---
title: width
slug: Web/CSS/@viewport/width
translation_of: Web/CSS/@viewport
---
<div>{{CSSRef}}</div>

<p>The <strong>width</strong> CSS descriptor is shorthand for setting both the <a href="/zh-CN/docs/Web/CSS/@viewport/min-width"><code>min-width</code></a> and the <a href="/zh-CN/docs/Web/CSS/@viewport/max-width"><code>max-width</code></a> descriptors of the viewport. By providing one viewport length value, that value will determine both the <code>min-width</code> and the <code>max-width</code> to the value provided.</p>

<p>If two viewport values are provided the first value will be set to the <code>min-width</code> and the second value will be set <code>max-width</code>.</p>

<h2 id="Syntax" name="Syntax">Syntax</h2>

<pre class="brush: css">/* An example with one viewport value: */
@viewport {
    width: 320px;
}

/* An example with two viewport values: */
@viewport {
    width: 320px, 120px;
}

</pre>



<h3 id="Values" name="Values">Values</h3>

<dl>
 <dt><code>auto</code></dt>
 <dd>The used value is calculated from the other CSS descriptors' values.</dd>
 <dt><code>&lt;length&gt;</code></dt>
 <dd>A non-negative absolute or relative length.</dd>
 <dt><code>&lt;percentage&gt;</code></dt>
 <dd>A percentage value relative to the width or height of the <span class="css">initial viewport</span> at zoom factor 1.0, for horizontal and vertical lengths respectively. Must be non-negative.</dd>
</dl>

<h3 id="Formal_syntax">Formal syntax</h3>

<pre class="syntaxbox">auto <a href="https://developer.mozilla.org/en-US/docs/CSS/Value_definition_syntax#Single_bar" title="Single bar">|</a> <a href="https://developer.mozilla.org/en-US/docs/Web/CSS/length">&lt;length&gt;</a> <a href="https://developer.mozilla.org/en-US/docs/CSS/Value_definition_syntax#Single_bar" title="Single bar">|</a> <a href="https://developer.mozilla.org/en-US/docs/Web/CSS/percentage" title="">&lt;percentage&gt;</a></pre>

<h2 id="Specifications" name="Specifications">Specifications</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{SpecName('CSS3 Device', '#descdef-viewport-min-width', '"min-width" descriptor')}}</td>
   <td>{{Spec2('CSS3 Device')}}</td>
   <td>Initial definition</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>

<p>{{ CompatibilityTable() }}</p>

<div id="compat-desktop">
<table class="compat-table" style="height: 93px; width: 950px;">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>29 (behind a flag)</td>
   <td>{{CompatNo}}</td>
   <td>10 {{property_prefix("-ms")}}</td>
   <td>11.10<br>
    Removed in 15<br>
    Reintroduced behind a flag in 16</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table" style="height: 93px; width: 948px;">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Chrome for Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>
    <table class="compat-table">
     <tbody>
      <tr>
       <td>4.4</td>
      </tr>
     </tbody>
    </table>
   </td>
   <td>
    <table class="compat-table">
     <tbody>
      <tr>
       <td>29</td>
      </tr>
     </tbody>
    </table>
   </td>
   <td>{{CompatNo}}</td>
   <td>10{{property_prefix("-ms")}}</td>
   <td>11.10<br>
    Removed in 15<br>
    Reintroduced behind a flag in 16</td>
   <td>{{CompatNo}}</td>
  </tr>
 </tbody>
</table>
</div>