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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 rel="stylesheet" href="http://www.w3.org/StyleSheets/TR/W3C-[STATUS]">
</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]/WD-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>Latest Editor Version:</dt>
<dd><a href="http://dev.w3.org/csswg/css3-mediaqueries/">http://dev.w3.org/csswg/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>
<!--copyright-->
<hr title="Separator for header">
</div>
<h2 class="no-num no-toc" id="abstract">Abstract</h2>
<p>HTML4 and CSS2 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 zero 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>
<p>For this publication of the Media Queries Working Draft the CSS WG would
like to solicit feedback on the parts that have changed since the last publication:</p>
<ul>
<li>Revision of the syntax section.
<li>Addition of the ''aspect-ratio'' and ''orientation'' media features.
</ul>
<!--status-->
<p>This specification is a <strong>Last Call Working Draft</strong>. All
persons are encouraged to review this document and <strong>send comments
to the <a href="http://lists.w3.org/Archives/Public/www-style/">www-style</a>
mailing list</strong> as described above. The
<strong>deadline for comments</strong> is <strong>21 November 2008</strong>.</p>
<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 <a href="http://www.w3.org/Style/CSS/Test/">CSS test suite</a>,
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 shipped, or is a "nightly build" (i.e., a development version
for the next release), but is not experimental (i.e., a version
specifically designed to pass the test suite and not intended for
daily usage going forward).</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 23 August 2008.-->
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>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 ''device-aspect-ratio'' media feature to be
at risk due to poor support in user agents. The ''orientation'' and
''aspect-ratio'' media features are also marked as risk as they have been
added since the last Candidate Recommendation.</p>
<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 CSS2 [[!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''. CSS2
defines the same list, removes ''aural'' and adds ''embossed'' and
''speech''. 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>
<p>However, the parsing rules for media queries are incompatible with those
of HTML4 so that they are consistent with those of media queries used in
CSS. It is expected that future versions of HTML refer to the media queries
specification directly so that this difference is resolved.</p>
<h2 id="media0">Media Queries</h2>
<p>A media query consists of a media type and zero or more
<span class="index">expressions</span> involving <span
class="index">media features</span>. If the media type is omitted it is
assumed to be ''all''.</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>
<p class="note">HTML has not yet been normatively updated to use media queries in the <code>media</code> attribute.</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 (as defined in the "Applies to" line),
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. If the comma-separated list is the empty
list it is assumed to specify the media query ''all''.</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>
<div class="example">
<p>Here are two examples of the empty media query list in HTML:</p>
<pre>
<span class="html-example"><link rel="stylesheet" href="example.css" media=""/></span>
<span class="html-example"><link rel="stylesheet" href="example.css" media=" "/></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>
<p class="note">Just like HTML, the [[XMLSTYLE]] specification has not yet
been updated to use media queries in the <code>media</code> pseudo-attribute.</p>
</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>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">CSS2 grammar</a> and
<a href="http://www.w3.org/TR/CSS21/syndata.html#syntax">CSS2 syntax</a>. As
such, rules not defined here are defined in CSS2. The
<code>media_query_list</code> production defined below replaces the
<code>medium</code> production from CSS2. [[!CSS21]]</p>
<pre>media_query_list
: S* media_query [ ',' S* media_query]* | S*
;
media_query
: [ONLY | NOT]? S* media_type S* [ AND S* expression ]*
| expression [ AND S* expression ]*
;
media_type
: IDENT
;
expression
: '(' S* media_feature S* [':' S* value]? ')' S*
;
media_feature
: IDENT
;</pre>
<p>COMMENT tokens, as defined by CSS2, do not occur in the grammar (to keep
it readable), but any number of these tokens may appear anywhere between
other tokens. [[!CSS21]]</p>
<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 CSS2
<code>term</code> production and <code>NOT</code>, <code>ONLY</code>,
<code>AND</code>, and <code>','</code> are to be added to the CSS2
<code>value</code> production.</p>
<p>CSS style sheets are generally case-insensitive, and this is
also the case for media queries.</p>
<p>In addition to conforming to the syntax, each media query needs to use
media types and media features according to their respective specification
in order to be considered conforming.</p>
<div class="example">
<p>Only the first media query is conforming in the example below because the
"example" media type does not exist.</p>
<pre>
@media all { body { background:lime } }
@media example { body { background:red } }
</pre>
</div>
<h3>Error Handling</h3>
<p>For media queries that are not conforming user agents need to follow the
rules described in this section.</p>
<ul>
<li>
<p><strong>Unknown media types.</strong> Unknown media types evaluate to
false, unless negated by the ''not'' keyword, in which case they evaluate
to true. Effectively, they are treated identically to known media types
that do not match the media type of the device.</p>
<div class="example">
<p>The media query "<code>unknown</code>" will evaluate to false, unless
<code>unknown</code> is actually a supported media type. Similarly,
"<code>not unknown</code>" will evaluate to true.</p>
</div>
<p class="note">Unknown media types are distinct from media types that do
not actually match the IDENT production. Those fall under the malformed
media query clause.</p>
<li>
<p><strong>Unknown media features.</strong> User agents are to ignore a
media query when one of the specified media features is unknown.</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>
<div class="example">
<pre>@media (min-orientation:portrait) { ... }</pre>
<p>Is dropped because the ''orientation'' feature does not accept the
''min-'' prefix.
</div>
<li>
<p><strong>Unknown media feature values.</strong> As with unknown media
features, user agents are to ignore a media query when one of the
specified media feature values is unknown.</p>
<div class="example">
<p>The media query <code>(color:20example)</code> specifies an unknown
value for the ''color'' media feature and is therefore ignored.</p>
</div>
<div class="example">
<p>This media query is invalid because negative lengths are not allowed
for the ''width'' media feature:
<pre>@media (min-width: -100px) { ... }</pre>
</div>
<li>
<p><strong>Malformed media query.</strong> User agents are to handle
unexpected tokens encountered while parsing a media query by reading until
the end of the media query, while observing
<a href="http://www.w3.org/TR/CSS21/syndata.html#block">the rules for
matching pairs</a> of (), [], {}, "", and '', and correctly handling
escapes. Media queries with unexpected tokens are ignored. [[!CSS21]]
<div class="example">
<pre>@media (example, all,), speech { /* only applicable to speech devices */ }
@media &test, screen { /* only applicable to screen devices */ }</pre>
</div>
<div class="example">
<p>The following is an malformed media query because having no space
between ''and'' and the expression is not allowed. (That is reserved for
the functional notation syntax.)</p>
<pre>@media all and(color) { ... }</pre>
</div>
<p>When all media queries in a media query list are ignored it is the same
as if "<code>not all</code>" was specified.</p>
<div class="example">
<p>The following lists of media queries would all end up as "<code>not
all</code>":</p>
<pre>@media test, @test { ... }
@media example { ... }
@media screen and (min-example), example { ...}</pre>
</div>
</ul>
<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. For a media
feature <var>feature</var>, <code>(<var>feature</var>)</code> will evaluate
to true if <code>(<var>feature</var>:<var>x</var>)</code> will evaluate to
true for a value <var>x</var> other than zero or zero followed by a unit
identifier (i.e., other than <code>0</code>, <code>0px</code>,
<code>0em</code>, etc.). Media features that are prefixed by min/max cannot
be used without a value. When a media feature prefixed with min/max is used
without a value it makes the media query malformed.</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 exceptions 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 targeted display
area of the output device. For continuous media, this is the width
of the viewport (as described by CSS2, section 9.1.1 [[!CSS21]]). For
paged media, this is the width of the page box (as described by CSS2,
section 13.2 [[!CSS21]]).</p>
<p>A specified <length> cannot be negative.</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 targeted display
area 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>
<p>A specified <length> cannot be negative.</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 rendering
surface of the output device. For continuous media, this is the width
of the screen. For paged media, this is the width of the page sheet
size.</p>
<p>A specified <length> cannot be negative.</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 rendering
surface of the output device. For continuous media, this is the height
of the screen. For paged media, this is the height of the page sheet
size.</p>
<p>A specified <length> cannot be negative.</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 (orientation:portrait) { ... }
@media all and (orientation:landscape) { ... }
</pre>
</div>
<h3>aspect-ratio</h3>
<div class="media-feature"><span class="label">Value:</span>
<ratio><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.</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>
<ratio><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.</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>
<p>A specified <integer> cannot be negative.</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>A specified <integer> cannot be negative.</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 min/max 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>
<p>A specified <integer> cannot be negative.</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>