction limits the
2933 loading of fonts for a given document to fonts loaded from the same
2934 origin. Fonts can only be loaded via the same host, port, and method
2935 combination as the containing document, using the <a
2936 href="http://www.w3.org/TR/html5/browsers.html#origin">origin matching
2937 algorithm</a> described in the <a href="#HTML5"
2938 rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification. The origin of
2939 the stylesheet containing <code>@font-face</code> rules is not used when
2940 deciding whether a font is same origin or not, only the origin of the
2941 containing document is used. The restriction applies to all font types.
2943 <p>Given a document located at http://example.com/page.html, fonts defined
2944 with ‘<a href="#descdef-src"><code class=property>src</code></a>’
2945 definitions considered cross origin must not be loaded:
2947 <pre>
2948 /* same origin (i.e. domain, protocol, port match document) */
2949 src: url(fonts/simple.ttf);
2950 src: url(//fonts/simple.ttf);
2952 /* cross origin, different protocol */
2953 src: url(https://example.com/fonts/simple.ttf);
2955 /* cross origin, different domain */
2956 src: url(http://another.example.com/fonts/simple.ttf);
2957 </pre>
2959 <h4 id=allowing-cross-origin-font-loading><span class=secno>4.9.2
2960 </span>Allowing cross-origin font loading</h4>
2962 <p>User agents must also implement the ability to relax this restriction
2963 using cross-site origin controls <a href="#CORS"
2964 rel=biblioentry>[CORS]<!--{{!CORS}}--></a> for fonts loaded via HTTP.
2965 Sites can explicitly allow cross-site downloading of font data using the
2966 <code>Access-Control-Allow-Origin</code> HTTP header. For other protocols,
2967 no explicit relaxation mechanism is defined or required.
2969 <p>For font loads over HTTP, cross-origin requests must be made with the
2970 following parameter settings which are used in conjunction with the <a
2971 href="http://www.w3.org/TR/cors/#cross-origin-request-0"> <em>cross-origin
2972 request algorithm</em></a> <a href="#CORS"
2973 rel=biblioentry>[CORS]<!--{{!CORS}}--></a>:
2975 <ul>
2976 <li><em>request URL</em> — the URL of the font resource in the <a
2977 href="#descdef-src"><code>src</code></a> descriptor
2979 <li><em>request method</em> — GET
2981 <li><em>author request headers</em> — none
2983 <li><em>request entity body</em> — empty
2985 <li><em>source origin</em> — the origin of the page which linked to the
2986 stylesheet
2988 <li><em>manual redirect flag</em> — false
2990 <li><em>omit credentials flag</em> — true
2992 <li><em>force preflight flag</em> — false
2993 </ul>
2995 <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
2996 Algorithm</h2>
2998 <p>The algorithm below describes how fonts are associated with individual
2999 runs of text. For each character in the run a font family is chosen and a
3000 particular font face is selected containing a glyph for that character.
3002 <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
3003 font family names</h3>
3005 <p>As part of the font matching algorithm outlined below, user agents must
3006 match font family names used in style rules with actual font family names
3007 contained in fonts available in a given environment or defined via
3008 <code>@font-face</code> rules. User agents must match these names case
3009 insensitively, using the "Default Caseless Matching" algorithm outlined in
3010 the Unicode specification <a href="#UNICODE6"
3011 rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This algorithm is
3012 detailed in section 3.13 entitled "Default Case Algorithms". Specifically,
3013 the algorithm must be applied without normalizing the strings involved and
3014 without applying any language-specific tailorings. The case folding method
3015 specified by this algorithm uses the case mappings with status field
3016 ‘<code class=property>C</code>’ or ‘<code class=property>F</code>’
3017 in the CaseFolding.txt file of the Unicode Character Database.
3019 <p class=note> Implementors should take care to verify that a given
3020 caseless string comparison implementation uses this precise algorithm and
3021 not assume that a given platform string matching routine follows it, as
3022 many of these have locale-specific behavior or use some level of string
3023 normalization.
3025 <p class=note> For authors this means that font family names are matched
3026 case insensitively, whether those names exist in a platform font or in the
3027 <code>@font-face</code> rules contained in a stylesheet. Authors should
3028 take care to ensure that names use a character sequence consistent with
3029 the actual font family name, particularly when using combining characters
3030 such as diacritical marks. For example, a family name that contains an
3031 uppercase A (U+0041) followed by a combining ring (U+030A) will
3032 <strong>not</strong> match a name that looks identical but which uses the
3033 precomposed lowercase a-ring character (U+00E5) instead of the combining
3034 sequence.
3036 <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
3037 styles</h3>
3039 <p>The procedure for choosing fonts consists of iterating over the font
3040 families determined by the font-family property, selecting a font face
3041 with the appropriate style based on other font properties and then
3042 determining whether a glyph exists for a given character. This is done
3043 using the <dfn id=character-map>character map</dfn> of the font, data
3044 which maps characters to the default glyph for that character. Codepoint
3045 sequences consisting of a base character followed by a sequence of
3046 combining characters are treated slightly differently, see the section on
3047 <a href="#cluster-matching">cluster matching</a> below.
3049 <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
3050 given font family is defined to be the face that would be selected if all
3051 font style properties were set to their initial value.
3053 <ol id=fontmatchingalg>
3054 <li>Using the computed font property values for a given element, the user
3055 agent starts with the first family name in the fontlist specified by the
3056 <span class=property>‘<a href="#descdef-font-family"><code
3057 class=property>font-family</code></a>’</span> property.
3059 <li>If the family name is unquoted and is a generic family name, the user
3060 agent looks up the appropriate font family name to be used. User agents
3061 may choose the generic font family to use based on the language of the
3062 containing element or the Unicode range of the character.
3064 <li>For other family names, the user agent attempts to find the family
3065 name among fonts defined via <code>@font-face</code> rules and then among
3066 available system fonts, matching names with a case-insensitive comparison
3067 as outlined <a href="#font-family-casing">in the section above</a>. On
3068 systems containing fonts with multiple localized font family names, user
3069 agents must match any of these names independent of the underlying system
3070 locale or platform API used. If the font resources defined for a given
3071 face in an @font-face rule are either not available or contain invalid
3072 font data, then the face should be treated as not present in the family.
3073 If no faces are present for a family defined via @font-face rules, the
3074 family should be treated as missing; matching a platform font with the
3075 same name must not occur in this case.
3077 <li>If a font family match occurs, the user agent assembles the set of
3078 font faces in that family and then narrows the set to a single face using
3079 other font properties in the order given below:
3080 <ol id=fontstylematchingalg>
3081 <li><span class=property>‘<a href="#propdef-font-stretch"><code
3082 class=property>font-stretch</code></a>’</span> is tried first. If the
3083 matching set contains faces with width values matching the ‘<a
3084 href="#propdef-font-stretch"><code
3085 class=property>font-stretch</code></a>’ value, faces with other width
3086 values are removed from the matching set. If there is no face that
3087 exactly matches the width value the nearest width is used instead. If
3088 the value of ‘<a href="#propdef-font-stretch"><code
3089 class=property>font-stretch</code></a>’ is ‘<a
3090 href="#normal2"><code class=property>normal</code></a>’ or one of the
3091 condensed values, narrower width values are checked first, then wider
3092 values. If the value of ‘<a href="#propdef-font-stretch"><code
3093 class=property>font-stretch</code></a>’ is one of the expanded
3094 values, wider values are checked first, followed by narrower values.
3095 Once the closest matching width has been determined by this process,
3096 faces with other widths are removed from the matching set.
3098 <li><span class=property>‘<a href="#propdef-font-style"><code
3099 class=property>font-style</code></a>’</span> is tried next. If the
3100 value of ‘<a href="#propdef-font-style"><code
3101 class=property>font-style</code></a>’ is ‘<code
3102 class=property>italic</code>’, italic faces are checked first, then
3103 oblique, then normal faces. If the value is ‘<code
3104 class=property>oblique</code>’, oblique faces are checked first, then
3105 italic faces and then normal faces. If the value is ‘<a
3106 href="#normal2"><code class=property>normal</code></a>’, normal faces
3107 are checked first, then oblique faces, then italic faces. Faces with
3108 other style values are excluded from the matching set. User agents are
3109 permitted to distinguish between italic and oblique faces within
3110 platform font families but this is not required, they may treat all
3111 italic or oblique faces as italic faces. However, within font families
3112 defined via <code>@font-face</code> rules, italic and oblique faces
3113 must be distinguished using the value of the ‘<a
3114 href="#propdef-font-style"><code
3115 class=property>font-style</code></a>’ descriptor.
3117 <li><span class=property>‘<a href="#propdef-font-weight"><code
3118 class=property>font-weight</code></a>’</span> is matched next, it
3119 will always reduce the matching set to a single font face. If
3120 bolder/lighter relative weights are used, the effective weight is
3121 calculated based on the inherited weight value, as described in the
3122 definition of the ‘<a href="#propdef-font-weight"><code
3123 class=property>font-weight</code></a>’ property. Given the desired
3124 weight and the weights of faces in the matching set after the steps
3125 above, if the desired weight is available that face matches. Otherwise,
3126 a weight is chosen using the rules below:
3127 <ul>
3128 <li>If the desired weight is less than 400, weights below the desired
3129 weight are checked in descending order followed by weights above the
3130 desired weight in ascending order until a match is found.
3132 <li>If the desired weight is greater than 500, weights above the
3133 desired weight are checked in ascending order followed by weights
3134 below the desired weight in descending order until a match is found.
3136 <li>If the desired weight is 400, 500 is checked first and then the
3137 rule for desired weights less than 400 is used.
3139 <li>If the desired weight is 500, 400 is checked first and then the
3140 rule for desired weights less than 400 is used.
3141 </ul>
3143 <li><span class=property>‘<a href="#propdef-font-size"><code
3144 class=property>font-size</code></a>’</span> must be matched within a
3145 UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
3146 are rounded to the nearest whole pixel, while the tolerance for
3147 bitmapped fonts could be as large as 20%.) Further computations, e.g.,
3148 by ‘<code class=property>em</code>’ values in other properties, are
3149 based on the <span class=property>‘<a href="#propdef-font-size"><code
3150 class=property>font-size</code></a>’</span> value that is used, not
3151 the one that is specified.
3152 </ol>
3154 <li>
3155 <p>If no matching face exists or the matched face does not contain a
3156 glyph for the character to be rendered, the next family name is selected
3157 and the previous two steps repeated. Glyphs from other faces in the
3158 family are not considered. The only exception is that user agents may
3159 optionally substitute a synthetic version of the <a
3160 href="#default-face"><em>default face</em></a> if that face supports a
3161 given glyph (e.g. a synthetic italic version of the regular face may be
3162 used if the italic face doesn't support glyphs for Arabic).</p>
3163 <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
3165 <p>If the matched font is defined via an <code>@font-face</code> rule and
3166 needs to be downloaded, the font resource is downloaded. While the
3167 download occurs, the user agent can either wait until the font is
3168 downloaded or render once with substituted font metrics and render again
3169 once the font is downloaded.</p>
3171 <li>If there are no more font families to be evaluated and no matching
3172 face has been found, then the user agent performs a <em>system font
3173 fallback</em> procedure to find the best match for the character to be
3174 rendered. The result of this procedure may vary across user agents.
3176 <li>If a particular character cannot be displayed using any font, the user
3177 agent should indicate by some means that a character is not being
3178 displayed, displaying either a symbolic representation of the missing
3179 glyph (e.g. using a <a
3180 href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
3181 Font</a>) or using the missing character glyph from a default font.
3182 </ol>
3184 <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
3186 <p>When text contains characters such as combining diacritics, ideally the
3187 base character should be rendered using the same font as the diacritic,
3188 this assures proper placement of the diacritic. For this reason, the font
3189 matching algorithm for clusters is more specialized than the general case
3190 of matching a single character by itself. For sequences containing
3191 variation selectors, which indicate the precise glyph to be used for a
3192 given character, user agents always attempt system font fallback to find
3193 the appropriate glyph before using the default glyph of the base
3194 character.
3196 <p>A font is considered to <em>support</em> a given character if (1) the
3197 character is contained in the font's <a
3198 href="#character-map"><em>character map</em></a> and (2) if required by
3199 the containing script, shaping information is available for that
3200 character. Some legacy fonts may include a given character in the <a
3201 href="#character-map"><em>character map</em></a> but lack the shaping
3202 information (e.g. <a
3203 href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
3204 layout tables</a> or <a
3205 href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&item_id=graphite_techAbout">Graphite
3206 tables</a>) necessary for correctly rendering text runs containing that
3207 character.
3209 <p>A sequence of codepoints containing combining diacritics or other
3210 modifiers is termed a grapheme cluster (see <a href="#CSS3TEXT"
3211 rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
3212 description). For a given cluster containing a base character, <em>b</em>
3213 and a sequence of combining characters <em>c1, c2…</em>, the entire
3214 cluster is matched using these steps:
3216 <ol>
3217 <li>For each family in the font list, a face is chosen using the style
3218 selection rules defined in the previous section.
3219 <ol>
3220 <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
3221 completely supported by the font, select this font for the sequence.
3223 <li>If a sequence of multiple codepoints is canonically equivalent to a
3224 single character and the font supports that character, select this font
3225 for the sequence.
3226 </ol>
3228 <li>If no font was found in the font list in step 1:
3229 <ol>
3230 <li>If <em>c1</em> is a variation selector, system fallback must be used
3231 to find a font that supports the full sequence of <em>b + c1</em>. If
3232 no font on the system supports the full sequence, match the single
3233 character <em>b</em> using the normal procedure for matching single
3234 characters and ignore the variation selector. Note: a sequence with
3235 more than one variation selector is treated as an encoding error and
3236 the trailing selectors are ignored.
3238 <li>Otherwise, the user agent may optionally use system font fallback to
3239 match a font that supports the entire cluster.
3240 </ol>
3242 <li>If no font is found in step 2, use the matching sequence from step 1
3243 to determine the longest sequence that is completely matched by a font in
3244 the font list and attempt to match the remaining combining characters
3245 separately using the rules for single characters.
3246 </ol>
3248 <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
3249 issues</h3>
3251 <p>The procedure above is always performed on text runs containing Unicode
3252 characters, documents using legacy encodings are assumed to have been
3253 transcoded before matching fonts. For fonts containing <a
3254 href="#character-map"><em title="character map">character maps</em></a>
3255 for both legacy encodings and Unicode, the contents of the legacy encoding
3256 <a href="#character-map"><em>character map</em></a> must have no effect on
3257 the results of the font matching process.
3259 <p>The font matching process does not assume that text runs are in either
3260 normalized or denormalized form (see <a href="#CHARMOD-NORM"
3261 rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
3262 details). Layout engines often convert base character plus combining
3263 character sequences into precomposed characters if they exist. The font
3264 matching algorithm outlined here supports both ways and fonts can
3265 generally support either but variations can occur. Authors should always
3266 tailor their choice of fonts to their content, including whether that
3267 content contains normalized or denormalized character streams.
3269 <p>If a given character is a Private-Use Area Unicode codepoint and none of
3270 the fonts in the fontlist contain a glyph for that codepoint, user agents
3271 must display some form of missing glyph symbol for that character rather
3272 than attempting system font fallback for that codepoint. When matching the
3273 replacement character U+FFFD, user agents may skip the font matching
3274 process and immediately display some form of missing glyph symbol, they
3275 are not required to display the glyph from the font that would be selected
3276 by the font matching process.
3278 <p>In general, the fonts for a given family will all have the same or
3279 similar <a href="#character-map"><em title="character map">character
3280 maps</em></a>. The process outlined here is designed to handle even font
3281 families containing faces with widely variant <a href="#character-map"><em
3282 title="character map">character maps</em></a>. However, authors are
3283 cautioned that the use of such families can lead to unexpected results.
3285 <p>Optimizations of this process are allowed provided that an
3286 implementation behaves as if the algorithm had been followed exactly.
3287 Matching occurs in a well-defined order to insure that the results are as
3288 consistent as possible across user agents, given an identical set of
3289 available fonts and rendering technology.
3291 <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
3292 changes since CSS 2.1</h3>
3294 <p>The algorithm above is different from CSS 2.1 in a number of key places.
3295 These changes were made to better reflect actual font matching behavior
3296 across user agent implementations.
3298 <p>Differences compared to the font matching algorithm in CSS 2.1:
3300 <ul>
3301 <li>The algorithm includes font-stretch matching.
3303 <li>All possible font-style matching scenarios are delineated.
3305 <li>Small-caps fonts are not matched as part of the font matching process,
3306 they are now handled via font features.
3308 <li>Unicode variation selector matching is required.
3310 <li>Cluster sequences are matched as a unit.
3311 </ul>
3313 <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
3314 examples</h3>
3316 <div class=example>
3317 <p>It's useful to note that the CSS selector syntax may be used to create
3318 language-sensitive typography. For example, some Chinese and Japanese
3319 characters are unified to have the same Unicode code point, although the
3320 abstract glyphs are not the same in the two languages.
3322 <pre>*:lang(ja-jp) { font: 900 14pt/16pt "Heisei Mincho W9", serif; }
3323 *:lang(zh-tw) { font: 800 14pt/16.5pt "Li Sung", serif; }
3324 </pre>
3326 <p>This selects any element that has the given language - Japanese or
3327 Traditional Chinese - and uses the appropriate font.
3328 </div>
3330 <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
3332 <p>Modern font technologies support a variety of advanced typographic and
3333 language-specific font features. Using these features, a single font can
3334 provide glyphs for a wide range of ligatures, contextual and stylistic
3335 alternates, tabular and old-style figures, small capitals, automatic
3336 fractions, swashes, and alternates specific to a given language. To allow
3337 authors control over these font capabilities, the font-variant property
3338 has been expanded for CSS3, it now functions as a shorthand for a set of
3339 properties that provide control over stylistic font features.
3341 <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
3342 selection and positioning</h3>
3344 <p>Simple fonts used for displaying Latin text use a very basic processing
3345 model, fonts contain a <a href="#character-map"><em>character map</em></a>
3346 which maps a given character to a glyph for that character. Glyphs for
3347 subsequent characters are simply placed next in line along a run of text.
3348 Font formats such as OpenType and AAT (Apple Advanced Typography) use a
3349 richer processing model, the glyph for a given character can be chosen and
3350 positioned not just based on a single character, but also based on
3351 surrounding characters along with the language, script, and features
3352 enabled for the text. Font features may be required for specific scripts,
3353 or recommended as enabled by default or they may be stylistic features
3354 meant to be used under author control.
3356 <p>For a good visual overview of these features, see the <a
3357 href="#OPENTYPE-FONT-GUIDE"
3358 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
3359 For a detailed description of glyph processing for OpenType fonts, see <a
3360 href="#WINDOWS-GLYPH-PROC"
3361 rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
3363 <p>Stylistic font features can be classified into two broad categories,
3364 ones that affect the harmonization of glyph shapes with the surrounding
3365 context, such as kerning and ligature features, and those such as the
3366 small-caps, subscript/superscript and alternate features that affect shape
3367 selection.
3369 <p>The subproperties of font-variant listed below are used to control these
3370 stylistic font features; they do not control features that are required
3371 for displaying certain scripts, such as the OpenType features used when
3372 displaying Arabic or Indic language text. They affect glyph selection and
3373 positioning, they do not affect font selection as described in the font
3374 matching section (except in cases required for compatibility with CSS
3375 2.1).
3377 <p>To assure consistent behavior across user agents, the equivalent
3378 OpenType property settings are listed for individual properties and must
3379 be considered normative. When using other font formats these should be
3380 used as a guideline to map CSS font feature property values to specific
3381 font features.
3383 <h3 id=language-specific-support><span class=secno>6.2
3384 </span>Language-specific display</h3>
3386 <p>OpenType also supports language-specific glyph selection and
3387 positioning, so that text can be displayed correctly in cases where the
3388 language dictates a specific display behavior. Languages often share a
3389 common script but the shape of certain letters may vary across those
3390 languages, such as the variations in certain Cyrillic letters used in
3391 Russian and Bulgarian text. In Latin text, it's common to render "fi" with
3392 an explicit fi-ligature that lacks a dot on the "i". However, in languages
3393 such as Turkish which uses both a dotted-i and a dotless-i, it's important
3394 to not use this ligature or use a specialized version that contains a dot
3395 over the "i". The example below shows language-specific variations based
3396 on stylistic traditions found in Spanish, Italian and French orthography:
3398 <div class=featex><img alt="language specific forms, spanish"
3399 src=locl-1.png></div>
3401 <div class=featex><img alt="language specific forms, italian"
3402 src=locl-2.png></div>
3404 <div class=featex><img alt="language specific forms, french"
3405 src=locl-3.png></div>
3407 <p>If the content language of the element is known, according to the rules
3408 of the <a
3409 href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
3410 language</a>, user agents are required to infer the OpenType language
3411 system from the content language and use that when selecting and
3412 positioning glyphs using an OpenType font.
3414 <p>For OpenType fonts, in some cases it may be necessary to explicitly
3415 declare the OpenType language to be used, for example when displaying text
3416 in a given language that uses the typographic conventions of another
3417 language or when the font does not explicitly support a given language but
3418 supports a language that shares common typographic conventions. The ‘<a
3419 href="#propdef-font-language-override"><code
3420 class=property>font-language-override</code></a>’ property is used for
3421 this purpose.</p>
3422 <!-- prop: font-kerning -->
3424 <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
3425 href="#propdef-font-kerning">font-kerning</a> property</h3>
3427 <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
3428 <tbody>
3429 <tr>
3430 <td>Name:
3432 <td><dfn id=propdef-font-kerning>font-kerning</dfn>
3434 <tr>
3435 <td>Value:
3437 <td>auto | normal | none
3439 <tr>
3440 <td>Initial:
3442 <td>auto
3444 <tr>
3445 <td>Applies to:
3447 <td>all elements
3449 <tr>
3450 <td>Inherited:
3452 <td>yes
3454 <tr>
3455 <td>Percentages:
3457 <td>N/A
3459 <tr>
3460 <td>Media:
3462 <td>visual
3464 <tr>
3465 <td>Computed value:
3467 <td>as specified
3469 <tr>
3470 <td>Animatable:
3472 <td>no
3473 </table>
3475 <p>Kerning is the contextual adjustment of inter-glyph spacing. This
3476 property controls metric kerning, kerning that utilizes adjustment data
3477 contained in the font. The value ‘<a href="#normal2"><code
3478 class=property>normal</code></a>’ implies that kerning is applied while
3479 the value ‘<code class=property>none</code>’ implies that kerning is
3480 not applied when rendering text. If the value is ‘<code
3481 class=property>auto</code>’, a user agent is free to choose whether
3482 kerning is enabled or not by default and to vary that default based on the
3483 underlying text script.
3485 <p>For fonts that do not include kerning data this property will have no
3486 visible effect. When rendering with OpenType fonts, the <a
3487 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
3488 specification suggests that kerning be enabled by default. When kerning is
3489 enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
3490 vertical text runs the <span class=tag>vkrn</span> feature is enabled).
3491 User agents must also support fonts that only support kerning via data
3492 contained in a ‘<code class=property>kern</code>’ font table, as
3493 detailed in the OpenType specification. Authors may prefer to disable
3494 kerning in situations where performance is more important than precise
3495 appearance. If the ‘<code class=property>letter-spacing</code>’
3496 property is defined, kerning adjustments are considered part of the
3497 default spacing, letter spacing adjustments are made after kerning has
3498 been applied.</p>
3499 <!-- prop: font-variant-ligatures -->
3501 <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
3502 the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
3503 property</h3>
3505 <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
3506 <tbody>
3507 <tr>
3508 <td>Name:
3510 <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
3512 <tr>
3513 <td>Value:
3515 <td>normal | none | [ <a
3516 href="#common-lig-values"><var><common-lig-values></var></a> ||
3517 <a
3518 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
3519 || <a
3520 href="#historical-lig-values"><var><historical-lig-values></var></a>
3521 || <a
3522 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
3523 ]
3525 <tr>
3526 <td>Initial:
3528 <td>normal
3530 <tr>
3531 <td>Applies to:
3533 <td>all elements
3535 <tr>
3536 <td>Inherited:
3538 <td>yes
3540 <tr>
3541 <td>Percentages:
3543 <td>N/A
3545 <tr>
3546 <td>Media:
3548 <td>visual
3550 <tr>
3551 <td>Computed value:
3553 <td>as specified
3555 <tr>
3556 <td>Animatable:
3558 <td>no
3559 </table>
3561 <p>Ligatures and contextual forms are ways of combining glyphs to produce
3562 more harmonized forms. A value of ‘<a href="#normal2"><code
3563 class=property>normal</code></a>’ implies that common default features
3564 are enabled, <a href="#font-feature-resolution">as described in detail in
3565 the next section</a>. For OpenType fonts, common ligatures and contextual
3566 forms are on by default, discretionary and historical ligatures are not. A
3567 value of ‘<code class=property>none</code>’ implies that all types of
3568 ligatures and contextual forms covered by this property are explicitly
3569 disabled. In situations where ligatures are not considered necessary, this
3570 may improve the speed of text rendering.
3572 <pre
3573 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>
3575 <pre
3576 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>
3578 <pre
3579 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>
3581 <pre
3582 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>
3584 <p>Individual values have the following meanings:
3586 <dl>
3587 <dt><dfn id=common-ligatures>common-ligatures</dfn>
3589 <dd>Enables display of common ligatures (OpenType features: <span
3590 class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
3591 enabled by default.
3592 </dl>
3594 <div class=featex><img alt="common ligature example" src=liga.png></div>
3596 <dl>
3597 <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
3599 <dd>Disables display of common ligatures (OpenType features: <span
3600 class=tag>liga, clig</span>).
3602 <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
3604 <dd>Enables display of discretionary ligatures (OpenType feature: <span
3605 class=tag>dlig</span>). Which ligatures are discretionary, or optional,
3606 is decided by the type designer so authors will need to refer to the
3607 documentation of a given font to understand which ligatures are
3608 considered discretionary.
3609 </dl>
3611 <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
3613 <dl>
3614 <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
3616 <dd>Disables display of discretionary ligatures (OpenType feature: <span
3617 class=tag>dlig</span>).
3619 <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
3621 <dd>Enables display of historical ligatures (OpenType feature: <span
3622 class=tag>hlig</span>).
3623 </dl>
3625 <div class=featex><img alt="historical ligature example" src=hlig.png></div>
3627 <dl>
3628 <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
3630 <dd>Disables display of historical ligatures (OpenType feature: <span
3631 class=tag>hlig</span>).
3633 <dt><dfn id=contextual>contextual</dfn>
3635 <dd>Enables display of contextual alternates (OpenType feature: <span
3636 class=tag>calt</span>). Although not strictly a ligature feature, like
3637 ligatures this feature is commonly used to harmonize the shapes of glyphs
3638 with the surrounding context. For OpenType fonts, this feature is on by
3639 default.
3640 </dl>
3642 <div class=featex><img alt="contextual alternate example" src=calt.png></div>
3644 <dl>
3645 <dt><dfn id=no-contextual>no-contextual</dfn>
3647 <dd>Disables display of contextual alternates (OpenType feature: <span
3648 class=tag>calt</span>).
3649 </dl>
3651 <p>Required ligatures, needed for correctly rendering complex scripts, are
3652 not affected by the settings above, including ‘<code
3653 class=property>none</code>’ (OpenType feature: <span
3654 class=tag>rlig</span>).</p>
3655 <!-- prop: font-variant-position -->
3657 <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
3658 and superscript forms: the <a
3659 href="#propdef-font-variant-position">font-variant-position</a> property</h3>
3661 <table class=propdef id=namefont-variant-positionvaluenormal-sub>
3662 <tbody>
3663 <tr>
3664 <td>Name:
3666 <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
3668 <tr>
3669 <td>Value:
3671 <td>normal | sub | super
3673 <tr>
3674 <td>Initial:
3676 <td>normal
3678 <tr>
3679 <td>Applies to:
3681 <td>all elements
3683 <tr>
3684 <td>Inherited:
3686 <td>yes
3688 <tr>
3689 <td>Percentages:
3691 <td>N/A
3693 <tr>
3694 <td>Media:
3696 <td>visual
3698 <tr>
3699 <td>Computed value:
3701 <td>as specified
3703 <tr>
3704 <td>Animatable:
3706 <td>no
3707 </table>
3709 <p>This property is used to enable typographic subscript and superscript
3710 glyphs. These are alternate glyphs designed within the same em-box as
3711 default glyphs and are intended to be laid out on the same baseline as the
3712 default glyphs, with no resizing or repositioning of the baseline. They
3713 are explicitly designed to match the surrounding text and to be more
3714 readable without affecting the line height.
3716 <div class=figure><img alt="comparison between real subscript glyphs and
3717 synthesized ones" src=realsubscripts.png>
3718 <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
3719 (bottom)
3720 </div>
3722 <p>The values ‘<code class=property>sub</code>’ and ‘<code
3723 class=property>super</code>’ imply the appropriate variant glyph is
3724 displayed when available in the font (OpenType features: <span
3725 class=tag>subs, sups</span>). A value of ‘<a href="#normal2"><code
3726 class=property>normal</code></a>’ implies neither of these alternate
3727 glyphs are substituted.
3729 <p>Because of the semantic nature of subscripts and superscripts, when the
3730 value is either ‘<code class=property>sub</code>’ or ‘<code
3731 class=property>super</code>’ for a given contiguous run of text, if a
3732 variant glyph is not available for all the characters in the run,
3733 simulated glyphs must be synthesized for all characters using reduced
3734 forms of the glyphs that would be used without this feature applied. This
3735 is done to avoid a mixture of variant glyphs and synthesized ones that
3736 would not align correctly.
3738 <p>In the case of OpenType fonts that lack subscript or superscript glyphs
3739 for a given character, user agents must use the appropriate subscript and
3740 superscript metrics specified in the selected font's <a
3741 href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
3742 table</a> <a href="#OPENTYPE"
3743 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
3744 and offset of the synthesized substitutes.
3746 <p>In the past, user agents have used font-size and vertical-align to
3747 simulate subscripts and superscripts for the <span class=tag>sub</span>
3748 and <span class=tag>sup</span> elements. To allow a backwards compatible
3749 way of defining subscripts and superscripts, it is recommended that
3750 authors use conditional rules <a href="#CSS3-CONDITIONAL"
3751 rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
3752 older user agents will still render subscripts and superscripts via the
3753 older mechanism.
3755 <p>Authors should note that fonts typically only provide subscript and
3756 superscript glyphs for a subset of all characters supported by the font.
3757 While subscript and superscript glyphs are often available for Latin
3758 numbers, glyphs for punctuation and letter characters are less frequently
3759 provided. The synthetic fallback rules defined for this property assure
3760 that subscripts and superscripts will always appear but the appearance may
3761 not match author expectations if the font used does not provide the
3762 appropriate alternate glyph for all characters contained in a subscript or
3763 superscript.
3765 <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
3766 using superscript metrics" src=superscript-alt-synth.png>
3767 <p class=caption>Superscript alternate glyph (left), synthesized
3768 superscript glyphs (middle), and incorrect mixture of the two (right)
3769 </div>
3771 <p>This property is not cumulative, applying it to subelements within a
3772 subscript or superscript won't nest the placement of a subscript or
3773 superscript glyph. Images contained within text runs where the value of
3774 this property is ‘<code class=property>sub</code>’ or ‘<code
3775 class=property>super</code>’ will be drawn just as they would if the
3776 value was ‘<a href="#normal2"><code class=property>normal</code></a>’.
3777 Likewise, text decorations such as underlines or emphasis marks will
3778 render in the same position as they would for the default glyphs, since
3779 this property does not affect the baseline position.
3781 <p>Because of these limitations, font-variant-position is not recommended
3782 for use in user agent stylesheets. Authors should use it in cases where
3783 subscripts or superscripts will only contain the narrow range of
3784 characters supported by the fonts specified.
3786 <div class=example>
3787 <p>A typical user agent default style for the <span class=tag>sub</span>
3788 element:</p>
3790 <pre>sub {
3791 vertical-align: sub;
3792 font-size: smaller;
3793 line-height: normal;
3794 }
3795 </pre>
3797 <p>Using font-variant-position to specify typographic subscripts in a way
3798 that will still show subscripts in older user agents:</p>
3800 <pre>@supports ( font-variant-position: sub ) {
3802 sub {
3803 vertical-align: inherit;
3804 font-size: 100%;
3805 line-height: inherit;
3806 font-variant-position: sub;
3807 }
3809 }
3810 </pre>
3812 <p>User agents that support the ‘<a
3813 href="#propdef-font-variant-position"><code
3814 class=property>font-variant-position</code></a>’ property will select a
3815 subscript variant glyph and render this without adjusting the baseline or
3816 font-size. Older user agents will ignore the ‘<a
3817 href="#propdef-font-variant-position"><code
3818 class=property>font-variant-position</code></a>’ property definition
3819 and use the standard defaults for subscripts.</p>
3820 </div>
3821 <!-- prop: font-variant-caps -->
3823 <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
3824 the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
3826 <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
3827 <tbody>
3828 <tr>
3829 <td>Name:
3831 <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
3833 <tr>
3834 <td>Value:
3836 <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
3837 | unicase | titling-caps
3839 <tr>
3840 <td>Initial:
3842 <td>normal
3844 <tr>
3845 <td>Applies to:
3847 <td>all elements
3849 <tr>
3850 <td>Inherited:
3852 <td>yes
3854 <tr>
3855 <td>Percentages:
3857 <td>N/A
3859 <tr>
3860 <td>Media:
3862 <td>visual
3864 <tr>
3865 <td>Computed value:
3867 <td>as specified
3869 <tr>
3870 <td>Animatable:
3872 <td>no
3873 </table>
3875 <p>Specifies control over capitalized forms.
3877 <p>Individual values have the following meanings:
3879 <dl>
3880 <dt><dfn id=normal>normal</dfn>
3882 <dd>None of the features listed below are enabled.
3884 <dt><dfn id=small-caps>small-caps</dfn>
3886 <dd>Enables display of small capitals (OpenType feature: <span
3887 class=tag>smcp</span>). Small-caps glyphs typically use the form of
3888 uppercase letters but are reduced to the size of lowercase letters.
3889 </dl>
3891 <div class=featex><img alt="small-caps example" src=smcp.png></div>
3893 <dl>
3894 <dt><dfn id=all-small-caps>all-small-caps</dfn>
3896 <dd>Enables display of small capitals for both upper and lowercase letters
3897 (OpenType features: <span class=tag>c2sc, smcp</span>).
3899 <dt><dfn id=petite-caps>petite-caps</dfn>
3901 <dd>Enables display of petite capitals (OpenType feature: <span
3902 class=tag>pcap</span>).
3904 <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
3906 <dd>Enables display of petite capitals for both upper and lowercase
3907 letters (OpenType features: <span class=tag>c2pc, pcap</span>).
3909 <dt><dfn id=unicase>unicase</dfn>
3911 <dd>Enables display of mixture of small capitals for uppercase letters
3912 with normal lowercase letters (OpenType feature: <span
3913 class=tag>unic</span>).
3915 <dt><dfn id=titling-caps>titling-caps</dfn>
3917 <dd>Enables display of titling capitals (OpenType feature: <span
3918 class=tag>titl</span>). Uppercase letter glyphs are often designed for
3919 use with lowercase letters. When used in all uppercase titling sequences
3920 they can appear too strong. Titling capitals are designed specifically
3921 for this situation.
3922 </dl>
3924 <p>This property allows the selection of alternate glyphs used for small or
3925 petite capitals or for titling. These glyphs are specifically designed to
3926 blend well with the surrounding normal glyphs, to maintain the weight and
3927 readability which suffers when text is simply resized to fit this purpose.
3929 <p>The availability of these glyphs is based on whether a given feature is
3930 defined or not in the feature list of the font. User agents can optionally
3931 decide this on a per-script basis but should explicitly not decide this on
3932 a per-character basis.
3934 <p>Some fonts may only support a subset or none of the features described
3935 for this property. For backwards compatibility with CSS 2.1, if ‘<a
3936 href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
3937 href="#all-small-caps"><code class=property>all-small-caps</code></a>’
3938 is specified but small-caps glyphs are not available for a given font,
3939 user agents should simulate a small-caps font, for example by taking a
3940 normal font and replacing the glyphs for lowercase letters with scaled
3941 versions of the glyphs for uppercase characters (replacing the glyphs for
3942 both upper and lowercase letters in the case of ‘<a
3943 href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
3945 <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
3946 real small-caps" class=hires src=synthetic-vs-real-small-caps.png
3947 width=512px>
3948 <p class=caption>Synthetic vs. real small-caps
3949 </div>
3951 <p>To match the surrounding text, a font may provide alternate glyphs for
3952 caseless characters when these features are enabled but when a user agent
3953 simulates small capitals, it must not attempt to simulate alternates for
3954 codepoints which are considered caseless.
3956 <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
3957 characters with small-caps, all-small-caps enabled" class=hires
3958 src=small-capitals-variations.png width=418px>
3959 <p class=caption>Caseless characters with small-caps, all-small-caps
3960 enabled
3961 </div>
3963 <p>If either ‘<a href="#petite-caps"><code
3964 class=property>petite-caps</code></a>’ or ‘<a
3965 href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
3966 is specified for a font that doesn't support these features, the property
3967 behaves as if ‘<a href="#small-caps"><code
3968 class=property>small-caps</code></a>’ or ‘<a
3969 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
3970 respectively, had been specified. If ‘<a href="#unicase"><code
3971 class=property>unicase</code></a>’ is specified for a font that doesn't
3972 support that feature, the property behaves as if ‘<a
3973 href="#small-caps"><code class=property>small-caps</code></a>’ was
3974 applied only to lowercased uppercase letters. If ‘<a
3975 href="#titling-caps"><code class=property>titling-caps</code></a>’ is
3976 specified with a font that does not support this feature, this property
3977 has no visible effect. When simulated small capital glyphs are used, for
3978 scripts that lack uppercase and lowercase letters, ‘<a
3979 href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
3980 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
3981 ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
3982 ‘<a href="#all-petite-caps"><code
3983 class=property>all-petite-caps</code></a>’ and ‘<a
3984 href="#unicase"><code class=property>unicase</code></a>’ have no visible
3985 effect.
3987 <p>When casing transforms are used to simulate small capitals, the casing
3988 transformations should match those used for the <span
3989 class=property>‘<code class=property>text-transform</code>’</span>
3990 property.
3992 <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
3993 replace glyphs in a small-caps font so that the text appears in all
3994 uppercase letters.
3996 <div class=figure style="padding: 0; margin: auto;"><img alt="using
3997 all-small-caps in acronym-laden text" class=hires
3998 src=acronym-laden-text.png width=596px>
3999 <p class=caption>Using small capitals to improve readability in
4000 acronym-laden text
4001 </div>
4003 <div class=example>
4004 <p>Quotes rendered italicised, with small-caps on the first line:</p>
4006 <pre>blockquote { font-style: italic; }
4007 blockquote:first-line { font-variant: small-caps; }
4009 <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>
4010 </pre>
4011 </div>
4012 <!-- prop: font-variant-numeric -->
4014 <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
4015 formatting: the <a
4016 href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
4018 <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
4019 <tbody>
4020 <tr>
4021 <td>Name:
4023 <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
4025 <tr>
4026 <td>Value:
4028 <td>normal | [ <a
4029 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
4030 || <a
4031 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
4032 || <a
4033 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
4034 || <a href="#ordinal">ordinal</a> || <a
4035 href="#slashed-zero">slashed-zero</a> ]
4037 <tr>
4038 <td>Initial:
4040 <td>normal
4042 <tr>
4043 <td>Applies to:
4045 <td>all elements
4047 <tr>
4048 <td>Inherited:
4050 <td>yes
4052 <tr>
4053 <td>Percentages:
4055 <td>N/A
4057 <tr>
4058 <td>Media:
4060 <td>visual
4062 <tr>
4063 <td>Computed value:
4065 <td>as specified
4067 <tr>
4068 <td>Animatable:
4070 <td>no
4071 </table>
4073 <p>Specifies control over numerical forms.
4075 <pre
4076 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>
4078 <pre
4079 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>
4081 <pre
4082 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>
4084 <p>Individual values have the following meanings:
4086 <dl>
4087 <dt><dfn id=normal0>normal</dfn>
4089 <dd>None of the features listed below are enabled.
4091 <dt><dfn id=lining-nums>lining-nums</dfn>
4093 <dd>Enables display of lining numerals (OpenType feature: <span
4094 class=tag>lnum</span>).
4096 <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
4098 <dd>Enables display of old-style numerals (OpenType feature: <span
4099 class=tag>onum</span>).
4101 <dt><dfn id=proportional-nums>proportional-nums</dfn>
4103 <dd>Enables display of proportional numerals (OpenType feature: <span
4104 class=tag>pnum</span>).
4106 <dt><dfn id=tabular-nums>tabular-nums</dfn>
4108 <dd>Enables display of tabular numerals (OpenType feature: <span
4109 class=tag>tnum</span>).
4110 </dl>
4112 <p>The example below shows how these different properties can be combined
4113 to influence the rendering of tabular data with fonts that support these
4114 features. Within normal paragraph text, proportional numbers are used
4115 while tabular numbers are used so that columns of numbers line up
4116 properly:
4118 <div class=figure style="padding: 0; margin: auto;"><img alt="combining
4119 number styles" src=numberstyles.png>
4120 <p class=caption>Using number styles
4121 </div>
4123 <dl>
4124 <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
4126 <dd>Enables display of lining diagonal fractions (OpenType feature: <span
4127 class=tag>frac</span>).
4128 </dl>
4130 <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
4132 <dl>
4133 <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
4135 <dd>Enables display of lining stacked fractions (OpenType feature: <span
4136 class=tag>afrc</span>).
4137 </dl>
4139 <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
4141 <dl>
4142 <dt><dfn id=ordinal>ordinal</dfn>
4144 <dd>Enables display of forms used with ordinal numbers (OpenType feature:
4145 <span class=tag>ordn</span>).
4147 <dt><dfn id=slashed-zero>slashed-zero</dfn>
4149 <dd>Enables display of slashed zeros (OpenType feature: <span
4150 class=tag>zero</span>).
4151 </dl>
4153 <div class=featex><img alt="slashed zero example" src=zero.png></div>
4155 <div class=example id=steak-marinade>
4156 <p>A simple flank steak marinade recipe, rendered with automatic fractions
4157 and old-style numerals:</p>
4159 <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
4161 <h4>Steak marinade:</h4>
4162 <ul>
4163 <li><span class="amount">2</span> tbsp olive oil</li>
4164 <li><span class="amount">1</span> tbsp lemon juice</li>
4165 <li><span class="amount">1</span> tbsp soy sauce</li>
4166 <li><span class="amount">1 1/2</span> tbsp dry minced onion</li>
4167 <li><span class="amount">2 1/2</span> tsp italian seasoning</li>
4168 <li>Salt &amp; pepper</li>
4169 </ul>
4171 <p>Mix the meat with the marinade and let it sit covered in the refrigerator
4172 for a few hours or overnight.</p>
4173 </pre>
4174 </div>
4175 <!-- prop: font-variant-alternates -->
4177 <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
4178 and swashes: the <a
4179 href="#propdef-font-variant-alternates">font-variant-alternates</a>
4180 property</h3>
4182 <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
4183 <tbody>
4184 <tr>
4185 <td>Name:
4187 <td><dfn
4188 id=propdef-font-variant-alternates>font-variant-alternates</dfn>
4190 <tr>
4191 <td>Value:
4193 <td>normal | [ <a href="#stylistic"
4194 title=stylistic>stylistic(<feature-value-name>)</a> || <a
4195 href="#historical-forms">historical-forms</a> || <a href="#styleset"
4196 title=styleset>styleset(<feature-value-name> #)</a> || <a
4197 href="#character-variant"
4198 title=character-variant>character-variant(<feature-value-name>
4199 #)</a> || <a href="#swash"
4200 title=swash>swash(<feature-value-name>)</a> || <a
4201 href="#ornaments"
4202 title=ornaments>ornaments(<feature-value-name>)</a> || <a
4203 href="#annotation"
4204 title=annotation>annotation(<feature-value-name>)</a> ]
4206 <tr>
4207 <td>Initial:
4209 <td>normal
4211 <tr>
4212 <td>Applies to:
4214 <td>all elements
4216 <tr>
4217 <td>Inherited:
4219 <td>yes
4221 <tr>
4222 <td>Percentages:
4224 <td>N/A
4226 <tr>
4227 <td>Media:
4229 <td>visual
4231 <tr>
4232 <td>Computed value:
4234 <td>as specified
4236 <tr>
4237 <td>Animatable:
4239 <td>no
4240 </table>
4242 <p>For any given character, fonts can provide a variety of alternate glyphs
4243 in addition to the default glyph for that character. This property
4244 provides control over the selection of these alternate glyphs.
4246 <p>In cases where multiple alternates are possible, authors define a
4247 <code><feature-value-name></code> using the
4248 <code>@font-feature-values</code> rule described below to indicate the
4249 specific alternate to be used. The nature of these alternates is font
4250 specific, so the rule defines values for a specific font family or set of
4251 families. When a particular value has not been defined for a given family,
4252 the named value is treated as if the feature had omitted from the style
4253 rule. If a given value is outside the range supported by a given font, the
4254 value is ignored. These values never apply to generic font families, nor
4255 to families selected as part of system font fallback. Values that behave
4256 this way are marked as <em>font specific</em>.
4258 <p>Individual values have the following meanings:
4260 <dl>
4261 <dt><dfn id=normal1>normal</dfn>
4263 <dd>None of the features listed below are enabled.
4265 <dt><dfn id=stylistic
4266 title=stylistic>stylistic(<feature-value-name>)</dfn>
4268 <dd>Enables display of stylistic alternates (<em>font specific</em>,
4269 OpenType feature: <span class=tag>salt
4270 <feature-value-name></span>).
4271 </dl>
4273 <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
4275 <dl>
4276 <dt><dfn id=historical-forms>historical-forms</dfn>
4278 <dd>Enables display of historical forms (OpenType feature: <span
4279 class=tag>hist</span>).
4280 </dl>
4282 <div class=featex><img alt="historical form example" src=hist.png></div>
4284 <dl>
4285 <dt><dfn id=styleset title=styleset>styleset(<feature-value-name>
4286 #)</dfn>
4288 <dd>Enables display with stylistic sets (<em>font specific</em>, OpenType
4289 feature: <span class=tag>ss<feature-index></span> OpenType
4290 currently defines <span class=tag>ss01</span> through <span
4291 class=tag>ss20</span>).
4292 </dl>
4294 <div class=featex><img alt="styleset example" src=ssnn.png></div>
4296 <dl>
4297 <dt><dfn id=character-variant
4298 title=character-variant>character-variant(<feature-value-name>
4299 #)</dfn>
4301 <dd>Enables display of specific character variants (<em>font
4302 specific</em>, OpenType feature: <span
4303 class=tag>cv<feature-index></span> OpenType currently defines <span
4304 class=tag>cv01</span> through <span class=tag>cv99</span>).
4306 <dt><dfn id=swash title=swash>swash(<feature-value-name>)</dfn>
4308 <dd>Enables display of swash glyphs (<em>font specific</em>, OpenType
4309 feature: <span class=tag>swsh <feature-index>, cswh
4310 <feature-index></span>).
4311 </dl>
4313 <div class=featex><img alt="swash example" src=swsh.png></div>
4315 <dl>
4316 <dt><dfn id=ornaments
4317 title=ornaments>ornaments(<feature-value-name>)</dfn>
4319 <dd>Enables replacement of default glyphs with ornaments, if provided in
4320 the font (<em>font specific</em>, OpenType feature: <span class=tag>ornm
4321 <feature-index></span>). Some fonts may offer ornament glyphs as
4322 alternates for a wide collection of characters; however, displaying
4323 arbitrary characters (e.g., alphanumerics) as ornaments is poor practice
4324 as it distorts the semantics of the data. Font designers are encouraged
4325 to encode all ornaments (except those explicitly encoded in the Unicode
4326 Dingbats blocks, etc.) as alternates for the bullet character (U+2022) to
4327 allow authors to select the desired glyph using
4328 <feature-value-name>.
4329 </dl>
4331 <div class=featex><img alt="ornaments example" src=ornm.png></div>
4333 <dl>
4334 <dt><dfn id=annotation
4335 title=annotation>annotation(<feature-value-name>)</dfn>
4337 <dd>Enables display of alternate annotation forms (<em>font specific</em>,
4338 OpenType feature: <span class=tag>nalt <feature-index></span>).
4339 </dl>
4341 <div class=featex><img alt="alternate annotation form example"
4342 src=nalt.png></div>
4344 <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
4345 specific alternates: the <code>@font-feature-values</code> rule</h3>
4347 <p>Several of the possible values of ‘<a
4348 href="#propdef-font-variant-alternates"><code
4349 class=property>font-variant-alternates</code></a>’ listed above are
4350 labeled as "font specific". For these features fonts may define not just a
4351 single glyph but a set of alternate glyphs with an index to select a given
4352 alternate. Since these are font family specific, the
4353 <code>@font-feature-values</code> rule is used to define named-values for
4354 these indices for a given family.
4356 <p>In the case of the swash Q in the example shown above, the swash could
4357 be specified using these style rules:
4359 <pre>
4361 @font-feature-values Jupiter Sans {
4362 @swash {
4363 delicate: 1;
4364 flowing: 2;
4365 }
4366 }
4368 h2 { font-family: Jupiter Sans, sans-serif; }
4370 /* show the second swash variant in h2 headings */
4371 h2:first-letter { font-variant-alternates: swash(flowing); }
4373 <h2>Quick</h2></pre>
4375 <p>When Jupiter Sans is present, the second alternate swash alternate will
4376 be displayed. When not present, no swash character will be shown, since
4377 the specific named-value "flowing" is only defined for the Jupiter Sans
4378 family. The @-mark indicates the name of the property value for which a
4379 named-value can be used. The name "flowing" is chosen by the author, the
4380 values specified within a given font's data.
4382 <p>In terms of the grammar, this specification defines the following
4383 productions:</p>
4384 <!--
4385 <pre><dfn>supports_rule</dfn>
4386 : <i>SUPPORTS_SYM</i> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <i>supports_condition</i> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <i>group_rule_body</i>
4387 ;
4389 <dfn>supports_condition</dfn>
4390 : <i>supports_negation</i> | <i>supports_conjunction</i> | <i>supports_disjunction</i> |
4391 <i>supports_condition_in_parens</i>
4392 ;
4394 <dfn>supports_condition_in_parens</dfn>
4395 : ( '(' <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* <i>supports_condition</i> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>* ')' ) | <i>supports_declaration_condition</i> |
4396 <i>general_enclosed</i>
4397 ;
4399 <dfn>supports_negation</dfn>
4400 : <a href="http://www.w3.org/TR/css3-mediaqueries/#syntax"><i>NOT</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>+ <i>supports_condition_in_parens</i>
4401 ;
4403 <dfn>supports_conjunction</dfn>
4404 : <i>supports_condition_in_parens</i> ( <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>+ <a href="http://www.w3.org/TR/css3-mediaqueries/#syntax"><i>AND</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>+ <i>supports_condition_in_parens</i> )+
4405 ;
4407 <dfn>supports_disjunction</dfn>
4408 : <i>supports_condition_in_parens</i> ( <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>+ <i>OR</i> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>+ <i>supports_condition_in_parens</i> )+
4409 ;
4411 <dfn>supports_declaration_condition</dfn>
4412 : '(' <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>declaration</i></a> ')'
4413 ;
4415 <dfn>general_enclosed</dfn>
4416 : ( <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>FUNCTION</i></a> | '(' ) ( <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>any</i></a> | <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>unused</i></a> )* ')'
4417 ;
4418 </pre>
4420 -->
4422 <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
4423 : <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>*
4424 '{' <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>*
4425 ;
4427 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
4428 : <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> ]*
4429 ;
4431 <dfn id=fontfamilyname>font_family_name</dfn>
4432 : <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> ]* ]
4433 ;
4435 <dfn id=featurevalueblock>feature_value_block</dfn>
4436 : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4437 '{' <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>*
4438 ;
4440 <dfn id=featuretype>feature_type</dfn>:
4441 <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
4442 ;
4444 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
4445 : <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> ]*
4446 ;
4447 </pre>
4449 <p>The following new token is introduced:
4451 <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>;}
4452 </pre>
4454 <p>Feature value blocks are treated <a
4455 href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">similar to
4456 at-rules</a>, they consist of everything up to the next block or
4457 semi-colon, whichever comes first.
4459 <p>Font feature values rules define a set of values for a specific font
4460 feature as used for a given set of families. Effectively, they define a
4461 mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
4462 ⟨values⟩ are the indices used for specific features defined for a
4463 given font.
4465 <p>The font family list uses the same syntax as that used for the ‘<a
4466 href="#descdef-font-family"><code class=property>font-family</code></a>’
4467 property. Within feature value blocks, the feature type is ‘<code
4468 class=css>@</code>’ followed by the name of the font-specific property
4469 value (e.g. <a href="#swash"><code>@swash</code></a>). The feature type
4470 must match, using an ASCII case-insensitive comparison, one of the
4471 <em>font specific</em> values of the <a
4472 href="#propdef-font-variant-alternates"><code>font-variant-alternates</code></a>
4473 property. The values associated with a given idenitifier are limited to
4474 integer values 0 or greater.
4476 <p>If syntax errors occur within the font family list, the entire rule must
4477 be ignored. When syntax errors occur within a feature value definition,
4478 such as invalid identifiers or values, the entire feature value definition
4479 must be omitted, similar to the way syntax errors in style declarations
4480 are handled. When the <code><feature-type></code> is invalid, the
4481 entire associated feature value block must be ignored.
4483 <pre>@font-feature-values Bongo {
4484 @swash { ornate: 1; }
4485 annotation { boxed: 4; } /* should be @annotation! */
4486 @swash { double-loops: 1; flowing: -1; } /* negative value */
4487 @ornaments ; /* incomplete definition */
4488 @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
4489 <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none;">redrum</a> /* random editing mistake */
4490 }</pre>
4492 <p>The example above is equivalent to:
4494 <pre>@font-feature-values Bongo {
4495 @swash { ornate: 1; }
4496 @swash { double-loops: 1; }
4497 @styleset { double-W: 14; sharp-terminals: 16 1; }
4498 }</pre>
4500 <p>If multiple <code>@font-feature-values</code> rules are defined for a
4501 given family, the resulting values defined are the union of these rules.
4502 This allows a set of named-values to be defined for a given font family
4503 globally for a site and specific additions made per-page. If the same
4504 <feature-value-name> is defined mulitple times for a given
4505 font-variant value, the last defined value is used.
4507 <pre>
4508 site.css:
4510 @font-feature-values Mercury Serif {
4511 @styleset {
4512 stacked-g: 3; /* "two-storey" versions of g, a */
4513 stacked-a: 4;
4514 }
4515 }
4517 page.css:
4519 @font-feature-values Mercury Serif {
4520 @styleset {
4521 geometric-m: 7; /* alternate version of m */
4522 }
4523 }
4525 body {
4526 font-family: Mercury Serif, serif;
4528 /* enable both the use of stacked g and alternate m */
4529 font-variant-alternates: styleset(stacked-g, geometric-m);
4530 }</pre>
4532 <p>Only named font families are allowed for <font-family>, rules that
4533 include generic or system fonts in the list of font families are
4534 considered syntax errors and the contents of the rules are ignored.
4535 However, if a user agent defines a generic font to be a specific named
4536 font (e.g. Helvetica), the settings associated with that family name will
4537 be used.
4539 <p>For <font-variant-property-value>, only font specific property value
4540 names supported by the ‘<a href="#propdef-font-variant"><code
4541 class=property>font-variant</code></a>’ property are recognized,
4542 definitions for other value names cause a syntax error and are ignored.
4543 Each property value that is font specific is clearly marked as such.
4544 Feature value names follow the rules of CSS user identifiers and are
4545 case-sensitive. They are unique only for a given set of font families and
4546 font-variant property value; the same identifier used with a different
4547 font-variant property value is treated as a separate and distinct value.
4549 <p>Using a commonly named value allows authors to use a single style rule
4550 to cover a set of fonts for which the underlying selector is different for
4551 each font. If either font in the example below is found, a circled number
4552 glyph will be used:
4554 <pre>@font-feature-values Taisho Gothic {
4555 @annotation { boxed: 1; circled: 4; }
4556 }
4558 @font-feature-values Otaru Kisa {
4559 @annotation { circled: 1; black-boxed: 3; }
4560 }
4562 h3.title {
4563 /* circled form defined for both fonts */
4564 font-family: Taisho Gothic, Otaru Kisa;
4565 font-variant: annotation(circled);
4566 }</pre>
4568 <p>Most font specific font-variant property values take a single value
4569 (e.g. swash). The character-variant property value allows two values and
4570 styleset allows an unlimited number. If a larger number of values are
4571 assigned to a given name, a syntax error occurs and the entire
4572 <font-feature-values-declaration> is ignored.
4574 <p>For the styleset property value, multiple values indicate the style sets
4575 to be enabled. Values between 1 and 99 enable OpenType features <span
4576 class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
4577 OpenType standard only officially defines <span class=tag>ss01</span>
4578 through <span class=tag>ss20</span>. Values greater than 99 or equal to 0
4579 are ignored but do not generate a syntax error when parsed.
4581 <pre>@font-feature-values Mars Serif {
4582 @styleset {
4583 alt-g: 1; /* implies ss01 = 1 */
4584 curly-quotes: 3; /* implies ss03 = 1 */
4585 code: 4 5; /* implies ss04 = 1, ss05 = 1 */
4586 }
4588 @styleset {
4589 dumb: 125; /* >99, ignored */
4590 }
4592 @swash {
4593 swishy: 3 5; /* more than 1 value for swash, syntax error */
4594 }
4595 }
4597 p.codeblock {
4598 /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
4599 font-variant-alternates: styleset(curly-quotes, code);
4600 }</pre>
4602 <p>For character-variant, a single value between 1 and 99 indicates the
4603 enabling of OpenType feature <span class=tag>cv01</span> through <span
4604 class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
4605 to 0 are ignored but do not generate a syntax error when parsed. When two
4606 values are listed, the first value indicates the feature used and the
4607 second the value passed for that feature. When two value names imply
4608 different settings for the same underlying feature the last setting is
4609 used.
4611 <pre>@font-feature-values MM Greek {
4612 @character-variant { alpha-2: 1 2; } /* implies cv01 = 2 */
4613 @character-variant { beta-3: 2 3; } /* implies cv02 = 3 */
4614 @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, ignored */
4615 @character-variant { gamma: 12; } /* implies cv12 = 1 */
4616 @character-variant { zeta: 20 3; } /* implies cv20 = 3 */
4617 @character-variant { zeta-2: 20 2; } /* implies cv20 = 2 */
4618 @character-variant { silly: 105; } /* >99, ignored */
4619 @character-variant { dumb: 323 3; } /* >99, ignored */
4620 }
4622 #title {
4623 /* use the third alternate beta, first alternate gamma */
4624 font-variant-alternates: character-variant(beta-3, gamma);
4625 }
4627 p {
4628 /* zeta-2 follows zeta, implies cv20 = 2 */
4629 font-variant-alternates: character-variant(zeta, zeta-2);
4630 }
4632 .special {
4633 /* zeta follows zeta-2, implies cv20 = 3 */
4634 font-variant-alternates: character-variant(zeta-2, zeta);
4635 }</pre>
4637 <p>See the <a href="#om-fontfeaturevalues">object model reference
4638 section</a> for a description of the interfaces used to modify these rules
4639 via the CSS Object Model.
4641 <div class=figure><img alt="Matching text on Byzantine seals using
4642 character variants" src=byzantineseal.png>
4643 <p class=caption>Byzantine seal text displayed with character variants
4644 </div>
4646 <div class=example>
4647 <p>In the figure above, the text in red is rendered using a font
4648 containing character variants that mimic the character forms found on a
4649 Byzantine seal from the 8th century A.D. Two lines below is the same text
4650 displayed in a font without variants. Note the two variants for U and N
4651 used on the seal.</p>
4653 <pre>@font-feature-values Athena Ruby {
4654 @character-variant {
4655 leo-B: 2 1;
4656 leo-M: 13 3;
4657 leo-alt-N: 14 1;
4658 leo-N: 14 2;
4659 leo-T: 20 1;
4660 leo-U: 21 2;
4661 leo-alt-U: 21 4;
4662 }
4663 }
4665 p {
4666 font-variant: discretionary-ligatures,
4667 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
4668 }
4670 span.alt-N {
4671 font-variant-alternates: character-variant(leo-alt-N);
4672 }
4674 span.alt-U {
4675 font-variant-alternates: character-variant(leo-alt-U);
4676 }
4678 <p>ENO....UP͞RSTU<span class="alt-U">U</span>͞<span class="alt-U">U</span>ΚΑΙTỤẠG̣IUPNS</p>
4680 <p>LEON|ΚΑΙCONSTA|NTI<span class="alt-N">N</span>OS..|STOIBAṢ.|LIṢROM|AIO<span class="alt-N">N</span></p>
4681 </pre>
4682 </div>
4684 <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
4685 Asian text rendering: the <a
4686 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
4687 property</h3>
4689 <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
4690 <tbody>
4691 <tr>
4692 <td>Name:
4694 <td><dfn
4695 id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
4697 <tr>
4698 <td>Value:
4700 <td>normal | [ <a
4701 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
4702 || <a
4703 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
4704 || <a href="#ruby">ruby</a> ]
4706 <tr>
4707 <td>Initial:
4709 <td>normal
4711 <tr>
4712 <td>Applies to:
4714 <td>all elements
4716 <tr>
4717 <td>Inherited:
4719 <td>yes
4721 <tr>
4722 <td>Percentages:
4724 <td>N/A
4726 <tr>
4727 <td>Media:
4729 <td>visual
4731 <tr>
4732 <td>Computed value:
4734 <td>as specified
4736 <tr>
4737 <td>Animatable:
4739 <td>no
4740 </table>
4742 <p>Allows control of glyph substitution and sizing in East Asian text.
4744 <pre
4745 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>
4747 <pre
4748 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>
4750 <p>Individual values have the following meanings:
4752 <dl>
4753 <dt><dfn id=normal2>normal</dfn>
4755 <dd>None of the features listed below are enabled.
4757 <dt><dfn id=jis78>jis78</dfn>
4759 <dd>Enables rendering of JIS78 forms (OpenType feature: <span
4760 class=tag>jp78</span>).
4761 </dl>
4763 <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
4765 <dl>
4766 <dt><dfn id=jis83>jis83</dfn>
4768 <dd>Enables rendering of JIS83 forms (OpenType feature: <span
4769 class=tag>jp83</span>).
4771 <dt><dfn id=jis90>jis90</dfn>
4773 <dd>Enables rendering of JIS90 forms (OpenType feature: <span
4774 class=tag>jp90</span>).
4776 <dt><dfn id=jis04>jis04</dfn>
4778 <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
4779 class=tag>jp04</span>).
4780 <p>The various JIS variants reflect the glyph forms defined in different
4781 Japanese national standards. Fonts generally include glyphs defined by
4782 the most recent national standard but it's sometimes necessary to use
4783 older variants, to match signage for example.</p>
4785 <dt><dfn id=simplified>simplified</dfn>
4787 <dd>Enables rendering of simplified forms (OpenType feature: <span
4788 class=tag>smpl</span>).
4789 <p>The ‘<a href="#simplified"><code
4790 class=property>simplified</code></a>’ and ‘<a
4791 href="#traditional"><code class=property>traditional</code></a>’
4792 values allow control over the glyph forms for characters which have been
4793 simplified over time but for which the older, traditional form is still
4794 used in some contexts. The exact set of characters and glyph forms will
4795 vary to some degree by context for which a given font was designed.</p>
4797 <dt><dfn id=traditional>traditional</dfn>
4799 <dd>Enables rendering of traditional forms (OpenType feature: <span
4800 class=tag>trad</span>).
4801 </dl>
4803 <div class=featex><img alt="tradtional form example" src=trad.png></div>
4805 <dl>
4806 <dt><dfn id=full-width>full-width</dfn>
4808 <dd>Enables rendering of full-width variants (OpenType feature: <span
4809 class=tag>fwid</span>).
4811 <dt><dfn id=proportional-width>proportional-width</dfn>
4813 <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
4814 <span class=tag>pwid</span>).
4815 </dl>
4817 <div class=featex><img alt="proportionally spaced Japanese example"
4818 src=pwid.png></div>
4820 <dl>
4821 <dt><dfn id=ruby>ruby</dfn>
4823 <dd>Enables display of ruby variant glyphs (OpenType feature: <span
4824 class=tag>ruby</span>). Since ruby text is generally smaller than the
4825 associated body text, font designers can design special glyphs for use
4826 with ruby that are more readable than scaled down versions of the default
4827 glyphs. Only glyph selection is affected, there is no associated font
4828 scaling or other change that affects line layout. The red ruby text below
4829 is shown with default glyphs (top) and with ruby variant glyphs (bottom).
4830 Note the slight difference in stroke thickness.
4831 </dl>
4833 <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
4835 <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
4836 for font rendering: the <a href="#propdef-font-variant">font-variant</a>
4837 property</h3>
4839 <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
4840 <tbody>
4841 <tr>
4842 <td>Name:
4844 <td><dfn id=propdef-font-variant>font-variant</dfn>
4846 <tr>
4847 <td>Value:
4849 <td>normal | none | [ <a
4850 href="#common-lig-values"><var><common-lig-values></var></a> ||
4851 <a
4852 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
4853 || <a
4854 href="#historical-lig-values"><var><historical-lig-values></var></a>
4855 || <a
4856 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
4857 || <a href="#stylistic"><var
4858 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
4859 href="#historical-forms"><var>historical-forms</var></a> || <a
4860 href="#styleset"><var
4861 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
4862 href="#character-variant"><var
4863 title=character-variant>character-variant(<feature-value-name>
4864 #)</var></a> || <a href="#swash"><var
4865 title=swash>swash(<feature-value-name>)</var></a> || <a
4866 href="#ornaments"><var
4867 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
4868 href="#annotation"><var
4869 title=annotation>annotation(<feature-value-name>)</var></a> || [
4870 <a href="#small-caps"><i>small-caps</i></a> | <a
4871 href="#all-small-caps"><i>all-small-caps</i></a> | <a
4872 href="#petite-caps"><i>petite-caps</i></a> | <a
4873 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
4874 href="#unicase"><i>unicase</i></a> | <a
4875 href="#titling-caps"><i>titling-caps</i></a> ] || <a
4876 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
4877 || <a
4878 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
4879 || <a
4880 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
4881 || <a href="#ordinal"><i>ordinal</i></a> || <a
4882 href="#slashed-zero"><i>slashed-zero</i></a> || <a
4883 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
4884 || <a
4885 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
4886 || <a href="#ruby"><i>ruby</i></a> ]
4888 <tr>
4889 <td>Initial:
4891 <td>normal
4893 <tr>
4894 <td>Applies to:
4896 <td>all elements
4898 <tr>
4899 <td>Inherited:
4901 <td>yes
4903 <tr>
4904 <td>Percentages:
4906 <td>see individual properties
4908 <tr>
4909 <td>Media:
4911 <td>visual
4913 <tr>
4914 <td>Computed value:
4916 <td>see individual properties
4918 <tr>
4919 <td>Animatable:
4921 <td>see individual properties
4922 </table>
4924 <p>The value ‘<a href="#normal2"><code
4925 class=property>normal</code></a>’ resets all other font feature
4926 properties to their inital value. The ‘<code
4927 class=property>none</code>’ value sets ‘<a
4928 href="#propdef-font-variant-ligatures"><code
4929 class=property>font-variant-ligatures</code></a>’ to ‘<code
4930 class=property>none</code>’ and resets all other font feature properties
4931 to their initial value. Like other shorthands, using ‘<a
4932 href="#propdef-font-variant"><code
4933 class=property>font-variant</code></a>’ resets unspecified font-variant
4934 subproperties to their initial values. It does not reset the values of
4935 either ‘<a href="#propdef-font-language-override"><code
4936 class=property>font-language-override</code></a>’ or ‘<a
4937 href="#propdef-font-feature-settings"><code
4938 class=property>font-feature-settings</code></a>’.
4940 <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
4941 font feature settings control: the <a
4942 href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
4944 <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
4945 <tbody>
4946 <tr>
4947 <td>Name:
4949 <td><dfn id=propdef-font-feature-settings>font-feature-settings</dfn>
4951 <tr>
4952 <td>Value:
4954 <td>normal | <a
4955 href="#feature-tag-value"><var><feature-tag-value></var></a> #
4957 <tr>
4958 <td>Initial:
4960 <td>normal
4962 <tr>
4963 <td>Applies to:
4965 <td>all elements
4967 <tr>
4968 <td>Inherited:
4970 <td>yes
4972 <tr>
4973 <td>Percentages:
4975 <td>N/A
4977 <tr>
4978 <td>Media:
4980 <td>visual
4982 <tr>
4983 <td>Computed value:
4985 <td>as specified
4987 <tr>
4988 <td>Animatable:
4990 <td>no
4991 </table>
4993 <p>This property provides low-level control over OpenType font features. It
4994 is intended as a way of providing access to font features that are not
4995 widely used but are needed for a particular use case. A value of ‘<a
4996 href="#normal2"><code class=property>normal</code></a>’ means that no
4997 change in glyph selection or positioning occurs due to this property.
4999 <p>
5001 <pre>/* enable small caps and use second swash alternate */
5002 font-feature-settings: "smcp", "swsh" 2;</pre>
5004 <p>Feature tag values have the following syntax:
5006 <pre
5007 class=prod><dfn id=feature-tag-value><var><feature-tag-value></var></dfn> = <string> [ <integer> | on | off ]?</pre>
5009 <p>The <string> is a case-sensitive OpenType feature tag. As
5010 specified in the OpenType specification, feature tags contain four ASCII
5011 characters. Tag strings longer or shorter than four characters, or
5012 containing characters outside the U+20–7E codepoint range are invalid.
5013 User agents must not use a feature tag created by truncating or padding
5014 the string to four characters. Feature tags need only match a feature tag
5015 defined in the font, they are not limited to explicitly registered
5016 OpenType features. Fonts defining custom feature tags should follow the <a
5017 href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
5018 rules</a> defined in the OpenType specification <a
5019 href="#OPENTYPE-FEATURES"
5020 rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
5021 Feature tags not present in the font are ignored; a user agent must not
5022 attempt to synthesize fallback behavior based on these feature tags.
5024 <p>This means that explicitly disabling the <span class=tag>kern</span>
5025 feature will not affect the application of kerning data found in the
5026 ‘<code class=property>kern</code>’ table (as opposed to kerning data
5027 associated with the <span class=tag>kern</span> feature in the ‘<code
5028 class=property>GPOS</code>’ table). Authors should use the ‘<a
5029 href="#propdef-font-kerning"><code
5030 class=property>font-kerning</code></a>’ property to explictly enable or
5031 disable kerning since this property affects both types of kerning.
5033 <p>If present, a value indicates an index used for glyph selection. An
5034 <integer> value must be 0 or greater. A value of 0 indicates that
5035 the feature is disabled. For boolean features, a value of 1 enables the
5036 feature. For non-boolean features, a value of 1 or greater enables the
5037 feature and indicates the feature selection index. A value of ‘<code
5038 class=property>on</code>’ is synonymous with 1 and ‘<code
5039 class=property>off</code>’ is synonymous with 0. If the value is
5040 omitted, a value of 1 is assumed.
5042 <pre>
5043 font-feature-settings: "dlig" 1; /* dlig=1 enable discretionary ligatures */
5044 font-feature-settings: "smcp" on; /* smcp=1 enable small caps */
5045 font-feature-settings: 'c2sc'; /* c2sc=1 enable caps to small caps */
5046 font-feature-settings: "liga" off; /* liga=0 no common ligatures */
5047 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
5048 font-feature-settings: "tnum" "hist"; /* invalid, need a comma-delimited list */
5049 font-feature-settings: "palin" off; /* good idea but invalid tagname */
5050 font-feature-settings: "PKRN"; /* PKRN=1 enable custom feature */
5051 font-feature-settings: dlig; /* invalid, tag must be a string */
5052 </pre>
5054 <p>When values greater than the range supported by the font are specified,
5055 the behavior is explicitly undefined. For boolean features, in general
5056 these will enable the feature. For non-boolean features, out of range
5057 values will in general be equivalent to a 0 value. However, in both cases
5058 the exact behavior will depend upon the way the font is designed
5059 (specifically, which type of lookup is used to define the feature).
5061 <p>Authors should generally use ‘<a href="#propdef-font-variant"><code
5062 class=property>font-variant</code></a>’ and its related subproperties
5063 whenever possible and only use this property for special cases where its
5064 use is the only way of accessing a particular infrequently used font
5065 feature.
5067 <p>Although specifically defined for OpenType feature tags, feature tags
5068 for other modern font formats that support font features may be added in
5069 the future. Where possible, features defined for other font formats should
5070 attempt to follow the pattern of registered OpenType tags.
5072 <div class=example>
5073 <p>The Japanese text below will be rendered with half-width kana
5074 characters:</p>
5076 <pre lang=ja>
5077 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
5079 <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>
5080 </pre>
5081 </div>
5083 <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
5084 language override: the <a
5085 href="#propdef-font-language-override">font-language-override</a> property</h3>
5087 <table class=propdef id=namefont-language-overridevaluenormal-lt>
5088 <tbody>
5089 <tr>
5090 <td>Name:
5092 <td><dfn id=propdef-font-language-override>font-language-override</dfn>
5094 <tr>
5095 <td>Value:
5097 <td>normal | <string>
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>N/A
5119 <tr>
5120 <td>Media:
5122 <td>visual
5124 <tr>
5125 <td>Computed value:
5127 <td>as specified
5129 <tr>
5130 <td>Animatable:
5132 <td>no
5133 </table>
5135 <p>The value of ‘<a href="#normal2"><code
5136 class=property>normal</code></a>’ implies that when rendering with
5137 OpenType fonts the language of the document is used to infer the OpenType
5138 language system, used to select language specific features when rendering.
5139 The value of the <string> is a single three-letter OpenType <a
5140 href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
5141 system tag</a>, defined in the layout tag registry of the OpenType
5142 specification.
5144 <div class=example>
5145 <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
5146 Declaration of Human Rights</a> has been translated into a wide variety
5147 of languages. In Turkish, Article 9 of this document might be marked up
5148 as below:</p>
5150 <pre lang=tr><body lang="tr">
5152 <h4>Madde 9</h4>
5153 <p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.</p>
5154 </pre>
5156 <p>Here the user agent uses the value of the ‘<code
5157 class=property>lang</code>’ attribute when rendering text and
5158 appropriately renders this text without ‘<code
5159 class=property>fi</code>’ ligatures. There is no need to use the ‘<a
5160 href="#propdef-font-language-override"><code
5161 class=property>font-language-override</code></a>’ property.</p>
5163 <p>However, a given font may lack support for a specific language. In this
5164 situation authors may need to use the typographic conventions of a
5165 related language that are supported by that font:</p>
5167 <pre lang=mk><body lang="mk"> <!-- Macedonian lang code -->
5169 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
5171 <h4>Члeн 9</h4>
5172 <p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.</p>
5174 </pre>
5176 <p>The Macedonian text here will be rendered using Serbian typographic
5177 conventions, with the assumption that the font specified supports
5178 Serbian.</p>
5179 </div>
5181 <p><a id=rendering-considerations></a>
5183 <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
5184 Resolution</h2>
5186 <p>As described in the previous section, font features can be enabled in a
5187 variety of ways, either via the use of ‘<a
5188 href="#propdef-font-variant"><code
5189 class=property>font-variant</code></a>’ or ‘<a
5190 href="#propdef-font-feature-settings"><code
5191 class=property>font-feature-settings</code></a>’ in a style rule or
5192 within an <code>@font-face</code> rule. The resolution order for the union
5193 of these settings is defined below. Features defined via CSS properties
5194 are applied on top of layout engine default features.
5196 <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
5198 <p>For OpenType fonts, user agents must enable the default features defined
5199 in the OpenType documentation for a given script and writing mode.
5200 Required ligatures, common ligatures and contextual forms must be enabled
5201 by default (OpenType features: <span class=tag>rlig, liga, clig,
5202 calt</span>), along with localized forms (OpenType feature: <span
5203 class=tag>locl</span>), and features required for proper display of
5204 composed characters and marks (OpenType features: <span class=tag>ccmp,
5205 mark, mkmk</span>). These features must always be enabled, even when the
5206 value of the ‘<a href="#propdef-font-variant"><code
5207 class=property>font-variant</code></a>’ and ‘<a
5208 href="#propdef-font-feature-settings"><code
5209 class=property>font-feature-settings</code></a>’ properties is ‘<a
5210 href="#normal2"><code class=property>normal</code></a>’. Individual
5211 features are only disabled when explicitly overridden by the author, as
5212 when ‘<a href="#propdef-font-variant-ligatures"><code
5213 class=property>font-variant-ligatures</code></a>’ is set to ‘<a
5214 href="#no-common-ligatures"><code
5215 class=property>no-common-ligatures</code></a>’. For handling complex
5216 scripts such as <a
5217 href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
5218 <a
5219 href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
5220 or <a
5221 href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
5222 additional features are required. For upright text within vertical text
5223 runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
5224 must be enabled.
5226 <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
5228 <p>General and font specific font feature property settings are resolved in
5229 the order below, in ascending precedence order. This ordering is used to
5230 construct a combined list of font features that affect a given text run.
5232 <ol>
5233 <li>Font features enabled by default, including features required for a
5234 given script.
5236 <li>If the font is defined via an <code>@font-face</code> rule, the font
5237 features implied by the font-variant descriptor in the
5238 <code>@font-face</code> rule.
5240 <li>If the font is defined via an <code>@font-face</code> rule, the font
5241 features implied by the font-feature-settings descriptor in the
5242 <code>@font-face</code> rule.
5244 <li>Feature settings determined by properties other than ‘<a
5245 href="#propdef-font-variant"><code
5246 class=property>font-variant</code></a>’ or ‘<a
5247 href="#propdef-font-feature-settings"><code
5248 class=property>font-feature-settings</code></a>’. For example, setting
5249 a non-default value for the ‘<code
5250 class=property>letter-spacing</code>’ property disables ligatures.
5252 <li>Font features implied by the value of the ‘<a
5253 href="#propdef-font-variant"><code
5254 class=property>font-variant</code></a>’ property, the related
5255 font-variant subproperties and any other CSS property that may use
5256 OpenType features (e.g. the ‘<a href="#propdef-font-kerning"><code
5257 class=property>font-kerning</code></a>’ property).
5259 <li>Font features implied by the value of ‘<a
5260 href="#propdef-font-feature-settings"><code
5261 class=property>font-feature-settings</code></a>’ property.
5262 </ol>
5264 <p>This ordering allows authors to set up a general set of defaults for
5265 fonts within their <code>@font-face</code> rules, then override them with
5266 property settings for specific elements. General property settings
5267 override the settings in <code>@font-face</code> rules and low-level font
5268 feature settings override ‘<a href="#propdef-font-variant"><code
5269 class=property>font-variant</code></a>’ property settings.
5271 <p>For situations where the combined list of font feature settings contains
5272 more than one value for the same feature, the last value is used. When a
5273 font lacks support for a given underlying font feature, text is simply
5274 rendered as if that font feature was not enabled; font fallback does not
5275 occur and no attempt is made to synthesize the feature except where
5276 explicitly noted for specific properties.
5278 <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
5279 precedence examples</h3>
5281 <div class=example>
5282 <p>With the styles below, numbers are rendered proportionally when used
5283 within a paragraph but are shown in tabular form within tables of prices:</p>
5285 <pre>body {
5286 font-variant-numeric: proportional-nums;
5287 }
5289 table.prices td {
5290 font-variant-numeric: tabular-nums;
5291 }
5292 </pre>
5293 </div>
5295 <div class=example>
5296 <p>When the font-variant descriptor is used within an
5297 <code>@font-face</code> rule, it only applies to the font defined by that
5298 rule.</p>
5300 <pre>@font-face {
5301 font-family: MainText;
5302 src: url(http://example.com/font.ttf);
5303 font-variant: oldstyle-nums proportional-nums styleset(1,3);
5304 }
5306 body {
5307 font-family: MainText, Helvetica;
5308 }
5310 table.prices td {
5311 font-variant-numeric: tabular-nums;
5312 }
5313 </pre>
5315 <p>In this case, old-style numerals will be used throughout but only where
5316 the font "MainText" is used. Just as in the previous example, tabular
5317 values will be used in price tables since ‘<a
5318 href="#tabular-nums"><code class=property>tabular-nums</code></a>’
5319 appears in a general style rule and its use is mutually exclusive with
5320 ‘<a href="#proportional-nums"><code
5321 class=property>proportional-nums</code></a>’. Stylistic alternate sets
5322 will only be used where MainText is used.</p>
5323 </div>
5325 <div class=example>
5326 <p>The <code>@font-face</code> rule can also be used to access font
5327 features in locally available fonts via the use of <code>local()</code>
5328 in the ‘<a href="#descdef-src"><code class=property>src</code></a>’
5329 descriptor of the <code>@font-face</code> definition:</p>
5331 <pre>@font-face {
5332 font-family: BodyText;
5333 src: local("HiraMaruPro-W4");
5334 font-variant: proportional-width;
5335 font-feature-settings: "ital"; /* Latin italics within CJK text feature */
5336 }
5338 body { font-family: BodyText, serif; }
5339 </pre>
5341 <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
5342 text rendering occurs, Japanese kana will be proportionally spaced and
5343 Latin text will be italicised. Text rendered with the fallback serif font
5344 will use default rendering properties.</p>
5345 </div>
5347 <div class=example>
5348 <p>In the example below, discretionary ligatures are enabled only for a
5349 downloadable font but are disabled within spans of class "special":</p>
5351 <pre>@font-face {
5352 font-family: main;
5353 src: url(fonts/ffmeta.woff) format("woff");
5354 font-variant: discretionary-ligatures;
5355 }
5357 body { font-family: main, Helvetica; }
5358 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5359 </pre>
5361 <p>Adding an discretionary style rule with the <code>@font-face</code>
5362 above:</p>
5364 <pre>body { font-family: main, Helvetica; }
5365 span { font-feature-settings: "dlig"; }
5366 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5367 </pre>
5369 <p>Within spans of class "special", discretionary ligatures <em>will</em>
5370 be rendered. This is because both the ‘<a
5371 href="#propdef-font-feature-settings"><code
5372 class=property>font-feature-settings</code></a>’ and ‘<a
5373 href="#propdef-font-variant-ligatures"><code
5374 class=property>font-variant-ligatures</code></a>’ properties apply to
5375 these spans. Although the ‘<code class=css>no-discretionary
5376 ligatures</code>’ setting of ‘<a
5377 href="#propdef-font-variant-ligatures"><code
5378 class=property>font-variant-ligatures</code></a>’ effectively disables
5379 the OpenType <span class=tag>dlig</span> feature, because the ‘<a
5380 href="#propdef-font-feature-settings"><code
5381 class=property>font-feature-settings</code></a>’ is resolved after
5382 that, the ‘<code class=property>dlig</code>’ value reenables
5383 discretionary ligatures.</p>
5384 </div>
5386 <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
5388 <p>The contents of <code>@font-face</code> and
5389 <code>@font-feature-values</code> rules can be accessed via the following
5390 extensions to the CSS Object Model.
5392 <h3 id=om-fontface><span class=secno>8.1 </span>The <a
5393 href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
5395 <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
5396 <code>@font-face</code> rule.
5398 <pre class=idl>
5399 interface CSSFontFaceRule : CSSRule {
5400 attribute DOMString family;
5401 attribute DOMString src;
5402 attribute DOMString style;
5403 attribute DOMString weight;
5404 attribute DOMString stretch;
5405 attribute DOMString unicodeRange;
5406 attribute DOMString variant;
5407 attribute DOMString featureSettings;
5408 }</pre>
5410 <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
5411 rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
5412 defined a different variant of this rule. This definition supercedes that
5413 one.
5415 <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
5416 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5417 interface</h3>
5419 <p>The <code>CSSRule</code> interface is extended as follows:
5421 <pre class=idl>partial interface CSSRule {
5422 const unsigned short FONT_FEATURE_VALUES_RULE = 14;
5423 }</pre>
5425 <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
5426 interface represents a <code>@font-feature-values</code> rule.
5428 <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
5429 readonly attribute DOMString familyList;
5430 readonly attribute DOMString valueText;
5431 };</pre>
5433 <dl class=idl-attributes>
5434 <dt><var>familyList</var> of type <code>DOMString</code>, readonly
5436 <dd>The list of one or more font families for which a given set of feature
5437 values is defined.
5439 <dt><var>valueText</var> of type <code>DOMString</code>, readonly
5441 <dd>Serialized set of feature values.
5442 </dl>
5444 <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
5445 properties to CSS properties</h2>
5447 <p><em>This appendix is included as background for some of the problems and
5448 situations that are described in other sections. It should be viewed as
5449 informative only.</em>
5451 <p>Font properties in CSS are designed to be independent of the underlying
5452 font formats used; they can be used to specify bitmap fonts, Type1 fonts,
5453 SVG fonts in addition to the common TrueType and OpenType fonts. But there
5454 are facets of the TrueType and OpenType formats that often cause confusion
5455 for authors and present challenges to implementers on different platforms.
5457 <p>Originally developed at Apple, TrueType was designed as an outline font
5458 format for both screen and print. Microsoft joined Apple in developing the
5459 TrueType format and both platforms have supported TrueType fonts since
5460 then. Font data in the TrueType format consists of a set of tables
5461 distinguished with common four-letter tag names, each containing a
5462 specific type of data. For example, naming information, including
5463 copyright and license information, is stored in the ‘<code
5464 class=property>name</code>’ table. The <a
5465 href="#character-map"><em>character map</em></a> (‘<code
5466 class=property>cmap</code>’) table contains a mapping of character
5467 encodings to glyphs. Apple later added additional tables for supporting
5468 enhanced typographic functionality; these are now called Apple Advanced
5469 Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
5470 tables for advanced typography and called their format OpenType <a
5471 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
5473 <p>In many cases the font data used under Microsoft Windows or Linux is
5474 slightly different from the data used under Apple's Mac OS X because the
5475 TrueType format allowed for explicit variation across platforms. This
5476 includes font metrics, names and <a href="#character-map"><em>character
5477 map</em></a> data.
5479 <p>Specifically, font family name data is handled differently across
5480 platforms. For TrueType and OpenType fonts these names are contained in
5481 the ‘<code class=property>name</code>’ table, in name records with
5482 name ID 1. Mulitple names can be stored for different locales but
5483 Microsoft recommends fonts always include at least a US English version of
5484 the name. On Windows, Microsoft made the decision for backwards
5485 compatibility to limit this family name to a maximum of four faces; for
5486 larger groupings the "preferred family" (name ID 16) or "WWS family" (name
5487 ID 21) can be used. Other platforms such as OSX don't have this
5488 limitation, the family name is used to define all possible groupings.
5490 <p>Other name table data provides names used to uniquely identify a
5491 specific face within a family. The full font name (name ID 4) and the
5492 Postscript name (name ID 6) describe a single face uniquely. The bold face
5493 of the Gill Sans family has a fullname of "Gill Sans Bold" and a
5494 Postscript name of "GillSans-Bold". There can be multiple localized
5495 versions of the fullname for a given face but the Postscript name is
5496 always a unique name made from a limited set of ASCII characters.
5498 <p>On various platforms, different names are used to search for a font. For
5499 example, with the Windows GDI CreateIndirectFont API, either a family or
5500 fullname can be used to lookup a face while on Mac OS X the
5501 CTFontCreateWithName API call is used to lookup a given face using the
5502 fullname and Postscript name. Under Linux, the fontconfig API allows fonts
5503 to be searched using any of these names. In situations where platform
5504 API's automatically substitute other font choices, it may be necessary to
5505 verify a returned font matches a given name.
5507 <p>The weight of a given face can be determined via the usWeightClass field
5508 of the OS/2 table or inferred from the style name (name ID 2). Likewise,
5509 the width can be determined via the usWidthClass of the OS/2 table or
5510 inferred from the style name. For historical reasons related to synthetic
5511 bolding at weights 200 or lower with the Windows GDI API, font designers
5512 have sometimes skewed values in the OS/2 table to avoid these weights.
5514 <p>Rendering complex scripts that use contextual shaping such as Thai,
5515 Arabic and Devanagari requires features present only in OpenType or AAT
5516 fonts. Currently, complex script rendering is supported on Windows and
5517 Linux using OpenType font features while both OpenType and AAT font
5518 features are used under Mac OS X.
5520 <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
5522 <h3 class=no-num id=recent-changes> Changes from the <a
5523 href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">February 2013
5524 CSS3 Fonts Working Draft</a></h3>
5526 <p>Major changes include:
5528 <ul>
5529 <li>Moved font load events into a separate <a
5530 href="http://dev.w3.org/csswg/css3-font-load-events/">spec</a>
5532 <li>Tightened error handling rules for <code>@font-feature-values</code>
5533 rules
5535 <li>Added grammar productions for <code>@font-face</code> and
5536 <code>@font-feature-values</code> rules
5538 <li>Tightened definition of synthetic oblique
5540 <li>Revised definition of ‘<a href="#descdef-unicode-range"><code
5541 class=property>unicode-range</code></a>’ descriptor
5542 </ul>
5544 <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
5546 <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
5547 their help and feedback. John Hudson was kind enough to take the time to
5548 explain the subtleties of OpenType language tags and provided the example
5549 of character variant usage for displaying text on Byzantine seals. Ken
5550 Lunde and Eric Muller provided valuable feedback on CJK OpenType features
5551 and Unicode variation selectors. The idea for supporting font features by
5552 using font-variant subproperties originated with Håkon Wium Lie, Adam
5553 Twardoch and Tal Leming. Elika Etemad supplied some of the initial design
5554 ideas for the <code>@font-feature-values</code> rule. Thanks also to House
5555 Industries for allowing the use of Ed Interlock in the discretionary
5556 ligatures example.
5558 <p>A special thanks to Robert Bringhurst for the sublime mind expansion
5559 that is <em>The Elements of Typographic Style</em>.
5561 <h2 class=no-num id=conformance> Conformance</h2>
5563 <h3 class=no-num id=conventions> Document Conventions</h3>
5565 <p>Conformance requirements are expressed with a combination of descriptive
5566 assertions and RFC 2119 terminology. The key words “MUST”, “MUST
5567 NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
5568 “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
5569 normative parts of this document are to be interpreted as described in RFC
5570 2119. However, for readability, these words do not appear in all uppercase
5571 letters in this specification.
5573 <p>All of the text of this specification is normative except sections
5574 explicitly marked as non-normative, examples, and notes. <a
5575 href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
5577 <p>Examples in this specification are introduced with the words “for
5578 example” or are set apart from the normative text with
5579 <code>class="example"</code>, like this:
5581 <div class=example>
5582 <p>This is an example of an informative example.
5583 </div>
5585 <p>Informative notes begin with the word “Note” and are set apart from
5586 the normative text with <code>class="note"</code>, like this:
5588 <p class=note>Note, this is an informative note.
5590 <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
5592 <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
5593 classes:
5595 <dl>
5596 <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
5597 sheet</dfn>
5599 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
5600 style sheet</a>.
5602 <dt><dfn id=renderer>renderer</dfn>
5604 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5605 that interprets the semantics of a style sheet and renders documents that
5606 use them.
5608 <dt><dfn id=authoring-tool>authoring tool</dfn>
5610 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5611 that writes a style sheet.
5612 </dl>
5614 <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
5615 declarations that use properties defined in this module have values that
5616 are valid according to the generic CSS grammar and the individual grammars
5617 of each property as given in this module.
5619 <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
5620 interpreting the style sheet as defined by the appropriate specifications,
5621 it supports all the features defined by CSS Fonts Level 3 Module by
5622 parsing them correctly and rendering the document accordingly. However,
5623 the inability of a UA to correctly render a document due to limitations of
5624 the device does not make the UA non-conformant. (For example, a UA is not
5625 required to render color on a monochrome monitor.)
5627 <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
5628 style sheets that are syntactically correct according to the generic CSS
5629 grammar and the individual grammars of each feature in this module, and
5630 meet all other conformance requirements of style sheets as described in
5631 this module.
5633 <h3 class=no-num id=partial> Partial Implementations</h3>
5635 <p>So that authors can exploit the forward-compatible parsing rules to
5636 assign fallback values, CSS renderers <strong>must</strong> treat as
5637 invalid (and <a
5638 href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
5639 appropriate</a>) any at-rules, properties, property values, keywords, and
5640 other syntactic constructs for which they have no usable level of support.
5641 In particular, user agents <strong>must not</strong> selectively ignore
5642 unsupported component values and honor supported values in a single
5643 multi-value property declaration: if any value is considered invalid (as
5644 unsupported values must be), CSS requires that the entire declaration be
5645 ignored.
5647 <h3 class=no-num id=experimental> Experimental Implementations</h3>
5649 <p>To avoid clashes with future CSS features, the CSS2.1 specification
5650 reserves a <a
5651 href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
5652 syntax</a> for proprietary and experimental extensions to CSS.
5654 <p>Prior to a specification reaching the Candidate Recommendation stage in
5655 the W3C process, all implementations of a CSS feature are considered
5656 experimental. The CSS Working Group recommends that implementations use a
5657 vendor-prefixed syntax for such features, including those in W3C Working
5658 Drafts. This avoids incompatibilities with future changes in the draft.
5660 <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
5662 <p>Once a specification reaches the Candidate Recommendation stage,
5663 non-experimental implementations are possible, and implementors should
5664 release an unprefixed implementation of any CR-level feature they can
5665 demonstrate to be correctly implemented according to spec.
5667 <p>To establish and maintain the interoperability of CSS across
5668 implementations, the CSS Working Group requests that non-experimental CSS
5669 renderers submit an implementation report (and, if necessary, the
5670 testcases used for that implementation report) to the W3C before releasing
5671 an unprefixed implementation of any CSS features. Testcases submitted to
5672 W3C are subject to review and correction by the CSS Working Group.
5674 <p>Further information on submitting testcases and implementation reports
5675 can be found from on the CSS Working Group's website at <a
5676 href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
5677 Questions should be directed to the <a
5678 href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
5679 mailing list.
5681 <h2 class=no-num id=references>References</h2>
5683 <h3 class=no-num id=normative-references>Normative References</h3>
5684 <!--begin-normative-->
5685 <!-- Sorted by label -->
5687 <dl class=bibliography>
5688 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
5689 <!---->
5691 <dt id=CHARMOD>[CHARMOD]
5693 <dd>Martin J. Dürst; et al. <a
5694 href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
5695 Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
5696 2005. W3C Recommendation. URL: <a
5697 href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
5698 </dd>
5699 <!---->
5701 <dt id=CORS>[CORS]
5703 <dd>Anne van Kesteren. <a
5704 href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
5705 Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
5706 Recommendation. (Work in progress.) URL: <a
5707 href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
5708 </dd>
5709 <!---->
5711 <dt id=CSS21>[CSS21]
5713 <dd>Bert Bos; et al. <a
5714 href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
5715 Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
5716 2011. W3C Recommendation. URL: <a
5717 href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
5718 </dd>
5719 <!---->
5721 <dt id=CSS3VAL>[CSS3VAL]
5723 <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
5724 href="http://www.w3.org/TR/2012/CR-css3-values-20120828/"><cite>CSS
5725 Values and Units Module Level 3.</cite></a> 28 August 2012. W3C Candidate
5726 Recommendation. (Work in progress.) URL: <a
5727 href="http://www.w3.org/TR/2012/CR-css3-values-20120828/">http://www.w3.org/TR/2012/CR-css3-values-20120828/</a>
5728 </dd>
5729 <!---->
5731 <dt id=HTML5>[HTML5]
5733 <dd>Ian Hickson. <a
5734 href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
5735 17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
5736 <a
5737 href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
5738 </dd>
5739 <!---->
5741 <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
5743 <dd><a
5744 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip"><cite>Information
5745 technology — Coding of audio-visual objects — Part 22: Open Font
5746 Format.</cite></a> International Organization for Standardization.
5747 ISO/IEC 14496-22:2009. URL: <a
5748 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>
5749 </dd>
5750 <!---->
5752 <dt id=OPENTYPE>[OPENTYPE]
5754 <dd><a
5755 href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
5756 specification.</cite></a> Microsoft. URL: <a
5757 href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
5758 </dd>
5759 <!---->
5761 <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
5763 <dd><a
5764 href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
5765 feature registry.</cite></a> Microsoft. URL: <a
5766 href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
5767 </dd>
5768 <!---->
5770 <dt id=RFC2119>[RFC2119]
5772 <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
5773 words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
5774 RFC 2119. URL: <a
5775 href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
5776 </dd>
5777 <!---->
5779 <dt id=UAX15>[UAX15]
5781 <dd>Mark Davis; Ken Whistler. <a
5782 href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
5783 Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
5784 href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
5785 </dd>
5786 <!---->
5788 <dt id=UAX29>[UAX29]
5790 <dd>Mark Davis. <a
5791 href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
5792 Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
5793 URL: <a
5794 href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
5795 </dd>
5796 <!---->
5798 <dt id=UNICODE6>[UNICODE6]
5800 <dd>The Unicode Consortium. <a
5801 href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
5802 Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
5803 Version 6.2.0 URL: <a
5804 href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
5805 </dd>
5806 <!---->
5807 </dl>
5808 <!--end-normative-->
5809 <!--{{!CSS21}}-->
5810 <!--{{!CSS3VAL}}-->
5811 <!--{{!OPENTYPE}}-->
5812 <!--{{!OPENTYPE-FEATURES}}-->
5813 <!--{{!OPEN-FONT-FORMAT}}-->
5814 <!--{{!UNICODE6}}-->
5815 <!--{{!UAX15}}-->
5816 <!--{{!UAX29}}-->
5817 <!--{{!CORS}}-->
5818 <!--{{!HTML5}}-->
5819 <!--{{!CHARMOD}}-->
5821 <h3 class=no-num id=other-references>Other References</h3>
5822 <!--begin-informative-->
5823 <!-- Sorted by label -->
5825 <dl class=bibliography>
5826 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
5827 <!---->
5829 <dt id=AAT-FEATURES>[AAT-FEATURES]
5831 <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
5832 Advanced Typography font feature registry.</cite></a> Apple. URL: <a
5833 href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
5834 </dd>
5835 <!---->
5837 <dt id=ARABIC-TYPO>[ARABIC-TYPO]
5839 <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
5840 Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
5841 <!---->
5843 <dt id=CHARMOD-NORM>[CHARMOD-NORM]
5845 <dd>François Yergeau; et al. <a
5846 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
5847 Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
5848 W3C Working Draft. (Work in progress.) URL: <a
5849 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
5850 </dd>
5851 <!---->
5853 <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
5855 <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
5856 O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
5857 <!---->
5859 <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
5861 <dd>L. David Baron. <a
5862 href="http://www.w3.org/TR/2012/WD-css3-conditional-20121213/"><cite>CSS
5863 Conditional Rules Module Level 3.</cite></a> 13 December 2012. W3C
5864 Working Draft. (Work in progress.) URL: <a
5865 href="http://www.w3.org/TR/2012/WD-css3-conditional-20121213/">http://www.w3.org/TR/2012/WD-css3-conditional-20121213/</a>
5866 </dd>
5867 <!---->
5869 <dt id=CSS3TEXT>[CSS3TEXT]
5871 <dd>Elika J. Etemad; Koji Ishii. <a
5872 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
5873 Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
5874 progress.) URL: <a
5875 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
5876 </dd>
5877 <!---->
5879 <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
5881 <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
5882 and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
5883 ISBN 0-201-17633-5.</dd>
5884 <!---->
5886 <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
5888 <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
5889 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
5890 Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
5891 2000. W3C Recommendation. URL: <a
5892 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>
5893 </dd>
5894 <!---->
5896 <dt id=ELEMTYPO>[ELEMTYPO]
5898 <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
5899 4.</cite> Hartley & Marks. 2013. ISBN 0-88179-212-8.</dd>
5900 <!---->
5902 <dt id=LANGCULTTYPE>[LANGCULTTYPE]
5904 <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
5905 ISBN 1-932026-01-0.</dd>
5906 <!---->
5908 <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
5910 <dd><a
5911 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
5912 User Guide.</cite></a> FontShop International. URL: <a
5913 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
5914 </dd>
5915 <!---->
5917 <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
5919 <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
5920 Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
5921 href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
5922 <!---->
5924 <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
5926 <dd>John Hudson. <a
5927 href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
5928 Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
5929 href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
5930 </dd>
5931 <!---->
5932 </dl>
5933 <!--end-informative-->
5934 <!--{{ARABIC-TYPO}}-->
5935 <!--{{CJKV-INFO-PROCESSING}}-->
5936 <!--{{DIGITAL-TYPOGRAPHY}}-->
5937 <!--{{DOM-LEVEL-2-STYLE}}-->
5938 <!--{{ELEMTYPO}}-->
5939 <!--{{LANGCULTTYPE}}-->
5940 <!--{{OPENTYPE-FONT-GUIDE}}-->
5941 <!--{{RASTER-TRAGEDY}}-->
5942 <!--{{WINDOWS-GLYPH-PROC}}-->
5943 <!--{{CHARMOD-NORM}}-->
5944 <!--{{AAT-FEATURES}}-->
5945 <!--{{CSS3-CONDITIONAL}}-->
5946 <!--{{CSS3TEXT}}-->
5948 <h2 class=no-num id=index>Index</h2>
5949 <!--begin-index-->
5951 <ul class=indexlist>
5952 <li><var><absolute-size></var>, <a href="#absolute-size-value"
5953 title="<absolute-size>"><strong>3.5</strong></a>
5955 <li><var><common-lig-values></var>, <a href="#common-lig-values"
5956 title="<common-lig-values>"><strong>6.4</strong></a>
5958 <li><var><contextual-alt-values></var>, <a
5959 href="#contextual-alt-values"
5960 title="<contextual-alt-values>"><strong>6.4</strong></a>
5962 <li><var><discretionary-lig-values></var>, <a
5963 href="#discretionary-lig-values"
5964 title="<discretionary-lig-values>"><strong>6.4</strong></a>
5966 <li><var><east-asian-variant-values></var>, <a
5967 href="#east-asian-variant-values"
5968 title="<east-asian-variant-values>"><strong>6.10</strong></a>
5970 <li><var><east-asian-width-values></var>, <a
5971 href="#east-asian-width-values"
5972 title="<east-asian-width-values>"><strong>6.10</strong></a>
5974 <li><var><family-name></var>, <a href="#family-name-value"
5975 title="<family-name>"><strong>3.1</strong></a>
5977 <li><var><feature-tag-value></var>, <a href="#feature-tag-value"
5978 title="<feature-tag-value>"><strong>6.12</strong></a>
5980 <li><var><font-face-name></var>, <a href="#font-face-name-value"
5981 title="<font-face-name>"><strong>4.3</strong></a>
5983 <li><var><font-variant-css21></var>, <a
5984 href="#font-variant-css21-values"
5985 title="<font-variant-css21>"><strong>3.7</strong></a>
5987 <li><var><generic-family></var>, <a href="#generic-family-value"
5988 title="<generic-family>"><strong>3.1</strong></a>
5990 <li><var><historical-lig-values></var>, <a
5991 href="#historical-lig-values"
5992 title="<historical-lig-values>"><strong>6.4</strong></a>
5994 <li><var><length></var>, <a href="#length-size-value"
5995 title="<length>"><strong>3.5</strong></a>
5997 <li><var><number></var>, <a href="#aspect-ratio-value"
5998 title="<number>"><strong>3.6</strong></a>
6000 <li><var><numeric-figure-values></var>, <a
6001 href="#numeric-figure-values"
6002 title="<numeric-figure-values>"><strong>6.7</strong></a>
6004 <li><var><numeric-fraction-values></var>, <a
6005 href="#numeric-fraction-values"
6006 title="<numeric-fraction-values>"><strong>6.7</strong></a>
6008 <li><var><numeric-spacing-values></var>, <a
6009 href="#numeric-spacing-values"
6010 title="<numeric-spacing-values>"><strong>6.7</strong></a>
6012 <li><var><percentage></var>, <a href="#percentage-size-value"
6013 title="<percentage>"><strong>3.5</strong></a>
6015 <li><var><relative-size></var>, <a href="#relative-size-value"
6016 title="<relative-size>"><strong>3.5</strong></a>
6018 <li><var><urange></var>, <a href="#urange-value"
6019 title="<urange>"><strong>4.5</strong></a>
6021 <li>@font-face, <a href="#font-face" title="@font-face">4.1</a>, <a
6022 href="#font-face0" title="@font-face">4.3</a>
6024 <li>all-petite-caps, <a href="#all-petite-caps"
6025 title=all-petite-caps><strong>6.6</strong></a>
6027 <li>all-small-caps, <a href="#all-small-caps"
6028 title=all-small-caps><strong>6.6</strong></a>
6030 <li>annotation, <a href="#annotation"
6031 title=annotation><strong>6.8</strong></a>
6033 <li>aspect value, <a href="#aspect-value0" title="aspect
6034 value"><strong>3.6</strong></a>
6036 <li>authoring tool, <a href="#authoring-tool" title="authoring
6037 tool"><strong>#</strong></a>
6039 <li>character map, <a href="#character-map" title="character
6040 map"><strong>5.2</strong></a>
6042 <li>character-variant, <a href="#character-variant"
6043 title=character-variant><strong>6.8</strong></a>
6045 <li>common-ligatures, <a href="#common-ligatures"
6046 title=common-ligatures><strong>6.4</strong></a>
6048 <li>contextual, <a href="#contextual"
6049 title=contextual><strong>6.4</strong></a>
6051 <li>CSSFontFaceRule, <a href="#cssfontfacerule"
6052 title=CSSFontFaceRule><strong>8.1</strong></a>
6054 <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
6055 title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
6057 <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
6058 of"><strong>#</strong></a>
6060 <li>default face, <a href="#default-face" title="default
6061 face"><strong>5.2</strong></a>
6063 <li>descriptor_declaration, <a href="#descriptordeclaration"
6064 title="descriptor_declaration"><strong>4.1</strong></a>
6066 <li>diagonal-fractions, <a href="#diagonal-fractions"
6067 title=diagonal-fractions><strong>6.7</strong></a>
6069 <li>discretionary-ligatures, <a href="#discretionary-ligatures"
6070 title=discretionary-ligatures><strong>6.4</strong></a>
6072 <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
6073 of"><strong>#</strong></a>
6075 <li>feature_type, <a href="#featuretype"
6076 title="feature_type"><strong>6.9</strong></a>
6078 <li>feature_value_block, <a href="#featurevalueblock"
6079 title="feature_value_block"><strong>6.9</strong></a>
6081 <li>feature_value_definition, <a href="#featurevaluedefinition"
6082 title="feature_value_definition"><strong>6.9</strong></a>
6084 <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
6086 <li>font-family, <a href="#descdef-font-family"
6087 title=font-family><strong>4.2</strong></a>, <a
6088 href="#propdef-font-family" title=font-family><strong>3.1</strong></a>
6090 <li>font-feature-settings, <a href="#propdef-font-feature-settings"
6091 title=font-feature-settings><strong>6.12</strong></a>
6093 <li>font-feature-settings (descriptor), <a
6094 href="#descdef-font-feature-settings" title="font-feature-settings
6095 (descriptor)"><strong>4.7</strong></a>
6097 <li>font-kerning, <a href="#propdef-font-kerning"
6098 title=font-kerning><strong>6.3</strong></a>
6100 <li>font-language-override, <a href="#propdef-font-language-override"
6101 title=font-language-override><strong>6.13</strong></a>
6103 <li>font-size, <a href="#propdef-font-size"
6104 title=font-size><strong>3.5</strong></a>
6106 <li>font-size-adjust, <a href="#propdef-font-size-adjust"
6107 title=font-size-adjust><strong>3.6</strong></a>
6109 <li>font-stretch, <a href="#propdef-font-stretch"
6110 title=font-stretch><strong>3.3</strong></a>
6112 <li>font-stretch (descriptor), <a href="#descdef-font-stretch"
6113 title="font-stretch (descriptor)"><strong>4.4</strong></a>
6115 <li>font-style, <a href="#propdef-font-style"
6116 title=font-style><strong>3.4</strong></a>
6118 <li>font-style (descriptor), <a href="#descdef-font-style"
6119 title="font-style (descriptor)"><strong>4.4</strong></a>
6121 <li>font-synthesis, <a href="#propdef-font-synthesis"
6122 title=font-synthesis><strong>3.8</strong></a>
6124 <li>font-variant, <a href="#propdef-font-variant"
6125 title=font-variant><strong>6.11</strong></a>
6127 <li>font-variant (descriptor), <a href="#descdef-font-variant"
6128 title="font-variant (descriptor)"><strong>4.7</strong></a>
6130 <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
6131 title=font-variant-alternates><strong>6.8</strong></a>
6133 <li>font-variant-caps, <a href="#propdef-font-variant-caps"
6134 title=font-variant-caps><strong>6.6</strong></a>
6136 <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
6137 title=font-variant-east-asian><strong>6.10</strong></a>
6139 <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
6140 title=font-variant-ligatures><strong>6.4</strong></a>
6142 <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
6143 title=font-variant-numeric><strong>6.7</strong></a>
6145 <li>font-variant-position, <a href="#propdef-font-variant-position"
6146 title=font-variant-position><strong>6.5</strong></a>
6148 <li>font-weight, <a href="#propdef-font-weight"
6149 title=font-weight><strong>3.2</strong></a>
6151 <li>font-weight (descriptor), <a href="#descdef-font-weight"
6152 title="font-weight (descriptor)"><strong>4.4</strong></a>
6154 <li>font_face_rule, <a href="#fontfacerule"
6155 title="font_face_rule"><strong>4.1</strong></a>
6157 <li>FONT_FACE_SYM, <a href="#fontfacesym"
6158 title="FONT_FACE_SYM"><strong>4.1</strong></a>
6160 <li>font_family_name, <a href="#fontfamilyname"
6161 title="font_family_name"><strong>6.9</strong></a>
6163 <li>font_family_name_list, <a href="#fontfamilynamelist"
6164 title="font_family_name_list"><strong>6.9</strong></a>
6166 <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
6167 title="font_feature_values_rule"><strong>6.9</strong></a>
6169 <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
6170 title="FONT_FEATURE_VALUES_SYM"><strong>6.9</strong></a>
6172 <li>full-width, <a href="#full-width"
6173 title=full-width><strong>6.10</strong></a>
6175 <li>historical-forms, <a href="#historical-forms"
6176 title=historical-forms><strong>6.8</strong></a>
6178 <li>historical-ligatures, <a href="#historical-ligatures"
6179 title=historical-ligatures><strong>6.4</strong></a>
6181 <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
6183 <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
6185 <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
6187 <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
6189 <li>lining-nums, <a href="#lining-nums"
6190 title=lining-nums><strong>6.7</strong></a>
6192 <li>monospace, definition of, <a href="#monospace0" title="monospace,
6193 definition of"><strong>#</strong></a>
6195 <li>no-common-ligatures, <a href="#no-common-ligatures"
6196 title=no-common-ligatures><strong>6.4</strong></a>
6198 <li>no-contextual, <a href="#no-contextual"
6199 title=no-contextual><strong>6.4</strong></a>
6201 <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
6202 title=no-discretionary-ligatures><strong>6.4</strong></a>
6204 <li>no-historical-ligatures, <a href="#no-historical-ligatures"
6205 title=no-historical-ligatures><strong>6.4</strong></a>
6207 <li>normal, <a href="#normal" title=normal><strong>6.6</strong></a>, <a
6208 href="#normal0" title=normal><strong>6.7</strong></a>, <a href="#normal1"
6209 title=normal><strong>6.8</strong></a>, <a href="#normal2"
6210 title=normal><strong>6.10</strong></a>
6212 <li>oldstyle-nums, <a href="#oldstyle-nums"
6213 title=oldstyle-nums><strong>6.7</strong></a>
6215 <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
6217 <li>ornaments, <a href="#ornaments"
6218 title=ornaments><strong>6.8</strong></a>
6220 <li>petite-caps, <a href="#petite-caps"
6221 title=petite-caps><strong>6.6</strong></a>
6223 <li>proportional-nums, <a href="#proportional-nums"
6224 title=proportional-nums><strong>6.7</strong></a>
6226 <li>proportional-width, <a href="#proportional-width"
6227 title=proportional-width><strong>6.10</strong></a>
6229 <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
6231 <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
6233 <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
6234 definition of"><strong>#</strong></a>
6236 <li>serif, definition of, <a href="#serif0" title="serif, definition
6237 of"><strong>#</strong></a>
6239 <li>simplified, <a href="#simplified"
6240 title=simplified><strong>6.10</strong></a>
6242 <li>slashed-zero, <a href="#slashed-zero"
6243 title=slashed-zero><strong>6.7</strong></a>
6245 <li>small-caps, <a href="#small-caps"
6246 title=small-caps><strong>6.6</strong></a>
6248 <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
6250 <li>stacked-fractions, <a href="#stacked-fractions"
6251 title=stacked-fractions><strong>6.7</strong></a>
6253 <li>style sheet
6254 <ul>
6255 <li>as conformance class, <a href="#style-sheet" title="style sheet, as
6256 conformance class"><strong>#</strong></a>
6257 </ul>
6259 <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
6261 <li>stylistic, <a href="#stylistic"
6262 title=stylistic><strong>6.8</strong></a>
6264 <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
6266 <li>tabular-nums, <a href="#tabular-nums"
6267 title=tabular-nums><strong>6.7</strong></a>
6269 <li>titling-caps, <a href="#titling-caps"
6270 title=titling-caps><strong>6.6</strong></a>
6272 <li>traditional, <a href="#traditional"
6273 title=traditional><strong>6.10</strong></a>
6275 <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
6277 <li>unicode-range, <a href="#descdef-unicode-range"
6278 title=unicode-range><strong>4.5</strong></a>
6280 <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
6282 <li>width, <a href="#width" title=width><strong>2</strong></a>
6283 </ul>
6284 <!--end-index-->
6286 <h2 class=no-num id=property-index>Property index</h2>
6287 <!--begin-properties-->
6289 <table class=proptable>
6290 <thead>
6291 <tr>
6292 <th>Property
6294 <th>Values
6296 <th>Initial
6298 <th>Applies to
6300 <th>Inh.
6302 <th>Percentages
6304 <th>Media
6306 <tbody>
6307 <tr>
6308 <th><a class=property href="#propdef-font">font</a>
6310 <td>[ [ <‘font-style’> || <font-variant-css21> ||
6311 <‘font-weight’> || <‘font-stretch’ ]?
6312 <‘font-size’> [ / <‘line-height’> ]?
6313 <‘font-family’> ] | caption | icon | menu | message-box |
6314 small-caption | status-bar
6316 <td>see individual properties
6318 <td>all elements
6320 <td>yes
6322 <td>see individual properties
6324 <td>visual
6326 <tr>
6327 <th><a class=property href="#descdef-font-family">font-family</a>
6329 <td>[ <family-name> | <generic-family> ] #
6331 <td>depends on user agent
6333 <td>all elements
6335 <td>yes
6337 <td>N/A
6339 <td>visual
6341 <tr>
6342 <th><a class=property
6343 href="#propdef-font-feature-settings">font-feature-settings</a>
6345 <td>normal | <feature-tag-value> #
6347 <td>normal
6349 <td>all elements
6351 <td>yes
6353 <td>N/A
6355 <td>visual
6357 <tr>
6358 <th><a class=property href="#propdef-font-kerning">font-kerning</a>
6360 <td>auto | normal | none
6362 <td>auto
6364 <td>all elements
6366 <td>yes
6368 <td>N/A
6370 <td>visual
6372 <tr>
6373 <th><a class=property
6374 href="#propdef-font-language-override">font-language-override</a>
6376 <td>normal | <string>
6378 <td>normal
6380 <td>all elements
6382 <td>yes
6384 <td>N/A
6386 <td>visual
6388 <tr>
6389 <th><a class=property href="#propdef-font-size">font-size</a>
6391 <td><absolute-size> | <relative-size> | <length> |
6392 <percentage>
6394 <td>medium
6396 <td>all elements
6398 <td>yes
6400 <td>refer to parent element's font size
6402 <td>visual
6404 <tr>
6405 <th><a class=property
6406 href="#propdef-font-size-adjust">font-size-adjust</a>
6408 <td>none | auto | <number>
6410 <td>none
6412 <td>all elements
6414 <td>yes
6416 <td>N/A
6418 <td>visual
6420 <tr>
6421 <th><a class=property href="#propdef-font-stretch">font-stretch</a>
6423 <td>normal | ultra-condensed | extra-condensed | condensed |
6424 semi-condensed | semi-expanded | expanded | extra-expanded |
6425 ultra-expanded
6427 <td>normal
6429 <td>all elements
6431 <td>yes
6433 <td>N/A
6435 <td>visual
6437 <tr>
6438 <th><a class=property href="#propdef-font-style">font-style</a>
6440 <td>normal | italic | oblique
6442 <td>normal
6444 <td>all elements
6446 <td>yes
6448 <td>N/A
6450 <td>visual
6452 <tr>
6453 <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
6455 <td>none | [ weight || style ]
6457 <td>weight style
6459 <td>all elements
6461 <td>yes
6463 <td>N/A
6465 <td>visual
6467 <tr>
6468 <th><a class=property href="#propdef-font-variant">font-variant</a>
6470 <td>normal | none | [ <common-lig-values> ||
6471 <discretionary-lig-values> || <historical-lig-values> ||
6472 <contextual-alt-values> || stylistic(<feature-value-name>)
6473 || historical-forms || styleset(<feature-value-name> #) ||
6474 character-variant(<feature-value-name> #) ||
6475 swash(<feature-value-name>) ||
6476 ornaments(<feature-value-name>) ||
6477 annotation(<feature-value-name>) || [ small-caps | all-small-caps
6478 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
6479 <numeric-figure-values> || <numeric-spacing-values> ||
6480 <numeric-fraction-values> || ordinal || slashed-zero ||
6481 <east-asian-variant-values> || <east-asian-width-values> ||
6482 ruby ]
6484 <td>normal
6486 <td>all elements
6488 <td>yes
6490 <td>see individual properties
6492 <td>visual
6494 <tr>
6495 <th><a class=property
6496 href="#propdef-font-variant-alternates">font-variant-alternates</a>
6498 <td>normal | [ stylistic(<feature-value-name>) || historical-forms
6499 || styleset(<feature-value-name> #) ||
6500 character-variant(<feature-value-name> #) ||
6501 swash(<feature-value-name>) ||
6502 ornaments(<feature-value-name>) ||
6503 annotation(<feature-value-name>) ]
6505 <td>normal
6507 <td>all elements
6509 <td>yes
6511 <td>N/A
6513 <td>visual
6515 <tr>
6516 <th><a class=property
6517 href="#propdef-font-variant-caps">font-variant-caps</a>
6519 <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
6520 | unicase | titling-caps
6522 <td>normal
6524 <td>all elements
6526 <td>yes
6528 <td>N/A
6530 <td>visual
6532 <tr>
6533 <th><a class=property
6534 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
6536 <td>normal | [ <east-asian-variant-values> ||
6537 <east-asian-width-values> || ruby ]
6539 <td>normal
6541 <td>all elements
6543 <td>yes
6545 <td>N/A
6547 <td>visual
6549 <tr>
6550 <th><a class=property
6551 href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
6553 <td>normal | none | [ <common-lig-values> ||
6554 <discretionary-lig-values> || <historical-lig-values> ||
6555 <contextual-alt-values> ]
6557 <td>normal
6559 <td>all elements
6561 <td>yes
6563 <td>N/A
6565 <td>visual
6567 <tr>
6568 <th><a class=property
6569 href="#propdef-font-variant-numeric">font-variant-numeric</a>
6571 <td>normal | [ <numeric-figure-values> ||
6572 <numeric-spacing-values> || <numeric-fraction-values> ||
6573 ordinal || slashed-zero ]
6575 <td>normal
6577 <td>all elements
6579 <td>yes
6581 <td>N/A
6583 <td>visual
6585 <tr>
6586 <th><a class=property
6587 href="#propdef-font-variant-position">font-variant-position</a>
6589 <td>normal | sub | super
6591 <td>normal
6593 <td>all elements
6595 <td>yes
6597 <td>N/A
6599 <td>visual
6601 <tr>
6602 <th><a class=property href="#propdef-font-weight">font-weight</a>
6604 <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
6605 | 700 | 800 | 900
6607 <td>normal
6609 <td>all elements
6611 <td>yes
6613 <td>N/A
6615 <td>visual
6616 </table>
6617 <!--end-properties-->
6618 <!--begin-descriptors-->
6620 <table class=proptable>
6621 <thead>
6622 <tr>
6623 <th>Descriptor
6625 <th>Value
6627 <th>Initial
6629 <th>Percentages
6631 <th>Media
6633 <tbody>
6634 <tr>
6635 <th><a class=property href="#descdef-font-family">font-family</a>
6637 <td><family-name>
6639 <td>N/A
6641 <tr>
6642 <th><a class=property
6643 href="#propdef-font-feature-settings">font-feature-settings</a>
6645 <td>normal | <feature-tag-value> #
6647 <td>normal
6649 <tr>
6650 <th><a class=property href="#propdef-font-stretch">font-stretch</a>
6652 <td>normal | ultra-condensed | extra-condensed | condensed |
6653 semi-condensed | semi-expanded | expanded | extra-expanded |
6654 ultra-expanded
6656 <td>normal
6658 <tr>
6659 <th><a class=property href="#propdef-font-style">font-style</a>
6661 <td>normal | italic | oblique
6663 <td>normal
6665 <tr>
6666 <th><a class=property href="#propdef-font-variant">font-variant</a>
6668 <td>normal | none | [ <common-lig-values> ||
6669 <discretionary-lig-values> || <historical-lig-values> ||
6670 <contextual-alt-values> || stylistic(<feature-value-name>)
6671 || historical-forms || styleset(<feature-value-name> #) ||
6672 character-variant(<feature-value-name> #) ||
6673 swash(<feature-value-name>) ||
6674 ornaments(<feature-value-name>) ||
6675 annotation(<feature-value-name>) || [ small-caps | all-small-caps
6676 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
6677 <numeric-figure-values> || <numeric-spacing-values> ||
6678 <numeric-fraction-values> || ordinal || slashed-zero ||
6679 <east-asian-variant-values> || <east-asian-width-values> ||
6680 ruby ]
6682 <td>normal
6684 <tr>
6685 <th><a class=property href="#propdef-font-weight">font-weight</a>
6687 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
6689 <td>normal
6691 <tr>
6692 <th><a class=property href="#descdef-src">src</a>
6694 <td>[ <url> [format(<string> #)]? | <font-face-name> ] #
6696 <td>N/A
6698 <tr>
6699 <th><a class=property href="#descdef-unicode-range">unicode-range</a>
6701 <td><urange> #
6703 <td>U+0-10FFFF
6704 </table>
6705 <!--end-descriptors-->
6706 <script type="text/javascript">
6707 window.onload = function () {
6708 if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
6709 var i, hiresElements = document.getElementsByClassName("hires");
6710 for (i = 0; i < hiresElements.length; i++) {
6711 var h = hiresElements[i];
6712 if (h.tagName != "IMG") continue;
6713 var src = h.getAttribute("src");
6714 var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
6715 h.src = src2x;
6716 }
6717 }
6718 </script>
6719 </html>
6720 <!-- Keep this comment at the end of the file
6721 Local variables:
6722 mode: sgml
6723 sgml-declaration:"~/SGML/HTML4.decl"
6724 sgml-default-doctype-name:"html"
6725 sgml-minimize-attributes:t
6726 sgml-nofill-elements:("pre" "style" "br")
6727 sgml-live-element-indicator:t
6728 sgml-omittag:nil
6729 sgml-shorttag:nil
6730 sgml-namecase-general:t
6731 sgml-general-insert-case:lower
6732 sgml-always-quote-attributes:t
6733 sgml-indent-step:nil
6734 sgml-indent-data:t
6735 sgml-parent-document:nil
6736 sgml-exposed-tags:nil
6737 sgml-local-catalogs:nil
6738 sgml-local-ecat-files:nil
6739 End:
6740 -->
6741 <!--
6743 to do:
6745 - wording of OpenType family name handling
6746 - handling combining sequences in the font matching algorithm
6747 - fix-up fi ligature example
6749 -->
