css-fonts/Fonts.html@f7084873c602
css-fonts/Fonts.html
Fri, 31 May 2013 15:40:35 +0900
- author
- John Daggett <jdaggett@mozilla.com>
- date
- Fri, 31 May 2013 15:40:35 +0900
- changeset 8313
- f7084873c602
- parent 8312
- 4fb97110e8dc
- child 8356
- 46cef6470f58
- permissions
- -rw-r--r--
[css-fonts] font feature properties copyedits
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-31-may-2013>Editor's Draft 31
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-20130531/">http://www.w3.org/TR/2013/ED-css3-fonts-20130531/</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
604 title="font-family!!property">font-family</dfn>
606 <tr>
607 <td>Value:
609 <td>[ <a href="#family-name-value"><var><family-name></var></a> |
610 <a href="#generic-family-value"><var><generic-family></var></a> ]
611 #
613 <tr>
614 <td>Initial:
616 <td>depends on user agent
618 <tr>
619 <td>Applies to:
621 <td>all elements
623 <tr>
624 <td>Inherited:
626 <td>yes
628 <tr>
629 <td>Percentages:
631 <td>N/A
633 <tr>
634 <td>Media:
636 <td>visual
638 <tr>
639 <td>Computed value:
641 <td>as specified
643 <tr>
644 <td>Animatable:
646 <td>no
647 </table>
649 <p>This property specifies a prioritized list of font family names or
650 generic family names. A font family defines a set of faces that vary in
651 weight, width or slope. CSS uses the combination of a family name with
652 other style attributes to select an individual face. Using this selection
653 mechanism, rather than selecting a face via the style name as is often
654 done in design applications, allows some degree of regularity in textual
655 display when fallback occurs.
657 <p class=note>Designers should note that the CSS definition of font
658 attributes used for selection are explicitly not intended to define a font
659 taxonomy. A type designer's idea of a family may often extend to a set of
660 faces that vary along axes other than just the standard axes of weight,
661 width and slope. A family may extend to include both a set of serif faces
662 and a set of sans-serif faces or vary along axes that are unique to that
663 family. The CSS font selection mechanism merely provides a way to
664 determine the “closest” substitute when substitution is necessary.
666 <p>Unlike other CSS properties, component values are a comma-separated list
667 indicating alternatives. A user agent iterates through the list of family
668 names until it matches an available font that contains a glyph for the
669 character to be rendered. This allows for differences in available fonts
670 across platforms and for differences in the range of characters supported
671 by individual fonts.
673 <p>A font family name only specifies a name given to a set of font faces,
674 it does not specify an individual face. For example, given the
675 availability of the fonts below, Futura would match but Futura Medium
676 would not:
678 <div class=figure><img alt="family and face names"
679 src=familyvsfacename.png>
680 <p class=caption>Family and individual face names
681 </div>
683 <p>Consider the example below:
685 <div class=example>
686 <pre>body {
687 font-family: Helvetica, Verdana, sans-serif;
688 }</pre>
690 <p>If Helvetica is available it will be used when rendering. If neither
691 Helvetica nor Verdana is present, then the user-agent-defined sans serif
692 font will be used.</p>
693 </div>
695 <p>There are two types of font family names:
697 <dl>
698 <dt><dfn id=family-name-value><var><family-name></var></dfn>
700 <dd>The name of a font family of choice such as Helvetica or Verdana in
701 the previous example.
703 <dt><dfn id=generic-family-value><var><generic-family></var></dfn>
705 <dd> The following generic family keywords are defined: ‘<a
706 href="#serif"><code class=property>serif</code></a>’, ‘<a
707 href="#sans-serif"><code class=property>sans-serif</code></a>’, ‘<a
708 href="#cursive"><code class=property>cursive</code></a>’, ‘<a
709 href="#fantasy"><code class=property>fantasy</code></a>’, and ‘<a
710 href="#monospace"><code class=property>monospace</code></a>’. These
711 keywords can be used as a general fallback mechanism when an author's
712 desired font choices are not available. As keywords, they must not be
713 quoted. Authors are encouraged to append a generic font family as a last
714 alternative for improved robustness.
715 </dl>
717 <p>Font family names other than generic families must either be given
718 quoted as <a
719 href="//www.w3.org/TR/CSS21/syndata.html#strings">strings,</a> or unquoted
720 as a sequence of one or more <a
721 href="//www.w3.org/TR/CSS21/syndata.html#value-def-identifier">identifiers.</a>
722 This means most punctuation characters and digits at the start of each
723 token must be escaped in unquoted font family names.
725 <p>To illustrate this, the following declarations are invalid:
727 <pre>
728 font-family: Red/Black, sans-serif;
729 font-family: "Lucida" Grande, sans-serif;
730 font-family: Ahem!, sans-serif;
731 font-family: test@foo, sans-serif;
732 font-family: #POUND, sans-serif;
733 font-family: Hawaii 5-0, sans-serif;
734 </pre>
736 <p>If a sequence of identifiers is given as a font family name, the
737 computed value is the name converted to a string by joining all the
738 identifiers in the sequence by single spaces.
740 <p>To avoid mistakes in escaping, it is recommended to quote font family
741 names that contain white space, digits, or punctuation characters other
742 than hyphens:
744 <pre>
745 body { font-family: "New Century Schoolbook", serif }
747 <BODY STYLE="font-family: '21st Century', fantasy">
748 </pre>
750 <p>Font family <em>names</em> that happen to be the same as a keyword value
751 (‘<code class=property>inherit</code>’, ‘<a href="#serif"><code
752 class=property>serif</code></a>’, ‘<a href="#sans-serif"><code
753 class=property>sans-serif</code></a>’, ‘<a href="#monospace"><code
754 class=property>monospace</code></a>’, ‘<a href="#fantasy"><code
755 class=property>fantasy</code></a>’, and ‘<a href="#cursive"><code
756 class=property>cursive</code></a>’) must be quoted to prevent confusion
757 with the keywords with the same names. The keywords ‘<code
758 class=property>initial</code>’ and ‘<code
759 class=property>default</code>’ are reserved for future use and must also
760 be quoted when used as font names. UAs must not consider these keywords as
761 matching the <a
762 href="#family-name-value"><var><family-name></var></a> type.
764 <p>The precise way a set of fonts are grouped into font families varies
765 depending upon the platform font management API's. The Windows GDI API
766 only allows four faces to be grouped into a family while the DirectWrite
767 API and API's on OSX and other platforms support font families with a
768 variety of weights, widths and slopes (see <a
769 href="#platform-props-to-css">Appendix A</a> for more details).
771 <p>Some font formats allow fonts to carry multiple localizations of the
772 family name. User agents must recognize and correctly match all of these
773 names independent of the underlying platform localization, system API used
774 or document encoding:
776 <div class=figure><img alt="examples of localized family names"
777 src=localizedfamilynames.png>
778 <p class=caption>Localized family names
779 </div>
781 <h4 id=generic-font-families><span class=secno>3.1.1 </span>Generic font
782 families</h4>
784 <p>All five generic font families are defined to exist in all CSS
785 implementations (they need not necessarily map to five distinct actual
786 fonts). User agents should provide reasonable default choices for the
787 generic font families, which express the characteristics of each family as
788 well as possible within the limits allowed by the underlying technology.
789 User agents are encouraged to allow users to select alternative choices
790 for the generic fonts.
792 <h5 class="no-num no-toc"> <span class=index-def id=serif0 title="serif,
793 definition of"><a name=serif-def><dfn id=serif>serif</dfn></a></span></h5>
795 <p>Serif fonts represent the formal text style for a script. This often
796 means but is not limited to glyphs that have finishing strokes, flared or
797 tapering ends, or have actual serifed endings (including slab serifs).
798 Serif fonts are typically proportionately-spaced. They often display a
799 greater variation between thick and thin strokes than fonts from the ‘<a
800 href="#sans-serif"><code class=property>sans-serif</code></a>’ generic
801 font family. CSS uses the term ‘<a href="#serif"><code
802 class=property>serif</code></a>’ to apply to a font for any script,
803 although other names may be more familiar for particular scripts, such as
804 Mincho (Japanese), Sung, Song or Kai (Chinese), Batang (Korean). For
805 Arabic, the Naskh style would correspond to ‘<a href="#serif"><code
806 class=property>serif</code></a>’ more due to its typographic role rather
807 than its actual design style. Any font that is so described may be used to
808 represent the generic ‘<a href="#serif"><code
809 class=property>serif</code></a>’ family.
811 <div class=figure><img alt="sample serif fonts" src=serifexamples.png>
812 <p class=caption>Sample serif fonts
813 </div>
815 <h5 class="no-num no-toc"> <span class=index-def id=sans-serif0
816 title="sans-serif, definition of"> <a name=sans-serif-def><dfn
817 id=sans-serif>sans-serif</dfn></a></span></h5>
819 <p>Glyphs in sans-serif fonts, as the term is used in CSS, are generally
820 low contrast (vertical and horizontal stems have the close to the same
821 thickness) and have stroke endings that are plain -- without any flaring,
822 cross stroke, or other ornamentation. Sans-serif fonts are typically
823 proportionately-spaced. They often have little variation between thick and
824 thin strokes, compared to fonts from the ‘<a href="#serif"><code
825 class=property>serif</code></a>’ family. CSS uses the term ‘<a
826 href="#sans-serif"><code class=property>sans-serif</code></a>’ to apply
827 to a font for any script, although other names may be more familiar for
828 particular scripts, such as Gothic (Japanese), Hei (Chinese), or Gulim
829 (Korean). Any font that is so described may be used to represent the
830 generic ‘<a href="#sans-serif"><code
831 class=property>sans-serif</code></a>’ family.
833 <div class=figure><img alt="sample sans-serif fonts"
834 src=sansserifexamples.png>
835 <p class=caption>Sample sans-serif fonts
836 </div>
838 <h5 class="no-num no-toc"> <span class=index-def id=cursive0
839 title="cursive, definition of"> <a name=cursive-def><dfn
840 id=cursive>cursive</dfn></a></span></h5>
842 <p>Glyphs in cursive fonts generally use a more informal script style, and
843 the result looks more like handwritten pen or brush writing than printed
844 letterwork. CSS uses the term ‘<a href="#cursive"><code
845 class=property>cursive</code></a>’ to apply to a font for any script,
846 although other names such as Chancery, Brush, Swing and Script are also
847 used in font names.
849 <div class=figure><img alt="sample cursive fonts" src=cursiveexamples.png>
850 <p class=caption>Sample cursive fonts
851 </div>
853 <h5 class="no-num no-toc"> <span class=index-def id=fantasy0
854 title="fantasy, definition of"> <a name=fantasy-def><dfn
855 id=fantasy>fantasy</dfn></a></span></h5>
857 <p>Fantasy fonts are primarily decorative or expressive fonts that contain
858 playful representations of characters. These do not include Pi or Picture
859 fonts which do not represent actual characters.
861 <div class=figure><img alt="sample fantasy fonts" src=fantasyexamples.png>
862 <p class=caption>Sample fantasy fonts
863 </div>
865 <h5 class="no-num no-toc"> <span class=index-def id=monospace0
866 title="monospace, definition of"> <a name=monospace-def><dfn
867 id=monospace>monospace</dfn></a></span></h5>
869 <p>The sole criterion of a monospace font is that all glyphs have the same
870 fixed width. This is often used to render samples of computer code.
872 <div class=figure><img alt="sample monospace fonts"
873 src=monospaceexamples.png>
874 <p class=caption>Sample monospace fonts
875 </div>
876 <!-- prop: font-weight -->
878 <h3 id=font-weight-prop><span class=secno>3.2 </span>Font weight: the <a
879 href="#propdef-font-weight">font-weight</a> property</h3>
881 <table class=propdef id=namefont-weightvaluenormal-bold-bolder-l>
882 <tbody>
883 <tr>
884 <td>Name:
886 <td><dfn id=propdef-font-weight
887 title="font-weight!!property">font-weight</dfn>
889 <tr>
890 <td>Value:
892 <td><a href="#font-weight-normal-value"
893 title="normal!!font-weight">normal</a> | <a href="#bold">bold</a> | <a
894 href="#bolder">bolder</a> | <a href="#lighter">lighter</a> | <a
895 href="#font-weight-numeric-values" title="100...900 weight
896 values">100</a> | <a href="#font-weight-numeric-values"
897 title="100...900 weight values">200</a> | <a
898 href="#font-weight-numeric-values" title="100...900 weight
899 values">300</a> | <a href="#font-weight-numeric-values"
900 title="100...900 weight values">400</a> | <a
901 href="#font-weight-numeric-values" title="100...900 weight
902 values">500</a> | <a href="#font-weight-numeric-values"
903 title="100...900 weight values">600</a> | <a
904 href="#font-weight-numeric-values" title="100...900 weight
905 values">700</a> | <a href="#font-weight-numeric-values"
906 title="100...900 weight values">800</a> | <a
907 href="#font-weight-numeric-values" title="100...900 weight
908 values">900</a>
910 <tr>
911 <td>Initial:
913 <td>normal
915 <tr>
916 <td>Applies to:
918 <td>all elements
920 <tr>
921 <td>Inherited:
923 <td>yes
925 <tr>
926 <td>Percentages:
928 <td>N/A
930 <tr>
931 <td>Media:
933 <td>visual
935 <tr>
936 <td>Computed value:
938 <td>numeric weight value (see description)
940 <tr>
941 <td>Animatable:
943 <td>as <a
944 href="http://dev.w3.org/csswg/css3-transitions/#animtype-font-weight">font
945 weight</a>
946 </table>
948 <p>The <a href="#propdef-font-weight"
949 title="font-weight!!property">‘<code
950 class=property>font-weight</code>’</a> property specifies the weight of
951 glyphs in the font, their degree of blackness or stroke thickness.
953 <p>Values have the following meanings:
955 <dl>
956 <dt><dfn id=font-weight-numeric-values title="100...900 weight values">100
957 to 900</dfn>
959 <dd>These values form an ordered sequence, where each number indicates a
960 weight that is at least as dark as its predecessor. These roughly
961 correspond to the commonly used weight names below:
962 </dl>
964 <ul>
965 <li>100 - Thin
967 <li>200 - Extra Light (Ultra Light)
969 <li>300 - Light
971 <li>400 - Normal
973 <li>500 - Medium
975 <li>600 - Semi Bold (Demi Bold)
977 <li>700 - Bold
979 <li>800 - Extra Bold (Ultra Bold)
981 <li>900 - Black (Heavy)
982 </ul>
984 <dl>
985 <dt><dfn id=font-weight-normal-value
986 title="normal!!font-weight">normal</dfn>
988 <dd>Same as ‘<code class=css>400</code>’.
990 <dt><dfn id=bold>bold</dfn>
992 <dd>Same as ‘<code class=css>700</code>’.
994 <dt><dfn id=bolder>bolder</dfn>
996 <dd>Specifies a bolder weight than the inherited value.
998 <dt><dfn id=lighter>lighter</dfn>
1000 <dd>Specifies a lighter weight than the inherited value.
1001 </dl>
1003 <p>Font formats that use a scale other than a nine-step scale should map
1004 their scale onto the CSS scale so that 400 roughly corresponds with a face
1005 that would be labeled as Regular, Book, Roman and 700 roughly matches a
1006 face that would be labeled as Bold. Or weights may be inferred from the
1007 style names, ones that correspond roughly with the scale above. The scale
1008 is relative, so a face with a larger weight value must never appear
1009 lighter. If style names are used to infer weights, care should be taken to
1010 handle variations in style names across locales.
1012 <p>Quite often there are only a few weights available for a particular font
1013 family. When a weight is specified for which no face exists, a face with a
1014 nearby weight is used. In general, bold weights map to faces with heavier
1015 weights and light weights map to faces with lighter weights (see the <a
1016 href="#font-matching-algorithm">font matching section below</a> for a
1017 precise definition). The examples here illustrate which face is used for
1018 different weights, grey indicates a face for that weight does not exist so
1019 a face with a nearby weight is used:
1021 <div class=figure><img alt="weight mappings for a family with 400, 700 and
1022 900 weights" src=optimaweights.png>
1023 <p class=caption>Weight mappings for a font family with 400, 700 and 900
1024 weight faces
1025 </div>
1027 <div class=figure><img alt="weight mappings for a family with 300, 600
1028 weights" src=hiraginoweights.png>
1029 <p class=caption>Weight mappings for a font family with 300 and 600 weight
1030 faces
1031 </div>
1033 <p>Although the practice is not well-loved by typographers, bold faces are
1034 often synthesized by user agents for faces that lack actual bold faces.
1035 For the purposes of style matching, these faces must be treated as if they
1036 exist within the family. Authors can explicitly avoid this behavior by
1037 using the ‘<a href="#propdef-font-synthesis"><code
1038 class=property>font-synthesis</code></a>’ property.
1040 <p>Specified values of ‘<a href="#bolder"><code
1041 class=property>bolder</code></a>’ and ‘<a href="#lighter"><code
1042 class=property>lighter</code></a>’ indicate weights relative to the
1043 weight of the parent element. The computed weight is calculated based on
1044 the inherited <a href="#propdef-font-weight"
1045 title="font-weight!!property">‘<code
1046 class=property>font-weight</code>’</a> value using the chart below.
1048 <table class=data id=bolderlighter summary="Bolder/lighter mappings">
1049 <thead>
1050 <tr>
1051 <th>Inherited value
1053 <th>bolder
1055 <th>lighter
1057 <tbody>
1058 <tr>
1059 <th>100
1061 <td>400
1063 <td>100
1065 <tr>
1066 <th>200
1068 <td>400
1070 <td>100
1072 <tr>
1073 <th>300
1075 <td>400
1077 <td>100
1079 <tr>
1080 <th>400
1082 <td>700
1084 <td>100
1086 <tr>
1087 <th>500
1089 <td>700
1091 <td>100
1093 <tr>
1094 <th>600
1096 <td>900
1098 <td>400
1100 <tr>
1101 <th>700
1103 <td>900
1105 <td>400
1107 <tr>
1108 <th>800
1110 <td>900
1112 <td>700
1114 <tr>
1115 <th>900
1117 <td>900
1119 <td>700
1120 </table>
1122 <p>The table above is equivalent to selecting the next relative bolder or
1123 lighter face, given a font family containing normal and bold faces along
1124 with a thin and a heavy face. Authors who desire finer control over the
1125 exact weight values used for a given element may use numerical values
1126 instead of relative weights.</p>
1127 <!-- prop: font-stretch -->
1129 <h3 id=font-stretch-prop><span class=secno>3.3 </span>Font width: the <a
1130 href="#propdef-font-stretch">font-stretch</a> property</h3>
1132 <table class=propdef id=namefont-stretchvalue-normal-ultra-conde>
1133 <tbody>
1134 <tr>
1135 <td>Name:
1137 <td><dfn id=propdef-font-stretch
1138 title="font-stretch!!property">font-stretch</dfn>
1140 <tr>
1141 <td>Value:
1143 <td> <a href="#font-stretch-normal-value"
1144 title="normal!!font-stretch">normal</a> | <a
1145 href="#ultra-condensed">ultra-condensed</a> | <a
1146 href="#extra-condensed">extra-condensed</a> | <a
1147 href="#condensed">condensed</a> | <a
1148 href="#semi-condensed-">semi-condensed</a> | <a
1149 href="#semi-expanded">semi-expanded</a> | <a
1150 href="#expanded">expanded</a> | <a
1151 href="#extra-expanded">extra-expanded</a> | <a
1152 href="#ultra-expanded">ultra-expanded</a>
1154 <tr>
1155 <td>Initial:
1157 <td>normal
1159 <tr>
1160 <td>Applies to:
1162 <td>all elements
1164 <tr>
1165 <td>Inherited:
1167 <td>yes
1169 <tr>
1170 <td>Percentages:
1172 <td>N/A
1174 <tr>
1175 <td>Media:
1177 <td>visual
1179 <tr>
1180 <td>Computed value:
1182 <td>as specified
1184 <tr>
1185 <td>Animatable:
1187 <td>as <a href="#font-stretch-animation">font stretch</a>
1188 </table>
1190 <p>The <a href="#propdef-font-stretch"
1191 title="font-stretch!!property">‘<code
1192 class=property>font-stretch</code>’</a> property selects a normal,
1193 condensed, or expanded face from a font family. Absolute keyword values
1194 have the following ordering, from narrowest to widest:
1196 <ul>
1197 <li><dfn id=ultra-condensed>ultra-condensed</dfn>
1199 <li><dfn id=extra-condensed>extra-condensed</dfn>
1201 <li><dfn id=condensed>condensed</dfn>
1203 <li><dfn id=semi-condensed->semi-condensed </dfn>
1205 <li><dfn id=font-stretch-normal-value
1206 title="normal!!font-stretch">normal</dfn>
1208 <li><dfn id=semi-expanded>semi-expanded</dfn>
1210 <li><dfn id=expanded>expanded</dfn>
1212 <li><dfn id=extra-expanded>extra-expanded</dfn>
1214 <li><dfn id=ultra-expanded>ultra-expanded</dfn>
1215 </ul>
1217 <p>When a face does not exist for a given width, normal or condensed values
1218 map to a narrower face, otherwise a wider face. Conversely, expanded
1219 values map to a wider face, otherwise a narrower face. The figure below
1220 shows how the nine font-stretch property settings affect font selection
1221 for font family containing a variety of widths, grey indicates a width for
1222 which no face exists and a different width is substituted:
1224 <div class=figure><img alt="width mappings for a family with condensed,
1225 normal and expanded faces" src=universwidths.png>
1226 <p class=caption>Width mappings for a font family with condensed, normal
1227 and expanded width faces
1228 </div>
1230 <p id=font-stretch-animation>Animation of font stretch: Font stretch is
1231 interpolated in discrete steps. The interpolation happens as though the
1232 ordered values are equally spaced real numbers. The interpolation result
1233 is rounded to the nearest value, with values exactly halfway between two
1234 values rounded towards the later value in the list above.</p>
1235 <!-- prop: font-style -->
1237 <h3 id=font-style-prop><span class=secno>3.4 </span>Font style: the <a
1238 href="#propdef-font-style">font-style</a> property</h3>
1240 <table class=propdef id=namefont-stylevaluenormal-italic-oblique>
1241 <tbody>
1242 <tr>
1243 <td>Name:
1245 <td><dfn id=propdef-font-style
1246 title="font-style!!property">font-style</dfn>
1248 <tr>
1249 <td>Value:
1251 <td><a href="#font-style-normal-value"
1252 title="normal!!font-style">normal</a> | <a href="#italic">italic</a> |
1253 <a href="#oblique">oblique</a>
1255 <tr>
1256 <td>Initial:
1258 <td>normal
1260 <tr>
1261 <td>Applies to:
1263 <td>all elements
1265 <tr>
1266 <td>Inherited:
1268 <td>yes
1270 <tr>
1271 <td>Percentages:
1273 <td>N/A
1275 <tr>
1276 <td>Media:
1278 <td>visual
1280 <tr>
1281 <td>Computed value:
1283 <td>as specified
1285 <tr>
1286 <td>Animatable:
1288 <td>no
1289 </table>
1291 <p>The <a href="#propdef-font-style" title="font-style!!property">‘<code
1292 class=property>font-style</code>’</a> property allows italic or oblique
1293 faces to be selected. Italic forms are generally cursive in nature while
1294 oblique faces are typically sloped versions of the regular face. Oblique
1295 faces can be simulated by artificially sloping the glyphs of the regular
1296 face. Compare the artificially sloped renderings of Palatino ‘<code
1297 class=property>a</code>’ and Baskerville ‘<code
1298 class=property>N</code>’ in grey with the actual italic versions:
1300 <div class=figure><img alt="artificial sloping vs. real italics"
1301 src=realvsfakeitalics.png>
1302 <p class=caption>Artificial sloping versus real italics
1303 </div>
1305 <p>Values have the following meanings:
1307 <dl>
1308 <dt><dfn id=font-style-normal-value
1309 title="normal!!font-style">normal</dfn>
1311 <dd>selects a face that is classified as a normal face, one that is
1312 neither italic or obliqued
1314 <dt><dfn id=italic>italic</dfn>
1316 <dd>selects a font that is labeled as an italic face, or an oblique face
1317 if one is not
1319 <dt><dfn id=oblique>oblique</dfn>
1321 <dd>selects a font that is labeled as an oblique face, or an italic face
1322 if one is not
1323 </dl>
1325 <p>If no italic or oblique face is available, oblique faces can be
1326 synthesized by rendering non-obliqued faces with a right sloping
1327 transformation applied. When synthesizing these faces, the transformation
1328 should apply to all glyphs in the same way and not vary based on codepoint
1329 or due to horizontal or vertical line orientation.
1331 <p class=issue>It has been <a
1332 href="http://lists.w3.org/Archives/Public/www-style/2013May/0272.html">proposed</a>
1333 that for vertical text runs, synthetic italics should not mimic normal
1334 italic glyphs but instead mimic the customs of Japanese obliquing
1335 (斜体、shatai), where the obliquing is applied across the text run
1336 regardless of glyph orientation.
1338 <p>Many scripts lack the tradition of mixing a cursive form within text
1339 rendered with a normal face. Chinese, Japanese and Korean fonts almost
1340 always lack italic or oblique faces. Fonts that support a mixture of
1341 scripts will sometimes omit specific scripts such as Arabic from the set
1342 of glyphs supported in the italic face. User agents should be careful
1343 about making <a href="#character-map"><em>character map</em></a>
1344 assumptions across faces.</p>
1345 <!-- prop: font-size -->
1347 <h3 id=font-size-prop><span class=secno>3.5 </span>Font size: the <a
1348 href="#propdef-font-size">font-size</a> property</h3>
1350 <table class=propdef id=namefont-sizevalueltabsolute-sizegt-ltre>
1351 <tbody>
1352 <tr>
1353 <td>Name:
1355 <td><dfn id=propdef-font-size>font-size</dfn>
1357 <tr>
1358 <td>Value:
1360 <td><a href="#absolute-size-value"><var><absolute-size></var></a>
1361 | <a href="#relative-size-value"><var><relative-size></var></a> |
1362 <a href="#length-size-value"><var><length></var></a> | <a
1363 href="#percentage-size-value"><var><percentage></var></a>
1365 <tr>
1366 <td>Initial:
1368 <td>medium
1370 <tr>
1371 <td>Applies to:
1373 <td>all elements
1375 <tr>
1376 <td>Inherited:
1378 <td>yes
1380 <tr>
1381 <td>Percentages:
1383 <td>refer to parent element's font size
1385 <tr>
1386 <td>Media:
1388 <td>visual
1390 <tr>
1391 <td>Computed value:
1393 <td>absolute length
1395 <tr>
1396 <td>Animatable:
1398 <td>as <a
1399 href="http://dev.w3.org/csswg/css3-transitions/#animtype-length">length</a>
1400 </table>
1402 <p>This property indicates the desired height of glyphs from the font. For
1403 scalable fonts, the font-size is a scale factor applied to the EM unit of
1404 the font. (Note that certain glyphs may bleed outside their EM box.) For
1405 non-scalable fonts, the font-size is converted into absolute units and
1406 matched against the declared font-size of the font, using the same
1407 absolute coordinate space for both of the matched values. Values have the
1408 following meanings:
1410 <dl>
1411 <dt><dfn id=absolute-size-value><var><absolute-size></var></dfn>
1413 <dd> An <a
1414 href="#absolute-size-value"><var><absolute-size></var></a> keyword
1415 refers to an entry in a table of font sizes computed and kept by the user
1416 agent. Possible values are:
1417 <p> [ xx-small | x-small | small | medium | large | x-large | xx-large ]</p>
1419 <dt><dfn id=relative-size-value><var><relative-size></var></dfn>
1421 <dd> A <a href="#relative-size-value"><var><relative-size></var></a>
1422 keyword is interpreted relative to the table of font sizes and the
1423 computed ‘<a href="#propdef-font-size"><code
1424 class=property>font-size</code></a>’ of the parent element. Possible
1425 values are:
1426 <p> [ larger | smaller ]
1428 <p> For example, if the parent element has a font size of ‘<code
1429 class=property>medium</code>’, a value of ‘<code
1430 class=property>larger</code>’ will make the font size of the current
1431 element be ‘<code class=property>large</code>’. If the parent
1432 element's size is not close to a table entry, the user agent is free to
1433 interpolate between table entries or round off to the closest one. The
1434 user agent may have to extrapolate table values if the numerical value
1435 goes beyond the keywords.
1437 <dt><dfn id=length-size-value><var><length></var></dfn>
1439 <dd>A length value specifies an absolute font size (independent of the
1440 user agent's font table). Negative lengths are illegal.
1442 <dt><dfn id=percentage-size-value><var><percentage></var></dfn>
1444 <dd>A percentage value specifies an absolute font size relative to the
1445 parent element's font size. Use of percentage values, or values in
1446 ‘<code class=property>em</code>’s, leads to more robust and
1447 cascadable style sheets.
1448 </dl>
1450 <p>The following table provides user agent guidelines for the absolute-size
1451 scaling factor and their mapping to HTML heading and absolute font-sizes.
1452 The ‘<code class=property>medium</code>’ value is used as the
1453 reference middle value. The user agent may fine-tune these values for
1454 different fonts or different types of display devices.
1456 <table class=data>
1457 <thead>
1458 <tr>
1459 <th>CSS absolute-size values
1461 <th>xx-small
1463 <th>x-small
1465 <th>small
1467 <th>medium
1469 <th>large
1471 <th>x-large
1473 <th>xx-large
1475 <th>
1477 <tbody>
1478 <tr>
1479 <th>scaling factor
1481 <td>3/5
1483 <td>3/4
1485 <td>8/9
1487 <td>1
1489 <td>6/5
1491 <td>3/2
1493 <td>2/1
1495 <td>3/1
1497 <tr>
1498 <th>HTML headings
1500 <td>h6
1502 <td>
1504 <td>h5
1506 <td>h4
1508 <td>h3
1510 <td>h2
1512 <td>h1
1514 <td>
1516 <tr>
1517 <th>HTML font sizes
1519 <td>1
1521 <td>
1523 <td>2
1525 <td>3
1527 <td>4
1529 <td>5
1531 <td>6
1533 <td>7
1534 </table>
1536 <p class=note><em><strong>Note 1.</strong> To preserve readability, an UA
1537 applying these guidelines should nevertheless avoid creating font-size
1538 resulting in less than 9 device pixels per EM unit on a computer
1539 display.</em>
1541 <p class=note><em><strong>Note 2.</strong> In CSS1, the suggested scaling
1542 factor between adjacent indexes was 1.5 which user experience proved to be
1543 too large. In CSS2, the suggested scaling factor for computer screen
1544 between adjacent indexes was 1.2 which still created issues for the small
1545 sizes. The new scaling factor varies between each index to provide a
1546 better readability.</em>
1548 <p>The actual value of this property may differ from the computed value due
1549 a numerical value on ‘<a href="#propdef-font-size-adjust"><code
1550 class=property>font-size-adjust</code></a>’ and the unavailability of
1551 certain font sizes.
1553 <p>Child elements inherit the computed <a class=noxref
1554 href="#font-size-prop"> <span class=property>‘<code
1555 class=property>font-size</code>’</span></a> value (otherwise, the effect
1556 of <a class=noxref href="#font-size-adjust-prop"><span
1557 class=property>‘<code
1558 class=property>font-size-adjust</code>’</span></a> would compound).
1560 <div class=example>
1561 <p style="display:none">Example(s):
1563 <p>
1565 <pre>p { font-size: 12pt; }
1566 blockquote { font-size: larger }
1567 em { font-size: 150% }
1568 em { font-size: 1.5em }
1569 </pre>
1570 </div>
1571 <!-- prop: font-size-adjust -->
1573 <h3 id=font-size-adjust-prop><span class=secno>3.6 </span>Relative sizing:
1574 the <a href="#propdef-font-size-adjust">font-size-adjust</a> property</h3>
1576 <table class=propdef id=namefont-size-adjustvaluenone-auto-ltnum>
1577 <tbody>
1578 <tr>
1579 <td>Name:
1581 <td><dfn id=propdef-font-size-adjust>font-size-adjust</dfn>
1583 <tr>
1584 <td>Value:
1586 <td><a href="#font-size-adjust-none-value"
1587 title="none!!font-size-adjust">none</a> | <a
1588 href="#font-size-adjust-auto-value"
1589 title="auto!!font-size-adjust">auto</a> | <a
1590 href="#aspect-ratio-value"><var><number></var></a>
1592 <tr>
1593 <td>Initial:
1595 <td>none
1597 <tr>
1598 <td>Applies to:
1600 <td>all elements
1602 <tr>
1603 <td>Inherited:
1605 <td>yes
1607 <tr>
1608 <td>Percentages:
1610 <td>N/A
1612 <tr>
1613 <td>Media:
1615 <td>visual
1617 <tr>
1618 <td>Computed value:
1620 <td>as specified
1622 <tr>
1623 <td>Animatable:
1625 <td>as <a
1626 href="http://dev.w3.org/csswg/css3-transitions/#animtype-number">number</a>
1627 </table>
1629 <p>For any given font size, the apparent size and legibility of text varies
1630 across fonts. For scripts such as Latin or Cyrillic that distinguish
1631 between upper and lowercase letters, the relative height of lowercase
1632 letters compared to their uppercase counterparts is a determining factor
1633 of legibility. This is commonly referred to as the <a class=index-def
1634 href="#aspect-value" id=aspect-value0 title="aspect value"><dfn
1635 id=aspect-value>aspect value</dfn></a>. Precisely defined, it is equal to
1636 the x-height of a font divided by the font size.
1638 <p>In situations where font fallback occurs, fallback fonts may not share
1639 the same aspect ratio as the desired font family and will thus appear less
1640 readable. The font-size-adjust property is a way to preserve the
1641 readability of text when font fallback occurs. It does this by adjusting
1642 the font-size so that the x-height is the same regardless of the font
1643 used.
1645 <div class=example>
1646 <p>The style defined below defines Verdana as the desired font family, but
1647 if Verdana is not available Futura or Times will be used.</p>
1649 <pre>p {
1650 font-family: Verdana, Futura, Times;
1651 }
1653 <p>Lorem ipsum dolor sit amet, ...</p>
1654 </pre>
1656 <p>Verdana has a relatively high aspect ratio, lowercase letters are
1657 relatively tall compared to uppercase letters, so at small sizes text
1658 appears legible. Times has a lower aspect ratio and so if fallback
1659 occurs, the text will be less legible at small sizes than Verdana.</p>
1660 </div>
1662 <p>How text rendered in each of these fonts compares is shown below, the
1663 columns show text rendered in Verdana, Futura and Times. The same
1664 font-size value is used across cells within each row and red lines are
1665 included to show the differences in x-height. In the upper half each row
1666 is rendered in the same font-size value. The same is true for the lower
1667 half but in this half the font-size-adjust property is also set so that
1668 the actual font size is adjusted to preserve the x-height across each row.
1669 Note how small text remains relatively legible across each row in the
1670 lower half.
1672 <div class=figure><img alt="text with and without font-size-adjust"
1673 src=fontsizeadjust.png>
1674 <p class=caption>Text with and without the use of font-size-adjust
1675 </div>
1677 <p>This property allows authors to specify an aspect value for an element
1678 that will effectively preserve the x-height of the first choice font,
1679 whether it is substituted or not. Values have the following meanings:
1681 <dl>
1682 <dt><dfn id=font-size-adjust-none-value
1683 title="none!!font-size-adjust">none</dfn>
1685 <dd>Do not preserve the font's x-height.
1687 <dt><dfn id=font-size-adjust-auto-value
1688 title="auto!!font-size-adjust">auto</dfn>
1690 <dd>Behaves just like <number>, except the number used is the aspect
1691 value calculated by user agents for the first font in the list of fonts
1692 defined for the initial value of the <a href="#propdef-font-family"
1693 title="font-family!!property">‘<code
1694 class=property>font-family</code>’</a> property. Effectively this is
1695 the default font used when <a href="#propdef-font-family"
1696 title="font-family!!property">‘<code
1697 class=property>font-family</code>’</a> is not otherwise specified.
1698 <p>Authors can use this value to specify that font size should be
1699 normalized across fonts based on the x-height without the need to
1700 specify the aspect ratio explicitly.</p>
1702 <dt><dfn id=aspect-ratio-value><var><number></var></dfn>
1704 <dd>Specifies the aspect value used in the calculation below to calculate
1705 the adjusted font size:
1706 <pre>c = ( a / a' ) s
1707 </pre>
1709 <p>where:</p>
1711 <pre>s = font-size value
1712 a = aspect value as specified by the font-size-adjust property
1713 a' = aspect value of actual font
1714 c = adjusted font-size to use
1715 </pre>
1717 <p>This value applies to any font that is selected but in typical usage
1718 it should be based on the aspect value of the first font in the
1719 font-family list. If this is specified accurately, the <tt>(a/a')</tt>
1720 term in the formula above is effectively 1 for the first font and no
1721 adjustment occurs. If the value is specified inaccurately, text rendered
1722 using the first font in the family list will display differently in
1723 older user agents that don't support font-size-adjust.</p>
1724 </dl>
1726 <p>Authors can calculate the aspect value for a given font by comparing
1727 spans with the same content but different font-size-adjust properties. If
1728 the same font-size is used, the spans will match when the font-size-adjust
1729 value is accurate for the given font.
1731 <div class=example>
1732 <p>Two spans with borders are used to determine the aspect value of a
1733 font. The font-size is the same for both spans but the font-size-adjust
1734 property is specified only for the right span. Starting with a value of
1735 0.5, the aspect value can be adjusted until the borders around the two
1736 letters line up.</p>
1738 <pre>p {
1739 font-family: Futura;
1740 font-size: 500px;
1741 }
1743 span {
1744 border: solid 1px red;
1745 }
1747 .adjust {
1748 font-size-adjust: 0.5;
1749 }
1751 <p><span>b</span><span class="adjust">b</span></p>
1752 </pre>
1754 <div class=figure><img alt="Futura with an aspect value of 0.5"
1755 src=beforefontsizeadjust.png>
1756 <p class=caption>Futura with an aspect value of 0.5
1757 </div>
1759 <p>The box on the right is a bit bigger than the one on the left, so the
1760 aspect value of this font is something less than 0.5. Adjust the value
1761 until the boxes align.</p>
1762 </div>
1763 <!-- prop: font -->
1765 <h3 id=font-prop><span class=secno>3.7 </span>Shorthand font property: the
1766 <a href="#propdef-font">font</a> property</h3>
1768 <table class=propdef id=namefontvalue-ltlsquofont-stylersquogt-l>
1769 <tbody>
1770 <tr>
1771 <td>Name:
1773 <td><dfn id=propdef-font>font</dfn>
1775 <tr>
1776 <td>Value:
1778 <td>[ [ <var><<a href="#propdef-font-style"
1779 title="font-style!!property">‘<code
1780 class=property>font-style</code>’</a>></var> || <a
1781 href="#font-variant-css21-values"><var><font-variant-css21></var></a>
1782 || <var><<a href="#propdef-font-weight"
1783 title="font-weight!!property">‘<code
1784 class=property>font-weight</code>’</a>></var> || <var><<a
1785 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
1786 class=property>font-stretch</code>’</a></var> ]? <var><‘<a
1787 href="#propdef-font-size"><code
1788 class=property>font-size</code></a>’></var> [ / <var><‘<code
1789 class=property>line-height</code>’></var> ]? <var><<a
1790 href="#propdef-font-family" title="font-family!!property">‘<code
1791 class=property>font-family</code>’</a>></var> ] | caption | icon |
1792 menu | message-box | small-caption | status-bar
1794 <tr>
1795 <td>Initial:
1797 <td>see individual properties
1799 <tr>
1800 <td>Applies to:
1802 <td>all elements
1804 <tr>
1805 <td>Inherited:
1807 <td>yes
1809 <tr>
1810 <td>Percentages:
1812 <td>see individual properties
1814 <tr>
1815 <td>Media:
1817 <td>visual
1819 <tr>
1820 <td>Computed value:
1822 <td>see individual properties
1824 <tr>
1825 <td>Animatable:
1827 <td>see individual properties
1828 </table>
1830 <p>The <span class=property>‘<a href="#propdef-font"><code
1831 class=property>font</code></a>’</span> property is, except as described
1832 below, a shorthand property for setting <a href="#propdef-font-style"
1833 title="font-style!!property">‘<code
1834 class=property>font-style</code>’</a>, <a href="#propdef-font-variant"
1835 title="font-variant!!property">‘<code
1836 class=property>font-variant</code>’</a>, <a href="#propdef-font-weight"
1837 title="font-weight!!property">‘<code
1838 class=property>font-weight</code>’</a>, <a href="#propdef-font-stretch"
1839 title="font-stretch!!property">‘<code
1840 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1841 href="#propdef-font-size"><code
1842 class=property>font-size</code></a>’</span>, <a class=property
1843 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1844 class=property>line-height</code>’</a>, <a href="#propdef-font-family"
1845 title="font-family!!property">‘<code
1846 class=property>font-family</code>’</a> at the same place in the
1847 stylesheet. Values for the <a href="#propdef-font-variant"
1848 title="font-variant!!property">‘<code
1849 class=property>font-variant</code>’</a> property may also be included
1850 but only those supported in CSS 2.1, none of the <a
1851 href="#propdef-font-variant" title="font-variant!!property">‘<code
1852 class=property>font-variant</code>’</a> values added in this
1853 specification can be used in the <span class=property>‘<a
1854 href="#propdef-font"><code class=property>font</code></a>’</span>
1855 shorthand:
1857 <pre
1858 class=prod><dfn id=font-variant-css21-values><var><font-variant-css21></var></dfn> = [normal | small-caps]</pre>
1860 <p>The syntax of this property is based on a traditional typographical
1861 shorthand notation to set multiple properties related to fonts.
1863 <p>All subproperties of the ‘<a href="#propdef-font"><code
1864 class=property>font</code></a>’ property are first reset to their
1865 initial values, including those listed above plus <span
1866 class=property>‘<a href="#propdef-font-size-adjust"><code
1867 class=property>font-size-adjust</code></a>’</span>, <span
1868 class=property>‘<a href="#propdef-font-kerning"><code
1869 class=property>font-kerning</code></a>’</span>, subproperties of <a
1870 href="#propdef-font-variant" title="font-variant!!property">‘<code
1871 class=property>font-variant</code>’</a> and and <span>‘<a
1872 href="#propdef-font-language-override"><code
1873 class=property>font-language-override</code></a>’</span>. Then, those
1874 properties that are given explicit values in the <span
1875 class=property>‘<a href="#propdef-font"><code
1876 class=property>font</code></a>’</span> shorthand are set to those
1877 values. For a definition of allowed and initial values, see the previously
1878 defined properties. For reasons of backwards compatibility, it is not
1879 possible to set <span class=property>‘<a
1880 href="#propdef-font-size-adjust"><code
1881 class=property>font-size-adjust</code></a>’</span> to anything other
1882 than its initial value using the <span class=property>‘<a
1883 href="#propdef-font"><code class=property>font</code></a>’</span>
1884 shorthand property; instead, use the individual property.
1886 <div class=example>
1887 <p style="display:none">Example(s):
1889 <p>
1891 <pre>p { font: 12pt/14pt sans-serif }
1892 p { font: 80% sans-serif }
1893 p { font: x-large/110% "new century schoolbook", serif }
1894 p { font: bold italic large Palatino, serif }
1895 p { font: normal small-caps 120%/120% fantasy }
1896 p { font: condensed oblique 12pt "Helvetica Neue", serif; }
1897 </pre>
1899 <p> In the second rule, the font size percentage value (‘<code
1900 class=css>80%</code>’) refers to the computed ‘<a
1901 href="#propdef-font-size"><code class=property>font-size</code></a>’ of
1902 the parent element. In the third rule, the line height percentage
1903 (‘<code class=css>110%</code>’) refers to the font size of the
1904 element itself.
1906 <p>The first three rules do not specify the <a
1907 href="#propdef-font-variant" title="font-variant!!property">‘<code
1908 class=property>font-variant</code>’</a> and <a
1909 href="#propdef-font-weight" title="font-weight!!property">‘<code
1910 class=property>font-weight</code>’</a> explicitly, so these properties
1911 receive their initial values (‘<a href="#normal"><code
1912 class=property>normal</code></a>’). Notice that the font family name
1913 "new century schoolbook", which contains spaces, is enclosed in quotes.
1914 The fourth rule sets the <a href="#propdef-font-weight"
1915 title="font-weight!!property">‘<code
1916 class=property>font-weight</code>’</a> to ‘<a href="#bold"><code
1917 class=property>bold</code></a>’, the <a href="#propdef-font-style"
1918 title="font-style!!property">‘<code
1919 class=property>font-style</code>’</a> to ‘<a href="#italic"><code
1920 class=property>italic</code></a>’, and implicitly sets <a
1921 href="#propdef-font-variant" title="font-variant!!property">‘<code
1922 class=property>font-variant</code>’</a> to ‘<a href="#normal"><code
1923 class=property>normal</code></a>’.
1925 <p> The fifth rule sets the <a href="#propdef-font-variant"
1926 title="font-variant!!property">‘<code
1927 class=property>font-variant</code>’</a> (‘<a href="#small-caps"><code
1928 class=property>small-caps</code></a>’), the <span class=property>‘<a
1929 href="#propdef-font-size"><code
1930 class=property>font-size</code></a>’</span> (120% of the parent's font
1931 size), the <a class=property
1932 href="http://www.w3.org/TR/CSS2/visudet.html#propdef-line-height">‘<code
1933 class=property>line-height</code>’</a> (120% of the font size) and the
1934 <a href="#propdef-font-family" title="font-family!!property">‘<code
1935 class=property>font-family</code>’</a> (‘<a href="#fantasy"><code
1936 class=property>fantasy</code></a>’). It follows that the keyword ‘<a
1937 href="#normal"><code class=property>normal</code></a>’ applies to the
1938 two remaining properties: <a href="#propdef-font-style"
1939 title="font-style!!property">‘<code
1940 class=property>font-style</code>’</a> and <a
1941 href="#propdef-font-weight" title="font-weight!!property">‘<code
1942 class=property>font-weight</code>’</a>.
1944 <p>The sixth rule sets the <a href="#propdef-font-style"
1945 title="font-style!!property">‘<code
1946 class=property>font-style</code>’</a>, <a href="#propdef-font-stretch"
1947 title="font-stretch!!property">‘<code
1948 class=property>font-stretch</code>’</a>, <span class=property>‘<a
1949 href="#propdef-font-size"><code
1950 class=property>font-size</code></a>’</span>, and <a
1951 href="#propdef-font-family" title="font-family!!property">‘<code
1952 class=property>font-family</code>’</a>, the other font properties being
1953 set to their initial values.
1954 </div>
1956 <p>Since the <a href="#propdef-font-stretch"
1957 title="font-stretch!!property">‘<code
1958 class=property>font-stretch</code>’</a> property was not defined in CSS
1959 2.1, when using <a href="#propdef-font-stretch"
1960 title="font-stretch!!property">‘<code
1961 class=property>font-stretch</code>’</a> values within ‘<a
1962 href="#propdef-font"><code class=property>font</code></a>’ rules,
1963 authors should include a extra version compatible with older user agents:
1965 <pre>p {
1966 font: 80% sans-serif; /* for older user agents */
1967 font: condensed 80% sans-serif;
1968 }</pre>
1970 <p>The following values refer to system fonts:
1972 <dl>
1973 <dt><strong>caption</strong>
1975 <dd>The font used for captioned controls (e.g., buttons, drop-downs,
1976 etc.).
1978 <dt><strong>icon</strong>
1980 <dd>The font used to label icons.
1982 <dt><strong>menu</strong>
1984 <dd>The font used in menus (e.g., dropdown menus and menu lists).
1986 <dt><strong>message-box</strong>
1988 <dd>The font used in dialog boxes.
1990 <dt><strong>small-caption</strong>
1992 <dd>The font used for labeling small controls.
1994 <dt><strong>status-bar</strong>
1996 <dd>The font used in window status bars.
1997 </dl>
1999 <p>System fonts may only be set as a whole; that is, the font family, size,
2000 weight, style, etc. are all set at the same time. These values may then be
2001 altered individually if desired. If no font with the indicated
2002 characteristics exists on a given platform, the user agent should either
2003 intelligently substitute (e.g., a smaller version of the ‘<code
2004 class=property>caption</code>’ font might be used for the ‘<code
2005 class=property>small-caption</code>’ font), or substitute a user agent
2006 default font. As for regular fonts, if, for a system font, any of the
2007 individual properties are not part of the operating system's available
2008 user preferences, those properties should be set to their initial values.
2010 <p>That is why this property is "almost" a shorthand property: system fonts
2011 can only be specified with this property, not with <a
2012 href="#propdef-font-family" title="font-family!!property">‘<code
2013 class=property>font-family</code>’</a> itself, so <span
2014 class=property>‘<a href="#propdef-font"><code
2015 class=property>font</code></a>’</span> allows authors to do more than
2016 the sum of its subproperties. However, the individual properties such as
2017 <a href="#propdef-font-weight" title="font-weight!!property">‘<code
2018 class=property>font-weight</code>’</a> are still given values taken from
2019 the system font, which can be independently varied.
2021 <p>Note that the keywords used for the system fonts listed above are only
2022 treated as keywords when they occur in the initial position, in other
2023 positions the same string is treated as part of the font family name:
2025 <pre> font: menu; /* use the font settings for system menus */
2026 font: large menu; /* use a font family named "menu" */</pre>
2028 <div class=example>
2029 <p style="display:none">Example(s):
2031 <p>
2033 <pre>button { font: 300 italic 1.3em/1.7em "FB Armada", sans-serif }
2034 button p { font: menu }
2035 button p em { font-weight: bolder }
2036 </pre>
2038 <p>If the font used for dropdown menus on a particular system happened to
2039 be, for example, 9-point Charcoal, with a weight of 600, then P elements
2040 that were descendants of BUTTON would be displayed as if this rule were
2041 in effect:
2043 <pre>button p { font: 600 9pt Charcoal }
2044 </pre>
2046 <p>Because the <span class=property>‘<a href="#propdef-font"><code
2047 class=property>font</code></a>’</span> shorthand resets to its initial
2048 value any property not explicitly given a value, this has the same effect
2049 as this declaration:
2051 <pre>button p {
2052 font-style: normal;
2053 font-variant: normal;
2054 font-weight: 600;
2055 font-size: 9pt;
2056 line-height: normal;
2057 font-family: Charcoal
2058 }
2059 </pre>
2060 </div>
2061 <!-- prop: font-synthesis -->
2063 <h3 id=font-synthesis-prop><span class=secno>3.8 </span>Controlling
2064 synthetic faces: the <a href="#propdef-font-synthesis">font-synthesis</a>
2065 property</h3>
2067 <table class=propdef id=namefont-synthesisvaluenone-weight-style>
2068 <tbody>
2069 <tr>
2070 <td>Name:
2072 <td><dfn id=propdef-font-synthesis>font-synthesis</dfn>
2074 <tr>
2075 <td>Value:
2077 <td>none | [ weight || style ]
2079 <tr>
2080 <td>Initial:
2082 <td>weight style
2084 <tr>
2085 <td>Applies to:
2087 <td>all elements
2089 <tr>
2090 <td>Inherited:
2092 <td>yes
2094 <tr>
2095 <td>Percentages:
2097 <td>N/A
2099 <tr>
2100 <td>Media:
2102 <td>visual
2104 <tr>
2105 <td>Computed value:
2107 <td>as specified
2109 <tr>
2110 <td>Animatable:
2112 <td>no
2113 </table>
2115 <p>This property controls whether user agents are allowed to synthesize
2116 bold or oblique font faces when a font family lacks bold or italic faces.
2117 If ‘<a href="#weight"><code class=property>weight</code></a>’ is not
2118 specified, user agents must not synthesize bold faces and if ‘<code
2119 class=property>style</code>’ is not specified user agents must not
2120 synthesize italic faces. A value of ‘<code class=property>none</code>’
2121 disallows all synthetic faces.
2123 <div class=example>
2124 <p>The style rule below disables the use of synthetically obliqued Arabic:</p>
2126 <pre>*:lang(ar) { font-synthesis: none; }
2127 </pre>
2128 </div>
2130 <h2 id=font-resources><span class=secno>4 </span>Font Resources</h2>
2132 <h3 id=font-face-rule><span class=secno>4.1 </span>The <dfn
2133 id=at-font-face-rule style="font-weight: inherit; font-style:
2134 inherit"><code>@font-face</code></dfn> rule</h3>
2136 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule allows
2137 for linking to fonts that are automatically fetched and activated when
2138 needed. This allows authors to select a font that closely matches the
2139 design goals for a given page rather than limiting the font choice to a
2140 set of fonts available on all platforms. A set of font descriptors define
2141 the location of a font resource, either locally or externally, along with
2142 the style characteristics of an individual face. Multiple <a
2143 href="#at-font-face-rule"><code>@font-face</code></a> rules can be used to
2144 construct font families with a variety of faces. Using CSS font matching
2145 rules, a user agent can selectively download only those faces that are
2146 needed for a given piece of text.
2148 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2149 consists of the <a href="#at-font-face-rule"><code>@font-face</code></a>
2150 at-keyword followed by a block of descriptor declarations. In terms of the
2151 grammar, this specification defines the following productions:
2153 <pre><dfn id=fontfacerule>font_face_rule</dfn>
2154 : <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>*
2155 ;
2157 <dfn id=descriptordeclaration>descriptor_declaration</dfn>
2158 : <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>
2159 ;</pre>
2161 <p>The following new definitions are introduced:
2163 <pre>- -|\\0{0,4}2d(\r\n|[ \t\r\n\f])?
2164 F f|\\0{0,4}(46|66)(\r\n|[ \t\r\n\f])?</pre>
2166 <p>The following new token is introduced:
2168 <pre>@{F}{O}{N}{T}{-}{F}{A}{C}{E} {return <dfn id=fontfacesym>FONT_FACE_SYM</dfn>;}</pre>
2170 <p>Each <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2171 specifies a value for every font descriptor, either implicitly or
2172 explicitly. Those not given explicit values in the rule take the initial
2173 value listed with each descriptor in this specification. These descriptors
2174 apply solely within the context of the <a
2175 href="#at-font-face-rule"><code>@font-face</code></a> rule in which they
2176 are defined, and do not apply to document language elements. There is no
2177 notion of which elements the descriptors apply to or whether the values
2178 are inherited by child elements. When a given descriptor occurs multiple
2179 times in a given <a href="#at-font-face-rule"><code>@font-face</code></a>
2180 rule, only the last descriptor declaration is used and all prior
2181 declarations for that descriptor are ignored.
2183 <div class=example>
2184 <p>To use a downloadable font called Gentium:</p>
2186 <pre>
2187 @font-face {
2188 font-family: Gentium;
2189 src: url(http://example.com/fonts/Gentium.ttf);
2190 }
2192 p { font-family: Gentium, serif; }
2193 </pre>
2195 <p>The user agent will download Gentium and use it when rendering text
2196 within paragraph elements. If for some reason the site serving the font
2197 is unavailable, the default serif font will be used.</p>
2198 </div>
2200 <p>A given set of <a href="#at-font-face-rule"><code>@font-face</code></a>
2201 rules define a set of fonts available for use within the documents that
2202 contain these rules. When font matching is done, fonts defined using these
2203 rules are considered before other available fonts on a system.
2205 <p>Downloaded fonts are only available to documents that reference them.
2206 The process of activating these fonts must not make them available to
2207 other applications or to documents that don't directly link to the same
2208 font. User agent implementers might consider it convenient to use
2209 downloaded fonts when rendering characters in other documents for which no
2210 other available font exists as part of the system font fallback procedure.
2211 However, this would cause a security leak since the contents of one page
2212 would be able to affect other pages, something an attacker could use as an
2213 attack vector. These restrictions do not affect caching behavior, fonts
2214 are cached the same way other web resources are cached.
2216 <p>This at-rule follows the forward-compatible parsing rules of CSS. Like
2217 properties in a declaration block, declarations of any descriptors that
2218 are not supported by the user agent must be ignored. <a
2219 href="#at-font-face-rule"><code>@font-face</code></a> rules require a
2220 font-family and src descriptor; if either of these are missing, the <a
2221 href="#at-font-face-rule"><code>@font-face</code></a> rule is invalid and
2222 must be ignored entirely.
2224 <p>In cases where user agents have limited platform resources or implement
2225 the ability to disable downloadable font resources, <a
2226 href="#at-font-face-rule"><code>@font-face</code></a> rules must simply be
2227 ignored; the behavior of individual descriptors as defined in this
2228 specification should not be altered.
2230 <h3 id=font-family-desc><span class=secno>4.2 </span>Font family: the <a
2231 href="#descdef-font-family">font-family</a> descriptor</h3>
2233 <table class=descdef>
2234 <tbody>
2235 <tr>
2236 <td>Name:
2238 <td><dfn id=descdef-font-family
2239 title="font-family!!descriptor">font-family</dfn>
2241 <tr>
2242 <td>Value:
2244 <td><a href="#family-name-value"><var><family-name></var></a>
2246 <tr>
2247 <td><em>Initial:</em>
2249 <td>N/A
2250 </table>
2252 <p>This descriptor defines the font family name that will be used in all
2253 CSS font family name matching. It is required for the <a
2254 href="#at-font-face-rule"><code>@font-face</code></a> rule to be valid. It
2255 overrides the font family names contained in the underlying font data. If
2256 the font family name is the same as a font family available in a given
2257 user's environment, it effectively hides the underlying font for documents
2258 that use the stylesheet. This permits a web author to freely choose
2259 font-family names without worrying about conflicts with font family names
2260 present in a given user's environment. Likewise, platform substitutions
2261 for a given font family name must not be used.
2263 <h3 id=src-desc><span class=secno>4.3 </span>Font reference: the <a
2264 href="#descdef-src">src</a> descriptor</h3>
2266 <table class=descdef>
2267 <tbody>
2268 <tr>
2269 <td>Name:
2271 <td><dfn id=descdef-src>src</dfn>
2273 <tr>
2274 <td>Value:
2276 <td>[ <url> [format(<string> #)]? | <a
2277 href="#font-face-name-value"><var><font-face-name></var></a> ] #
2279 <tr>
2280 <td><em>Initial:</em>
2282 <td>N/A
2283 </table>
2285 <p>This descriptor specifies the resource containing font data. It is
2286 required for the <a href="#at-font-face-rule"><code>@font-face</code></a>
2287 rule to be valid. Its value is a prioritized, comma-separated list of
2288 external references or locally-installed font face names. When a font is
2289 needed the user agent iterates over the set of references listed, using
2290 the first one it can successfully activate. Fonts containing invalid data
2291 or local font faces that are not found are ignored and the user agent
2292 loads the next font in the list.
2294 <p>As with other URLs in CSS, the URL may be relative, in which case it is
2295 resolved relative to the location of the style sheet containing the <a
2296 href="#at-font-face-rule"><code>@font-face</code></a> rule. In the case of
2297 SVG fonts, the URL points to an element within a document containing SVG
2298 font definitions. If the element reference is omitted, a reference to the
2299 first defined font is implied. Similarly, font container formats that can
2300 contain more than one font must load one and only one of the fonts for a
2301 given <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
2302 Fragment identifiers are used to indicate which font to load. If a
2303 container format lacks a defined fragment identifier scheme,
2304 implementations should use a simple 1-based indexing scheme (e.g.
2305 "font-collection#1" for the first font, "font-collection#2" for the second
2306 font).
2308 <pre>
2309 src: url(fonts/simple.ttf); /* load simple.ttf relative to stylesheet location */
2310 src: url(/fonts/simple.ttf); /* load simple.ttf from absolute location */
2311 src: url(fonts.svg#simple); /* load SVG font with id 'simple' */
2312 </pre>
2314 <p>External references consist of a URL, followed by an optional hint
2315 describing the format of the font resource referenced by that URL. The
2316 format hint contains a comma-separated list of format strings that denote
2317 well-known font formats. Conformant user agents must skip downloading a
2318 font resource if the format hints indicate only unsupported or unknown
2319 font formats. If no format hints are supplied, the user agent should
2320 download the font resource.
2322 <pre>
2323 /* load WOFF font if possible, otherwise use OpenType font */
2324 @font-face {
2325 font-family: bodytext;
2326 src: url(ideal-sans-serif.woff) format("woff"),
2327 url(basic-sans-serif.ttf) format("opentype");
2328 }
2329 </pre>
2331 <p>Format strings defined by this specification:
2333 <table class=data id=fontformats>
2334 <thead>
2335 <tr>
2336 <th>String
2338 <th>Font Format
2340 <th>Common extensions
2342 <tbody>
2343 <tr>
2344 <th>"woff"
2346 <td><a href="http://www.w3.org/TR/WOFF/">WOFF (Web Open Font Format)</a>
2348 <td>.woff
2350 <tr>
2351 <th>"truetype"
2353 <td><a
2354 href="http://www.microsoft.com/typography/otspec/default.htm">TrueType</a>
2356 <td>.ttf
2358 <tr>
2359 <th>"opentype"
2361 <td><a
2362 href="http://www.microsoft.com/typography/otspec/default.htm">OpenType</a>
2364 <td>.ttf, .otf
2366 <tr>
2367 <th>"embedded-opentype"
2369 <td><a
2370 href="http://www.w3.org/Submission/2008/SUBM-EOT-20080305/">Embedded
2371 OpenType</a>
2373 <td>.eot
2375 <tr>
2376 <th>"svg"
2378 <td><a href="http://www.w3.org/TR/SVG/fonts.html">SVG Font</a>
2380 <td>.svg, .svgz
2381 </table>
2383 <p>Given the overlap in common usage between TrueType and OpenType, the
2384 format hints "truetype" and "opentype" must be considered as synonymous; a
2385 format hint of "opentype" does not imply that the font contains Postscript
2386 CFF style glyph data or that it contains OpenType layout information (see
2387 <a href="#platform-props-to-css">Appendix A</a> for more background on
2388 this).
2390 <p>When authors would prefer to use a locally available copy of a given
2391 font and download it if it's not, <code>local()</code> can be used. The
2392 locally-installed <dfn
2393 id=font-face-name-value><var><font-face-name></var></dfn> argument
2394 to <code>local()</code> is a format-specific string that uniquely
2395 identifies a single font face within a larger family. The syntax for a <a
2396 href="#font-face-name-value"><var><font-face-name></var></a> is a
2397 unique font face name enclosed by "local(" and ")". The name can
2398 optionally be enclosed in quotes. If unquoted, the unquoted font family
2399 name processing conventions apply; the name must be a sequence of
2400 identifiers separated by whitespace which is converted to a string by
2401 joining the identifiers together separated by a single space.
2403 <pre>
2404 /* regular face of Gentium */
2405 @font-face {
2406 font-family: MyGentium;
2407 src: local(Gentium), /* use locally available Gentium */
2408 url(Gentium.ttf); /* otherwise, download it */
2409 }
2410 </pre>
2412 <p>For OpenType and TrueType fonts, this string is used to match only the
2413 Postscript name or the full font name in the name table of locally
2414 available fonts. Which type of name is used varies by platform and font,
2415 so authors should include both of these names to assure proper matching
2416 across platforms. Platform substitutions for a given font name must not be
2417 used.
2419 <pre>
2420 /* bold face of Gentium */
2421 @font-face {
2422 font-family: MyGentium;
2423 src: local(Gentium Bold), /* full font name */
2424 local(Gentium-Bold), /* Postscript name */
2425 url(GentiumBold.ttf); /* otherwise, download it */
2426 font-weight: bold;
2427 }
2428 </pre>
2430 <p>Just as a <a href="#at-font-face-rule"><code>@font-face</code></a> rule
2431 specifies the characteristics of a single font within a family, the unique
2432 name used with <code>local()</code> specifies a single font, not an entire
2433 font family. Defined in terms of OpenType font data, the Postscript name
2434 is found in the font's <a
2435 href="http://www.microsoft.com/typography/otspec/name.htm">name table</a>,
2436 in the name record with nameID = 6 (see <a href="#OPENTYPE"
2437 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> for more details). The
2438 Postscript name is the commonly used key for all fonts on OSX and for
2439 Postscript CFF fonts under Windows. The full font name (nameID = 4) is
2440 used as a unique key for fonts with TrueType glyphs on Windows.
2442 <p>For OpenType fonts with multiple localizations of the full font name,
2443 the US English version is used (language ID = 0x409 for Windows and
2444 language ID = 0 for Macintosh) or the first localization when a US English
2445 full font name is not available (the OpenType specification recommends
2446 that <a href="http://www.microsoft.com/typography/otspec/recom.htm">all
2447 fonts minimally include US English names</a>). User agents that also match
2448 other full font names, e.g. matching the Dutch name when the current
2449 system locale is set to Dutch, are considered non-conformant. This is done
2450 not to prefer English but to avoid matching inconsistencies across font
2451 versions and OS localizations, since font style names (e.g. "Bold") are
2452 frequently localized into many languages and the set of localizations
2453 available varies widely across platform and font version. User agents that
2454 match a concatenation of family name (nameID = 1) with style name (nameID
2455 = 2) are considered non-conformant.
2457 <p>This also allows for referencing faces that belong to larger families
2458 that cannot otherwise be referenced.
2460 <div class=example>
2461 <p>Use a local font or reference an SVG font in another document:</p>
2463 <pre>
2464 @font-face {
2465 font-family: Headline;
2466 src: local(Futura-Medium),
2467 url(fonts.svg#MyGeometricModern) format("svg");
2468 }
2469 </pre>
2471 <p>Create an alias for local Japanese fonts on different platforms:</p>
2473 <pre>
2474 @font-face {
2475 font-family: jpgothic;
2476 src: local(HiraKakuPro-W3), local(Meiryo), local(IPAPGothic);
2477 }
2478 </pre>
2480 <p>Reference a font face that cannot be matched within a larger family:</p>
2482 <pre>
2483 @font-face {
2484 font-family: Hoefler Text Ornaments;
2485 /* has the same font properties as Hoefler Text Regular */
2486 src: local(HoeflerText-Ornaments);
2487 }
2488 </pre>
2490 <p>Since localized fullnames never match, a document with the header style
2491 rules below would always render using the default serif font, regardless
2492 whether a particular system locale parameter is set to Finnish or not:</p>
2494 <pre>
2495 @font-face {
2496 font-family: SectionHeader;
2497 src: local("Arial Lihavoitu"); /* Finnish fullname for Arial Bold, should fail */
2498 font-weight: bold;
2499 }
2501 h2 { font-family: SectionHeader, serif; }
2502 </pre>
2504 <p>A conformant user agent would never load the font ‘<code
2505 class=css>gentium.eot</code>’ in the example below, since it is
2506 included in the first definition of the ‘<a href="#descdef-src"><code
2507 class=property>src</code></a>’ descriptor which is overridden by the
2508 second definition in the same <a
2509 href="#at-font-face-rule"><code>@font-face</code></a> rule:</p>
2511 <pre>
2512 @font-face {
2513 font-family: MainText;
2514 src: url(gentium.eot); /* for use with older non-conformant user agents */
2515 src: local("Gentium"), url(gentium.ttf); /* Overrides src definition */
2516 }
2517 </pre>
2518 </div>
2520 <h3 id=font-prop-desc><span class=secno>4.4 </span>Font property
2521 descriptors: the <a href="#descdef-font-style">font-style</a>, <a
2522 href="#descdef-font-weight">font-weight</a>, <a
2523 href="#descdef-font-stretch">font-stretch</a> descriptors</h3>
2525 <table class=descdef>
2526 <tbody>
2527 <tr>
2528 <td>Name:
2530 <td><dfn id=descdef-font-style
2531 title="font-style!!descriptor">font-style</dfn>
2533 <tr>
2534 <td>Value:
2536 <td>normal | italic | oblique
2538 <tr>
2539 <td><em>Initial:</em>
2541 <td>normal
2542 </table>
2544 <table class=descdef>
2545 <tbody>
2546 <tr>
2547 <td>Name:
2549 <td><dfn id=descdef-font-weight
2550 title="font-weight!!descriptor">font-weight</dfn>
2552 <tr>
2553 <td>Value:
2555 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
2557 <tr>
2558 <td><em>Initial:</em>
2560 <td>normal
2561 </table>
2563 <table class=descdef>
2564 <tbody>
2565 <tr>
2566 <td>Name:
2568 <td><dfn id=descdef-font-stretch
2569 title="font-stretch!!descriptor">font-stretch</dfn>
2571 <tr>
2572 <td>Value:
2574 <td>normal | ultra-condensed | extra-condensed | condensed |
2575 semi-condensed | semi-expanded | expanded | extra-expanded |
2576 ultra-expanded
2578 <tr>
2579 <td><em>Initial:</em>
2581 <td>normal
2582 </table>
2584 <p>These descriptors define the characteristics of a font face and are used
2585 in the process of matching styles to specific faces. For a font family
2586 defined with several <a
2587 href="#at-font-face-rule"><code>@font-face</code></a> rules, user agents
2588 can either download all faces in the family or use these descriptors to
2589 selectively download font faces that match actual styles used in document.
2590 The values for these descriptors are the same as those for the
2591 corresponding font properties except that relative keywords are not
2592 allowed, ‘<a href="#bolder"><code class=property>bolder</code></a>’
2593 and ‘<a href="#lighter"><code class=property>lighter</code></a>’. If
2594 these descriptors are omitted, initial values are assumed.
2596 <p>The value for these font face style attributes is used in place of the
2597 style implied by the underlying font data. This allows authors to combine
2598 faces in flexible combinations, even in situations where the original font
2599 data was arranged differently. User agents that implement synthetic
2600 bolding and obliquing must only apply synthetic styling in cases where the
2601 font descriptors imply this is needed, rather than based on the style
2602 attributes implied by the font data.
2604 <h3 id=unicode-range-desc><span class=secno>4.5 </span>Character range: the
2605 <a href="#descdef-unicode-range">unicode-range</a> descriptor</h3>
2607 <table class=descdef>
2608 <tbody>
2609 <tr>
2610 <td>Name:
2612 <td><dfn id=descdef-unicode-range>unicode-range</dfn>
2614 <tr>
2615 <td>Value:
2617 <td><a href="#urange-value"><var><urange></var></a> #
2619 <tr>
2620 <td><em>Initial:</em>
2622 <td>U+0-10FFFF
2623 </table>
2625 <p>This descriptor defines the set of Unicode codepoints that may be
2626 supported by the font face for which it is declared. The descriptor value
2627 is a comma-delimited list of Unicode range (<a
2628 href="#urange-value"><var><urange></var></a>) values. The union of
2629 these ranges defines the set of codepoints that serves as a hint for user
2630 agents when deciding whether or not to download a font resource for a
2631 given text run.
2633 <p>Each <dfn id=urange-value><var><urange></var></dfn> value is a <a
2634 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2635 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token made up of a
2636 "U+" or "u+" prefix followed by a codepoint range in one of the three
2637 forms listed below. Ranges that do not fit one of the these forms are
2638 invalid and cause the declaration to be ignored.
2640 <dl>
2641 <dt>single codepoint (e.g. U+416)
2643 <dd>a valid Unicode codepoint, represented as one to six hexadecimal
2644 digits
2646 <dt>interval range (e.g. U+400-4ff)
2648 <dd>represented as two hyphen-separated valid Unicode codepoints
2649 indicating the inclusive start and end codepoints of a range
2651 <dt>wildcard range (e.g. U+4??)
2653 <dd>defined by the set of codepoints implied when trailing ‘<code
2654 class=css>?</code>’ characters signify any hexadeximal digit
2655 </dl>
2657 <p>Individual codepoints are written using hexadecimal values that
2658 correspond to <a href="http://www.unicode.org/charts/">Unicode character
2659 codepoints</a>. Valid Unicode codepoint values vary between 0 and 10FFFF
2660 inclusive. Digit values of codepoints are ASCII case-insensitive. For
2661 interval ranges, the start and end codepoints must be valid Unicode values
2662 and the end codepoint must be greater than or equal to the start
2663 codepoint.
2665 <p>Wildcard ranges specified with ‘?’ that lack an initial digit (e.g.
2666 "U+???") are valid and equivalent to a wildcard range with an initial zero
2667 digit (e.g. "U+0???" = "U+0000-0FFF"). Wildcard ranges that extend beyond
2668 the range of valid Unicode codepoints are invalid. Because of this, the
2669 maximum number of trailing ‘<code class=css>?</code>’ wildcard
2670 characters is five, even though the <a
2671 href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><code
2672 title="UNICODE-RANGE token">UNICODE-RANGE</code></a> token accepts six.
2674 <p>Within the comma-delimited list of Unicode ranges in a ‘<a
2675 href="#descdef-unicode-range"><code
2676 class=property>unicode-range</code></a>’ descriptor declaration, ranges
2677 may overlap. The union of these ranges defines the set of codepoints for
2678 which the corresponding font may be used. User agents must not download or
2679 use the font for codepoints outside this set. User agents may normalize
2680 the list of ranges into a list that is different but represents the same
2681 set of codepoints.
2683 <p>The associated font might not contain glyphs for the entire set of
2684 codepoints defined by the ‘<a href="#descdef-unicode-range"><code
2685 class=property>unicode-range</code></a>’ descriptor. When the font is
2686 used the effective <a href="#character-map"><em>character map</em></a> is
2687 the intersection of the codepoints defined by ‘<a
2688 href="#descdef-unicode-range"><code
2689 class=property>unicode-range</code></a>’ with the font's <a
2690 href="#character-map"><em>character map</em></a>. This allows authors to
2691 define supported ranges in terms of broad ranges without worrying about
2692 the precise codepoint ranges supported by the underlying font.
2694 <h3 id=composite-fonts><span class=secno>4.6 </span>Using character ranges
2695 to define composite fonts</h3>
2697 <p>Multiple <a href="#at-font-face-rule"><code>@font-face</code></a> rules
2698 with different unicode ranges for the same family and style descriptor
2699 values can be used to create composite fonts that mix the glyphs from
2700 different fonts for different scripts. This can be used to combine fonts
2701 that only contain glyphs for a single script (e.g. Latin, Greek, Cyrillic)
2702 or it can be used by authors as a way of segmenting a font into fonts for
2703 commonly used characters and less frequently used characters. Since the
2704 user agent will only pull down the fonts it needs this helps reduce page
2705 bandwidth.
2707 <p>If the unicode ranges overlap for a set of <a
2708 href="#at-font-face-rule"><code>@font-face</code></a> rules with the same
2709 family and style descriptor values, the rules are ordered in the reverse
2710 order they were defined; the last rule defined is the first to be checked
2711 for a given character.
2713 <p>Example ranges for specific languages or characters:
2715 <dl>
2716 <dt>unicode-range: U+A5;
2718 <dd>a single code point, the yen/yuan symbol
2720 <dt>unicode-range: U+0-7F;
2722 <dd>code range for basic ASCII characters
2724 <dt>unicode-range: U+590-5ff;
2726 <dd>code range for Hebrew characters
2728 <dt>unicode-range: U+A5, U+4E00-9FFF, U+30??, U+FF00-FF9F;
2730 <dd>code range for Japanese kanji, hiragana and katakana characters plus
2731 yen/yuan symbol
2732 </dl>
2734 <div class=example>
2735 <p>The BBC provides news services in a wide variety of languages, many
2736 that are not well supported across all platforms. Using an <a
2737 href="#at-font-face-rule"><code>@font-face</code></a> rule, the BBC could
2738 provide a font for any of these languages, as it already does via a
2739 manual font download.</p>
2741 <pre>
2742 @font-face {
2743 font-family: BBCBengali;
2744 src: url(fonts/BBCBengali.ttf) format("opentype");
2745 unicode-range: U+00-FF, U+980-9FF;
2746 }
2747 </pre>
2748 </div>
2750 <div class=example>
2751 <p>Technical documents often require a wide range of symbols. The STIX
2752 Fonts project is one project aimed at providing fonts to support a wide
2753 range of technical typesetting in a standardized way. The example below
2754 shows the use of a font that provides glyphs for many of the mathematical
2755 and technical symbol ranges within Unicode:</p>
2757 <pre>
2758 @font-face {
2759 font-family: STIXGeneral;
2760 src: local(STIXGeneral), url(/stixfonts/STIXGeneral.otf);
2761 unicode-range: U+000-49F, U+2000-27FF, U+2900-2BFF, U+1D400-1D7FF;
2762 }
2763 </pre>
2764 </div>
2766 <div class=example>
2767 <p>This example shows how an author can override the glyphs used for Latin
2768 characters in a Japanese font with glyphs from a different font. The
2769 first rule specifies no range so it defaults to the entire range. The
2770 range specified in the second rule overlaps but takes precedence because
2771 it is defined later.</p>
2773 <pre>
2774 @font-face {
2775 font-family: JapaneseWithGentium;
2776 src: local(MSMincho);
2777 /* no range specified, defaults to entire range */
2778 }
2780 @font-face {
2781 font-family: JapaneseWithGentium;
2782 src: url(../fonts/Gentium.ttf);
2783 unicode-range: U+0-2FF;
2784 }
2785 </pre>
2786 </div>
2788 <div class=example>
2789 <p>Consider a family constructed to optimize bandwidth by separating out
2790 Latin, Japanese and other characters into different font files:</p>
2792 <pre>
2793 /* fallback font - size: 4.5MB */
2794 @font-face {
2795 font-family: DroidSans;
2796 src: url(DroidSansFallback.ttf);
2797 /* no range specified, defaults to entire range */
2798 }
2800 /* Japanese glyphs - size: 1.2MB */
2801 @font-face {
2802 font-family: DroidSans;
2803 src: url(DroidSansJapanese.ttf);
2804 unicode-range: U+3000-9FFF, U+ff??;
2805 }
2807 /* Latin, Greek, Cyrillic along with some
2808 punctuation and symbols - size: 190KB */
2809 @font-face {
2810 font-family: DroidSans;
2811 src: url(DroidSans.ttf);
2812 unicode-range: U+000-5FF, U+1e00-1fff, U+2000-2300;
2813 }
2814 </pre>
2816 <p>For simple Latin text, only the font for Latin characters is
2817 downloaded:</p>
2819 <pre>
2820 body { font-family: DroidSans; }
2822 <p>This is that</p>
2823 </pre>
2825 <p>In this case the user agent first checks the unicode-range for the font
2826 containing Latin characters (DroidSans.ttf). Since all the characters
2827 above are in the range U+0-5FF, the user agent downloads the font and
2828 renders the text with that font.</p>
2830 <p>Next, consider text that makes use of an arrow character (⇨):</p>
2832 <pre>
2833 <p>This &#x21e8; that<p>
2834 </pre>
2836 <p>The user agent again first checks the unicode-range of the font
2837 containing Latin characters. Since U+2000-2300 includes the arrow code
2838 point (U+21E8), the user agent downloads the font. For this character
2839 however the Latin font does not have a matching glyph, so the effective
2840 unicode-range used for font matching excludes this code point. Next, the
2841 user agent evaluates the Japanese font. The unicode-range for the
2842 Japanese font, U+3000-9FFF and U+ff??, does not include U+21E8, so the
2843 user agent does not download the Japanese font. Next the fallback font is
2844 considered. The <a href="#at-font-face-rule"><code>@font-face</code></a>
2845 rule for the fallback font does not define unicode-range so its value
2846 defaults to the range of all Unicode code points. The fallback font is
2847 downloaded and used to render the arrow character.</p>
2848 </div>
2850 <h3 id=font-rend-desc><span class=secno>4.7 </span>Font features: the <a
2851 href="#descdef-font-variant">font-variant</a> and <a
2852 href="#descdef-font-feature-settings">font-feature-settings</a>
2853 descriptors</h3>
2855 <table class=descdef>
2856 <tbody>
2857 <tr>
2858 <td>Name:
2860 <td><dfn id=descdef-font-variant
2861 title="font-variant!!descriptor">font-variant</dfn>
2863 <tr>
2864 <td>Value:
2866 <td><a href="#font-variant-normal-value"
2867 title="normal!!font-variant">normal</a> | <a
2868 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
2869 <a href="#common-lig-values"><var><common-lig-values></var></a>
2870 || <a
2871 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
2872 || <a
2873 href="#historical-lig-values"><var><historical-lig-values></var></a>
2874 || <a
2875 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
2876 || <a href="#stylistic"><var
2877 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
2878 href="#historical-forms"><var>historical-forms</var></a> || <a
2879 href="#styleset"><var
2880 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
2881 href="#character-variant"><var
2882 title=character-variant>character-variant(<feature-value-name>
2883 #)</var></a> || <a href="#swash"><var
2884 title=swash>swash(<feature-value-name>)</var></a> || <a
2885 href="#ornaments"><var
2886 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
2887 href="#annotation"><var
2888 title=annotation>annotation(<feature-value-name>)</var></a> || [
2889 <a href="#small-caps"><i>small-caps</i></a> | <a
2890 href="#all-small-caps"><i>all-small-caps</i></a> | <a
2891 href="#petite-caps"><i>petite-caps</i></a> | <a
2892 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
2893 href="#unicase"><i>unicase</i></a> | <a
2894 href="#titling-caps"><i>titling-caps</i></a> ] || <a
2895 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
2896 || <a
2897 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
2898 || <a
2899 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
2900 || <a href="#ordinal"><i>ordinal</i></a> || <a
2901 href="#slashed-zero"><i>slashed-zero</i></a> || <a
2902 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
2903 || <a
2904 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
2905 || <a href="#ruby"><i>ruby</i></a> ]
2907 <tr>
2908 <td><em>Initial:</em>
2910 <td>normal
2911 </table>
2913 <table class=descdef>
2914 <tbody>
2915 <tr>
2916 <td>Name:
2918 <td><dfn id=descdef-font-feature-settings
2919 title="font-feature-settings!!descriptor">font-feature-settings</dfn>
2921 <tr>
2922 <td>Value:
2924 <td><a href="#font-feature-settings-normal-value"
2925 title="normal!!font-feature-settings">normal</a> | <a
2926 href="#feature-tag-value"><var><feature-tag-value></var></a> #
2928 <tr>
2929 <td><em>Initial:</em>
2931 <td>normal
2932 </table>
2934 <p>These descriptors define initial settings that apply when the font
2935 defined by an <a href="#at-font-face-rule"><code>@font-face</code></a>
2936 rule is rendered. They do not affect font selection. Values are identical
2937 to those defined for the corresponding <a href="#propdef-font-variant"
2938 title="font-variant!!property">‘<code
2939 class=property>font-variant</code>’</a> and <a
2940 href="#propdef-font-feature-settings"
2941 title="font-feature-settings!!property">‘<code
2942 class=property>font-feature-settings</code>’</a> properties defined
2943 below except that the value ‘<code class=property>inherit</code>’ is
2944 omitted. When multiple font feature descriptors or properties are used,
2945 the cumulative effect on text rendering is detailed in the section <a
2946 href="#font-feature-resolution">Font Feature Resolution</a> below. In
2947 cases where specific values define synthesized fallback for certain <a
2948 href="#propdef-font-variant" title="font-variant!!property">‘<code
2949 class=property>font-variant</code>’</a> subproperties, the same
2950 synthesized fallback applies when used within those values are used with
2951 the <a href="#descdef-font-style" title="font-style!!descriptor">‘<code
2952 class=property>font-variant</code>’</a> descriptor.
2954 <h3 id=font-face-loading><span class=secno>4.8 </span>Font loading
2955 guidelines</h3>
2957 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule is
2958 designed to allow lazy loading of font resources that are only downloaded
2959 when used within a document. A stylesheet can include <a
2960 href="#at-font-face-rule"><code>@font-face</code></a> rules for a library
2961 of fonts of which only a select set are used; user agents must only
2962 download those fonts that are referred to within the style rules
2963 applicable to a given page. User agents that download all fonts defined in
2964 <a href="#at-font-face-rule"><code>@font-face</code></a> rules without
2965 considering whether those fonts are in fact used within a page are
2966 considered non-conformant. In cases where a font might be downloaded in
2967 character fallback cases, user agents may download a font if it's listed
2968 in a font list but is not actually used for a given text run.
2970 <pre>
2971 @font-face {
2972 font-family: GeometricModern;
2973 src: url(font.ttf);
2974 }
2976 p {
2977 /* font will be downloaded for pages with p elements */
2978 font-family: GeometricModern, sans-serif;
2979 }
2981 h2 {
2982 /* font may be downloaded for pages with h2 elements, even if Futura is available locally */
2983 font-family: Futura, GeometricModern, sans-serif;
2984 }
2985 </pre>
2987 <p>In cases where textual content is loaded before downloadable fonts are
2988 available, user agents may render text as it would be rendered if
2989 downloadable font resources are not available or they may render text
2990 transparently with fallback fonts to avoid a flash of text using a
2991 fallback font. In cases where the font download fails user agents must
2992 display text, simply leaving transparent text is considered non-conformant
2993 behavior. Authors are advised to use fallback fonts in their font lists
2994 that closely match the vertical metrics of the downloadable fonts to avoid
2995 large page reflows where possible.
2997 <h3 id=same-origin-restriction><span class=secno>4.9 </span>Same-origin
2998 restriction for fonts</h3>
3000 <h4 id=default-same-origin-restriction><span class=secno>4.9.1
3001 </span>Default same-origin restriction</h4>
3002 <!-- TPAC 2011 Resolution to require same-origin restriction for loading fonts:
3003 http://lists.w3.org/Archives/Public/www-style/2011Nov/0711.html
3004 http://www.w3.org/2011/10/31-webapps-minutes.html#item02
3005 -->
3007 <p>User agents must implement a same-origin restriction when loading fonts
3008 via the <a href="#at-font-face-rule"><code>@font-face</code></a>
3009 mechanism. This restriction limits the loading of fonts for a given
3010 document to fonts loaded from the same origin. Fonts can only be loaded
3011 via the same host, port, and method combination as the containing
3012 document, using the <a
3013 href="http://www.w3.org/TR/html5/browsers.html#origin">origin matching
3014 algorithm</a> described in the <a href="#HTML5"
3015 rel=biblioentry>[HTML5]<!--{{!HTML5}}--></a> specification. The origin of
3016 the stylesheet containing <a
3017 href="#at-font-face-rule"><code>@font-face</code></a> rules is not used
3018 when deciding whether a font is same origin or not, only the origin of the
3019 containing document is used. The restriction applies to all font types.
3021 <p>Given a document located at http://example.com/page.html, fonts defined
3022 with ‘<a href="#descdef-src"><code class=property>src</code></a>’
3023 definitions considered cross origin must not be loaded:
3025 <pre>
3026 /* same origin (i.e. domain, protocol, port match document) */
3027 src: url(fonts/simple.ttf);
3028 src: url(//fonts/simple.ttf);
3030 /* cross origin, different protocol */
3031 src: url(https://example.com/fonts/simple.ttf);
3033 /* cross origin, different domain */
3034 src: url(http://another.example.com/fonts/simple.ttf);
3035 </pre>
3037 <h4 id=allowing-cross-origin-font-loading><span class=secno>4.9.2
3038 </span>Allowing cross-origin font loading</h4>
3040 <p>User agents must also implement the ability to relax this restriction
3041 using cross-site origin controls <a href="#CORS"
3042 rel=biblioentry>[CORS]<!--{{!CORS}}--></a> for fonts loaded via HTTP.
3043 Sites can explicitly allow cross-site downloading of font data using the
3044 <code>Access-Control-Allow-Origin</code> HTTP header. For other protocols,
3045 no explicit relaxation mechanism is defined or required.
3047 <p>For font loads over HTTP, cross-origin requests must be made with the
3048 following parameter settings which are used in conjunction with the <a
3049 href="http://www.w3.org/TR/cors/#cross-origin-request-0"> <em>cross-origin
3050 request algorithm</em></a> <a href="#CORS"
3051 rel=biblioentry>[CORS]<!--{{!CORS}}--></a>:
3053 <ul>
3054 <li><em>request URL</em> — the URL of the font resource in the <a
3055 href="#descdef-src"><code>src</code></a> descriptor
3057 <li><em>request method</em> — GET
3059 <li><em>author request headers</em> — none
3061 <li><em>request entity body</em> — empty
3063 <li><em>source origin</em> — the origin of the page which linked to the
3064 stylesheet
3066 <li><em>manual redirect flag</em> — false
3068 <li><em>omit credentials flag</em> — true
3070 <li><em>force preflight flag</em> — false
3071 </ul>
3073 <h2 id=font-matching-algorithm><span class=secno>5 </span>Font Matching
3074 Algorithm</h2>
3076 <p>The algorithm below describes how fonts are associated with individual
3077 runs of text. For each character in the run a font family is chosen and a
3078 particular font face is selected containing a glyph for that character.
3080 <h3 id=font-family-casing><span class=secno>5.1 </span>Case sensitivity of
3081 font family names</h3>
3083 <p>As part of the font matching algorithm outlined below, user agents must
3084 match font family names used in style rules with actual font family names
3085 contained in fonts available in a given environment or defined via <a
3086 href="#at-font-face-rule"><code>@font-face</code></a> rules. User agents
3087 must match these names case insensitively, using the "Default Caseless
3088 Matching" algorithm outlined in the Unicode specification <a
3089 href="#UNICODE6" rel=biblioentry>[UNICODE6]<!--{{!UNICODE6}}--></a>. This
3090 algorithm is detailed in section 3.13 entitled "Default Case Algorithms".
3091 Specifically, the algorithm must be applied without normalizing the
3092 strings involved and without applying any language-specific tailorings.
3093 The case folding method specified by this algorithm uses the case mappings
3094 with status field ‘<code class=property>C</code>’ or ‘<code
3095 class=property>F</code>’ in the CaseFolding.txt file of the Unicode
3096 Character Database.
3098 <p class=note> Implementors should take care to verify that a given
3099 caseless string comparison implementation uses this precise algorithm and
3100 not assume that a given platform string matching routine follows it, as
3101 many of these have locale-specific behavior or use some level of string
3102 normalization.
3104 <p class=note> For authors this means that font family names are matched
3105 case insensitively, whether those names exist in a platform font or in the
3106 <a href="#at-font-face-rule"><code>@font-face</code></a> rules contained
3107 in a stylesheet. Authors should take care to ensure that names use a
3108 character sequence consistent with the actual font family name,
3109 particularly when using combining characters such as diacritical marks.
3110 For example, a family name that contains an uppercase A (U+0041) followed
3111 by a combining ring (U+030A) will <strong>not</strong> match a name that
3112 looks identical but which uses the precomposed lowercase a-ring character
3113 (U+00E5) instead of the combining sequence.
3115 <h3 id=font-style-matching><span class=secno>5.2 </span>Matching font
3116 styles</h3>
3118 <p>The procedure for choosing fonts consists of iterating over the font
3119 families determined by the font-family property, selecting a font face
3120 with the appropriate style based on other font properties and then
3121 determining whether a glyph exists for a given character. This is done
3122 using the <dfn id=character-map>character map</dfn> of the font, data
3123 which maps characters to the default glyph for that character. Codepoint
3124 sequences consisting of a base character followed by a sequence of
3125 combining characters are treated slightly differently, see the section on
3126 <a href="#cluster-matching">cluster matching</a> below.
3128 <p>For this procedure, the <dfn id=default-face>default face</dfn> for a
3129 given font family is defined to be the face that would be selected if all
3130 font style properties were set to their initial value.
3132 <ol id=fontmatchingalg>
3133 <li>Using the computed font property values for a given element, the user
3134 agent starts with the first family name in the fontlist specified by the
3135 <a href="#propdef-font-family" title="font-family!!property">‘<code
3136 class=property>font-family</code>’</a> property.
3138 <li>If the family name is unquoted and is a generic family name, the user
3139 agent looks up the appropriate font family name to be used. User agents
3140 may choose the generic font family to use based on the language of the
3141 containing element or the Unicode range of the character.
3143 <li>For other family names, the user agent attempts to find the family
3144 name among fonts defined via <a
3145 href="#at-font-face-rule"><code>@font-face</code></a> rules and then
3146 among available system fonts, matching names with a case-insensitive
3147 comparison as outlined <a href="#font-family-casing">in the section
3148 above</a>. On systems containing fonts with multiple localized font
3149 family names, user agents must match any of these names independent of
3150 the underlying system locale or platform API used. If the font resources
3151 defined for a given face in an <a
3152 href="#at-font-face-rule"><code>@font-face</code></a> rule are either not
3153 available or contain invalid font data, then the face should be treated
3154 as not present in the family. If no faces are present for a family
3155 defined via <a href="#at-font-face-rule"><code>@font-face</code></a>
3156 rules, the family should be treated as missing; matching a platform font
3157 with the same name must not occur in this case.
3159 <li>If a font family match occurs, the user agent assembles the set of
3160 font faces in that family and then narrows the set to a single face using
3161 other font properties in the order given below:
3162 <ol id=fontstylematchingalg>
3163 <li><a href="#propdef-font-stretch"
3164 title="font-stretch!!property">‘<code
3165 class=property>font-stretch</code>’</a> is tried first. If the
3166 matching set contains faces with width values matching the <a
3167 href="#propdef-font-stretch" title="font-stretch!!property">‘<code
3168 class=property>font-stretch</code>’</a> value, faces with other width
3169 values are removed from the matching set. If there is no face that
3170 exactly matches the width value the nearest width is used instead. If
3171 the value of <a href="#propdef-font-stretch"
3172 title="font-stretch!!property">‘<code
3173 class=property>font-stretch</code>’</a> is ‘<a href="#normal"><code
3174 class=property>normal</code></a>’ or one of the condensed values,
3175 narrower width values are checked first, then wider values. If the
3176 value of <a href="#propdef-font-stretch"
3177 title="font-stretch!!property">‘<code
3178 class=property>font-stretch</code>’</a> is one of the expanded
3179 values, wider values are checked first, followed by narrower values.
3180 Once the closest matching width has been determined by this process,
3181 faces with other widths are removed from the matching set.
3183 <li><a href="#propdef-font-style" title="font-style!!property">‘<code
3184 class=property>font-style</code>’</a> is tried next. If the value of
3185 <a href="#propdef-font-style" title="font-style!!property">‘<code
3186 class=property>font-style</code>’</a> is ‘<a href="#italic"><code
3187 class=property>italic</code></a>’, italic faces are checked first,
3188 then oblique, then normal faces. If the value is ‘<a
3189 href="#oblique"><code class=property>oblique</code></a>’, oblique
3190 faces are checked first, then italic faces and then normal faces. If
3191 the value is ‘<a href="#normal"><code
3192 class=property>normal</code></a>’, normal faces are checked first,
3193 then oblique faces, then italic faces. Faces with other style values
3194 are excluded from the matching set. User agents are permitted to
3195 distinguish between italic and oblique faces within platform font
3196 families but this is not required, they may treat all italic or oblique
3197 faces as italic faces. However, within font families defined via <a
3198 href="#at-font-face-rule"><code>@font-face</code></a> rules, italic and
3199 oblique faces must be distinguished using the value of the <a
3200 href="#descdef-font-style" title="font-style!!descriptor">‘<code
3201 class=property>font-style</code>’</a> descriptor.
3203 <li><a href="#propdef-font-weight"
3204 title="font-weight!!property">‘<code
3205 class=property>font-weight</code>’</a> is matched next, it will
3206 always reduce the matching set to a single font face. If bolder/lighter
3207 relative weights are used, the effective weight is calculated based on
3208 the inherited weight value, as described in the definition of the <a
3209 href="#propdef-font-weight" title="font-weight!!property">‘<code
3210 class=property>font-weight</code>’</a> property. Given the desired
3211 weight and the weights of faces in the matching set after the steps
3212 above, if the desired weight is available that face matches. Otherwise,
3213 a weight is chosen using the rules below:
3214 <ul>
3215 <li>If the desired weight is less than 400, weights below the desired
3216 weight are checked in descending order followed by weights above the
3217 desired weight in ascending order until a match is found.
3219 <li>If the desired weight is greater than 500, weights above the
3220 desired weight are checked in ascending order followed by weights
3221 below the desired weight in descending order until a match is found.
3223 <li>If the desired weight is 400, 500 is checked first and then the
3224 rule for desired weights less than 400 is used.
3226 <li>If the desired weight is 500, 400 is checked first and then the
3227 rule for desired weights less than 400 is used.
3228 </ul>
3230 <li><span class=property>‘<a href="#propdef-font-size"><code
3231 class=property>font-size</code></a>’</span> must be matched within a
3232 UA-dependent margin of tolerance. (Typically, sizes for scalable fonts
3233 are rounded to the nearest whole pixel, while the tolerance for
3234 bitmapped fonts could be as large as 20%.) Further computations, e.g.,
3235 by ‘<code class=property>em</code>’ values in other properties, are
3236 based on the <span class=property>‘<a href="#propdef-font-size"><code
3237 class=property>font-size</code></a>’</span> value that is used, not
3238 the one that is specified.
3239 </ol>
3241 <li>
3242 <p>If no matching face exists or the matched face does not contain a
3243 glyph for the character to be rendered, the next family name is selected
3244 and the previous two steps repeated. Glyphs from other faces in the
3245 family are not considered. The only exception is that user agents may
3246 optionally substitute a synthetic version of the <a
3247 href="#default-face"><em>default face</em></a> if that face supports a
3248 given glyph (e.g. a synthetic italic version of the regular face may be
3249 used if the italic face doesn't support glyphs for Arabic).</p>
3250 <!-- resolution on the above: http://lists.w3.org/Archives/Public/www-style/2012Nov/0292.html -->
3252 <p>If the matched font is defined via an <a
3253 href="#at-font-face-rule"><code>@font-face</code></a> rule and needs to
3254 be downloaded, the font resource is downloaded. While the download
3255 occurs, the user agent can either wait until the font is downloaded or
3256 render once with substituted font metrics and render again once the font
3257 is downloaded.</p>
3259 <li>If there are no more font families to be evaluated and no matching
3260 face has been found, then the user agent performs a <em>system font
3261 fallback</em> procedure to find the best match for the character to be
3262 rendered. The result of this procedure may vary across user agents.
3264 <li>If a particular character cannot be displayed using any font, the user
3265 agent should indicate by some means that a character is not being
3266 displayed, displaying either a symbolic representation of the missing
3267 glyph (e.g. using a <a
3268 href="http://en.wikipedia.org/wiki/Last_resort_font">Last Resort
3269 Font</a>) or using the missing character glyph from a default font.
3270 </ol>
3272 <h3 id=cluster-matching><span class=secno>5.3 </span>Cluster matching</h3>
3274 <p>When text contains characters such as combining diacritics, ideally the
3275 base character should be rendered using the same font as the diacritic,
3276 this assures proper placement of the diacritic. For this reason, the font
3277 matching algorithm for clusters is more specialized than the general case
3278 of matching a single character by itself. For sequences containing
3279 variation selectors, which indicate the precise glyph to be used for a
3280 given character, user agents always attempt system font fallback to find
3281 the appropriate glyph before using the default glyph of the base
3282 character.
3284 <p>A font is considered to <em>support</em> a given character if (1) the
3285 character is contained in the font's <a
3286 href="#character-map"><em>character map</em></a> and (2) if required by
3287 the containing script, shaping information is available for that
3288 character. Some legacy fonts may include a given character in the <a
3289 href="#character-map"><em>character map</em></a> but lack the shaping
3290 information (e.g. <a
3291 href="http://www.microsoft.com/typography/otspec/ttochap1.htm">OpenType
3292 layout tables</a> or <a
3293 href="http://scripts.sil.org/cms/scripts/page.php?site_id=projects&item_id=graphite_techAbout">Graphite
3294 tables</a>) necessary for correctly rendering text runs containing that
3295 character.
3297 <p>A sequence of codepoints containing combining diacritics or other
3298 modifiers is termed a grapheme cluster (see <a href="#CSS3TEXT"
3299 rel=biblioentry>[CSS3TEXT]<!--{{CSS3TEXT}}--></a> for a more complete
3300 description). For a given cluster containing a base character, <em>b</em>
3301 and a sequence of combining characters <em>c1, c2…</em>, the entire
3302 cluster is matched using these steps:
3304 <ol>
3305 <li>For each family in the font list, a face is chosen using the style
3306 selection rules defined in the previous section.
3307 <ol>
3308 <li>If all characters in the sequence <em>b + c1 + c2 …</em> are
3309 completely supported by the font, select this font for the sequence.
3311 <li>If a sequence of multiple codepoints is canonically equivalent to a
3312 single character and the font supports that character, select this font
3313 for the sequence.
3314 </ol>
3316 <li>If no font was found in the font list in step 1:
3317 <ol>
3318 <li>If <em>c1</em> is a variation selector, system fallback must be used
3319 to find a font that supports the full sequence of <em>b + c1</em>. If
3320 no font on the system supports the full sequence, match the single
3321 character <em>b</em> using the normal procedure for matching single
3322 characters and ignore the variation selector. Note: a sequence with
3323 more than one variation selector is treated as an encoding error and
3324 the trailing selectors are ignored.
3326 <li>Otherwise, the user agent may optionally use system font fallback to
3327 match a font that supports the entire cluster.
3328 </ol>
3330 <li>If no font is found in step 2, use the matching sequence from step 1
3331 to determine the longest sequence that is completely matched by a font in
3332 the font list and attempt to match the remaining combining characters
3333 separately using the rules for single characters.
3334 </ol>
3336 <h3 id=char-handling-issues><span class=secno>5.4 </span>Character handling
3337 issues</h3>
3339 <p>The procedure above is always performed on text runs containing Unicode
3340 characters, documents using legacy encodings are assumed to have been
3341 transcoded before matching fonts. For fonts containing <a
3342 href="#character-map"><em title="character map">character maps</em></a>
3343 for both legacy encodings and Unicode, the contents of the legacy encoding
3344 <a href="#character-map"><em>character map</em></a> must have no effect on
3345 the results of the font matching process.
3347 <p>The font matching process does not assume that text runs are in either
3348 normalized or denormalized form (see <a href="#CHARMOD-NORM"
3349 rel=biblioentry>[CHARMOD-NORM]<!--{{CHARMOD-NORM}}--></a> for more
3350 details). Layout engines often convert base character plus combining
3351 character sequences into precomposed characters if they exist. The font
3352 matching algorithm outlined here supports both ways and fonts can
3353 generally support either but variations can occur. Authors should always
3354 tailor their choice of fonts to their content, including whether that
3355 content contains normalized or denormalized character streams.
3357 <p>If a given character is a Private-Use Area Unicode codepoint and none of
3358 the fonts in the fontlist contain a glyph for that codepoint, user agents
3359 must display some form of missing glyph symbol for that character rather
3360 than attempting system font fallback for that codepoint. When matching the
3361 replacement character U+FFFD, user agents may skip the font matching
3362 process and immediately display some form of missing glyph symbol, they
3363 are not required to display the glyph from the font that would be selected
3364 by the font matching process.
3366 <p>In general, the fonts for a given family will all have the same or
3367 similar <a href="#character-map"><em title="character map">character
3368 maps</em></a>. The process outlined here is designed to handle even font
3369 families containing faces with widely variant <a href="#character-map"><em
3370 title="character map">character maps</em></a>. However, authors are
3371 cautioned that the use of such families can lead to unexpected results.
3373 <p>Optimizations of this process are allowed provided that an
3374 implementation behaves as if the algorithm had been followed exactly.
3375 Matching occurs in a well-defined order to insure that the results are as
3376 consistent as possible across user agents, given an identical set of
3377 available fonts and rendering technology.
3379 <h3 id=font-matching-changes><span class=secno>5.5 </span>Font matching
3380 changes since CSS 2.1</h3>
3382 <p>The algorithm above is different from CSS 2.1 in a number of key places.
3383 These changes were made to better reflect actual font matching behavior
3384 across user agent implementations.
3386 <p>Differences compared to the font matching algorithm in CSS 2.1:
3388 <ul>
3389 <li>The algorithm includes font-stretch matching.
3391 <li>All possible font-style matching scenarios are delineated.
3393 <li>Small-caps fonts are not matched as part of the font matching process,
3394 they are now handled via font features.
3396 <li>Unicode variation selector matching is required.
3398 <li>Cluster sequences are matched as a unit.
3399 </ul>
3401 <h3 id=font-matching-examples><span class=secno>5.6 </span>Font matching
3402 examples</h3>
3404 <div class=example>
3405 <p>It's useful to note that the CSS selector syntax may be used to create
3406 language-sensitive typography. For example, some Chinese and Japanese
3407 characters are unified to have the same Unicode code point, although the
3408 abstract glyphs are not the same in the two languages.
3410 <pre>*:lang(ja-jp) { font: 900 14pt/16pt "Heisei Mincho W9", serif; }
3411 *:lang(zh-tw) { font: 800 14pt/16.5pt "Li Sung", serif; }
3412 </pre>
3414 <p>This selects any element that has the given language - Japanese or
3415 Traditional Chinese - and uses the appropriate font.
3416 </div>
3418 <h2 id=font-rend-props><span class=secno>6 </span>Font Feature Properties</h2>
3420 <p>Modern font technologies support a variety of advanced typographic and
3421 language-specific font features. Using these features, a single font can
3422 provide glyphs for a wide range of ligatures, contextual and stylistic
3423 alternates, tabular and old-style figures, small capitals, automatic
3424 fractions, swashes, and alternates specific to a given language. To allow
3425 authors control over these font capabilities, the ‘<code
3426 class=property>font-variant</code>’ property has been expanded for CSS3.
3427 It now functions as a shorthand for a set of properties that provide
3428 control over stylistic font features.
3430 <h3 id=glyph-selection-positioning><span class=secno>6.1 </span>Glyph
3431 selection and positioning</h3>
3433 <p>Simple fonts used for displaying Latin text use a very basic processing
3434 model. Fonts contain a <a href="#character-map"><em>character map</em></a>
3435 which maps each character to a glyph for that character. Glyphs for
3436 subsequent characters are simply placed one after the other along a run of
3437 text. Modern font formats such as OpenType and AAT (Apple Advanced
3438 Typography) use a richer processing model. The glyph for a given character
3439 can be chosen and positioned not just based on the codepoint of the
3440 character itself, but also on adjacent characters as well as the language,
3441 script, and features enabled for the text. Font features may be required
3442 for specific scripts, or recommended as enabled by default or they might
3443 be stylistic features meant to be used under author control.
3445 <p>For a good visual overview of these features, see the <a
3446 href="#OPENTYPE-FONT-GUIDE"
3447 rel=biblioentry>[OPENTYPE-FONT-GUIDE]<!--{{OPENTYPE-FONT-GUIDE}}--></a>.
3448 For a detailed description of glyph processing for OpenType fonts, see <a
3449 href="#WINDOWS-GLYPH-PROC"
3450 rel=biblioentry>[WINDOWS-GLYPH-PROC]<!--{{WINDOWS-GLYPH-PROC}}--></a>.
3452 <p>Stylistic font features can be classified into two broad categories:
3453 ones that affect the harmonization of glyph shapes with the surrounding
3454 context, such as kerning and ligature features, and ones such as the
3455 small-caps, subscript/superscript and alternate features that affect shape
3456 selection.
3458 <p>The subproperties of <a href="#propdef-font-variant"
3459 title="font-variant!!property">‘<code
3460 class=property>font-variant</code>’</a> listed below are used to control
3461 these stylistic font features. They do not control features that are
3462 required for displaying certain scripts, such as the OpenType features
3463 used when displaying Arabic or Indic language text. They affect glyph
3464 selection and positioning, but do not affect font selection as described
3465 in the font matching section (except in cases required for compatibility
3466 with CSS 2.1).
3468 <p>To assure consistent behavior across user agents, the equivalent
3469 OpenType property settings are listed for individual properties and are
3470 normative. When using other font formats these should be used as a
3471 guideline to map CSS font feature property values to specific font
3472 features.
3474 <h3 id=language-specific-support><span class=secno>6.2
3475 </span>Language-specific display</h3>
3477 <p>OpenType also supports language-specific glyph selection and
3478 positioning, so that text can be displayed correctly in cases where the
3479 language dictates a specific display behavior. Many languages share a
3480 common script, but the shape of certain letters can vary across those
3481 languages. For example, certain Cyrillic letters have different shapes in
3482 Russian text than in Bulgarian. In Latin text, it's common to render "fi"
3483 with an explicit fi-ligature that lacks a dot on the "i". However, in
3484 languages such as Turkish which uses both a dotted-i and a dotless-i, it's
3485 important to not use this ligature or use a specialized version that
3486 contains a dot over the "i". The example below shows language-specific
3487 variations based on stylistic traditions found in Spanish, Italian and
3488 French orthography:
3490 <div class=featex><img alt="language specific forms, spanish"
3491 src=locl-1.png></div>
3493 <div class=featex><img alt="language specific forms, italian"
3494 src=locl-2.png></div>
3496 <div class=featex><img alt="language specific forms, french"
3497 src=locl-3.png></div>
3499 <p>If the content language of the element is known according to the rules
3500 of the <a
3501 href="http://www.w3.org/TR/CSS21/conform.html#doclanguage">document
3502 language</a>, user agents are required to infer the OpenType language
3503 system from the content language and use that when selecting and
3504 positioning glyphs using an OpenType font.
3506 <p>For OpenType fonts, in some cases it may be necessary to explicitly
3507 declare the OpenType language to be used, for example when displaying text
3508 in a given language that uses the typographic conventions of another
3509 language or when the font does not explicitly support a given language but
3510 supports a language that shares common typographic conventions. The ‘<a
3511 href="#propdef-font-language-override"><code
3512 class=property>font-language-override</code></a>’ property is used for
3513 this purpose.</p>
3514 <!-- prop: font-kerning -->
3516 <h3 id=font-kerning-prop><span class=secno>6.3 </span>Kerning: the <a
3517 href="#propdef-font-kerning">font-kerning</a> property</h3>
3519 <table class=propdef id=namefont-kerningvalueauto-normal-noneini>
3520 <tbody>
3521 <tr>
3522 <td>Name:
3524 <td><dfn id=propdef-font-kerning>font-kerning</dfn>
3526 <tr>
3527 <td>Value:
3529 <td><a href="#font-kerning-auto-value"
3530 title="auto!!font-kerning">auto</a> | <a
3531 href="#font-kerning-normal-value"
3532 title="normal!!font-kerning">normal</a> | <a
3533 href="#font-kerning-none-value" title="none!!font-kerning">none</a>
3535 <tr>
3536 <td>Initial:
3538 <td>auto
3540 <tr>
3541 <td>Applies to:
3543 <td>all elements
3545 <tr>
3546 <td>Inherited:
3548 <td>yes
3550 <tr>
3551 <td>Percentages:
3553 <td>N/A
3555 <tr>
3556 <td>Media:
3558 <td>visual
3560 <tr>
3561 <td>Computed value:
3563 <td>as specified
3565 <tr>
3566 <td>Animatable:
3568 <td>no
3569 </table>
3571 <p>Kerning is the contextual adjustment of inter-glyph spacing. This
3572 property controls metric kerning, kerning that utilizes adjustment data
3573 contained in the font.
3575 <dl>
3576 <dt><dfn id=font-kerning-auto-value title="auto!!font-kerning">auto</dfn>
3578 <dd>Specifies that kerning is applied at the discretion of the user agent
3580 <dt><dfn id=font-kerning-normal-value
3581 title="normal!!font-kerning">normal</dfn>
3583 <dd>Specifies that kerning is applied
3585 <dt><dfn id=font-kerning-none-value title="none!!font-kerning">none</dfn>
3587 <dd>Specifies that kerning is not applied
3588 </dl>
3590 <p>For fonts that do not include kerning data this property will have no
3591 visible effect. When rendering with OpenType fonts, the <a
3592 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>
3593 specification suggests that kerning be enabled by default. When kerning is
3594 enabled, the OpenType <span class=tag>kern</span> feature is enabled (for
3595 vertical text runs the <span class=tag>vkrn</span> feature is enabled
3596 instead). User agents must also support fonts that only support kerning
3597 via data contained in a <span class=tag>kern</span> font table, as
3598 detailed in the OpenType specification. If the ‘<code
3599 class=property>letter-spacing</code>’ property is defined, kerning
3600 adjustments are considered part of the default spacing and letter spacing
3601 adjustments are made after kerning has been applied.
3603 <p>When set to ‘<code class=property>auto</code>’, user agents can
3604 determine whether to apply kerning or not based on a number of factors:
3605 text size, script, or other factors that influence text processing speed.
3606 Authors who want proper kerning should use ‘<a href="#normal"><code
3607 class=property>normal</code></a>’ to explicitly enable kerning.
3608 Likewise, some authors may prefer to disable kerning in situations where
3609 performance is more important than precise appearance. However, in
3610 well-designed modern implementations the use of kerning generally does not
3611 have a large impact on text rendering speed.</p>
3612 <!-- prop: font-variant-ligatures -->
3614 <h3 id=font-variant-ligatures-prop><span class=secno>6.4 </span>Ligatures:
3615 the <a href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
3616 property</h3>
3618 <table class=propdef id=namefont-variant-ligaturesvaluenormal-no>
3619 <tbody>
3620 <tr>
3621 <td>Name:
3623 <td><dfn id=propdef-font-variant-ligatures>font-variant-ligatures</dfn>
3625 <tr>
3626 <td>Value:
3628 <td><a href="#font-variant-ligatures-normal-value"
3629 title="normal!!font-variant-ligatures">normal</a> | <a
3630 href="#font-variant-ligatures-none-value"
3631 title="none!!font-variant-ligatures">none</a> | [ <a
3632 href="#common-lig-values"><var><common-lig-values></var></a> ||
3633 <a
3634 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
3635 || <a
3636 href="#historical-lig-values"><var><historical-lig-values></var></a>
3637 || <a
3638 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
3639 ]
3641 <tr>
3642 <td>Initial:
3644 <td>normal
3646 <tr>
3647 <td>Applies to:
3649 <td>all elements
3651 <tr>
3652 <td>Inherited:
3654 <td>yes
3656 <tr>
3657 <td>Percentages:
3659 <td>N/A
3661 <tr>
3662 <td>Media:
3664 <td>visual
3666 <tr>
3667 <td>Computed value:
3669 <td>as specified
3671 <tr>
3672 <td>Animatable:
3674 <td>no
3675 </table>
3677 <p>Ligatures and contextual forms are ways of combining glyphs to produce
3678 more harmonized forms.
3680 <pre
3681 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>
3683 <pre
3684 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>
3686 <pre
3687 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>
3689 <pre
3690 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>
3692 <p>Individual values have the following meanings:
3694 <dl>
3695 <dt><dfn id=font-variant-ligatures-normal-value
3696 title="normal!!font-variant-ligatures">normal</dfn>
3698 <dd>A value of ‘<a href="#normal"><code
3699 class=property>normal</code></a>’ specifies that common default
3700 features are enabled, <a href="#font-feature-resolution">as described in
3701 detail in the next section</a>. For OpenType fonts, common ligatures and
3702 contextual forms are on by default, discretionary and historical
3703 ligatures are not.
3705 <dt><dfn id=font-variant-ligatures-none-value
3706 title="none!!font-variant-ligatures">none</dfn>
3708 <dd>Specifies that all types of ligatures and contextual forms covered by
3709 this property are explicitly disabled. In situations where ligatures are
3710 not considered necessary, this may improve the speed of text rendering.
3712 <dt><dfn id=common-ligatures>common-ligatures</dfn>
3714 <dd>Enables display of common ligatures (OpenType features: <span
3715 class=tag>liga, clig</span>). For OpenType fonts, common ligatures are
3716 enabled by default.
3717 </dl>
3719 <div class=featex><img alt="common ligature example" src=liga.png></div>
3721 <dl>
3722 <dt><dfn id=no-common-ligatures>no-common-ligatures</dfn>
3724 <dd>Disables display of common ligatures (OpenType features: <span
3725 class=tag>liga, clig</span>).
3727 <dt><dfn id=discretionary-ligatures>discretionary-ligatures</dfn>
3729 <dd>Enables display of discretionary ligatures (OpenType feature: <span
3730 class=tag>dlig</span>). Which ligatures are discretionary or optional is
3731 decided by the type designer, so authors will need to refer to the
3732 documentation of a given font to understand which ligatures are
3733 considered discretionary.
3734 </dl>
3736 <div class=featex><img alt="discretionary ligature example" src=dlig.png></div>
3738 <dl>
3739 <dt><dfn id=no-discretionary-ligatures>no-discretionary-ligatures</dfn>
3741 <dd>Disables display of discretionary ligatures (OpenType feature: <span
3742 class=tag>dlig</span>).
3744 <dt><dfn id=historical-ligatures>historical-ligatures</dfn>
3746 <dd>Enables display of historical ligatures (OpenType feature: <span
3747 class=tag>hlig</span>).
3748 </dl>
3750 <div class=featex><img alt="historical ligature example" src=hlig.png></div>
3752 <dl>
3753 <dt><dfn id=no-historical-ligatures>no-historical-ligatures</dfn>
3755 <dd>Disables display of historical ligatures (OpenType feature: <span
3756 class=tag>hlig</span>).
3758 <dt><dfn id=contextual>contextual</dfn>
3760 <dd>Enables display of contextual alternates (OpenType feature: <span
3761 class=tag>calt</span>). Although not strictly a ligature feature, like
3762 ligatures this feature is commonly used to harmonize the shapes of glyphs
3763 with the surrounding context. For OpenType fonts, this feature is on by
3764 default.
3765 </dl>
3767 <div class=featex><img alt="contextual alternate example" src=calt.png></div>
3769 <dl>
3770 <dt><dfn id=no-contextual>no-contextual</dfn>
3772 <dd>Disables display of contextual alternates (OpenType feature: <span
3773 class=tag>calt</span>).
3774 </dl>
3776 <p>Required ligatures, needed for correctly rendering complex scripts, are
3777 not affected by the settings above, including ‘<code
3778 class=property>none</code>’ (OpenType feature: <span
3779 class=tag>rlig</span>).</p>
3780 <!-- prop: font-variant-position -->
3782 <h3 id=font-variant-position-prop><span class=secno>6.5 </span>Subscript
3783 and superscript forms: the <a
3784 href="#propdef-font-variant-position">font-variant-position</a> property</h3>
3786 <table class=propdef id=namefont-variant-positionvaluenormal-sub>
3787 <tbody>
3788 <tr>
3789 <td>Name:
3791 <td><dfn id=propdef-font-variant-position>font-variant-position</dfn>
3793 <tr>
3794 <td>Value:
3796 <td><span title="normal!!font-variant-position">normal</span> | <a
3797 href="#sub">sub</a> | <a href="#super">super</a>
3799 <tr>
3800 <td>Initial:
3802 <td>normal
3804 <tr>
3805 <td>Applies to:
3807 <td>all elements
3809 <tr>
3810 <td>Inherited:
3812 <td>yes
3814 <tr>
3815 <td>Percentages:
3817 <td>N/A
3819 <tr>
3820 <td>Media:
3822 <td>visual
3824 <tr>
3825 <td>Computed value:
3827 <td>as specified
3829 <tr>
3830 <td>Animatable:
3832 <td>no
3833 </table>
3835 <p>This property is used to enable typographic subscript and superscript
3836 glyphs. These are alternate glyphs designed within the same em-box as
3837 default glyphs and are intended to be laid out on the same baseline as the
3838 default glyphs, with no resizing or repositioning of the baseline. They
3839 are explicitly designed to match the surrounding text and to be more
3840 readable without affecting the line height.
3842 <div class=figure><img alt="comparison between real subscript glyphs and
3843 synthesized ones" src=realsubscripts.png>
3844 <p class=caption>Subscript glyphs (top) vs. typical synthesized subscripts
3845 (bottom)
3846 </div>
3848 <p>Individual values have the following meanings:
3850 <dl>
3851 <dt><dfn id=normal>normal</dfn>
3853 <dd>None of the features listed below are enabled.
3855 <dt><dfn id=sub>sub</dfn>
3857 <dd>Enables display of subscript variants (OpenType feature: <span
3858 class=tag>subs</span>).
3860 <dt><dfn id=super>super</dfn>
3862 <dd>Enables display of superscript variants (OpenType feature: <span
3863 class=tag>sups</span>).
3864 </dl>
3866 <p>Because of the semantic nature of subscripts and superscripts, when the
3867 value is either ‘<a href="#sub"><code class=property>sub</code></a>’
3868 or ‘<a href="#super"><code class=property>super</code></a>’ for a
3869 given contiguous run of text, if a variant glyph is not available for all
3870 the characters in the run, simulated glyphs must be synthesized for all
3871 characters using reduced forms of the glyphs that would be used without
3872 this feature applied. This is done per run to avoid a mixture of variant
3873 glyphs and synthesized ones that would not align correctly. In the case of
3874 OpenType fonts that lack subscript or superscript glyphs for a given
3875 character, user agents must use the appropriate subscript and superscript
3876 metrics specified in the selected font's <a
3877 href="http://www.microsoft.com/typography/otspec/os2.htm#subxs">OS/2
3878 table</a> <a href="#OPENTYPE"
3879 rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a> to calculate the size
3880 and offset of the synthesized substitutes.
3882 <div class=figure><img alt="alternate superscripts vs. glyphs synthesized
3883 using superscript metrics" src=superscript-alt-synth.png>
3884 <p class=caption>Superscript alternate glyph (left), synthesized
3885 superscript glyphs (middle), and incorrect mixture of the two (right)
3886 </div>
3888 <p>In the past, user agents have used font-size and vertical-align to
3889 simulate subscripts and superscripts for the <a class=tag
3890 href="#sub">sub</a> and <span class=tag>sup</span> elements. To allow a
3891 backwards compatible way of defining subscripts and superscripts, it is
3892 recommended that authors use conditional rules <a href="#CSS3-CONDITIONAL"
3893 rel=biblioentry>[CSS3-CONDITIONAL]<!--{{CSS3-CONDITIONAL}}--></a> so that
3894 older user agents will still render subscripts and superscripts via the
3895 older mechanism.
3897 <p>Authors should note that fonts typically only provide subscript and
3898 superscript glyphs for a subset of all characters supported by the font.
3899 For example, while subscript and superscript glyphs are often available
3900 for Latin numbers, glyphs for punctuation and letter characters are less
3901 frequently provided. The synthetic fallback rules defined for this
3902 property assure that subscripts and superscripts will always appear but
3903 the appearance may not match author expectations if the font used does not
3904 provide the appropriate alternate glyph for all characters contained in a
3905 subscript or superscript.
3907 <p>This property is not cumulative. Applying it to elements within a
3908 subscript or superscript won't nest the placement of a subscript or
3909 superscript glyph. Images contained within text runs where the value of
3910 this property is ‘<a href="#sub"><code class=property>sub</code></a>’
3911 or ‘<a href="#super"><code class=property>super</code></a>’ will be
3912 drawn just as they would if the value was ‘<a href="#normal"><code
3913 class=property>normal</code></a>’. Likewise, text decorations such as
3914 underlines or emphasis marks will render in the same position as they
3915 would for the default glyphs, since this property does not affect the
3916 baseline position.
3918 <p class=issue>Some have suggested that text decorations should apply to
3919 the visual baseline of the variant glyphs, rather than the baseline
3920 defined by the font.
3922 <p>Because of these limitations, ‘<a
3923 href="#propdef-font-variant-position"><code
3924 class=property>font-variant-position</code></a>’ is not recommended for
3925 use in user agent stylesheets. Authors should use it in cases where
3926 subscripts or superscripts will only contain the narrow range of
3927 characters supported by the fonts specified.
3929 <div class=example>
3930 <p>A typical user agent default style for the <a class=tag
3931 href="#sub">sub</a> element:</p>
3933 <pre>sub {
3934 vertical-align: sub;
3935 font-size: smaller;
3936 line-height: normal;
3937 }
3938 </pre>
3940 <p>Using font-variant-position to specify typographic subscripts in a way
3941 that will still show subscripts in older user agents:</p>
3943 <pre>@supports ( font-variant-position: sub ) {
3945 sub {
3946 vertical-align: baseline;
3947 font-size: 100%;
3948 line-height: inherit;
3949 font-variant-position: sub;
3950 }
3952 }
3953 </pre>
3955 <p>User agents that support the ‘<a
3956 href="#propdef-font-variant-position"><code
3957 class=property>font-variant-position</code></a>’ property will select a
3958 subscript variant glyph and render this without adjusting the baseline or
3959 font-size. Older user agents will ignore the ‘<a
3960 href="#propdef-font-variant-position"><code
3961 class=property>font-variant-position</code></a>’ property definition
3962 and use the standard defaults for subscripts.</p>
3963 </div>
3964 <!-- prop: font-variant-caps -->
3966 <h3 id=font-variant-caps-prop><span class=secno>6.6 </span>Capitalization:
3967 the <a href="#propdef-font-variant-caps">font-variant-caps</a> property</h3>
3969 <table class=propdef id=namefont-variant-capsvaluenormal-small-c>
3970 <tbody>
3971 <tr>
3972 <td>Name:
3974 <td><dfn id=propdef-font-variant-caps>font-variant-caps</dfn>
3976 <tr>
3977 <td>Value:
3979 <td><a href="#font-variant-caps-normal-value"
3980 title="normal!!font-variant-caps">normal</a> | <a
3981 href="#small-caps">small-caps</a> | <a
3982 href="#all-small-caps">all-small-caps</a> | <a
3983 href="#petite-caps">petite-caps</a> | <a
3984 href="#all-petite-caps">all-petite-caps</a> | <a
3985 href="#unicase">unicase</a> | <a href="#titling-caps">titling-caps</a>
3987 <tr>
3988 <td>Initial:
3990 <td>normal
3992 <tr>
3993 <td>Applies to:
3995 <td>all elements
3997 <tr>
3998 <td>Inherited:
4000 <td>yes
4002 <tr>
4003 <td>Percentages:
4005 <td>N/A
4007 <tr>
4008 <td>Media:
4010 <td>visual
4012 <tr>
4013 <td>Computed value:
4015 <td>as specified
4017 <tr>
4018 <td>Animatable:
4020 <td>no
4021 </table>
4023 <p>This property allows the selection of alternate glyphs used for small or
4024 petite capitals or for titling. These glyphs are specifically designed to
4025 blend well with the surrounding normal glyphs, to maintain the weight and
4026 readability which suffers when text is simply resized to fit this purpose.
4028 <p>Individual values have the following meanings:
4030 <dl>
4031 <dt><dfn id=font-variant-caps-normal-value
4032 title="normal!!font-variant-caps">normal</dfn>
4034 <dd>None of the features listed below are enabled.
4036 <dt><dfn id=small-caps>small-caps</dfn>
4038 <dd>Enables display of small capitals (OpenType feature: <span
4039 class=tag>smcp</span>). Small-caps glyphs typically use the form of
4040 uppercase letters but are reduced to the size of lowercase letters.
4041 </dl>
4043 <div class=featex><img alt="small-caps example" src=smcp.png></div>
4045 <dl>
4046 <dt><dfn id=all-small-caps>all-small-caps</dfn>
4048 <dd>Enables display of small capitals for both upper and lowercase letters
4049 (OpenType features: <span class=tag>c2sc, smcp</span>).
4051 <dt><dfn id=petite-caps>petite-caps</dfn>
4053 <dd>Enables display of petite capitals (OpenType feature: <span
4054 class=tag>pcap</span>).
4056 <dt><dfn id=all-petite-caps>all-petite-caps</dfn>
4058 <dd>Enables display of petite capitals for both upper and lowercase
4059 letters (OpenType features: <span class=tag>c2pc, pcap</span>).
4061 <dt><dfn id=unicase>unicase</dfn>
4063 <dd>Enables display of mixture of small capitals for uppercase letters
4064 with normal lowercase letters (OpenType feature: <span
4065 class=tag>unic</span>).
4067 <dt><dfn id=titling-caps>titling-caps</dfn>
4069 <dd>Enables display of titling capitals (OpenType feature: <span
4070 class=tag>titl</span>). Uppercase letter glyphs are often designed for
4071 use with lowercase letters. When used in all uppercase titling sequences
4072 they can appear too strong. Titling capitals are designed specifically
4073 for this situation.
4074 </dl>
4076 <p>The availability of these glyphs is based on whether a given feature is
4077 defined or not in the feature list of the font. User agents can optionally
4078 decide this on a per-script basis but should explicitly not decide this on
4079 a per-character basis.
4081 <p>Some fonts may only support a subset or none of the features described
4082 for this property. For backwards compatibility with CSS 2.1, if ‘<a
4083 href="#small-caps"><code class=property>small-caps</code></a>’ or ‘<a
4084 href="#all-small-caps"><code class=property>all-small-caps</code></a>’
4085 is specified but small-caps glyphs are not available for a given font,
4086 user agents should simulate a small-caps font, for example by taking a
4087 normal font and replacing the glyphs for lowercase letters with scaled
4088 versions of the glyphs for uppercase characters (replacing the glyphs for
4089 both upper and lowercase letters in the case of ‘<a
4090 href="#all-small-caps"><code class=property>all-small-caps</code></a>’).
4092 <div class=figure style="padding: 0; margin: auto;"><img alt="synthetic vs.
4093 real small-caps" class=hires src=synthetic-vs-real-small-caps.png
4094 width=512px>
4095 <p class=caption>Synthetic vs. real small-caps
4096 </div>
4098 <p>To match the surrounding text, a font may provide alternate glyphs for
4099 caseless characters when these features are enabled but when a user agent
4100 simulates small capitals, it must not attempt to simulate alternates for
4101 codepoints which are considered caseless.
4103 <div class=figure style="padding: 0; margin: auto;"><img alt="caseless
4104 characters with small-caps, all-small-caps enabled" class=hires
4105 src=small-capitals-variations.png width=418px>
4106 <p class=caption>Caseless characters with small-caps, all-small-caps
4107 enabled
4108 </div>
4110 <p>If either ‘<a href="#petite-caps"><code
4111 class=property>petite-caps</code></a>’ or ‘<a
4112 href="#all-petite-caps"><code class=property>all-petite-caps</code></a>’
4113 is specified for a font that doesn't support these features, the property
4114 behaves as if ‘<a href="#small-caps"><code
4115 class=property>small-caps</code></a>’ or ‘<a
4116 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4117 respectively, had been specified. If ‘<a href="#unicase"><code
4118 class=property>unicase</code></a>’ is specified for a font that doesn't
4119 support that feature, the property behaves as if ‘<a
4120 href="#small-caps"><code class=property>small-caps</code></a>’ was
4121 applied only to lowercased uppercase letters. If ‘<a
4122 href="#titling-caps"><code class=property>titling-caps</code></a>’ is
4123 specified with a font that does not support this feature, this property
4124 has no visible effect. When simulated small capital glyphs are used, for
4125 scripts that lack uppercase and lowercase letters, ‘<a
4126 href="#small-caps"><code class=property>small-caps</code></a>’, ‘<a
4127 href="#all-small-caps"><code class=property>all-small-caps</code></a>’,
4128 ‘<a href="#petite-caps"><code class=property>petite-caps</code></a>’,
4129 ‘<a href="#all-petite-caps"><code
4130 class=property>all-petite-caps</code></a>’ and ‘<a
4131 href="#unicase"><code class=property>unicase</code></a>’ have no visible
4132 effect.
4134 <p>When casing transforms are used to simulate small capitals, the casing
4135 transformations must match those used for the <span
4136 class=property>‘<code class=property>text-transform</code>’</span>
4137 property.
4139 <p>As a last resort, unscaled uppercase letter glyphs in a normal font may
4140 replace glyphs in a small-caps font so that the text appears in all
4141 uppercase letters.
4143 <div class=figure style="padding: 0; margin: auto;"><img alt="using
4144 all-small-caps in acronym-laden text" class=hires
4145 src=acronym-laden-text.png width=596px>
4146 <p class=caption>Using small capitals to improve readability in
4147 acronym-laden text
4148 </div>
4150 <div class=example>
4151 <p>Quotes rendered italicised, with small-caps on the first line:</p>
4153 <pre>blockquote { font-style: italic; }
4154 blockquote:first-line { font-variant: small-caps; }
4156 <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>
4157 </pre>
4158 </div>
4159 <!-- prop: font-variant-numeric -->
4161 <h3 id=font-variant-numeric-prop><span class=secno>6.7 </span>Numerical
4162 formatting: the <a
4163 href="#propdef-font-variant-numeric">font-variant-numeric</a> property</h3>
4165 <table class=propdef id=namefont-variant-numericvaluenormal-ltnu>
4166 <tbody>
4167 <tr>
4168 <td>Name:
4170 <td><dfn id=propdef-font-variant-numeric>font-variant-numeric</dfn>
4172 <tr>
4173 <td>Value:
4175 <td><a href="#font-variant-numeric-normal-value"
4176 title="normal!!font-variant-numeric">normal</a> | [ <a
4177 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
4178 || <a
4179 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
4180 || <a
4181 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
4182 || <a href="#ordinal">ordinal</a> || <a
4183 href="#slashed-zero">slashed-zero</a> ]
4185 <tr>
4186 <td>Initial:
4188 <td>normal
4190 <tr>
4191 <td>Applies to:
4193 <td>all elements
4195 <tr>
4196 <td>Inherited:
4198 <td>yes
4200 <tr>
4201 <td>Percentages:
4203 <td>N/A
4205 <tr>
4206 <td>Media:
4208 <td>visual
4210 <tr>
4211 <td>Computed value:
4213 <td>as specified
4215 <tr>
4216 <td>Animatable:
4218 <td>no
4219 </table>
4221 <p>Specifies control over numerical forms. The example below shows how some
4222 of these values can be combined to influence the rendering of tabular data
4223 with fonts that support these features. Within normal paragraph text,
4224 proportional numbers are used while tabular numbers are used so that
4225 columns of numbers line up properly:
4227 <div class=figure style="padding: 0; margin: auto;"><img alt="combining
4228 number styles" src=numberstyles.png>
4229 <p class=caption>Using number styles
4230 </div>
4232 <p>Possible combinations:
4234 <pre
4235 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>
4237 <pre
4238 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>
4240 <pre
4241 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>
4243 <p>Individual values have the following meanings:
4245 <dl>
4246 <dt><dfn id=font-variant-numeric-normal-value
4247 title="normal!!font-variant-numeric">normal</dfn>
4249 <dd>None of the features listed below are enabled.
4251 <dt><dfn id=lining-nums>lining-nums</dfn>
4253 <dd>Enables display of lining numerals (OpenType feature: <span
4254 class=tag>lnum</span>).
4256 <dt><dfn id=oldstyle-nums>oldstyle-nums</dfn>
4258 <dd>Enables display of old-style numerals (OpenType feature: <span
4259 class=tag>onum</span>).
4261 <dt><dfn id=proportional-nums>proportional-nums</dfn>
4263 <dd>Enables display of proportional numerals (OpenType feature: <span
4264 class=tag>pnum</span>).
4266 <dt><dfn id=tabular-nums>tabular-nums</dfn>
4268 <dd>Enables display of tabular numerals (OpenType feature: <span
4269 class=tag>tnum</span>).
4271 <dt><dfn id=diagonal-fractions>diagonal-fractions</dfn>
4273 <dd>Enables display of lining diagonal fractions (OpenType feature: <span
4274 class=tag>frac</span>).
4275 </dl>
4277 <div class=featex><img alt="diagonal fraction example" src=frac.png></div>
4279 <dl>
4280 <dt><dfn id=stacked-fractions>stacked-fractions</dfn>
4282 <dd>Enables display of lining stacked fractions (OpenType feature: <span
4283 class=tag>afrc</span>).
4284 </dl>
4286 <div class=featex><img alt="stacked fraction example" src=afrc.png></div>
4288 <dl>
4289 <dt><dfn id=ordinal>ordinal</dfn>
4291 <dd>Enables display of forms used with ordinal numbers (OpenType feature:
4292 <span class=tag>ordn</span>).
4294 <dt><dfn id=slashed-zero>slashed-zero</dfn>
4296 <dd>Enables display of slashed zeros (OpenType feature: <span
4297 class=tag>zero</span>).
4298 </dl>
4300 <div class=featex><img alt="slashed zero example" src=zero.png></div>
4302 <div class=example id=steak-marinade>
4303 <p>A simple flank steak marinade recipe, rendered with automatic fractions
4304 and old-style numerals:</p>
4306 <pre>.amount { font-variant-numeric: oldstyle-nums diagonal-fractions; }
4308 <h4>Steak marinade:</h4>
4309 <ul>
4310 <li><span class="amount">2</span> tbsp olive oil</li>
4311 <li><span class="amount">1</span> tbsp lemon juice</li>
4312 <li><span class="amount">1</span> tbsp soy sauce</li>
4313 <li><span class="amount">1 1/2</span> tbsp dry minced onion</li>
4314 <li><span class="amount">2 1/2</span> tsp italian seasoning</li>
4315 <li>Salt &amp; pepper</li>
4316 </ul>
4318 <p>Mix the meat with the marinade and let it sit covered in the refrigerator
4319 for a few hours or overnight.</p>
4320 </pre>
4322 <p>Note that the fraction feature is only applied to values not the entire
4323 paragraph. Fonts often implement this feature using contextual rules
4324 based on the use of the slash (‘<code class=css>/</code>’) character.
4325 As such, it's not suitable for use as a paragraph-level style.</p>
4326 </div>
4327 <!-- prop: font-variant-alternates -->
4329 <h3 id=font-variant-alternates-prop><span class=secno>6.8 </span>Alternates
4330 and swashes: the <a
4331 href="#propdef-font-variant-alternates">font-variant-alternates</a>
4332 property</h3>
4334 <table class=propdef id=namefont-variant-alternatesvaluenormal-s>
4335 <tbody>
4336 <tr>
4337 <td>Name:
4339 <td><dfn
4340 id=propdef-font-variant-alternates>font-variant-alternates</dfn>
4342 <tr>
4343 <td>Value:
4345 <td>normal | [ <a href="#stylistic"
4346 title=stylistic>stylistic(<feature-value-name>)</a> || <a
4347 href="#historical-forms">historical-forms</a> || <a href="#styleset"
4348 title=styleset>styleset(<feature-value-name> #)</a> || <a
4349 href="#character-variant"
4350 title=character-variant>character-variant(<feature-value-name>
4351 #)</a> || <a href="#swash"
4352 title=swash>swash(<feature-value-name>)</a> || <a
4353 href="#ornaments"
4354 title=ornaments>ornaments(<feature-value-name>)</a> || <a
4355 href="#annotation"
4356 title=annotation>annotation(<feature-value-name>)</a> ]
4358 <tr>
4359 <td>Initial:
4361 <td>normal
4363 <tr>
4364 <td>Applies to:
4366 <td>all elements
4368 <tr>
4369 <td>Inherited:
4371 <td>yes
4373 <tr>
4374 <td>Percentages:
4376 <td>N/A
4378 <tr>
4379 <td>Media:
4381 <td>visual
4383 <tr>
4384 <td>Computed value:
4386 <td>as specified
4388 <tr>
4389 <td>Animatable:
4391 <td>no
4392 </table>
4394 <p>For any given character, fonts can provide a variety of alternate glyphs
4395 in addition to the default glyph for that character. This property
4396 provides control over the selection of these alternate glyphs.
4398 <p>For many of the property values listed below, several different
4399 alternate glyphs are available. How many alternates are available and what
4400 they represent is font-specific, so these are each marked <em>font
4401 specific</em> in the value definitions below. Because the nature of these
4402 alternates is font-specific, the <a
4403 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4404 rule is used to define values for a specific font family or set of
4405 families that associate a font-specific numeric
4406 <code><feature-index></code> with a custom
4407 <code><feature-value-name></code>, which is then used in this
4408 property to select specific alternates:
4410 <pre>@font-feature-values Noble Script { @swash { swishy: 1; flowing: 2; } }
4412 p {
4413 font-family: Noble Script;
4414 font-variant-alternates: swash(flowing); /* use swash alternate #2 */
4415 }</pre>
4417 <p>When a particular <code><feature-value-name></code> has not been
4418 defined for a given family or for a particular feature type, the computed
4419 value must be the same as if it had been defined. However, property values
4420 that contain these undefined <code><feature-value-name></code>
4421 identifiers must be ignored when choosing glyphs.
4423 <pre>/* these two style rules are effectively the same */
4424 p { font-variant-alternates: swash(unknown-value); } /* not a defined value, ignored */
4425 p { font-variant-alternates: normal; }
4426 </pre>
4428 <p>This allows values to be defined and used for a given set of font
4429 families but ignored if fallback occurs, since the font family name would
4430 be different. If a given value is outside the range supported by a given
4431 font, the value is ignored. These values never apply to generic font
4432 families.
4434 <p>Individual values have the following meanings:
4436 <dl>
4437 <dt><dfn id=font-variant-alternates-normal-value
4438 title="normal!!font-variant-alternates">normal</dfn>
4440 <dd>None of the features listed below are enabled.
4442 <dt><dfn id=historical-forms>historical-forms</dfn>
4444 <dd>Enables display of historical forms (OpenType feature: <span
4445 class=tag>hist</span>).
4446 </dl>
4448 <div class=featex><img alt="historical form example" src=hist.png></div>
4450 <dl>
4451 <dt><dfn id=stylistic
4452 title=stylistic>stylistic(<feature-value-name>)</dfn>
4454 <dd>Enables display of stylistic alternates (<em>font specific</em>,
4455 OpenType feature: <span class=tag>salt <feature-index></span>).
4456 </dl>
4458 <div class=featex><img alt="stylistic alternate example" src=salt.png></div>
4460 <dl>
4461 <dt><dfn id=styleset title=styleset>styleset(<feature-value-name>
4462 #)</dfn>
4464 <dd>Enables display with stylistic sets (<em>font specific</em>, OpenType
4465 feature: <span class=tag>ss<feature-index></span> OpenType
4466 currently defines <span class=tag>ss01</span> through <span
4467 class=tag>ss20</span>).
4468 </dl>
4470 <div class=featex><img alt="styleset example" src=ssnn.png></div>
4472 <dl>
4473 <dt><dfn id=character-variant
4474 title=character-variant>character-variant(<feature-value-name>
4475 #)</dfn>
4477 <dd>Enables display of specific character variants (<em>font
4478 specific</em>, OpenType feature: <span
4479 class=tag>cv<feature-index></span> OpenType currently defines <span
4480 class=tag>cv01</span> through <span class=tag>cv99</span>).
4482 <dt><dfn id=swash title=swash>swash(<feature-value-name>)</dfn>
4484 <dd>Enables display of swash glyphs (<em>font specific</em>, OpenType
4485 feature: <span class=tag>swsh <feature-index>, cswh
4486 <feature-index></span>).
4487 </dl>
4489 <div class=featex><img alt="swash example" src=swsh.png></div>
4491 <dl>
4492 <dt><dfn id=ornaments
4493 title=ornaments>ornaments(<feature-value-name>)</dfn>
4495 <dd>Enables replacement of default glyphs with ornaments, if provided in
4496 the font (<em>font specific</em>, OpenType feature: <span class=tag>ornm
4497 <feature-index></span>). Some fonts may offer ornament glyphs as
4498 alternates for a wide collection of characters; however, displaying
4499 arbitrary characters (e.g., alphanumerics) as ornaments is poor practice
4500 as it distorts the semantics of the data. Font designers are encouraged
4501 to encode all ornaments (except those explicitly encoded in the Unicode
4502 Dingbats blocks, etc.) as alternates for the bullet character (U+2022) to
4503 allow authors to select the desired glyph using ‘<a
4504 href="#ornaments"><code class=property>ornaments</code></a>’.
4505 </dl>
4507 <div class=featex><img alt="ornaments example" src=ornm.png></div>
4509 <dl>
4510 <dt><dfn id=annotation
4511 title=annotation>annotation(<feature-value-name>)</dfn>
4513 <dd>Enables display of alternate annotation forms (<em>font specific</em>,
4514 OpenType feature: <span class=tag>nalt <feature-index></span>).
4515 </dl>
4517 <div class=featex><img alt="alternate annotation form example"
4518 src=nalt.png></div>
4520 <h3 id=font-feature-values><span class=secno>6.9 </span>Defining font
4521 specific alternates: the <dfn id=at-font-feature-values-rule
4522 style="font-weight: inherit; font-style:
4523 inherit"><code>@font-feature-values</code></dfn> rule</h3>
4525 <p>Several of the possible values of ‘<a
4526 href="#propdef-font-variant-alternates"><code
4527 class=property>font-variant-alternates</code></a>’ listed above are
4528 labeled as "font specific". For these features fonts may define not just a
4529 single glyph but a set of alternate glyphs with an index to select a given
4530 alternate. Since these are font family specific, the <a
4531 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4532 rule is used to define named-values for these indices for a given family.
4534 <p>In the case of the swash Q in the example shown above, the swash could
4535 be specified using these style rules:
4537 <pre>
4539 @font-feature-values Jupiter Sans {
4540 @swash {
4541 delicate: 1;
4542 flowing: 2;
4543 }
4544 }
4546 h2 { font-family: Jupiter Sans, sans-serif; }
4548 /* show the second swash variant in h2 headings */
4549 h2:first-letter { font-variant-alternates: swash(flowing); }
4551 <h2>Quick</h2></pre>
4553 <p>When Jupiter Sans is present, the second alternate swash alternate will
4554 be displayed. When not present, no swash character will be shown, since
4555 the specific named-value "flowing" is only defined for the Jupiter Sans
4556 family. The @-mark indicates the name of the property value for which a
4557 named-value can be used. The name "flowing" is chosen by the author, the
4558 values specified within a given font's data.
4560 <p>In terms of the grammar, this specification defines the following
4561 productions:
4563 <pre><dfn id=fontfeaturevaluesrule>font_feature_values_rule</dfn>
4564 : <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>*
4565 '{' <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>*
4566 ;
4568 <dfn id=fontfamilynamelist>font_family_name_list</dfn>
4569 : <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> ]*
4570 ;
4572 <dfn id=fontfamilyname>font_family_name</dfn>
4573 : <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> ]* ]
4574 ;
4576 <dfn id=featurevalueblock>feature_value_block</dfn>
4577 : <a href="#featuretype"><i>feature_type</i></a> <a href="http://www.w3.org/TR/CSS21/grammar.html#scanner"><i>S</i></a>*
4578 '{' <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>*
4579 ;
4581 <dfn id=featuretype>feature_type</dfn>:
4582 <a href="http://www.w3.org/TR/CSS21/syndata.html#tokenization"><i>ATKEYWORD</i></a>
4583 ;
4585 <dfn id=featurevaluedefinition>feature_value_definition</dfn>
4586 : <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> ]*
4587 ;
4588 </pre>
4590 <p>The following new token is introduced:
4592 <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>;}
4593 </pre>
4595 <p>Feature value blocks are treated <a
4596 href="http://www.w3.org/TR/CSS2/syndata.html#at-rules">similar to
4597 at-rules</a>, they consist of everything up to the next block or
4598 semi-colon, whichever comes first.
4600 <p>Font feature values rules define a set of values for a specific font
4601 feature as used for a given set of families. Effectively, they define a
4602 mapping of ⟨family, feature, ident⟩ → ⟨values⟩ where
4603 ⟨values⟩ are the indices used for specific features defined for a
4604 given font.
4606 <p>The font family list uses the same syntax as that used for the <a
4607 href="#propdef-font-family" title="font-family!!property">‘<code
4608 class=property>font-family</code>’</a> property. Within feature value
4609 blocks, the feature type is ‘<code class=css>@</code>’ followed by the
4610 name of the font-specific property value (e.g. <a
4611 href="#swash"><code>@swash</code></a>). The feature type must match, using
4612 an ASCII case-insensitive comparison, one of the <em>font specific</em>
4613 values of the ‘<a href="#propdef-font-variant-alternates"><code
4614 class=property>font-variant-alternates</code></a>’ property. The values
4615 associated with a given idenitifier are limited to integer values 0 or
4616 greater.
4618 <p>If syntax errors occur within the font family list, the entire rule must
4619 be ignored. When syntax errors occur within a feature value definition,
4620 such as invalid identifiers or values, the entire feature value definition
4621 must be omitted, similar to the way syntax errors in style declarations
4622 are handled. When the <code><feature-type></code> is invalid, the
4623 entire associated feature value block must be ignored.
4625 <pre>@font-feature-values Bongo {
4626 @swash { ornate: 1; }
4627 annotation { boxed: 4; } /* should be @annotation! */
4628 @swash { double-loops: 1; flowing: -1; } /* negative value */
4629 @ornaments ; /* incomplete definition */
4630 @styleset { double-W: 14; sharp-terminals: 16 1 } /* missing ; */
4631 <a href="http://www.angryalien.com/0504/shiningbunnies.html" style="text-decoration: none;">redrum</a> /* random editing mistake */
4632 }</pre>
4634 <p>The example above is equivalent to:
4636 <pre>@font-feature-values Bongo {
4637 @swash { ornate: 1; }
4638 @swash { double-loops: 1; }
4639 @styleset { double-W: 14; sharp-terminals: 16 1; }
4640 }</pre>
4642 <p>If multiple <a
4643 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
4644 rules are defined for a given family, the resulting values defined are the
4645 union of these rules. This allows a set of named-values to be defined for
4646 a given font family globally for a site and specific additions made
4647 per-page. If the same <feature-value-name> is defined mulitple times
4648 for a given <a href="#propdef-font-variant"
4649 title="font-variant!!property">‘<code
4650 class=property>font-variant</code>’</a> value, the last defined value is
4651 used.
4653 <pre>
4654 site.css:
4656 @font-feature-values Mercury Serif {
4657 @styleset {
4658 stacked-g: 3; /* "two-storey" versions of g, a */
4659 stacked-a: 4;
4660 }
4661 }
4663 page.css:
4665 @font-feature-values Mercury Serif {
4666 @styleset {
4667 geometric-m: 7; /* alternate version of m */
4668 }
4669 }
4671 body {
4672 font-family: Mercury Serif, serif;
4674 /* enable both the use of stacked g and alternate m */
4675 font-variant-alternates: styleset(stacked-g, geometric-m);
4676 }</pre>
4678 <p>Only named font families are allowed for <font-family>, rules that
4679 include generic or system fonts in the list of font families are
4680 considered syntax errors and the contents of the rules are ignored.
4681 However, if a user agent defines a generic font to be a specific named
4682 font (e.g. Helvetica), the settings associated with that family name will
4683 be used.
4685 <p>For <font-variant-property-value>, only font specific property value
4686 names supported by the <a href="#propdef-font-variant"
4687 title="font-variant!!property">‘<code
4688 class=property>font-variant</code>’</a> property are recognized,
4689 definitions for other value names cause a syntax error and are ignored.
4690 Each property value that is font specific is clearly marked as such.
4691 Feature value names follow the rules of CSS user identifiers and are
4692 case-sensitive. They are unique only for a given set of font families and
4693 <a href="#propdef-font-variant" title="font-variant!!property">‘<code
4694 class=property>font-variant</code>’</a> property value; the same
4695 identifier used with a different <a href="#propdef-font-variant"
4696 title="font-variant!!property">‘<code
4697 class=property>font-variant</code>’</a> property value is treated as a
4698 separate and distinct value.
4700 <p>Using a commonly named value allows authors to use a single style rule
4701 to cover a set of fonts for which the underlying selector is different for
4702 each font. If either font in the example below is found, a circled number
4703 glyph will be used:
4705 <pre>@font-feature-values Taisho Gothic {
4706 @annotation { boxed: 1; circled: 4; }
4707 }
4709 @font-feature-values Otaru Kisa {
4710 @annotation { circled: 1; black-boxed: 3; }
4711 }
4713 h3.title {
4714 /* circled form defined for both fonts */
4715 font-family: Taisho Gothic, Otaru Kisa;
4716 font-variant: annotation(circled);
4717 }</pre>
4719 <p>Most font specific <a href="#propdef-font-variant"
4720 title="font-variant!!property">‘<code
4721 class=property>font-variant</code>’</a> property values take a single
4722 value (e.g. swash). The character-variant property value allows two values
4723 and styleset allows an unlimited number. If a larger number of values are
4724 assigned to a given name, a syntax error occurs and the entire
4725 <font-feature-values-declaration> is ignored.
4727 <p>For the styleset property value, multiple values indicate the style sets
4728 to be enabled. Values between 1 and 99 enable OpenType features <span
4729 class=tag>ss01</span> through <span class=tag>ss99</span>. However, the
4730 OpenType standard only officially defines <span class=tag>ss01</span>
4731 through <span class=tag>ss20</span>. Values greater than 99 or equal to 0
4732 are ignored but do not generate a syntax error when parsed.
4734 <pre>@font-feature-values Mars Serif {
4735 @styleset {
4736 alt-g: 1; /* implies ss01 = 1 */
4737 curly-quotes: 3; /* implies ss03 = 1 */
4738 code: 4 5; /* implies ss04 = 1, ss05 = 1 */
4739 }
4741 @styleset {
4742 dumb: 125; /* >99, ignored */
4743 }
4745 @swash {
4746 swishy: 3 5; /* more than 1 value for swash, syntax error */
4747 }
4748 }
4750 p.codeblock {
4751 /* implies ss03 = 1, ss04 = 1, ss05 = 1 */
4752 font-variant-alternates: styleset(curly-quotes, code);
4753 }</pre>
4755 <p>For character-variant, a single value between 1 and 99 indicates the
4756 enabling of OpenType feature <span class=tag>cv01</span> through <span
4757 class=tag>cv99</span>. For OpenType fonts, values greater than 99 or equal
4758 to 0 are ignored but do not generate a syntax error when parsed. When two
4759 values are listed, the first value indicates the feature used and the
4760 second the value passed for that feature. When two value names imply
4761 different settings for the same underlying feature the last setting is
4762 used.
4764 <pre>@font-feature-values MM Greek {
4765 @character-variant { alpha-2: 1 2; } /* implies cv01 = 2 */
4766 @character-variant { beta-3: 2 3; } /* implies cv02 = 3 */
4767 @character-variant { epsilon: 5 3 6; } /* more than 2 values, syntax error, ignored */
4768 @character-variant { gamma: 12; } /* implies cv12 = 1 */
4769 @character-variant { zeta: 20 3; } /* implies cv20 = 3 */
4770 @character-variant { zeta-2: 20 2; } /* implies cv20 = 2 */
4771 @character-variant { silly: 105; } /* >99, ignored */
4772 @character-variant { dumb: 323 3; } /* >99, ignored */
4773 }
4775 #title {
4776 /* use the third alternate beta, first alternate gamma */
4777 font-variant-alternates: character-variant(beta-3, gamma);
4778 }
4780 p {
4781 /* zeta-2 follows zeta, implies cv20 = 2 */
4782 font-variant-alternates: character-variant(zeta, zeta-2);
4783 }
4785 .special {
4786 /* zeta follows zeta-2, implies cv20 = 3 */
4787 font-variant-alternates: character-variant(zeta-2, zeta);
4788 }</pre>
4790 <p>See the <a href="#om-fontfeaturevalues">object model reference
4791 section</a> for a description of the interfaces used to modify these rules
4792 via the CSS Object Model.
4794 <div class=figure><img alt="Matching text on Byzantine seals using
4795 character variants" src=byzantineseal.png>
4796 <p class=caption>Byzantine seal text displayed with character variants
4797 </div>
4799 <div class=example>
4800 <p>In the figure above, the text in red is rendered using a font
4801 containing character variants that mimic the character forms found on a
4802 Byzantine seal from the 8th century A.D. Two lines below is the same text
4803 displayed in a font without variants. Note the two variants for U and N
4804 used on the seal.</p>
4806 <pre>@font-feature-values Athena Ruby {
4807 @character-variant {
4808 leo-B: 2 1;
4809 leo-M: 13 3;
4810 leo-alt-N: 14 1;
4811 leo-N: 14 2;
4812 leo-T: 20 1;
4813 leo-U: 21 2;
4814 leo-alt-U: 21 4;
4815 }
4816 }
4818 p {
4819 font-variant: discretionary-ligatures,
4820 character-variant(leo-B, leo-M, leo-N, leo-T, leo-U);
4821 }
4823 span.alt-N {
4824 font-variant-alternates: character-variant(leo-alt-N);
4825 }
4827 span.alt-U {
4828 font-variant-alternates: character-variant(leo-alt-U);
4829 }
4831 <p>ENO....UP͞RSTU<span class="alt-U">U</span>͞<span class="alt-U">U</span>ΚΑΙTỤẠG̣IUPNS</p>
4833 <p>LEON|ΚΑΙCONSTA|NTI<span class="alt-N">N</span>OS..|STOIBAṢ.|LIṢROM|AIO<span class="alt-N">N</span></p>
4834 </pre>
4835 </div>
4837 <h3 id=font-variant-east-asian-prop><span class=secno>6.10 </span>East
4838 Asian text rendering: the <a
4839 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
4840 property</h3>
4842 <table class=propdef id=namefont-variant-east-asianvaluenormal-l>
4843 <tbody>
4844 <tr>
4845 <td>Name:
4847 <td><dfn
4848 id=propdef-font-variant-east-asian>font-variant-east-asian</dfn>
4850 <tr>
4851 <td>Value:
4853 <td><a href="#font-variant-east-asian-normal-value"
4854 title="normal!!font-variant-east-asian">normal</a> | [ <a
4855 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
4856 || <a
4857 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
4858 || <a href="#ruby">ruby</a> ]
4860 <tr>
4861 <td>Initial:
4863 <td>normal
4865 <tr>
4866 <td>Applies to:
4868 <td>all elements
4870 <tr>
4871 <td>Inherited:
4873 <td>yes
4875 <tr>
4876 <td>Percentages:
4878 <td>N/A
4880 <tr>
4881 <td>Media:
4883 <td>visual
4885 <tr>
4886 <td>Computed value:
4888 <td>as specified
4890 <tr>
4891 <td>Animatable:
4893 <td>no
4894 </table>
4896 <p>Allows control of glyph substitution and sizing in East Asian text.
4898 <pre
4899 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>
4901 <pre
4902 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>
4904 <p>Individual values have the following meanings:
4906 <dl>
4907 <dt><dfn id=font-variant-east-asian-normal-value
4908 title="normal!!font-variant-east-asian">normal</dfn>
4910 <dd>None of the features listed below are enabled.
4912 <dt><dfn id=jis78>jis78</dfn>
4914 <dd>Enables rendering of JIS78 forms (OpenType feature: <span
4915 class=tag>jp78</span>).
4916 </dl>
4918 <div class=featex><img alt="JIS78 form example" src=jp78.png></div>
4920 <dl>
4921 <dt><dfn id=jis83>jis83</dfn>
4923 <dd>Enables rendering of JIS83 forms (OpenType feature: <span
4924 class=tag>jp83</span>).
4926 <dt><dfn id=jis90>jis90</dfn>
4928 <dd>Enables rendering of JIS90 forms (OpenType feature: <span
4929 class=tag>jp90</span>).
4931 <dt><dfn id=jis04>jis04</dfn>
4933 <dd>Enables rendering of JIS2004 forms (OpenType feature: <span
4934 class=tag>jp04</span>).
4935 <p>The various JIS variants reflect the glyph forms defined in different
4936 Japanese national standards. Fonts generally include glyphs defined by
4937 the most recent national standard but it's sometimes necessary to use
4938 older variants, to match signage for example.</p>
4940 <dt><dfn id=simplified>simplified</dfn>
4942 <dd>Enables rendering of simplified forms (OpenType feature: <span
4943 class=tag>smpl</span>).
4945 <dt><dfn id=traditional>traditional</dfn>
4947 <dd>Enables rendering of traditional forms (OpenType feature: <span
4948 class=tag>trad</span>).
4949 </dl>
4951 <p>The ‘<a href="#simplified"><code
4952 class=property>simplified</code></a>’ and ‘<a
4953 href="#traditional"><code class=property>traditional</code></a>’ values
4954 allow control over the glyph forms for characters which have been
4955 simplified over time but for which the older, traditional form is still
4956 used in some contexts. The exact set of characters and glyph forms will
4957 vary to some degree by context for which a given font was designed.
4959 <div class=featex><img alt="tradtional form example" src=trad.png></div>
4961 <dl>
4962 <dt><dfn id=full-width>full-width</dfn>
4964 <dd>Enables rendering of full-width variants (OpenType feature: <span
4965 class=tag>fwid</span>).
4967 <dt><dfn id=proportional-width>proportional-width</dfn>
4969 <dd>Enables rendering of proportionally-spaced variants (OpenType feature:
4970 <span class=tag>pwid</span>).
4971 </dl>
4973 <div class=featex><img alt="proportionally spaced Japanese example"
4974 src=pwid.png></div>
4976 <dl>
4977 <dt><dfn id=ruby>ruby</dfn>
4979 <dd>Enables display of ruby variant glyphs (OpenType feature: <span
4980 class=tag>ruby</span>). Since ruby text is generally smaller than the
4981 associated body text, font designers can design special glyphs for use
4982 with ruby that are more readable than scaled down versions of the default
4983 glyphs. Only glyph selection is affected, there is no associated font
4984 scaling or other change that affects line layout. The red ruby text below
4985 is shown with default glyphs (top) and with ruby variant glyphs (bottom).
4986 Note the slight difference in stroke thickness.
4987 </dl>
4989 <div class=featex><img alt="ruby variant example" src=rubyshinkansen.png></div>
4991 <h3 id=font-variant-prop><span class=secno>6.11 </span>Overall shorthand
4992 for font rendering: the <a href="#propdef-font-variant">font-variant</a>
4993 property</h3>
4995 <table class=propdef id=namefont-variantvaluenormal-none-ltcommo>
4996 <tbody>
4997 <tr>
4998 <td>Name:
5000 <td><dfn id=propdef-font-variant
5001 title="font-variant!!property">font-variant</dfn>
5003 <tr>
5004 <td>Value:
5006 <td><a href="#font-variant-normal-value"
5007 title="normal!!font-variant">normal</a> | <a
5008 href="#font-variant-none-value" title="none!!font-variant">none</a> | [
5009 <a href="#common-lig-values"><var><common-lig-values></var></a>
5010 || <a
5011 href="#discretionary-lig-values"><var><discretionary-lig-values></var></a>
5012 || <a
5013 href="#historical-lig-values"><var><historical-lig-values></var></a>
5014 || <a
5015 href="#contextual-alt-values"><var><contextual-alt-values></var></a>
5016 || <a href="#stylistic"><var
5017 title=stylistic>stylistic(<feature-value-name>)</var></a> || <a
5018 href="#historical-forms"><var>historical-forms</var></a> || <a
5019 href="#styleset"><var
5020 title=styleset>styleset(<feature-value-name> #)</var></a> || <a
5021 href="#character-variant"><var
5022 title=character-variant>character-variant(<feature-value-name>
5023 #)</var></a> || <a href="#swash"><var
5024 title=swash>swash(<feature-value-name>)</var></a> || <a
5025 href="#ornaments"><var
5026 title=ornaments>ornaments(<feature-value-name>)</var></a> || <a
5027 href="#annotation"><var
5028 title=annotation>annotation(<feature-value-name>)</var></a> || [
5029 <a href="#small-caps"><i>small-caps</i></a> | <a
5030 href="#all-small-caps"><i>all-small-caps</i></a> | <a
5031 href="#petite-caps"><i>petite-caps</i></a> | <a
5032 href="#all-petite-caps"><i>all-petite-caps</i></a> | <a
5033 href="#unicase"><i>unicase</i></a> | <a
5034 href="#titling-caps"><i>titling-caps</i></a> ] || <a
5035 href="#numeric-figure-values"><var><numeric-figure-values></var></a>
5036 || <a
5037 href="#numeric-spacing-values"><var><numeric-spacing-values></var></a>
5038 || <a
5039 href="#numeric-fraction-values"><var><numeric-fraction-values></var></a>
5040 || <a href="#ordinal"><i>ordinal</i></a> || <a
5041 href="#slashed-zero"><i>slashed-zero</i></a> || <a
5042 href="#east-asian-variant-values"><var><east-asian-variant-values></var></a>
5043 || <a
5044 href="#east-asian-width-values"><var><east-asian-width-values></var></a>
5045 || <a href="#ruby"><i>ruby</i></a> ]
5047 <tr>
5048 <td>Initial:
5050 <td>normal
5052 <tr>
5053 <td>Applies to:
5055 <td>all elements
5057 <tr>
5058 <td>Inherited:
5060 <td>yes
5062 <tr>
5063 <td>Percentages:
5065 <td>see individual properties
5067 <tr>
5068 <td>Media:
5070 <td>visual
5072 <tr>
5073 <td>Computed value:
5075 <td>see individual properties
5077 <tr>
5078 <td>Animatable:
5080 <td>see individual properties
5081 </table>
5083 <p>The <a href="#propdef-font-variant"
5084 title="font-variant!!property">‘<code
5085 class=property>font-variant</code>’</a> property is a shorthand for all
5086 font-variant subproperties. The value <dfn id=font-variant-normal-value
5087 title="normal!!font-variant">‘<code
5088 class=property>normal</code>’</dfn> resets all subproperties of <a
5089 href="#propdef-font-variant" title="font-variant!!property">‘<code
5090 class=property>font-variant</code>’</a> to their inital value. The <dfn
5091 id=font-variant-none-value title="none!!font-variant">‘<code
5092 class=property>none</code>’</dfn> value sets ‘<a
5093 href="#propdef-font-variant-ligatures"><code
5094 class=property>font-variant-ligatures</code></a>’ to ‘<code
5095 class=property>none</code>’ and resets all other font feature properties
5096 to their initial value. Like other shorthands, using <a
5097 href="#propdef-font-variant" title="font-variant!!property">‘<code
5098 class=property>font-variant</code>’</a> resets unspecified <a
5099 href="#propdef-font-variant" title="font-variant!!property">‘<code
5100 class=property>font-variant</code>’</a> subproperties to their initial
5101 values. It does not reset the values of either ‘<a
5102 href="#propdef-font-language-override"><code
5103 class=property>font-language-override</code></a>’ or <a
5104 href="#propdef-font-feature-settings"
5105 title="font-feature-settings!!property">‘<code
5106 class=property>font-feature-settings</code>’</a>.
5108 <h3 id=font-feature-settings-prop><span class=secno>6.12 </span>Low-level
5109 font feature settings control: the <a
5110 href="#propdef-font-feature-settings">font-feature-settings</a> property</h3>
5112 <table class=propdef id=namefont-feature-settingsvaluenormal-ltf>
5113 <tbody>
5114 <tr>
5115 <td>Name:
5117 <td><dfn id=propdef-font-feature-settings
5118 title="font-feature-settings!!property">font-feature-settings</dfn>
5120 <tr>
5121 <td>Value:
5123 <td><a href="#font-feature-settings-normal-value"
5124 title="normal!!font-feature-settings">normal</a> | <a
5125 href="#feature-tag-value"><var><feature-tag-value></var></a> #
5127 <tr>
5128 <td>Initial:
5130 <td>normal
5132 <tr>
5133 <td>Applies to:
5135 <td>all elements
5137 <tr>
5138 <td>Inherited:
5140 <td>yes
5142 <tr>
5143 <td>Percentages:
5145 <td>N/A
5147 <tr>
5148 <td>Media:
5150 <td>visual
5152 <tr>
5153 <td>Computed value:
5155 <td>as specified
5157 <tr>
5158 <td>Animatable:
5160 <td>no
5161 </table>
5163 <p>This property provides low-level control over OpenType font features. It
5164 is intended as a way of providing access to font features that are not
5165 widely used but are needed for a particular use case.
5167 <p>Authors should generally use <a href="#propdef-font-variant"
5168 title="font-variant!!property">‘<code
5169 class=property>font-variant</code>’</a> and its related subproperties
5170 whenever possible and only use this property for special cases where its
5171 use is the only way of accessing a particular infrequently used font
5172 feature.
5174 <pre>/* enable small caps and use second swash alternate */
5175 font-feature-settings: "smcp", "swsh" 2;</pre>
5177 <p>A value of <dfn id=font-feature-settings-normal-value
5178 title="normal!!font-feature-settings">‘<code
5179 class=property>normal</code>’</dfn> means that no change in glyph
5180 selection or positioning occurs due to this property.
5182 <p>Feature tag values have the following syntax:
5184 <pre
5185 class=prod><dfn id=feature-tag-value><var><feature-tag-value></var></dfn> = <string> [ <integer> | on | off ]?</pre>
5187 <p>The <string> is a case-sensitive OpenType feature tag. As
5188 specified in the OpenType specification, feature tags contain four ASCII
5189 characters. Tag strings longer or shorter than four characters, or
5190 containing characters outside the U+20–7E codepoint range are invalid.
5191 Feature tags need only match a feature tag defined in the font, so they
5192 are not limited to explicitly registered OpenType features. Fonts defining
5193 custom feature tags should follow the <a
5194 href="http://www.microsoft.com/typography/otspec/featuretags.htm">tag name
5195 rules</a> defined in the OpenType specification <a
5196 href="#OPENTYPE-FEATURES"
5197 rel=biblioentry>[OPENTYPE-FEATURES]<!--{{!OPENTYPE-FEATURES}}--></a>.
5198 Feature tags not present in the font are ignored; a user agent must not
5199 attempt to synthesize fallback behavior based on these feature tags.
5201 <p>This means that explicitly disabling the <span class=tag>kern</span>
5202 feature will not affect the application of kerning data found in the
5203 ‘<code class=property>kern</code>’ table (as opposed to kerning data
5204 associated with the <span class=tag>kern</span> feature in the ‘<code
5205 class=property>GPOS</code>’ table). Authors should use the ‘<a
5206 href="#propdef-font-kerning"><code
5207 class=property>font-kerning</code></a>’ property to explictly enable or
5208 disable kerning since this property affects both types of kerning.
5210 <p>If present, a value indicates an index used for glyph selection. An
5211 <integer> value must be 0 or greater. A value of 0 indicates that
5212 the feature is disabled. For boolean features, a value of 1 enables the
5213 feature. For non-boolean features, a value of 1 or greater enables the
5214 feature and indicates the feature selection index. A value of ‘<code
5215 class=property>on</code>’ is synonymous with 1 and ‘<code
5216 class=property>off</code>’ is synonymous with 0. If the value is
5217 omitted, a value of 1 is assumed.
5219 <pre>
5220 font-feature-settings: "dlig" 1; /* dlig=1 enable discretionary ligatures */
5221 font-feature-settings: "smcp" on; /* smcp=1 enable small caps */
5222 font-feature-settings: 'c2sc'; /* c2sc=1 enable caps to small caps */
5223 font-feature-settings: "liga" off; /* liga=0 no common ligatures */
5224 font-feature-settings: "tnum", 'hist'; /* tnum=1, hist=1 enable tabular numbers and historical forms */
5225 font-feature-settings: "tnum" "hist"; /* invalid, need a comma-delimited list */
5226 font-feature-settings: "palin" off; /* good idea but invalid tagname */
5227 font-feature-settings: "PKRN"; /* PKRN=1 enable custom feature */
5228 font-feature-settings: dlig; /* invalid, tag must be a string */
5229 </pre>
5231 <p>When values greater than the range supported by the font are specified,
5232 the behavior is explicitly undefined. For boolean features, in general
5233 these will enable the feature. For non-boolean features, out of range
5234 values will in general be equivalent to a 0 value. However, in both cases
5235 the exact behavior will depend upon the way the font is designed
5236 (specifically, which type of lookup is used to define the feature).
5238 <p>Although specifically defined for OpenType feature tags, feature tags
5239 for other modern font formats that support font features may be added in
5240 the future. Where possible, features defined for other font formats should
5241 attempt to follow the pattern of registered OpenType tags.
5243 <div class=example>
5244 <p>The Japanese text below will be rendered with half-width kana
5245 characters:</p>
5247 <pre lang=ja>
5248 body { font-feature-settings: "hwid"; /* Half-width OpenType feature */ }
5250 <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>
5251 </pre>
5252 </div>
5254 <h3 id=font-language-override-prop><span class=secno>6.13 </span>Font
5255 language override: the <a
5256 href="#propdef-font-language-override">font-language-override</a> property</h3>
5258 <table class=propdef id=namefont-language-overridevaluenormal-lt>
5259 <tbody>
5260 <tr>
5261 <td>Name:
5263 <td><dfn id=propdef-font-language-override>font-language-override</dfn>
5265 <tr>
5266 <td>Value:
5268 <td><a href="#font-language-override-normal-value"
5269 title="normal!!font-language-override">normal</a> | <a
5270 href="#font-language-override-string-value"><var><string></var></a>
5272 <tr>
5273 <td>Initial:
5275 <td><a href="#font-language-override-normal-value"
5276 title="normal!!font-language-override">normal</a>
5278 <tr>
5279 <td>Applies to:
5281 <td>all elements
5283 <tr>
5284 <td>Inherited:
5286 <td>yes
5288 <tr>
5289 <td>Percentages:
5291 <td>N/A
5293 <tr>
5294 <td>Media:
5296 <td>visual
5298 <tr>
5299 <td>Computed value:
5301 <td>as specified
5303 <tr>
5304 <td>Animatable:
5306 <td>no
5307 </table>
5309 <p>Normally, authors can control the use of language-specific glyph
5310 substitutions and positioning by setting the content language of an
5311 element, as <a href="#language-specific-support">described above</a>:
5313 <pre><!-- Display text using S'gaw Karen specific features -->
5314 <p lang="ksw">...</p></pre>
5316 <p>In some cases, authors may need to specify a language system that
5317 differs from the content language, for example due to the need to mimic
5318 another language's typographic traditions. The ‘<a
5319 href="#propdef-font-language-override"><code
5320 class=property>font-language-override</code></a>’ property allows
5321 authors to explicitly specify the language system of the font, overriding
5322 the language system implied by the content language.
5324 <p>Values have the following meanings:
5326 <dl>
5327 <dt><dfn id=font-language-override-normal-value
5328 title="normal!!font-language-override">normal</dfn>
5330 <dd>specifies that when rendering with OpenType fonts, the content
5331 language of the element is used to infer the OpenType language system
5333 <dt><dfn
5334 id=font-language-override-string-value><var><string></var></dfn>
5336 <dd>single three-letter OpenType <a
5337 href="http://www.microsoft.com/typography/otspec/languagetags.htm">language
5338 system tag</a>, specifies the OpenType language system to be used instead
5339 of the language system implied by the language of the element
5340 </dl>
5342 <p>Use of invalid OpenType language system tags must not generate a parse
5343 error but must be ignored when doing glyph selection and placement.
5345 <div class=example>
5346 <p>The <a href="http://www.un.org/en/documents/udhr/index.shtml">Universal
5347 Declaration of Human Rights</a> has been translated into a wide variety
5348 of languages. In Turkish, Article 9 of this document might be marked up
5349 as below:</p>
5351 <pre lang=tr><body lang="tr">
5353 <h4>Madde 9</h4>
5354 <p>Hiç kimse keyfi olarak tutuklanamaz, alıkonulanamaz veya sürülemez.</p>
5355 </pre>
5357 <p>Here the user agent uses the value of the ‘<code
5358 class=property>lang</code>’ attribute when rendering text and
5359 appropriately renders this text without ‘<code
5360 class=property>fi</code>’ ligatures. There is no need to use the ‘<a
5361 href="#propdef-font-language-override"><code
5362 class=property>font-language-override</code></a>’ property.</p>
5364 <p>However, a given font may lack support for a specific language. In this
5365 situation authors may need to use the typographic conventions of a
5366 related language that are supported by that font:</p>
5368 <pre lang=mk><body lang="mk"> <!-- Macedonian lang code -->
5370 body { font-language-override: "SRB"; /* Serbian OpenType language tag */ }
5372 <h4>Члeн 9</h4>
5373 <p>Никoj чoвeк нeмa дa бидe пoдлoжeн нa прoизвoлнo aпсeњe, притвoр или прoгoнувaњe.</p>
5375 </pre>
5377 <p>The Macedonian text here will be rendered using Serbian typographic
5378 conventions, with the assumption that the font specified supports
5379 Serbian.</p>
5380 </div>
5382 <p><a id=rendering-considerations></a>
5384 <h2 id=font-feature-resolution><span class=secno>7 </span>Font Feature
5385 Resolution</h2>
5387 <p>As described in the previous section, font features can be enabled in a
5388 variety of ways, either via the use of <a href="#propdef-font-variant"
5389 title="font-variant!!property">‘<code
5390 class=property>font-variant</code>’</a> or <a
5391 href="#propdef-font-feature-settings"
5392 title="font-feature-settings!!property">‘<code
5393 class=property>font-feature-settings</code>’</a> in a style rule or
5394 within an <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5395 The resolution order for the union of these settings is defined below.
5396 Features defined via CSS properties are applied on top of layout engine
5397 default features.
5399 <h3 id=default-features><span class=secno>7.1 </span>Default features</h3>
5401 <p>For OpenType fonts, user agents must enable the default features defined
5402 in the OpenType documentation for a given script and writing mode.
5403 Required ligatures, common ligatures and contextual forms must be enabled
5404 by default (OpenType features: <span class=tag>rlig, liga, clig,
5405 calt</span>), along with localized forms (OpenType feature: <span
5406 class=tag>locl</span>), and features required for proper display of
5407 composed characters and marks (OpenType features: <span class=tag>ccmp,
5408 mark, mkmk</span>). These features must always be enabled, even when the
5409 value of the <a href="#propdef-font-variant"
5410 title="font-variant!!property">‘<code
5411 class=property>font-variant</code>’</a> and <a
5412 href="#propdef-font-feature-settings"
5413 title="font-feature-settings!!property">‘<code
5414 class=property>font-feature-settings</code>’</a> properties is ‘<a
5415 href="#normal"><code class=property>normal</code></a>’. Individual
5416 features are only disabled when explicitly overridden by the author, as
5417 when ‘<a href="#propdef-font-variant-ligatures"><code
5418 class=property>font-variant-ligatures</code></a>’ is set to ‘<a
5419 href="#no-common-ligatures"><code
5420 class=property>no-common-ligatures</code></a>’. For handling complex
5421 scripts such as <a
5422 href="http://www.microsoft.com/typography/otfntdev/arabicot/features.aspx">Arabic</a>,
5423 <a
5424 href="http://www.microsoft.com/typography/otfntdev/mongolot/features.htm">Mongolian</a>
5425 or <a
5426 href="http://www.microsoft.com/typography/otfntdev/devanot/features.aspx">Devanagari</a>
5427 additional features are required. For upright text within vertical text
5428 runs, vertical alternates (OpenType feature: <span class=tag>vert</span>)
5429 must be enabled.
5431 <h3 id=feature-precedence><span class=secno>7.2 </span>Feature precedence</h3>
5433 <p>General and font specific font feature property settings are resolved in
5434 the order below, in ascending precedence order. This ordering is used to
5435 construct a combined list of font features that affect a given text run.
5437 <ol>
5438 <li>Font features enabled by default, including features required for a
5439 given script.
5441 <li>If the font is defined via an <a
5442 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5443 features implied by the font-variant descriptor in the <a
5444 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5446 <li>If the font is defined via an <a
5447 href="#at-font-face-rule"><code>@font-face</code></a> rule, the font
5448 features implied by the font-feature-settings descriptor in the <a
5449 href="#at-font-face-rule"><code>@font-face</code></a> rule.
5451 <li>Feature settings determined by properties other than <a
5452 href="#propdef-font-variant" title="font-variant!!property">‘<code
5453 class=property>font-variant</code>’</a> or <a
5454 href="#propdef-font-feature-settings"
5455 title="font-feature-settings!!property">‘<code
5456 class=property>font-feature-settings</code>’</a>. For example, setting
5457 a non-default value for the ‘<code
5458 class=property>letter-spacing</code>’ property disables ligatures.
5460 <li>Font features implied by the value of the <a
5461 href="#propdef-font-variant" title="font-variant!!property">‘<code
5462 class=property>font-variant</code>’</a> property, the related <a
5463 href="#propdef-font-variant" title="font-variant!!property">‘<code
5464 class=property>font-variant</code>’</a> subproperties and any other CSS
5465 property that may use OpenType features (e.g. the ‘<a
5466 href="#propdef-font-kerning"><code
5467 class=property>font-kerning</code></a>’ property).
5469 <li>Font features implied by the value of <a
5470 href="#propdef-font-feature-settings"
5471 title="font-feature-settings!!property">‘<code
5472 class=property>font-feature-settings</code>’</a> property.
5473 </ol>
5475 <p>This ordering allows authors to set up a general set of defaults for
5476 fonts within their <a
5477 href="#at-font-face-rule"><code>@font-face</code></a> rules, then override
5478 them with property settings for specific elements. General property
5479 settings override the settings in <a
5480 href="#at-font-face-rule"><code>@font-face</code></a> rules and low-level
5481 font feature settings override <a href="#propdef-font-variant"
5482 title="font-variant!!property">‘<code
5483 class=property>font-variant</code>’</a> property settings.
5485 <p>For situations where the combined list of font feature settings contains
5486 more than one value for the same feature, the last value is used. When a
5487 font lacks support for a given underlying font feature, text is simply
5488 rendered as if that font feature was not enabled; font fallback does not
5489 occur and no attempt is made to synthesize the feature except where
5490 explicitly noted for specific properties.
5492 <h3 id=feature-precedence-examples><span class=secno>7.3 </span>Feature
5493 precedence examples</h3>
5495 <div class=example>
5496 <p>With the styles below, numbers are rendered proportionally when used
5497 within a paragraph but are shown in tabular form within tables of prices:</p>
5499 <pre>body {
5500 font-variant-numeric: proportional-nums;
5501 }
5503 table.prices td {
5504 font-variant-numeric: tabular-nums;
5505 }
5506 </pre>
5507 </div>
5509 <div class=example>
5510 <p>When the font-variant descriptor is used within an <a
5511 href="#at-font-face-rule"><code>@font-face</code></a> rule, it only
5512 applies to the font defined by that rule.</p>
5514 <pre>@font-face {
5515 font-family: MainText;
5516 src: url(http://example.com/font.ttf);
5517 font-variant: oldstyle-nums proportional-nums styleset(1,3);
5518 }
5520 body {
5521 font-family: MainText, Helvetica;
5522 }
5524 table.prices td {
5525 font-variant-numeric: tabular-nums;
5526 }
5527 </pre>
5529 <p>In this case, old-style numerals will be used throughout but only where
5530 the font "MainText" is used. Just as in the previous example, tabular
5531 values will be used in price tables since ‘<a
5532 href="#tabular-nums"><code class=property>tabular-nums</code></a>’
5533 appears in a general style rule and its use is mutually exclusive with
5534 ‘<a href="#proportional-nums"><code
5535 class=property>proportional-nums</code></a>’. Stylistic alternate sets
5536 will only be used where MainText is used.</p>
5537 </div>
5539 <div class=example>
5540 <p>The <a href="#at-font-face-rule"><code>@font-face</code></a> rule can
5541 also be used to access font features in locally available fonts via the
5542 use of <code>local()</code> in the ‘<a href="#descdef-src"><code
5543 class=property>src</code></a>’ descriptor of the <a
5544 href="#at-font-face-rule"><code>@font-face</code></a> definition:</p>
5546 <pre>@font-face {
5547 font-family: BodyText;
5548 src: local("HiraMaruPro-W4");
5549 font-variant: proportional-width;
5550 font-feature-settings: "ital"; /* Latin italics within CJK text feature */
5551 }
5553 body { font-family: BodyText, serif; }
5554 </pre>
5556 <p>If available, a Japanese font "Hiragino Maru Gothic" will be used. When
5557 text rendering occurs, Japanese kana will be proportionally spaced and
5558 Latin text will be italicised. Text rendered with the fallback serif font
5559 will use default rendering properties.</p>
5560 </div>
5562 <div class=example>
5563 <p>In the example below, discretionary ligatures are enabled only for a
5564 downloadable font but are disabled within spans of class "special":</p>
5566 <pre>@font-face {
5567 font-family: main;
5568 src: url(fonts/ffmeta.woff) format("woff");
5569 font-variant: discretionary-ligatures;
5570 }
5572 body { font-family: main, Helvetica; }
5573 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5574 </pre>
5576 <p>Adding an discretionary style rule with the <a
5577 href="#at-font-face-rule"><code>@font-face</code></a> above:</p>
5579 <pre>body { font-family: main, Helvetica; }
5580 span { font-feature-settings: "dlig"; }
5581 span.special { font-variant-ligatures: no-discretionary-ligatures; }
5582 </pre>
5584 <p>Within spans of class "special", discretionary ligatures <em>will</em>
5585 be rendered. This is because both the <a
5586 href="#propdef-font-feature-settings"
5587 title="font-feature-settings!!property">‘<code
5588 class=property>font-feature-settings</code>’</a> and ‘<a
5589 href="#propdef-font-variant-ligatures"><code
5590 class=property>font-variant-ligatures</code></a>’ properties apply to
5591 these spans. Although the ‘<code class=css>no-discretionary
5592 ligatures</code>’ setting of ‘<a
5593 href="#propdef-font-variant-ligatures"><code
5594 class=property>font-variant-ligatures</code></a>’ effectively disables
5595 the OpenType <span class=tag>dlig</span> feature, because the <a
5596 href="#propdef-font-feature-settings"
5597 title="font-feature-settings!!property">‘<code
5598 class=property>font-feature-settings</code>’</a> is resolved after
5599 that, the ‘<code class=property>dlig</code>’ value reenables
5600 discretionary ligatures.</p>
5601 </div>
5603 <h2 id=object-model><span class=secno>8 </span>Object Model</h2>
5605 <p>The contents of <a href="#at-font-face-rule"><code>@font-face</code></a>
5606 and <a
5607 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5608 rules can be accessed via the following extensions to the CSS Object
5609 Model.
5611 <h3 id=om-fontface><span class=secno>8.1 </span>The <a
5612 href="#cssfontfacerule"><code>CSSFontFaceRule</code></a> interface</h3>
5614 <p>The <dfn id=cssfontfacerule>CSSFontFaceRule</dfn> interface represents a
5615 <a href="#at-font-face-rule"><code>@font-face</code></a> rule.
5617 <pre class=idl>
5618 interface CSSFontFaceRule : CSSRule {
5619 attribute DOMString family;
5620 attribute DOMString src;
5621 attribute DOMString style;
5622 attribute DOMString weight;
5623 attribute DOMString stretch;
5624 attribute DOMString unicodeRange;
5625 attribute DOMString variant;
5626 attribute DOMString featureSettings;
5627 }</pre>
5629 <p>The DOM Level 2 Style specification <a href="#DOM-LEVEL-2-STYLE"
5630 rel=biblioentry>[DOM-LEVEL-2-STYLE]<!--{{DOM-LEVEL-2-STYLE}}--></a>
5631 defined a different variant of this rule. This definition supercedes that
5632 one.
5634 <h3 id=om-fontfeaturevalues><span class=secno>8.2 </span>The <a
5635 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5636 interface</h3>
5638 <p>The <code>CSSRule</code> interface is extended as follows:
5640 <pre class=idl>partial interface CSSRule {
5641 const unsigned short FONT_FEATURE_VALUES_RULE = 14;
5642 }</pre>
5644 <p>The <dfn id=cssfontfeaturevaluesrule>CSSFontFeatureValuesRule</dfn>
5645 interface represents a <a
5646 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5647 rule.
5649 <pre class=idl>interface CSSFontFeatureValuesRule : CSSRule {
5650 readonly attribute DOMString familyList;
5651 readonly attribute DOMString valueText;
5652 };</pre>
5654 <dl class=idl-attributes>
5655 <dt><var>familyList</var> of type <code>DOMString</code>, readonly
5657 <dd>The list of one or more font families for which a given set of feature
5658 values is defined.
5660 <dt><var>valueText</var> of type <code>DOMString</code>, readonly
5662 <dd>Serialized set of feature values.
5663 </dl>
5665 <p class=issue>Should this be extended to make <a
5666 href="#cssfontfeaturevaluesrule"><code>CSSFontFeatureValuesRule</code></a>
5667 be a subclass of <code>CSSGroupingRule</code> with other CSSRule
5668 subclasses for each value definition block?
5670 <h2 class=no-num id=platform-props-to-css>Appendix A: Mapping platform font
5671 properties to CSS properties</h2>
5673 <p><em>This appendix is included as background for some of the problems and
5674 situations that are described in other sections. It should be viewed as
5675 informative only.</em>
5677 <p>Font properties in CSS are designed to be independent of the underlying
5678 font formats used; they can be used to specify bitmap fonts, Type1 fonts,
5679 SVG fonts in addition to the common TrueType and OpenType fonts. But there
5680 are facets of the TrueType and OpenType formats that often cause confusion
5681 for authors and present challenges to implementers on different platforms.
5683 <p>Originally developed at Apple, TrueType was designed as an outline font
5684 format for both screen and print. Microsoft joined Apple in developing the
5685 TrueType format and both platforms have supported TrueType fonts since
5686 then. Font data in the TrueType format consists of a set of tables
5687 distinguished with common four-letter tag names, each containing a
5688 specific type of data. For example, naming information, including
5689 copyright and license information, is stored in the ‘<code
5690 class=property>name</code>’ table. The <a
5691 href="#character-map"><em>character map</em></a> (‘<code
5692 class=property>cmap</code>’) table contains a mapping of character
5693 encodings to glyphs. Apple later added additional tables for supporting
5694 enhanced typographic functionality; these are now called Apple Advanced
5695 Typography, or AAT, fonts. Microsoft and Adobe developed a separate set of
5696 tables for advanced typography and called their format OpenType <a
5697 href="#OPENTYPE" rel=biblioentry>[OPENTYPE]<!--{{!OPENTYPE}}--></a>.
5699 <p>In many cases the font data used under Microsoft Windows or Linux is
5700 slightly different from the data used under Apple's Mac OS X because the
5701 TrueType format allowed for explicit variation across platforms. This
5702 includes font metrics, names and <a href="#character-map"><em>character
5703 map</em></a> data.
5705 <p>Specifically, font family name data is handled differently across
5706 platforms. For TrueType and OpenType fonts these names are contained in
5707 the ‘<code class=property>name</code>’ table, in name records with
5708 name ID 1. Mulitple names can be stored for different locales, but
5709 Microsoft recommends fonts always include at least a US English version of
5710 the name. On Windows, Microsoft made the decision for backwards
5711 compatibility to limit this family name to a maximum of four faces; for
5712 larger groupings the "preferred family" (name ID 16) or "WWS family" (name
5713 ID 21) can be used. Other platforms such as OSX don't have this
5714 limitation, so the family name is used to define all possible groupings.
5716 <p>Other name table data provides names used to uniquely identify a
5717 specific face within a family. The full font name (name ID 4) and the
5718 Postscript name (name ID 6) describe a single face uniquely. For example,
5719 the bold face of the Gill Sans family has a fullname of "Gill Sans Bold"
5720 and a Postscript name of "GillSans-Bold". There can be multiple localized
5721 versions of the fullname for a given face, but the Postscript name is
5722 always a unique name made from a limited set of ASCII characters.
5724 <p>On various platforms, different names are used to search for a font. For
5725 example, with the Windows GDI CreateIndirectFont API, either a family or
5726 fullname can be used to lookup a face, while on Mac OS X the
5727 CTFontCreateWithName API call is used to lookup a given face using the
5728 fullname and Postscript name. Under Linux, the fontconfig API allows fonts
5729 to be searched using any of these names. In situations where platform
5730 API's automatically substitute other font choices, it may be necessary to
5731 verify a returned font matches a given name.
5733 <p>The weight of a given face can be determined via the usWeightClass field
5734 of the OS/2 table or inferred from the style name (name ID 2). Likewise,
5735 the width can be determined via the usWidthClass of the OS/2 table or
5736 inferred from the style name. For historical reasons related to synthetic
5737 bolding at weights 200 or lower with the Windows GDI API, font designers
5738 have sometimes skewed values in the OS/2 table to avoid these weights.
5740 <p>Rendering complex scripts that use contextual shaping such as Thai,
5741 Arabic and Devanagari requires features present only in OpenType or AAT
5742 fonts. Currently, complex script rendering is supported on Windows and
5743 Linux using OpenType font features while both OpenType and AAT font
5744 features are used under Mac OS X.
5746 <h2 class=no-num id=ch-ch-ch-changes>Changes</h2>
5748 <h3 class=no-num id=recent-changes> Changes from the <a
5749 href="http://www.w3.org/TR/2013/WD-css3-fonts-20130212/">February 2013
5750 CSS3 Fonts Working Draft</a></h3>
5752 <p>Major changes include:
5754 <ul>
5755 <li>Moved font load events into a separate <a
5756 href="http://dev.w3.org/csswg/css3-font-load-events/">spec</a>
5758 <li>Tightened error handling rules for <a
5759 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5760 rules
5762 <li>Added grammar productions for <a
5763 href="#at-font-face-rule"><code>@font-face</code></a> and <a
5764 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5765 rules
5767 <li>Tightened definition of synthetic oblique
5769 <li>Revised definition of ‘<a href="#descdef-unicode-range"><code
5770 class=property>unicode-range</code></a>’ descriptor
5771 </ul>
5773 <h2 class=no-num id=acknowledgments>Acknowledgments</h2>
5775 <p>I'd like to thank Tal Leming, Jonathan Kew and Christopher Slye for all
5776 their help and feedback. John Hudson was kind enough to take the time to
5777 explain the subtleties of OpenType language tags and provided the example
5778 of character variant usage for displaying text on Byzantine seals. Ken
5779 Lunde and Eric Muller provided valuable feedback on CJK OpenType features
5780 and Unicode variation selectors. The idea for supporting font features by
5781 using <a href="#propdef-font-variant"
5782 title="font-variant!!property">‘<code
5783 class=property>font-variant</code>’</a> subproperties originated with
5784 Håkon Wium Lie, Adam Twardoch and Tal Leming. Elika Etemad supplied some
5785 of the initial design ideas for the <a
5786 href="#at-font-feature-values-rule"><code>@font-feature-values</code></a>
5787 rule. Thanks also to House Industries for allowing the use of Ed Interlock
5788 in the discretionary ligatures example.
5790 <p>A special thanks to Robert Bringhurst for the sublime mind expansion
5791 that is <em>The Elements of Typographic Style</em>.
5793 <h2 class=no-num id=conformance> Conformance</h2>
5795 <h3 class=no-num id=conventions> Document Conventions</h3>
5797 <p>Conformance requirements are expressed with a combination of descriptive
5798 assertions and RFC 2119 terminology. The key words “MUST”, “MUST
5799 NOT”, “REQUIRED”, “SHALL”, “SHALL NOT”, “SHOULD”,
5800 “SHOULD NOT”, “RECOMMENDED”, “MAY”, and “OPTIONAL” in the
5801 normative parts of this document are to be interpreted as described in RFC
5802 2119. However, for readability, these words do not appear in all uppercase
5803 letters in this specification.
5805 <p>All of the text of this specification is normative except sections
5806 explicitly marked as non-normative, examples, and notes. <a
5807 href="#RFC2119" rel=biblioentry>[RFC2119]<!--{{!RFC2119}}--></a>
5809 <p>Examples in this specification are introduced with the words “for
5810 example” or are set apart from the normative text with
5811 <code>class="example"</code>, like this:
5813 <div class=example>
5814 <p>This is an example of an informative example.
5815 </div>
5817 <p>Informative notes begin with the word “Note” and are set apart from
5818 the normative text with <code>class="note"</code>, like this:
5820 <p class=note>Note, this is an informative note.
5822 <h3 class=no-num id=conformance-classes> Conformance Classes</h3>
5824 <p>Conformance to CSS Fonts Level 3 Module is defined for three conformance
5825 classes:
5827 <dl>
5828 <dt><dfn id=style-sheet title="style sheet!!as conformance class">style
5829 sheet</dfn>
5831 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#style-sheet">CSS
5832 style sheet</a>.
5834 <dt><dfn id=renderer>renderer</dfn>
5836 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5837 that interprets the semantics of a style sheet and renders documents that
5838 use them.
5840 <dt><dfn id=authoring-tool>authoring tool</dfn>
5842 <dd>A <a href="http://www.w3.org/TR/CSS21/conform.html#user-agent">UA</a>
5843 that writes a style sheet.
5844 </dl>
5846 <p>A style sheet is conformant to CSS Fonts Level 3 Module if all of its
5847 declarations that use properties defined in this module have values that
5848 are valid according to the generic CSS grammar and the individual grammars
5849 of each property as given in this module.
5851 <p>A renderer is conformant to CSS Fonts Level 3 Module if, in addition to
5852 interpreting the style sheet as defined by the appropriate specifications,
5853 it supports all the features defined by CSS Fonts Level 3 Module by
5854 parsing them correctly and rendering the document accordingly. However,
5855 the inability of a UA to correctly render a document due to limitations of
5856 the device does not make the UA non-conformant. (For example, a UA is not
5857 required to render color on a monochrome monitor.)
5859 <p>An authoring tool is conformant to CSS Fonts Level 3 Module if it writes
5860 style sheets that are syntactically correct according to the generic CSS
5861 grammar and the individual grammars of each feature in this module, and
5862 meet all other conformance requirements of style sheets as described in
5863 this module.
5865 <h3 class=no-num id=partial> Partial Implementations</h3>
5867 <p>So that authors can exploit the forward-compatible parsing rules to
5868 assign fallback values, CSS renderers <strong>must</strong> treat as
5869 invalid (and <a
5870 href="http://www.w3.org/TR/CSS21/conform.html#ignore">ignore as
5871 appropriate</a>) any at-rules, properties, property values, keywords, and
5872 other syntactic constructs for which they have no usable level of support.
5873 In particular, user agents <strong>must not</strong> selectively ignore
5874 unsupported component values and honor supported values in a single
5875 multi-value property declaration: if any value is considered invalid (as
5876 unsupported values must be), CSS requires that the entire declaration be
5877 ignored.
5879 <h3 class=no-num id=experimental> Experimental Implementations</h3>
5881 <p>To avoid clashes with future CSS features, the CSS2.1 specification
5882 reserves a <a
5883 href="http://www.w3.org/TR/CSS21/syndata.html#vendor-keywords">prefixed
5884 syntax</a> for proprietary and experimental extensions to CSS.
5886 <p>Prior to a specification reaching the Candidate Recommendation stage in
5887 the W3C process, all implementations of a CSS feature are considered
5888 experimental. The CSS Working Group recommends that implementations use a
5889 vendor-prefixed syntax for such features, including those in W3C Working
5890 Drafts. This avoids incompatibilities with future changes in the draft.
5892 <h3 class=no-num id=testing> Non-Experimental Implementations</h3>
5894 <p>Once a specification reaches the Candidate Recommendation stage,
5895 non-experimental implementations are possible, and implementors should
5896 release an unprefixed implementation of any CR-level feature they can
5897 demonstrate to be correctly implemented according to spec.
5899 <p>To establish and maintain the interoperability of CSS across
5900 implementations, the CSS Working Group requests that non-experimental CSS
5901 renderers submit an implementation report (and, if necessary, the
5902 testcases used for that implementation report) to the W3C before releasing
5903 an unprefixed implementation of any CSS features. Testcases submitted to
5904 W3C are subject to review and correction by the CSS Working Group.
5906 <p>Further information on submitting testcases and implementation reports
5907 can be found from on the CSS Working Group's website at <a
5908 href="http://www.w3.org/Style/CSS/Test/">http://www.w3.org/Style/CSS/Test/</a>.
5909 Questions should be directed to the <a
5910 href="http://lists.w3.org/Archives/Public/public-css-testsuite">public-css-testsuite@w3.org</a>
5911 mailing list.
5913 <h2 class=no-num id=references>References</h2>
5915 <h3 class=no-num id=normative-references>Normative References</h3>
5916 <!--begin-normative-->
5917 <!-- Sorted by label -->
5919 <dl class=bibliography>
5920 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
5921 <!---->
5923 <dt id=CHARMOD>[CHARMOD]
5925 <dd>Martin J. Dürst; et al. <a
5926 href="http://www.w3.org/TR/2005/REC-charmod-20050215/"><cite>Character
5927 Model for the World Wide Web 1.0: Fundamentals.</cite></a> 15 February
5928 2005. W3C Recommendation. URL: <a
5929 href="http://www.w3.org/TR/2005/REC-charmod-20050215/">http://www.w3.org/TR/2005/REC-charmod-20050215/</a>
5930 </dd>
5931 <!---->
5933 <dt id=CORS>[CORS]
5935 <dd>Anne van Kesteren. <a
5936 href="http://www.w3.org/TR/2013/CR-cors-20130129/"><cite>Cross-Origin
5937 Resource Sharing.</cite></a> 29 January 2013. W3C Candidate
5938 Recommendation. (Work in progress.) URL: <a
5939 href="http://www.w3.org/TR/2013/CR-cors-20130129/">http://www.w3.org/TR/2013/CR-cors-20130129/</a>
5940 </dd>
5941 <!---->
5943 <dt id=CSS21>[CSS21]
5945 <dd>Bert Bos; et al. <a
5946 href="http://www.w3.org/TR/2011/REC-CSS2-20110607"><cite>Cascading Style
5947 Sheets Level 2 Revision 1 (CSS 2.1) Specification.</cite></a> 7 June
5948 2011. W3C Recommendation. URL: <a
5949 href="http://www.w3.org/TR/2011/REC-CSS2-20110607">http://www.w3.org/TR/2011/REC-CSS2-20110607</a>
5950 </dd>
5951 <!---->
5953 <dt id=CSS3VAL>[CSS3VAL]
5955 <dd>Håkon Wium Lie; Tab Atkins; Elika J. Etemad. <a
5956 href="http://www.w3.org/TR/2012/CR-css3-values-20120828/"><cite>CSS
5957 Values and Units Module Level 3.</cite></a> 28 August 2012. W3C Candidate
5958 Recommendation. (Work in progress.) URL: <a
5959 href="http://www.w3.org/TR/2012/CR-css3-values-20120828/">http://www.w3.org/TR/2012/CR-css3-values-20120828/</a>
5960 </dd>
5961 <!---->
5963 <dt id=HTML5>[HTML5]
5965 <dd>Ian Hickson. <a
5966 href="http://www.w3.org/TR/2012/CR-html5-20121217/"><cite>HTML5.</cite></a>
5967 17 December 2012. W3C Candidate Recommendation. (Work in progress.) URL:
5968 <a
5969 href="http://www.w3.org/TR/2012/CR-html5-20121217/">http://www.w3.org/TR/2012/CR-html5-20121217/</a>
5970 </dd>
5971 <!---->
5973 <dt id=OPEN-FONT-FORMAT>[OPEN-FONT-FORMAT]
5975 <dd><a
5976 href="http://standards.iso.org/ittf/PubliclyAvailableStandards/c052136_ISO_IEC_14496-22_2009(E).zip"><cite>Information
5977 technology — Coding of audio-visual objects — Part 22: Open Font
5978 Format.</cite></a> International Organization for Standardization.
5979 ISO/IEC 14496-22:2009. URL: <a
5980 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>
5981 </dd>
5982 <!---->
5984 <dt id=OPENTYPE>[OPENTYPE]
5986 <dd><a
5987 href="http://www.microsoft.com/typography/otspec/default.htm"><cite>OpenType
5988 specification.</cite></a> Microsoft. URL: <a
5989 href="http://www.microsoft.com/typography/otspec/default.htm">http://www.microsoft.com/typography/otspec/default.htm</a>
5990 </dd>
5991 <!---->
5993 <dt id=OPENTYPE-FEATURES>[OPENTYPE-FEATURES]
5995 <dd><a
5996 href="http://www.microsoft.com/typography/otspec/featurelist.htm"><cite>OpenType
5997 feature registry.</cite></a> Microsoft. URL: <a
5998 href="http://www.microsoft.com/typography/otspec/featurelist.htm">http://www.microsoft.com/typography/otspec/featurelist.htm</a>
5999 </dd>
6000 <!---->
6002 <dt id=RFC2119>[RFC2119]
6004 <dd>S. Bradner. <a href="http://www.ietf.org/rfc/rfc2119.txt"><cite>Key
6005 words for use in RFCs to Indicate Requirement Levels.</cite></a> Internet
6006 RFC 2119. URL: <a
6007 href="http://www.ietf.org/rfc/rfc2119.txt">http://www.ietf.org/rfc/rfc2119.txt</a>
6008 </dd>
6009 <!---->
6011 <dt id=UAX15>[UAX15]
6013 <dd>Mark Davis; Ken Whistler. <a
6014 href="http://www.unicode.org/reports/tr15/"><cite>Unicode Normalization
6015 Forms.</cite></a> 31 August 2012. Unicode Standard Annex #15. URL: <a
6016 href="http://www.unicode.org/reports/tr15/">http://www.unicode.org/reports/tr15/</a>
6017 </dd>
6018 <!---->
6020 <dt id=UAX29>[UAX29]
6022 <dd>Mark Davis. <a
6023 href="http://www.unicode.org/reports/tr29/"><cite>Unicode Text
6024 Segmentation.</cite></a> 12 September 2012. Unicode Standard Annex #29.
6025 URL: <a
6026 href="http://www.unicode.org/reports/tr29/">http://www.unicode.org/reports/tr29/</a>
6027 </dd>
6028 <!---->
6030 <dt id=UNICODE6>[UNICODE6]
6032 <dd>The Unicode Consortium. <a
6033 href="http://www.unicode.org/versions/Unicode6.2.0/"><cite>The Unicode
6034 Standard, Version 6.2.0.</cite></a> Defined by: The Unicode Standard,
6035 Version 6.2.0 URL: <a
6036 href="http://www.unicode.org/versions/Unicode6.2.0/">http://www.unicode.org/versions/Unicode6.2.0/</a>
6037 </dd>
6038 <!---->
6039 </dl>
6040 <!--end-normative-->
6041 <!--{{!CSS21}}-->
6042 <!--{{!CSS3VAL}}-->
6043 <!--{{!OPENTYPE}}-->
6044 <!--{{!OPENTYPE-FEATURES}}-->
6045 <!--{{!OPEN-FONT-FORMAT}}-->
6046 <!--{{!UNICODE6}}-->
6047 <!--{{!UAX15}}-->
6048 <!--{{!UAX29}}-->
6049 <!--{{!CORS}}-->
6050 <!--{{!HTML5}}-->
6051 <!--{{!CHARMOD}}-->
6053 <h3 class=no-num id=other-references>Other References</h3>
6054 <!--begin-informative-->
6055 <!-- Sorted by label -->
6057 <dl class=bibliography>
6058 <dd style="display: none"><!-- keeps the doc valid if the DL is empty -->
6059 <!---->
6061 <dt id=AAT-FEATURES>[AAT-FEATURES]
6063 <dd><a href="http://developer.apple.com/fonts/registry/"><cite>Apple
6064 Advanced Typography font feature registry.</cite></a> Apple. URL: <a
6065 href="http://developer.apple.com/fonts/registry/">http://developer.apple.com/fonts/registry/</a>
6066 </dd>
6067 <!---->
6069 <dt id=ARABIC-TYPO>[ARABIC-TYPO]
6071 <dd>Huda Smitshuijzen AbiFares. <cite>Arabic Typography: A Comprehensive
6072 Sourcebook.</cite> Saqi Books. 2001. ISBN 0-86356-347-3.</dd>
6073 <!---->
6075 <dt id=CHARMOD-NORM>[CHARMOD-NORM]
6077 <dd>François Yergeau; et al. <a
6078 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/"><cite>Character
6079 Model for the World Wide Web 1.0: Normalization.</cite></a> 1 May 2012.
6080 W3C Working Draft. (Work in progress.) URL: <a
6081 href="http://www.w3.org/TR/2012/WD-charmod-norm-20120501/">http://www.w3.org/TR/2012/WD-charmod-norm-20120501/</a>
6082 </dd>
6083 <!---->
6085 <dt id=CJKV-INFO-PROCESSING>[CJKV-INFO-PROCESSING]
6087 <dd>Ken Lunde. <cite>CJKV Information Processing, Second Edition.</cite>
6088 O'Reilly Media, Inc. 2009. ISBN 0-596-51447-1.</dd>
6089 <!---->
6091 <dt id=CSS3-CONDITIONAL>[CSS3-CONDITIONAL]
6093 <dd>L. David Baron. <a
6094 href="http://www.w3.org/TR/2012/WD-css3-conditional-20121213/"><cite>CSS
6095 Conditional Rules Module Level 3.</cite></a> 13 December 2012. W3C
6096 Working Draft. (Work in progress.) URL: <a
6097 href="http://www.w3.org/TR/2012/WD-css3-conditional-20121213/">http://www.w3.org/TR/2012/WD-css3-conditional-20121213/</a>
6098 </dd>
6099 <!---->
6101 <dt id=CSS3TEXT>[CSS3TEXT]
6103 <dd>Elika J. Etemad; Koji Ishii. <a
6104 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/"><cite>CSS Text
6105 Module Level 3.</cite></a> 13 November 2012. W3C Working Draft. (Work in
6106 progress.) URL: <a
6107 href="http://www.w3.org/TR/2012/WD-css3-text-20121113/">http://www.w3.org/TR/2012/WD-css3-text-20121113/</a>
6108 </dd>
6109 <!---->
6111 <dt id=DIGITAL-TYPOGRAPHY>[DIGITAL-TYPOGRAPHY]
6113 <dd>Richard Rubinstein. <cite>Digital Typography, An Introduction to Type
6114 and Composition for Computer System Design.</cite> Addison-Wesley. 1988.
6115 ISBN 0-201-17633-5.</dd>
6116 <!---->
6118 <dt id=DOM-LEVEL-2-STYLE>[DOM-LEVEL-2-STYLE]
6120 <dd>Chris Wilson; Philippe Le Hégaret; Vidur Apparao. <a
6121 href="http://www.w3.org/TR/2000/REC-DOM-Level-2-Style-20001113/"><cite>Document
6122 Object Model (DOM) Level 2 Style Specification.</cite></a> 13 November
6123 2000. W3C Recommendation. URL: <a
6124 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>
6125 </dd>
6126 <!---->
6128 <dt id=ELEMTYPO>[ELEMTYPO]
6130 <dd>Robert Bringhurst. <cite>The Elements of Typographic Style, Version
6131 4.</cite> Hartley & Marks. 2013. ISBN 0-88179-212-8.</dd>
6132 <!---->
6134 <dt id=LANGCULTTYPE>[LANGCULTTYPE]
6136 <dd>John D. Berry, Ed. <cite>Language Culture Type.</cite> Graphis. 2001.
6137 ISBN 1-932026-01-0.</dd>
6138 <!---->
6140 <dt id=OPENTYPE-FONT-GUIDE>[OPENTYPE-FONT-GUIDE]
6142 <dd><a
6143 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf"><cite>OpenType
6144 User Guide.</cite></a> FontShop International. URL: <a
6145 href="https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf">https://www.fontfont.com/staticcontent/downloads/FF_OT_User_Guide.pdf</a>
6146 </dd>
6147 <!---->
6149 <dt id=RASTER-TRAGEDY>[RASTER-TRAGEDY]
6151 <dd>Beat Stamm. <a href="http://www.rastertragedy.com/"><cite>The Raster
6152 Tragedy at Low-Resolution Revisited.</cite></a> 7 December 2011. URL: <a
6153 href="http://www.rastertragedy.com/">http://www.rastertragedy.com/</a></dd>
6154 <!---->
6156 <dt id=WINDOWS-GLYPH-PROC>[WINDOWS-GLYPH-PROC]
6158 <dd>John Hudson. <a
6159 href="http://www.microsoft.com/typography/developers/opentype/default.htm"><cite>Windows
6160 Glyph Processing.</cite></a> Microsoft Typogrraphy. URL: <a
6161 href="http://www.microsoft.com/typography/developers/opentype/default.htm">http://www.microsoft.com/typography/developers/opentype/default.htm</a>
6162 </dd>
6163 <!---->
6164 </dl>
6165 <!--end-informative-->
6166 <!--{{ARABIC-TYPO}}-->
6167 <!--{{CJKV-INFO-PROCESSING}}-->
6168 <!--{{DIGITAL-TYPOGRAPHY}}-->
6169 <!--{{DOM-LEVEL-2-STYLE}}-->
6170 <!--{{ELEMTYPO}}-->
6171 <!--{{LANGCULTTYPE}}-->
6172 <!--{{OPENTYPE-FONT-GUIDE}}-->
6173 <!--{{RASTER-TRAGEDY}}-->
6174 <!--{{WINDOWS-GLYPH-PROC}}-->
6175 <!--{{CHARMOD-NORM}}-->
6176 <!--{{AAT-FEATURES}}-->
6177 <!--{{CSS3-CONDITIONAL}}-->
6178 <!--{{CSS3TEXT}}-->
6180 <h2 class=no-num id=index>Index</h2>
6181 <!--begin-index-->
6183 <ul class=indexlist>
6184 <li>100...900 weight values, <a href="#font-weight-numeric-values"
6185 title="100...900 weight values"><strong>3.2</strong></a>
6187 <li><var><absolute-size></var>, <a href="#absolute-size-value"
6188 title="<absolute-size>"><strong>3.5</strong></a>
6190 <li><var><common-lig-values></var>, <a href="#common-lig-values"
6191 title="<common-lig-values>"><strong>6.4</strong></a>
6193 <li><var><contextual-alt-values></var>, <a
6194 href="#contextual-alt-values"
6195 title="<contextual-alt-values>"><strong>6.4</strong></a>
6197 <li><var><discretionary-lig-values></var>, <a
6198 href="#discretionary-lig-values"
6199 title="<discretionary-lig-values>"><strong>6.4</strong></a>
6201 <li><var><east-asian-variant-values></var>, <a
6202 href="#east-asian-variant-values"
6203 title="<east-asian-variant-values>"><strong>6.10</strong></a>
6205 <li><var><east-asian-width-values></var>, <a
6206 href="#east-asian-width-values"
6207 title="<east-asian-width-values>"><strong>6.10</strong></a>
6209 <li><var><family-name></var>, <a href="#family-name-value"
6210 title="<family-name>"><strong>3.1</strong></a>
6212 <li><var><feature-tag-value></var>, <a href="#feature-tag-value"
6213 title="<feature-tag-value>"><strong>6.12</strong></a>
6215 <li><var><font-face-name></var>, <a href="#font-face-name-value"
6216 title="<font-face-name>"><strong>4.3</strong></a>
6218 <li><var><font-variant-css21></var>, <a
6219 href="#font-variant-css21-values"
6220 title="<font-variant-css21>"><strong>3.7</strong></a>
6222 <li><var><generic-family></var>, <a href="#generic-family-value"
6223 title="<generic-family>"><strong>3.1</strong></a>
6225 <li><var><historical-lig-values></var>, <a
6226 href="#historical-lig-values"
6227 title="<historical-lig-values>"><strong>6.4</strong></a>
6229 <li><var><length></var>, <a href="#length-size-value"
6230 title="<length>"><strong>3.5</strong></a>
6232 <li><var><number></var>, <a href="#aspect-ratio-value"
6233 title="<number>"><strong>3.6</strong></a>
6235 <li><var><numeric-figure-values></var>, <a
6236 href="#numeric-figure-values"
6237 title="<numeric-figure-values>"><strong>6.7</strong></a>
6239 <li><var><numeric-fraction-values></var>, <a
6240 href="#numeric-fraction-values"
6241 title="<numeric-fraction-values>"><strong>6.7</strong></a>
6243 <li><var><numeric-spacing-values></var>, <a
6244 href="#numeric-spacing-values"
6245 title="<numeric-spacing-values>"><strong>6.7</strong></a>
6247 <li><var><percentage></var>, <a href="#percentage-size-value"
6248 title="<percentage>"><strong>3.5</strong></a>
6250 <li><var><relative-size></var>, <a href="#relative-size-value"
6251 title="<relative-size>"><strong>3.5</strong></a>
6253 <li><var><string></var>, <a
6254 href="#font-language-override-string-value"
6255 title="<string>"><strong>6.13</strong></a>
6257 <li><var><urange></var>, <a href="#urange-value"
6258 title="<urange>"><strong>4.5</strong></a>
6260 <li><code>@font-face</code>, <a href="#at-font-face-rule"
6261 title="@font-face"><strong>4.1</strong></a>
6263 <li><code>@font-feature-values</code>, <a
6264 href="#at-font-feature-values-rule"
6265 title="@font-feature-values"><strong>6.9</strong></a>
6267 <li>all-petite-caps, <a href="#all-petite-caps"
6268 title=all-petite-caps><strong>6.6</strong></a>
6270 <li>all-small-caps, <a href="#all-small-caps"
6271 title=all-small-caps><strong>6.6</strong></a>
6273 <li>annotation, <a href="#annotation"
6274 title=annotation><strong>6.8</strong></a>
6276 <li>aspect value, <a href="#aspect-value0" title="aspect
6277 value"><strong>3.6</strong></a>
6279 <li>authoring tool, <a href="#authoring-tool" title="authoring
6280 tool"><strong>#</strong></a>
6282 <li>auto
6283 <ul>
6284 <li>font-kerning, <a href="#font-kerning-auto-value" title="auto,
6285 font-kerning"><strong>6.3</strong></a>
6287 <li>font-size-adjust, <a href="#font-size-adjust-auto-value"
6288 title="auto, font-size-adjust"><strong>3.6</strong></a>
6289 </ul>
6291 <li>bold, <a href="#bold" title=bold><strong>3.2</strong></a>
6293 <li>bolder, <a href="#bolder" title=bolder><strong>3.2</strong></a>
6295 <li>character map, <a href="#character-map" title="character
6296 map"><strong>5.2</strong></a>
6298 <li>character-variant, <a href="#character-variant"
6299 title=character-variant><strong>6.8</strong></a>
6301 <li>common-ligatures, <a href="#common-ligatures"
6302 title=common-ligatures><strong>6.4</strong></a>
6304 <li>condensed, <a href="#condensed"
6305 title=condensed><strong>3.3</strong></a>
6307 <li>contextual, <a href="#contextual"
6308 title=contextual><strong>6.4</strong></a>
6310 <li>CSSFontFaceRule, <a href="#cssfontfacerule"
6311 title=CSSFontFaceRule><strong>8.1</strong></a>
6313 <li>CSSFontFeatureValuesRule, <a href="#cssfontfeaturevaluesrule"
6314 title=CSSFontFeatureValuesRule><strong>8.2</strong></a>
6316 <li>cursive, definition of, <a href="#cursive0" title="cursive, definition
6317 of"><strong>#</strong></a>
6319 <li>default face, <a href="#default-face" title="default
6320 face"><strong>5.2</strong></a>
6322 <li>descriptor_declaration, <a href="#descriptordeclaration"
6323 title="descriptor_declaration"><strong>4.1</strong></a>
6325 <li>diagonal-fractions, <a href="#diagonal-fractions"
6326 title=diagonal-fractions><strong>6.7</strong></a>
6328 <li>discretionary-ligatures, <a href="#discretionary-ligatures"
6329 title=discretionary-ligatures><strong>6.4</strong></a>
6331 <li>expanded, <a href="#expanded" title=expanded><strong>3.3</strong></a>
6333 <li>extra-condensed, <a href="#extra-condensed"
6334 title=extra-condensed><strong>3.3</strong></a>
6336 <li>extra-expanded, <a href="#extra-expanded"
6337 title=extra-expanded><strong>3.3</strong></a>
6339 <li>fantasy, definition of, <a href="#fantasy0" title="fantasy, definition
6340 of"><strong>#</strong></a>
6342 <li>feature_type, <a href="#featuretype"
6343 title="feature_type"><strong>6.9</strong></a>
6345 <li>feature_value_block, <a href="#featurevalueblock"
6346 title="feature_value_block"><strong>6.9</strong></a>
6348 <li>feature_value_definition, <a href="#featurevaluedefinition"
6349 title="feature_value_definition"><strong>6.9</strong></a>
6351 <li>font, <a href="#propdef-font" title=font><strong>3.7</strong></a>
6353 <li>font-family
6354 <ul>
6355 <li>descriptor, <a href="#descdef-font-family" title="font-family,
6356 descriptor"><strong>4.2</strong></a>
6358 <li>property, <a href="#propdef-font-family" title="font-family,
6359 property"><strong>3.1</strong></a>
6360 </ul>
6362 <li>font-feature-settings
6363 <ul>
6364 <li>descriptor, <a href="#descdef-font-feature-settings"
6365 title="font-feature-settings, descriptor"><strong>4.7</strong></a>
6367 <li>property, <a href="#propdef-font-feature-settings"
6368 title="font-feature-settings, property"><strong>6.12</strong></a>
6369 </ul>
6371 <li>font-kerning, <a href="#propdef-font-kerning"
6372 title=font-kerning><strong>6.3</strong></a>
6374 <li>font-language-override, <a href="#propdef-font-language-override"
6375 title=font-language-override><strong>6.13</strong></a>
6377 <li>font-size, <a href="#propdef-font-size"
6378 title=font-size><strong>3.5</strong></a>
6380 <li>font-size-adjust, <a href="#propdef-font-size-adjust"
6381 title=font-size-adjust><strong>3.6</strong></a>
6383 <li>font-stretch
6384 <ul>
6385 <li>descriptor, <a href="#descdef-font-stretch" title="font-stretch,
6386 descriptor"><strong>4.4</strong></a>
6388 <li>property, <a href="#propdef-font-stretch" title="font-stretch,
6389 property"><strong>3.3</strong></a>
6390 </ul>
6392 <li>font-style
6393 <ul>
6394 <li>descriptor, <a href="#descdef-font-style" title="font-style,
6395 descriptor"><strong>4.4</strong></a>
6397 <li>property, <a href="#propdef-font-style" title="font-style,
6398 property"><strong>3.4</strong></a>
6399 </ul>
6401 <li>font-synthesis, <a href="#propdef-font-synthesis"
6402 title=font-synthesis><strong>3.8</strong></a>
6404 <li>font-variant
6405 <ul>
6406 <li>descriptor, <a href="#descdef-font-variant" title="font-variant,
6407 descriptor"><strong>4.7</strong></a>
6409 <li>property, <a href="#propdef-font-variant" title="font-variant,
6410 property"><strong>6.11</strong></a>
6411 </ul>
6413 <li>font-variant-alternates, <a href="#propdef-font-variant-alternates"
6414 title=font-variant-alternates><strong>6.8</strong></a>
6416 <li>font-variant-caps, <a href="#propdef-font-variant-caps"
6417 title=font-variant-caps><strong>6.6</strong></a>
6419 <li>font-variant-east-asian, <a href="#propdef-font-variant-east-asian"
6420 title=font-variant-east-asian><strong>6.10</strong></a>
6422 <li>font-variant-ligatures, <a href="#propdef-font-variant-ligatures"
6423 title=font-variant-ligatures><strong>6.4</strong></a>
6425 <li>font-variant-numeric, <a href="#propdef-font-variant-numeric"
6426 title=font-variant-numeric><strong>6.7</strong></a>
6428 <li>font-variant-position, <a href="#propdef-font-variant-position"
6429 title=font-variant-position><strong>6.5</strong></a>
6431 <li>font-weight
6432 <ul>
6433 <li>descriptor, <a href="#descdef-font-weight" title="font-weight,
6434 descriptor"><strong>4.4</strong></a>
6436 <li>property, <a href="#propdef-font-weight" title="font-weight,
6437 property"><strong>3.2</strong></a>
6438 </ul>
6440 <li>font_face_rule, <a href="#fontfacerule"
6441 title="font_face_rule"><strong>4.1</strong></a>
6443 <li>FONT_FACE_SYM, <a href="#fontfacesym"
6444 title="FONT_FACE_SYM"><strong>4.1</strong></a>
6446 <li>font_family_name, <a href="#fontfamilyname"
6447 title="font_family_name"><strong>6.9</strong></a>
6449 <li>font_family_name_list, <a href="#fontfamilynamelist"
6450 title="font_family_name_list"><strong>6.9</strong></a>
6452 <li>font_feature_values_rule, <a href="#fontfeaturevaluesrule"
6453 title="font_feature_values_rule"><strong>6.9</strong></a>
6455 <li>FONT_FEATURE_VALUES_SYM, <a href="#fontfeaturevaluessym"
6456 title="FONT_FEATURE_VALUES_SYM"><strong>6.9</strong></a>
6458 <li>full-width, <a href="#full-width"
6459 title=full-width><strong>6.10</strong></a>
6461 <li>historical-forms, <a href="#historical-forms"
6462 title=historical-forms><strong>6.8</strong></a>
6464 <li>historical-ligatures, <a href="#historical-ligatures"
6465 title=historical-ligatures><strong>6.4</strong></a>
6467 <li>italic, <a href="#italic" title=italic><strong>3.4</strong></a>
6469 <li>jis04, <a href="#jis04" title=jis04><strong>6.10</strong></a>
6471 <li>jis78, <a href="#jis78" title=jis78><strong>6.10</strong></a>
6473 <li>jis83, <a href="#jis83" title=jis83><strong>6.10</strong></a>
6475 <li>jis90, <a href="#jis90" title=jis90><strong>6.10</strong></a>
6477 <li>lighter, <a href="#lighter" title=lighter><strong>3.2</strong></a>
6479 <li>lining-nums, <a href="#lining-nums"
6480 title=lining-nums><strong>6.7</strong></a>
6482 <li>monospace, definition of, <a href="#monospace0" title="monospace,
6483 definition of"><strong>#</strong></a>
6485 <li>no-common-ligatures, <a href="#no-common-ligatures"
6486 title=no-common-ligatures><strong>6.4</strong></a>
6488 <li>no-contextual, <a href="#no-contextual"
6489 title=no-contextual><strong>6.4</strong></a>
6491 <li>no-discretionary-ligatures, <a href="#no-discretionary-ligatures"
6492 title=no-discretionary-ligatures><strong>6.4</strong></a>
6494 <li>no-historical-ligatures, <a href="#no-historical-ligatures"
6495 title=no-historical-ligatures><strong>6.4</strong></a>
6497 <li>none
6498 <ul>
6499 <li>font-kerning, <a href="#font-kerning-none-value" title="none,
6500 font-kerning"><strong>6.3</strong></a>
6502 <li>font-size-adjust, <a href="#font-size-adjust-none-value"
6503 title="none, font-size-adjust"><strong>3.6</strong></a>
6505 <li>font-variant, <a href="#font-variant-none-value" title="none,
6506 font-variant"><strong>6.11</strong></a>
6508 <li>font-variant-ligatures, <a href="#font-variant-ligatures-none-value"
6509 title="none, font-variant-ligatures"><strong>6.4</strong></a>
6510 </ul>
6512 <li>normal, <a href="#normal" title=normal><strong>6.5</strong></a>
6513 <ul>
6514 <li>font-feature-settings, <a href="#font-feature-settings-normal-value"
6515 title="normal, font-feature-settings"><strong>6.12</strong></a>
6517 <li>font-kerning, <a href="#font-kerning-normal-value" title="normal,
6518 font-kerning"><strong>6.3</strong></a>
6520 <li>font-language-override, <a
6521 href="#font-language-override-normal-value" title="normal,
6522 font-language-override"><strong>6.13</strong></a>
6524 <li>font-stretch, <a href="#font-stretch-normal-value" title="normal,
6525 font-stretch"><strong>3.3</strong></a>
6527 <li>font-style, <a href="#font-style-normal-value" title="normal,
6528 font-style"><strong>3.4</strong></a>
6530 <li>font-variant, <a href="#font-variant-normal-value" title="normal,
6531 font-variant"><strong>6.11</strong></a>
6533 <li>font-variant-alternates, <a
6534 href="#font-variant-alternates-normal-value" title="normal,
6535 font-variant-alternates"><strong>6.8</strong></a>
6537 <li>font-variant-caps, <a href="#font-variant-caps-normal-value"
6538 title="normal, font-variant-caps"><strong>6.6</strong></a>
6540 <li>font-variant-east-asian, <a
6541 href="#font-variant-east-asian-normal-value" title="normal,
6542 font-variant-east-asian"><strong>6.10</strong></a>
6544 <li>font-variant-ligatures, <a
6545 href="#font-variant-ligatures-normal-value" title="normal,
6546 font-variant-ligatures"><strong>6.4</strong></a>
6548 <li>font-variant-numeric, <a href="#font-variant-numeric-normal-value"
6549 title="normal, font-variant-numeric"><strong>6.7</strong></a>
6551 <li>font-weight, <a href="#font-weight-normal-value" title="normal,
6552 font-weight"><strong>3.2</strong></a>
6553 </ul>
6555 <li>oblique, <a href="#oblique" title=oblique><strong>3.4</strong></a>
6557 <li>oldstyle-nums, <a href="#oldstyle-nums"
6558 title=oldstyle-nums><strong>6.7</strong></a>
6560 <li>ordinal, <a href="#ordinal" title=ordinal><strong>6.7</strong></a>
6562 <li>ornaments, <a href="#ornaments"
6563 title=ornaments><strong>6.8</strong></a>
6565 <li>petite-caps, <a href="#petite-caps"
6566 title=petite-caps><strong>6.6</strong></a>
6568 <li>proportional-nums, <a href="#proportional-nums"
6569 title=proportional-nums><strong>6.7</strong></a>
6571 <li>proportional-width, <a href="#proportional-width"
6572 title=proportional-width><strong>6.10</strong></a>
6574 <li>renderer, <a href="#renderer" title=renderer><strong>#</strong></a>
6576 <li>ruby, <a href="#ruby" title=ruby><strong>6.10</strong></a>
6578 <li>sans-serif, definition of, <a href="#sans-serif0" title="sans-serif,
6579 definition of"><strong>#</strong></a>
6581 <li>semi-condensed, <a href="#semi-condensed-"
6582 title=semi-condensed><strong>3.3</strong></a>
6584 <li>semi-expanded, <a href="#semi-expanded"
6585 title=semi-expanded><strong>3.3</strong></a>
6587 <li>serif, definition of, <a href="#serif0" title="serif, definition
6588 of"><strong>#</strong></a>
6590 <li>simplified, <a href="#simplified"
6591 title=simplified><strong>6.10</strong></a>
6593 <li>slashed-zero, <a href="#slashed-zero"
6594 title=slashed-zero><strong>6.7</strong></a>
6596 <li>small-caps, <a href="#small-caps"
6597 title=small-caps><strong>6.6</strong></a>
6599 <li>src, <a href="#descdef-src" title=src><strong>4.3</strong></a>
6601 <li>stacked-fractions, <a href="#stacked-fractions"
6602 title=stacked-fractions><strong>6.7</strong></a>
6604 <li>style sheet
6605 <ul>
6606 <li>as conformance class, <a href="#style-sheet" title="style sheet, as
6607 conformance class"><strong>#</strong></a>
6608 </ul>
6610 <li>styleset, <a href="#styleset" title=styleset><strong>6.8</strong></a>
6612 <li>stylistic, <a href="#stylistic"
6613 title=stylistic><strong>6.8</strong></a>
6615 <li>sub, <a href="#sub" title=sub><strong>6.5</strong></a>
6617 <li>super, <a href="#super" title=super><strong>6.5</strong></a>
6619 <li>swash, <a href="#swash" title=swash><strong>6.8</strong></a>
6621 <li>tabular-nums, <a href="#tabular-nums"
6622 title=tabular-nums><strong>6.7</strong></a>
6624 <li>titling-caps, <a href="#titling-caps"
6625 title=titling-caps><strong>6.6</strong></a>
6627 <li>traditional, <a href="#traditional"
6628 title=traditional><strong>6.10</strong></a>
6630 <li>ultra-condensed, <a href="#ultra-condensed"
6631 title=ultra-condensed><strong>3.3</strong></a>
6633 <li>ultra-expanded, <a href="#ultra-expanded"
6634 title=ultra-expanded><strong>3.3</strong></a>
6636 <li>unicase, <a href="#unicase" title=unicase><strong>6.6</strong></a>
6638 <li>unicode-range, <a href="#descdef-unicode-range"
6639 title=unicode-range><strong>4.5</strong></a>
6641 <li>weight, <a href="#weight" title=weight><strong>2</strong></a>
6643 <li>width, <a href="#width" title=width><strong>2</strong></a>
6644 </ul>
6645 <!--end-index-->
6647 <h2 class=no-num id=property-index>Property index</h2>
6648 <!--begin-properties-->
6650 <table class=proptable>
6651 <thead>
6652 <tr>
6653 <th>Property
6655 <th>Values
6657 <th>Initial
6659 <th>Applies to
6661 <th>Inh.
6663 <th>Percentages
6665 <th>Media
6667 <tbody>
6668 <tr>
6669 <th><a class=property href="#propdef-font">font</a>
6671 <td>[ [ <‘font-style’> || <font-variant-css21> ||
6672 <‘font-weight’> || <‘font-stretch’ ]?
6673 <‘font-size’> [ / <‘line-height’> ]?
6674 <‘font-family’> ] | caption | icon | menu | message-box |
6675 small-caption | status-bar
6677 <td>see individual properties
6679 <td>all elements
6681 <td>yes
6683 <td>see individual properties
6685 <td>visual
6687 <tr>
6688 <th><span class=property>font-family</span>
6690 <td>[ <family-name> | <generic-family> ] #
6692 <td>depends on user agent
6694 <td>all elements
6696 <td>yes
6698 <td>N/A
6700 <td>visual
6702 <tr>
6703 <th><span class=property>font-feature-settings</span>
6705 <td>normal | <feature-tag-value> #
6707 <td>normal
6709 <td>all elements
6711 <td>yes
6713 <td>N/A
6715 <td>visual
6717 <tr>
6718 <th><a class=property href="#propdef-font-kerning">font-kerning</a>
6720 <td>auto | normal | none
6722 <td>auto
6724 <td>all elements
6726 <td>yes
6728 <td>N/A
6730 <td>visual
6732 <tr>
6733 <th><a class=property
6734 href="#propdef-font-language-override">font-language-override</a>
6736 <td>normal | <string>
6738 <td>normal
6740 <td>all elements
6742 <td>yes
6744 <td>N/A
6746 <td>visual
6748 <tr>
6749 <th><a class=property href="#propdef-font-size">font-size</a>
6751 <td><absolute-size> | <relative-size> | <length> |
6752 <percentage>
6754 <td>medium
6756 <td>all elements
6758 <td>yes
6760 <td>refer to parent element's font size
6762 <td>visual
6764 <tr>
6765 <th><a class=property
6766 href="#propdef-font-size-adjust">font-size-adjust</a>
6768 <td>none | auto | <number>
6770 <td>none
6772 <td>all elements
6774 <td>yes
6776 <td>N/A
6778 <td>visual
6780 <tr>
6781 <th><span class=property>font-stretch</span>
6783 <td>normal | ultra-condensed | extra-condensed | condensed |
6784 semi-condensed | semi-expanded | expanded | extra-expanded |
6785 ultra-expanded
6787 <td>normal
6789 <td>all elements
6791 <td>yes
6793 <td>N/A
6795 <td>visual
6797 <tr>
6798 <th><span class=property>font-style</span>
6800 <td>normal | italic | oblique
6802 <td>normal
6804 <td>all elements
6806 <td>yes
6808 <td>N/A
6810 <td>visual
6812 <tr>
6813 <th><a class=property href="#propdef-font-synthesis">font-synthesis</a>
6815 <td>none | [ weight || style ]
6817 <td>weight style
6819 <td>all elements
6821 <td>yes
6823 <td>N/A
6825 <td>visual
6827 <tr>
6828 <th><span class=property>font-variant</span>
6830 <td>normal | none | [ <common-lig-values> ||
6831 <discretionary-lig-values> || <historical-lig-values> ||
6832 <contextual-alt-values> || stylistic(<feature-value-name>)
6833 || historical-forms || styleset(<feature-value-name> #) ||
6834 character-variant(<feature-value-name> #) ||
6835 swash(<feature-value-name>) ||
6836 ornaments(<feature-value-name>) ||
6837 annotation(<feature-value-name>) || [ small-caps | all-small-caps
6838 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
6839 <numeric-figure-values> || <numeric-spacing-values> ||
6840 <numeric-fraction-values> || ordinal || slashed-zero ||
6841 <east-asian-variant-values> || <east-asian-width-values> ||
6842 ruby ]
6844 <td>normal
6846 <td>all elements
6848 <td>yes
6850 <td>see individual properties
6852 <td>visual
6854 <tr>
6855 <th><a class=property
6856 href="#propdef-font-variant-alternates">font-variant-alternates</a>
6858 <td>normal | [ stylistic(<feature-value-name>) || historical-forms
6859 || styleset(<feature-value-name> #) ||
6860 character-variant(<feature-value-name> #) ||
6861 swash(<feature-value-name>) ||
6862 ornaments(<feature-value-name>) ||
6863 annotation(<feature-value-name>) ]
6865 <td>normal
6867 <td>all elements
6869 <td>yes
6871 <td>N/A
6873 <td>visual
6875 <tr>
6876 <th><a class=property
6877 href="#propdef-font-variant-caps">font-variant-caps</a>
6879 <td>normal | small-caps | all-small-caps | petite-caps | all-petite-caps
6880 | unicase | titling-caps
6882 <td>normal
6884 <td>all elements
6886 <td>yes
6888 <td>N/A
6890 <td>visual
6892 <tr>
6893 <th><a class=property
6894 href="#propdef-font-variant-east-asian">font-variant-east-asian</a>
6896 <td>normal | [ <east-asian-variant-values> ||
6897 <east-asian-width-values> || ruby ]
6899 <td>normal
6901 <td>all elements
6903 <td>yes
6905 <td>N/A
6907 <td>visual
6909 <tr>
6910 <th><a class=property
6911 href="#propdef-font-variant-ligatures">font-variant-ligatures</a>
6913 <td>normal | none | [ <common-lig-values> ||
6914 <discretionary-lig-values> || <historical-lig-values> ||
6915 <contextual-alt-values> ]
6917 <td>normal
6919 <td>all elements
6921 <td>yes
6923 <td>N/A
6925 <td>visual
6927 <tr>
6928 <th><a class=property
6929 href="#propdef-font-variant-numeric">font-variant-numeric</a>
6931 <td>normal | [ <numeric-figure-values> ||
6932 <numeric-spacing-values> || <numeric-fraction-values> ||
6933 ordinal || slashed-zero ]
6935 <td>normal
6937 <td>all elements
6939 <td>yes
6941 <td>N/A
6943 <td>visual
6945 <tr>
6946 <th><a class=property
6947 href="#propdef-font-variant-position">font-variant-position</a>
6949 <td>normal | sub | super
6951 <td>normal
6953 <td>all elements
6955 <td>yes
6957 <td>N/A
6959 <td>visual
6961 <tr>
6962 <th><span class=property>font-weight</span>
6964 <td>normal | bold | bolder | lighter | 100 | 200 | 300 | 400 | 500 | 600
6965 | 700 | 800 | 900
6967 <td>normal
6969 <td>all elements
6971 <td>yes
6973 <td>N/A
6975 <td>visual
6976 </table>
6977 <!--end-properties-->
6978 <!--begin-descriptors-->
6980 <table class=proptable>
6981 <thead>
6982 <tr>
6983 <th>Descriptor
6985 <th>Value
6987 <th>Initial
6989 <th>Percentages
6991 <th>Media
6993 <tbody>
6994 <tr>
6995 <th><span class=property>font-family</span>
6997 <td><family-name>
6999 <td>N/A
7001 <tr>
7002 <th><span class=property>font-feature-settings</span>
7004 <td>normal | <feature-tag-value> #
7006 <td>normal
7008 <tr>
7009 <th><span class=property>font-stretch</span>
7011 <td>normal | ultra-condensed | extra-condensed | condensed |
7012 semi-condensed | semi-expanded | expanded | extra-expanded |
7013 ultra-expanded
7015 <td>normal
7017 <tr>
7018 <th><span class=property>font-style</span>
7020 <td>normal | italic | oblique
7022 <td>normal
7024 <tr>
7025 <th><span class=property>font-variant</span>
7027 <td>normal | none | [ <common-lig-values> ||
7028 <discretionary-lig-values> || <historical-lig-values> ||
7029 <contextual-alt-values> || stylistic(<feature-value-name>)
7030 || historical-forms || styleset(<feature-value-name> #) ||
7031 character-variant(<feature-value-name> #) ||
7032 swash(<feature-value-name>) ||
7033 ornaments(<feature-value-name>) ||
7034 annotation(<feature-value-name>) || [ small-caps | all-small-caps
7035 | petite-caps | all-petite-caps | unicase | titling-caps ] ||
7036 <numeric-figure-values> || <numeric-spacing-values> ||
7037 <numeric-fraction-values> || ordinal || slashed-zero ||
7038 <east-asian-variant-values> || <east-asian-width-values> ||
7039 ruby ]
7041 <td>normal
7043 <tr>
7044 <th><span class=property>font-weight</span>
7046 <td>normal | bold | 100 | 200 | 300 | 400 | 500 | 600 | 700 | 800 | 900
7048 <td>normal
7050 <tr>
7051 <th><a class=property href="#descdef-src">src</a>
7053 <td>[ <url> [format(<string> #)]? | <font-face-name> ] #
7055 <td>N/A
7057 <tr>
7058 <th><a class=property href="#descdef-unicode-range">unicode-range</a>
7060 <td><urange> #
7062 <td>U+0-10FFFF
7063 </table>
7064 <!--end-descriptors-->
7065 <script type="text/javascript">
7066 window.onload = function () {
7067 if (!("devicePixelRatio" in window && window.devicePixelRatio > 1)) return;
7068 var i, hiresElements = document.getElementsByClassName("hires");
7069 for (i = 0; i < hiresElements.length; i++) {
7070 var h = hiresElements[i];
7071 if (h.tagName != "IMG") continue;
7072 var src = h.getAttribute("src");
7073 var src2x = src.replace(/\.\w+$/, function(m) { return "@2x" + m; });
7074 h.src = src2x;
7075 }
7076 }
7077 </script>
7078 </html>
7079 <!-- Keep this comment at the end of the file
7080 Local variables:
7081 mode: sgml
7082 sgml-declaration:"~/SGML/HTML4.decl"
7083 sgml-default-doctype-name:"html"
7084 sgml-minimize-attributes:t
7085 sgml-nofill-elements:("pre" "style" "br")
7086 sgml-live-element-indicator:t
7087 sgml-omittag:nil
7088 sgml-shorttag:nil
7089 sgml-namecase-general:t
7090 sgml-general-insert-case:lower
7091 sgml-always-quote-attributes:t
7092 sgml-indent-step:nil
7093 sgml-indent-data:t
7094 sgml-parent-document:nil
7095 sgml-exposed-tags:nil
7096 sgml-local-catalogs:nil
7097 sgml-local-ecat-files:nil
7098 End:
7099 -->
7100 <!--
7102 to do:
7104 - wording of OpenType family name handling
7105 - handling combining sequences in the font matching algorithm
7106 - fix-up fi ligature example
7108 -->
