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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<html lang="en-US">
<head>
<title>Media Queries</title>
<style type="text/css">
blockquote {
background: #eef;
padding: 0.5em;
margin: 1em 0;
border: thin solid black; }
pre { font-family: courier, monospace; font-weight: bold; white-space: pre-wrap }
.example pre em { font-style: normal }
span.label { font-style: italic }
</style>
<link rel="stylesheet" href="../default.css">
<link href="http://www.w3.org/StyleSheets/TR/W3C-[STATUS]" rel="stylesheet">
</head>
<body>
<div class="head">
<!--logo-->
<h1 id="media-queries">Media Queries</h1>
<h2 class="no-num no-toc" id="w3c-working">[LONGSTATUS] [DATE]</h2>
<dl>
<dt>This version:</dt>
<dd><a href="[VERSION]/">http://www.w3.org/TR/[YEAR]/ED-css3-mediaqueries-[CDATE]/</a></dd>
<dt>Latest version:</dt>
<dd><a href=
"http://www.w3.org/TR/css3-mediaqueries/">http://www.w3.org/TR/css3-mediaqueries/</a></dd>
<dt>Previous version:</dt>
<dd><a href=
"http://www.w3.org/TR/2007/CR-css3-mediaqueries-20070606/">http://www.w3.org/TR/2007/CR-css3-mediaqueries-20070606/</a></dd>
<dt>Editors:</dt>
<dd class="vcard"><a class="url fn n" lang="no" href="http://people.opera.com/howcome/">
<span class="given-name">Håkon</span> <span class="additional-name">Wium</span> <span class="family-name">Lie</span></a> <<span class="email">howcome @opera.com</span>></dd>
<dd class="vcard"><a class="url fn" lang="tr" href="http://tantek.com/">Tantek Çelik</a> <<span class="email">tantek @cs.stanford.edu</span>></dd>
<dd class="vcard"><span class="given-name">Daniel</span> <span class="family-name">Glazman</span> <<span class="email">daniel.glazman @disruptive-innovations.com</span>></dd>
<dd class="vcard"><a class="url fn n" lang="nl" href="http://annevankesteren.nl/">Anne van Kesteren</a>
<<span class="email">annevk@opera.com</span>></dd>
</dl>
<!--begin-copyright-->
<p>[If you keep the <!--comment-->, the copyright will be included
here automatically]</p>
<!--end-copyright-->
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc" id="abstract">Abstract</h2>
<p>HTML4 and CSS 2.1 currently support media-dependent style sheets
tailored for different <em>media types</em>. For example, a
document may use sans-serif fonts when displayed on a screen and
serif fonts when printed. "Screen" and "print" are two media
types that have been defined. <em>Media Queries</em> extend the
functionality of media types by allowing more precise labeling of
style sheets.</p>
<p>A Media Query consists of a media type and one or more
expressions to limit the scope of style sheets. Among the <em>media
features</em> that can be used in media queries are "width",
"height", and "color". By using Media Queries, presentations can be
tailored to a specific range of output devices without changing the
content itself.</p>
<h2 class="no-num no-toc" id="status">Status of this document</h2>
<!--begin-status-->
<p>[If you keep the <!--comment-->, the status boilerplate will be
included here automatically.]</p>
<!--end-status-->
<p>For this specification to exit the CR stage, the following
conditions shall be met:</p>
<ol>
<li><p>There must be at least two interoperable implementations. For
the purposes of this criterion, we define the following terms:</p>
<dl>
<dt>interoperable</dt>
<dd><p>passing the respective test case(s) in the CSS test suite,
or, if the implementation is not a Web browser, an equivalent
test. Every relevant test in the test suite should have an
equivalent test created if such a user agent (UA) is to be used to claim
interoperability. In addition if such a UA is to be used to claim
interoperability, then there must one or more additional UAs which
can also pass those equivalent tests in the same way for the
purpose of interoperability. The equivalent tests must be made
publicly available for the purposes of peer review. </p></dd>
<dt>implementation</dt>
<dd><p>a user agent which:</p>
<ol>
<li>implements the specification.</li>
<li>is available (i.e. publicly downloadable or available
through some other public point of sale mechanism). This is the
"show me" requirement.</li>
<li>is shipping (i.e. development, private or unofficial
versions are insufficient).</li>
<li>is not experimental (i.e. is intended for a wide audience
and could be used on a daily basis.)</li></ol></dd></dl></li>
<li><p>A minimum of another three months of the CR period must elapse. That is, this specification will not exit CR before 01 September 2007. When the specification exits CR, an implementation report will be published. At this point, no such report exists.</p></li>
<li><p>The specified technology must not be harmful for
accessibility.</p></li></ol>
<p>W3C Members
can also send comments directly to the CSS Working Group. The <a
href="http://www.w3.org/Style/css3-updates/css3-mediaqueries-comments">
comments received on the last working draft</a> are still
available.</p>
<h3 class="no-num no-toc">Features at risk</h3>
<p>The CSS WG has identified the aspect ratio media features
('aspect-ratio' and 'device-aspect-ratio') to be at risk due to poor
support in UAs. The 'orientation' media feature is also marked as risk as it
has been added since the last Candidate Recommendation.
<h2 class="no-num no-toc" id="contents">Table of contents</h2>
<!--toc-->
<h2>Background</h2>
<p>(This section is not normative.)</p>
<p>HTML4 [[HTML401]] and CSS 2.1 [[!CSS21]] currently support media-dependent
style sheets tailored for different media types. For example, a
document may use different style sheets for screen and print. In
HTML4, this can be written as:</p>
<div class="example">
<pre>
<link rel="stylesheet" type="text/css" media="screen" href="sans-serif.css">
<link rel="stylesheet" type="text/css" media="print" href="serif.css">
</pre>
</div>
<p>Inside a CSS style sheet, one can declare that sections apply to
certain media types:</p>
<div class="example">
<pre>
@media screen {
* { font-family: sans-serif }
}
</pre>
</div>
<p>The "print" and "screen" media types are defined in HTML4. The
complete list of media types in HTML4 is: "aural", "braille",
"handheld", "print", "projection", "screen", "tty", "tv". CSS 2.1 defines
the same list with the addition of "embossed" to differentiate between
braille tactile feedback devices and braille printers. CSS 2.1 uses
"speech" instead of "aural". Also, "all" is used to indicate that the
style sheet applies to all media types.</p>
<p>Media-specific style sheets are supported by several user
agents. The most commonly used feature is to distinguish between
"screen" and "print".</p>
<p>There have been requests for ways to describe in more detail
what type of output devices a style sheet applies to. Fortunately
HTML4 foresaw these requests and defined a forward-compatible
syntax for media types. Here is a quote from <a href=
"http://www.w3.org/TR/1998/REC-html40-19980424/types.html#h-6.13">HTML4,
section 6.13</a>:</p>
<blockquote cite="http://www.w3.org/TR/1998/REC-html40-19980424/types.html#h-6.13">
<p>Future versions of HTML may introduce new values and may allow
parameterized values. To facilitate the introduction of these
extensions, conforming user agents must be able to <span class=
"index-inst" id="parse" title="media descriptor::parsing of"><a id=
"idx-media-descriptor-1" name=
"idx-media-descriptor-1">parse</a></span> the <a class="noxref"
href=
"http://www.w3.org/TR/html40/present/styles.html#adef-media"><samp
class="ainst">media</samp></a> attribute value as follows:</p>
<ol>
<li>The value is a comma-separated list of entries. For example,
<pre>
media="screen, 3d-glasses, print and resolution > 90dpi"
</pre>
<p>is mapped to:</p>
<pre>
"screen"
"3d-glasses"
"print and resolution > 90dpi"
</pre>
</li>
<li>Each entry is truncated just before the first character that
isn't a US ASCII letter [a-zA-Z] (Unicode decimal 65-90, 97-122),
digit [0-9] (Unicode hex 30-39), or hyphen (45). In the example,
this gives:
<pre>
"screen"
"3d-glasses"
"print"
</pre>
</li>
</ol>
</blockquote>
<p>Media Queries, as described in this specification, build on the
mechanism outlined in HTML4. The syntax of Media Queries fit into the
media type syntax reserved in HTML4. The <code class="html">media</code>
attribute of HTML4 also exists in XHTML and generic XML. The same
syntax can also be used inside in the ''@media'' and ''@import'' rules
of CSS.</p>
<h2 id="media0">Media Queries</h2>
<p>A Media Query consists of a media type and one or more
<span class="index">expressions</span> involving <span
class="index">media features</span>.</p>
<div class="example">
<p>Here is a simple example written in HTML:</p>
<pre>
<span class="html-example"><link rel="stylesheet" media="screen and (color)" href="example.css" /></span>
</pre>
<p>This example expresses that a certain style sheet
(<code>example.css</code>) applies to devices of a certain media type
(''screen'') with certain feature (it must be a color screen).</p>
</div>
<div class="example">
<p>Here the same media query written in an @import-rule in CSS:</p>
<pre>
<span class="css-example">@import url(color.css) screen and (color);</span>
</pre>
</div>
<p>A Media Query is a logical expression that is either true or
false. A Media Query is true if the media type of the Media Query
matches the media type of the device where the user agent is running,
and all expressions in the Media Query are true. Also, a Media Query
which is otherwise false becomes true if the "not" keyword is
present.</p>
<p>When a Media Query is true, the corresponding style sheet is
applied as per the normal cascading rules.</p>
<p>Several Media Queries can be combined in a comma-separated list.
If one or more of the Media Queries in the comma-separated list is
true, the associated style sheet is applied, otherwise the
associated style sheet is ignored. </p>
<div class="example">
<p>Here is an example of several media queries in a comma-separated
list using the an @media-rule in CSS:</p>
<pre>
<span class="css-example">@media <em>screen and (color), projection and (color)</em> { ... }</span>
</pre>
</div>
<p>In the Media Queries syntax, the comma expresses a logical OR, while the ''and'' keyword
expresses a logical AND.</p>
<p>The logical NOT can be expressed through the ''not'' keyword. </p>
<div class="example">
<pre>
<span class="html-example"><link rel="stylesheet" media="<em>not screen and (color)</em>" href="example.css" /></span>
</pre>
</div>
<p>The presence of the keyword ''not'' at the beginning of the query
negates the result. I.e., if the Media Query had been true without the
''not'' keyword it will become false, and vice versa. User agents that
only support media types (as described in HTML4) will not recognize
the ''not'' keyword and the associated style sheet is therefore not
applied.</p>
<p>The keyword ''only'' can also be used to hide style sheets from
older user agents. User agents must process media queries starting
with ''only'' as if the ''only'' keyword was not present.</p>
<div class="example">
<pre>
<span class="html-example"><link rel="stylesheet" media="<em>only screen and (color)</em>" href="example.css" /></span>
</pre>
</div>
<p>The Media Queries syntax can be used with HTML, XHTML, XML [[XMLSTYLE]] and the @import and @media rules of CSS.</p>
<div class="example">
<p>Here is the same example written in HTML, XHTML, XML, @import and @media:</p>
<pre>
<span class="html-example"><link rel="stylesheet" media="<em>screen and (color), projection and (color)</em>" rel="stylesheet" href="example.css"></span>
<span class="html-example"><link rel="stylesheet" media="<em>screen and (color), projection and (color)</em>" rel="stylesheet" href="example.css" /></span>
<span class="xml-example"><?xml-stylesheet media="<em>screen and (color), projection and (color)</em>" rel="stylesheet" href="example.css" ?></span>
<span class="css-example">@import url(example.css) screen and (color), projection and (color);</span>
<span class="css-example">@media screen and (color), projection and (color) { ... }</span>
</pre>
</div>
<p>If a media feature does not apply to the device where the UA is
running, expressions involving the media feature will be false.</p>
<div class="example">
<p>The media feature ''device-aspect-ratio'' only applies to
visual devices. On an aural device, expressions involving
''device-aspect-ratio'' will therefore always be false:</p>
<pre>
<span class="html-example"><link rel="stylesheet" media="aural and (device-aspect-ratio: 16/9)" href="example.css" /></span>
</pre>
</div>
<p>Expressions will always be false if the unit of measurement does
not apply to the device. </p>
<div class="example">
<p>The ''px'' unit does not apply to ''tty''devices so the following media query is always false:</p>
<pre>
<span class="html-example"><link rel="stylesheet" media="tty and (min-device-width: 800px)" href="example.css" /></span>
</pre>
<p>Note that the media queries in this example would have
been true if the keyword ''not'' had been added to the beginning of
the media query.</p>
</div>
<p>A shorthand syntax is offered for media queries that apply to all
media types; the keyword ''all'' can be left out (along with the
trailing ''and'').
<div class="example">
<p>These two media queries are equivalent:</p>
<pre>
@media all and (orientation: portrait) { ... }
@media (orientation: portrait) { ... }
</pre>
</div>
<p>Expressions with with negative length values are always false.
<div class="example">
<p>This media query is false:
<pre>
@media (min-width: -100px) { ... }
</pre>
</div>
<p>To avoid circular dependencies, it is never necessary to apply the
style sheet in order to evaluate expressions. For example, the aspect
ratio of a printed document may be influenced by a style sheet, but
expressions involving ''device-aspect-ratio'' will be based on the
default aspect ratio of the user agent.</p>
<p class=note>User Agents agents are expected, but not required, to
re-evaluate and re-layout the page in response to changes in the user
environment, for example if the device is tilted from landscape to
portrait mode.
<h2>Syntax</h2>
<p>The media query syntax is described in terms of the
<a href="http://www.w3.org/TR/CSS21/grammar.html">CSS 2.1 grammar</a>. The
<code>media_query_list</code> production defined below replaces the
<code>medium</code> production from CSS 2.1. [[!CSS21]]</p>
<pre>media_query_list
: S* media_query [ ',' S* media_query]*
;
media_query
: [ONLY | NOT] S* media_type [ AND S* expression ]*
| expression [ AND S* expression ]*
;
media_type
: IDENT S*
;
expression
: '(' S* media_feature [':' S* expr]? ')' S*
;
media_feature
: IDENT S*
;</pre>
<p>the following new definitions are introduced:</p>
<pre>
L l|\\0{0,4}(4c|6c)(\r\n|[ \t\r\n\f])?|\\l
Y y|\\0{0,4}(59|79)(\r\n|[ \t\r\n\f])?|\\y</pre>
<p>The following new tokens are introduced:</p>
<pre>
{O}{N}{L}{Y} {return ONLY;}
{N}{O}{T} {return NOT;}
{A}{N}{D} {return AND;}
{num}{D}{P}{I} {return RESOLUTION;}
{num}{D}{P}{C}{M} {return RESOLUTION;}</pre>
<p><code>RESOLUTION</code> is to be added to the CSS 2.1
<code>term</code> production equivalently to other units.</p>
<p>CSS style sheets are generally case-insensitive, and this is
also the case for Media Queries.</p>
<p>Media queries involving unknown media types are ignored.</p>
<div class="example">
<p>Both these examples involve unknown media types and they are therefore ignored:</p>
<pre>
<span class="html-example"><link rel="stylesheet" media="<em>3d and (color)</em>" href="example.css" /></span>
<span class="html-example"><link rel="stylesheet" media="<em>not 3d and (color)</em>" href="example.css" /></span>
</pre>
<p>Because "3d" is an unknown type, the media query is
ignored and the associated style sheet will not be applied.</p>
</div>
<!--
<div class="example">
<p>In a comma-separated list of Media Queries, only those Media
Queries that involve unknown media types are ignored. In this example,
the first media query is ignored, but the second is not::</p>
<pre>
<span class="html-example"><link rel="stylesheet" media="<em>not 3d and (color), print</em>" href="example.css" /></span>
</pre>
</div>
-->
<p>Expressions involving unknown media features or unknown/illegal values are ignored.</p>
<div class="example">
<p>Consider this example:</p>
<pre>
<span class="html-example"><link rel="stylesheet" media="<em>all and (max-weight: 3kg) and (color)</em>" href="example.css" /></span>
</pre>
<p>Because "max-weight" is an unknown media feature, the media query is
ignored and the associated style sheet will not be applied.</p>
</div>
<p>If one media query in a comma-separated list is ignored, the other
media queries in the list are also ignored.</p>
<div class="example">
<pre>
<span class="html-example"><link rel="stylesheet" media="screen and (max-weight: 3kg) and (color), (color)" href="example.css" /></span>
</pre>
<p>In this example, the first media query is rejected due to an
unknown media feature and unknown value, but the second media query is
evaluated as if the first had not been specified.</p>
</div>
<!--
<p>For a definition of values used in Media Queries, see <a href=
"http://www.w3.org/TR/REC-CSS2/syndata.html#values">CSS2, section
4.3: Values and Units</a> {{!CSS21}}.</p>
-->
<h2 id="media1">Media features</h2>
<p>Syntactically, media features resemble CSS properties: they have
names and accept certain values. There are, however, several
important differences between properties and media features:</p>
<ul>
<li>Properties are used in <em>declarations</em> to give
information about how to present a document. Media features are
used in <em>expressions</em> to describe requirements of the output
device.</li>
<li>Most media features accept optional "min-" or "max-" prefixes
to express "greater or equal to" and "smaller or equal to"
constraints. This syntax is used to avoid "<" and ">"
characters which may conflict with HTML and XML. Those media features
that accept prefixes will most often be used with prefixes, but can
also be used alone.</li>
<li>Properties always require a value to form a declaration. Media
features, on the other hand, can also be used without a value in
which case the expression will be true if the media feature's value
in the output device is different from zero. </li>
<li>Properties may accept more complex values, e.g., calculations that
involve several other values. Media features only accept single
values: one keyword, one number, or a number with a unit identifier.
(The only exeptions are the aspect-ratio' and 'device-aspect-ratio'
media features.)
</li>
</ul>
<div class="example">
<p>For example, the ''color'' media feature can form expressions without a value
(''(color)''), or with a value (''(min-color: 1)'').</p>
</div>
<p class="note">This specification defines media features usable with visual and
tactile devices. Similarly, media features can be defined for aural
media types.</p>
<h3 id="width">width</h3>
<div class="media-feature"><span class="label">Value:</span>
<length><br>
<span class="label">Applies to:</span> visual and tactile media
types<br>
<span class="label">Accepts min/max prefixes:</span> yes<br>
</div>
<p>The ''width'' media feature describes the width of the rendering
surface of the output device. For continuous media, this is the width
of the viewport (as described by CSS 2.1, section 9.1.1 [[!CSS21]]). For
paged media, this is the width of the page box (as described by CSS 2.1,
section 13.2 [[!CSS21]]).</p>
<div class="example">
<p>For example, this Media Query expresses that the style sheet is
usable on printed output wider than 25cm:</p>
<pre>
<span class="html-example"><link rel="stylesheet" media="print and (min-width: 25cm)" href="http://...." /></span>
</pre>
</div>
<div class="example">
<p>This Media Query expresses that the style sheet is usable on
devices with viewport (the part of the screen/paper where the
document is rendered) widths between 400 and 700 pixels:</p>
<pre>
<span class="css-example">@media screen and (min-width: 400px) and (max-width: 700px) { ... }</span>
</pre>
</div>
<div class="example">
<p>This Media Query expresses that style sheet is usable on screen
and handheld devices if the width of the viewport is greater than
20em.</p>
<pre>
<span class="css-example">@media handheld and (min-width: 20em),
screen and (min-width: 20em) { ... }</span>
</pre>
<p>The ''em'' value is relative to the font size of the root
element.</p>
</div>
<h3 id="height">height</h3>
<div class="media-feature"><span class="label">Value:</span>
<length><br>
<span class="label">Applies to:</span> visual and tactile media
types<br>
<span class="label">Accepts min/max prefixes:</span> yes<br>
</div>
<p>The ''height'' media feature describes the height of the rendering
surface of the output device. For continuous media, this is the height
of the viewport. For paged media, this is the height of the page
box.</p>
<h3 id="device-width">device-width</h3>
<div class="media-feature"><span class="label">Value:</span> <length><br>
<span class="label">Applies to:</span> visual and tactile media types<br>
<span class="label">Accepts min/max prefixes:</span> yes<br>
</div>
<p>The ''device-width'' media feature describes the width of the
output device.</p>
<div class="example">
<pre>
<span class="css-example">@media screen and (device-width: 800px) { ... }</span>
</pre>
<p>In the example above, the style sheet will apply only to screens
that currently displays exactly 800 horizontal pixels. The ''px'' unit is
of the logical kind, as described in the <a href="#units">Units</a>
section.</p>
</div>
<h3 id="device-height">device-height</h3>
<div class="media-feature"><span class="label">Value:</span> <length><br>
<span class="label">Applies to:</span> visual and tactile media types<br>
<span class="label">Accepts min/max prefixes:</span> yes<br>
</div>
<p>The ''device-height'' media feature describes the height of the
output device.</p>
<div class="example">
<pre>
<span class="html-example"><link rel="stylesheet" media="screen and (device-height: 600px)" /></span>
</pre>
<p>In the example above, the style sheet will apply only to screens
that have exactly 600 vertical pixels. Note that the definition of the
''px'' unit is the same as in other parts of CSS.</p>
</div>
<h3>orientation</h3>
<div class="media-feature"><span class="label">Value:</span>
portrait | landscape<br>
<span class="label">Applies to:</span> bitmap media types<br>
<span class="label">Accepts min/max prefixes:</span> no<br>
</div>
<p>The ''orientation'' media feature describes the aspect ratio of the
viewport; if the viewport is wider than it is high, ''landscape'' will be
true, otherwise ''portrait'' will be true. A square viewport is considered
to be ''portrait''.
<div class="example">
<pre>
@media all and (portrait) { ... }
@media all and (landscape) { ... }
</pre>
</div>
<h3>aspect-ratio</h3>
<div class="media-feature"><span class="label">Value:</span>
<integer> / <integer><br>
<span class="label">Applies to:</span> bitmap media types<br>
<span class="label">Accepts min/max prefixes:</span> yes<br>
</div>
<p>The ''aspect-ratio'' media feature describes the aspect ratio of
the viewport. Aspect ratio is defined as the horizontal length of the
device's viewport divided by its vertical length. The value consists
of two positive integers separated by a ''/''.</p>
<div class="example">
<p>For example, if a screen device with square pixels has 1280 horizontal pixels and
720 vertical pixels (commonly referred to as "16:9"), the following
Media Queries will all match the device:</p>
<pre>
<span class="css-example">@media screen and (aspect-ratio: 16/9) { ... }
@media screen and (aspect-ratio: 32/18) { ... }
@media screen and (aspect-ratio: 1280/720) { ... }
@media screen and (aspect-ratio: 2560/1440) { ... }</span>
</pre>
</div>
<h3>device-aspect-ratio</h3>
<div class="media-feature"><span class="label">Value:</span>
<integer> / <integer><br>
<span class="label">Applies to:</span> bitmap media types<br>
<span class="label">Accepts min/max prefixes:</span> yes<br>
</div>
<p>The ''device-aspect-ratio'' media feature describes the aspect
ratio of the output device. The device aspect ratio is defined as the
horizontal length of the device's display divided by its vertical
length. The value consists of two positive integers separated by a
''/''.</p>
<!--
<p>In this specification, aspect ratio is defined as the number of
horizontal pixels over the number of vertical pixels.</p>
-->
<div class="example">
<p>For example, if a screen device with square pixels has 1280 horizontal pixels and
720 vertical pixels (commonly referred to as "16:9"), the following
Media Queries will all match the device:</p>
<pre>
<span class="css-example">@media screen and (device-aspect-ratio: 16/9) { ... }
@media screen and (device-aspect-ratio: 32/18) { ... }
@media screen and (device-aspect-ratio: 1280/720) { ... }
@media screen and (device-aspect-ratio: 2560/1440) { ... }</span>
</pre>
</div>
<!--
<p>Note that determining if a specified aspect ratio matches the
device aspect ratio can be done through multiplication (e.g.,
1280*9 = 11520 = 720*16) to avoid floating point operations.</p>
<div class="example">
<p>Using prefixes, <em>portrait</em> and <em>landscape</em> aspect
ratios can be expressed:</p>
<pre>
<span class="css-example">@media screen and (max-device-aspect-ratio: 1/1) /* portrait or square */
@media screen and (min-device-aspect-ratio: 1/1) /* landscape or square */</span>
</pre>
</div>
-->
<h3 id="color">color</h3>
<div class="media-feature"><span class="label">Value:</span> <integer><br>
<span class="label">Applies to:</span> visual media types<br>
<span class="label">Accept min/max prefixes:</span> yes<br>
</div>
<p>The ''color'' media feature describes the number of bits per color
component of the output device. If the device is not a color device,
the value is zero.</p>
<div class="example">
<p>For example, these two media queries express that a style sheet
applies to all color devices:</p>
<pre>
<span class="css-example">@media all and (color) { ... }
@media all and (min-color: 1) { ... }</span>
</pre>
</div>
<div class="example">
<p>This Media Query expresses that a style sheet applies to color
devices with 2 or more bits per color component:</p>
<pre>
<span class="css-example">@media all and (min-color: 2) { ... }</span>
</pre>
</div>
<p>If different color components are represented by
different number of bits, the smallest number is used.</p>
<div class="example">
<p>For instance, if an 8-bit color system represents the red
component with 3 bits, the green component with 3 bits and the blue
component with 2 bits, the ''color'' media feature will have a value
of 2.</p>
</div>
<p>In a device with indexed colors, the minimum number of bits per
color component in the lookup table is used.</p>
<p class="note">The described functionality is only able to describe color
capabilities at a superficial level. If further functionality is
required, RFC2531 [[RFC2531]] provides more specific media features
which may be supported at a later stage.</p>
<h3 id="color-index">color-index</h3>
<div class="media-feature"><span class="label">Value:</span>
<integer><br>
<span class="label">Applies to:</span> visual media types<br>
<span class="label">Accepts min/max prefixes:</span> yes<br>
</div>
<p>The ''color-index'' media feature describes the number of entries
in the color lookup table of the output device. If the device does not
use a color lookup table, the value is zero.
</p>
<div class="example">
<p>For example, here are two ways to express that a style sheet
applies to all color index devices:</p>
<pre>
<span class="css-example">@media all and (color-index) { ... }
@media all and (min-color-index: 1) { ... }</span>
</pre>
</div>
<div class="example">
<p>This Media Query expresses that a style sheet applies to a color
index device with 256 or more entries:</p>
<pre>
<span class="xml-example"><?xml-stylesheet media="all and (min-color-index: 256)"
href="http://www.example.com/..." ?></span>
</pre>
</div>
<h3 id="monochrome">monochrome</h3>
<div class="media-feature"><span class="label">Value:</span>
<integer><br>
<span class="label">Applies to:</span> visual media types<br>
<span class="label">Accepts prefixes:</span> yes<br>
</div>
<p>The ''monochrome'' media feature describes the number of bits per
pixel in a monochrome frame buffer. If the device is not a
monochrome device, the output device value will be 0.</p>
<div class="example">
<p>For example, here are two ways to express that a style sheet
applies to all monochrome devices:</p>
<pre>
<span class="css-example">@media all and (monochrome) { ... }
@media all and (min-monochrome: 1) { ... }</span>
</pre>
</div>
<div class="example">
<p>Express that a style sheet applies to monochrome
devices with more than 2 bits per pixels:</p>
<pre>
<span class="css-example">@media all and (min-monochrome: 2) { ... }</span>
</pre>
</div>
<div class="example">
<p>Express that there is one style sheet for color pages and another for monochrome:</p>
<pre>
<span class="html-example"><link rel="stylesheet" media="print and (color)" href="http://..." /></span>
<span class="html-example"><link rel="stylesheet" media="print and (monochrome)" href="http://..." /></span>
</pre>
</div>
<h3 id="resolution">resolution</h3>
<div class="media-feature"><span class="label">Value:</span>
<resolution><br>
<span class="label">Applies to:</span> bitmap media types<br>
<span class="label">Accepts min/max prefixes:</span> yes<br>
</div>
<p>The ''resolution'' media feature describes the resolution of the
output device, i.e. the density of the pixels. When querying devices
with non-square pixels, in ''min-resolution'' queries the least-dense
dimension must be compared to the specified value and in
''max-resolution'' queries the most-dense dimensions must be compared
instead. A ''resolution'' (without a "min-" or "max-" prefix) query
never matches a device with non-square pixels.
</p>
<div class="example">
<p>For example, this Media Query expresses that a style sheet is
usable on devices with resolution greater than 300 dots per
inch:</p>
<pre>
<span class="css-example">@media print and (min-resolution: 300dpi) { ... }</span>
</pre>
</div>
<div class="example">
<p>This Media Query expresses that a style sheet is
usable on devices with resolution greater than 118 dots per
centimeter:</p>
<pre>
<span class="css-example">@media print and (min-resolution: 118dpcm) { ... }</span>
</pre>
</div>
<h3 id="scan">scan</h3>
<div class="media-feature"><span class="label">Value:</span>
progressive | interlace<br>
<span class="label">Applies to:</span> "tv" media types<br>
<span class="label">Accepts min/max prefixes:</span> no<br>
</div>
<p>The ''scan'' media feature describes the scanning process of "tv"
output devices.</p>
<div class="example">
<p>For example, this Media Query expresses that a style sheet is
usable on tv devices with progressive scanning:</p>
<pre>
<span class="css-example">@media tv and (scan: progressive) { ... }</span>
</pre>
</div>
<h3 id="grid">grid</h3>
<div class="media-feature"><span class="label">Value:</span> <integer><br>
<span class="label">Applies to:</span> visual and tactile media types<br>
<span class="label">Accepts min/max prefixes:</span> no<br>
</div>
<p>The ''grid'' media feature is used to query whether the output device
is grid or bitmap. If the output device is grid-based (e.g., a "tty"
terminal, or a phone display with only one fixed font), the value will
be 1. Otherwise, the value will be 0.</p>
<p>The ''em'' unit has a special meaning in grid output devices. Since
the exact with of an ''em'' cannot be determined, one ''em'' is assumed to
be the width of one grid cell horizontally and the height of one grid
cell vertically. </p>
<div class="example">
<p>Here are two examples:</p>
<pre>
<span class="css-example">@media handheld and (grid) and (max-width: 15em) { ... }</span>
<span class="css-example">@media handheld and (grid) and (device-max-height: 7em) { ... }</span>
</pre>
</div>