---
title: <position>
slug: Web/CSS/position_value
translation_of: Web/CSS/position_value
---
<p>{{ CSSRef() }}</p>

<h2 id="概要">概要</h2>

<p><code>&lt;position&gt;</code> <a href="/en/CSS" title="CSS">CSS</a>  数据类型表示用于设置相对于框的位置的2D空间中的坐标。</p>

<p><img alt="" src="/files/3797/position_type.png" style="float: left; height: 208px; width: 306px;">特定坐标可以由具有特定偏移的两个关键字给出。关键字表示元素框的一条边或两条边之间的中心线：左，右，上，下或中心 (其表示左边缘和右边缘之间的中心，或者顶部边缘或底部边缘之间的中心，这取决于上下文).</p>

<div class="note">
<p> A keyword represents one edge of the element's box or the center line between two edges: <code>left</code>, <code>right</code>, <code>top</code>, <code>bottom</code> or <code>center</code> (which represents either the center between the left and right edges, or the center between the top or bottom edges, depending on the context).</p>
</div>

<p>{{ experimental_inline() }}一个偏移量可以是一个相对值用以表示 {{cssxref("&lt;percentage&gt;")}} （百分比），或是一个绝对的 {{cssxref("&lt;length&gt;")}} （长度）值。正值是向右或向下的偏移，看适用于哪一个。负值则是在另外方向上的偏移。</p>

<p> <code>&lt;position&gt;</code> 值表述的最终位置并不需要位于元素的盒子中。</p>

<p>如果仅指定单个偏移量，它将指定x轴坐标。当只有单个偏移量或关键字被指定时，对于另个轴的值将被假定为“center”。</p>

<h2 id="补间" style="">补间</h2>

<p>横坐标值和纵坐标值都独立进行补间。而由于两者（补间）速度都由同一 {{cssxref("&lt;timing-function&gt;")}} （函数）定义，点将沿一条直线移动。</p>

<h2 id="取值">取值</h2>

<pre class="brush:css">/* 1-value syntax */
<var>keyword</var>                  /* The corresponding edge, the other direction is corresponding to center, the middle of the edge */
<var>&lt;length&gt;</var> or <var>&lt;percentage&gt;</var> /* The position on the x-axis, 50% for the y-axis */

/* 2-value syntax */
<var>keyword</var> <var>keyword</var>          /* A keyword for each direction, the order is irrelevant */
<var>keyword</var> <var>value</var>            /* The value is the offset for the edge defined by the keyword */
</pre>

<h3 id="正式语法">正式语法</h3>

<pre class="syntaxbox">[ [ left | center | right | top | bottom | <var>&lt;percentage&gt;</var> | <var>&lt;length&gt;</var> ] |
                  [ left | center | right | <var>&lt;percentage&gt;</var> | <var>&lt;length&gt;</var> ] [ top | center | bottom | <var>&lt;percentage&gt;</var> | <var>&lt;length&gt;</var> ] |
                  [ center | [ left | right ] [ <var>&lt;percentage&gt;</var> | <var>&lt;length&gt;</var> ]? ] &amp;&amp;
                  [ center | [ top | bottom ] [ <var>&lt;percentage&gt;</var> | <var>&lt;length&gt;</var> ]? ]
                ]
</pre>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">规范</th>
   <th scope="col">状态</th>
   <th scope="col">注释</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{ SpecName('CSS3 Values', '#position', '&lt;position&gt;') }}</td>
   <td>{{ Spec2('CSS3 Values') }}</td>
   <td>Relists links to both definition, with the requirement to be coherent: if {{ SpecName('CSS3 Backgrounds', '', '') }} is supported, its definition of <code>&lt;position&gt;</code> must be used too.</td>
  </tr>
  <tr>
   <td>{{ SpecName('CSS3 Backgrounds', '#ltpositiongt', '&lt;position&gt;') }}</td>
   <td>{{ Spec2('CSS3 Backgrounds') }}</td>
   <td>Defines <code>&lt;position&gt;</code> explicitly and extends it to support offsets from any edge. {{ experimental_inline() }}</td>
  </tr>
  <tr>
   <td>{{ SpecName('CSS2.1', 'colors.html#background-properties', '&lt;position&gt;') }}</td>
   <td>{{ Spec2('CSS2.1') }}</td>
   <td>Allows combination of a keyword with a {{cssxref("&lt;length&gt;")}}, or {{cssxref("&lt;percentage&gt;")}} value.</td>
  </tr>
  <tr>
   <td>{{ SpecName('CSS1', '#background-position', '&lt;position&gt;') }}</td>
   <td>{{ Spec2('CSS1') }}</td>
   <td>Defines <code>&lt;position&gt;</code> anonymously as the value of {{ cssxref("background-position") }}.</td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

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

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>特性</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>1.0</td>
   <td>{{ CompatGeckoDesktop("1") }}</td>
   <td>4.0</td>
   <td>3.5</td>
   <td>1.0 (85)</td>
  </tr>
  <tr>
   <td>Combination of a keyword and a {{cssxref("&lt;length&gt;")}}, or {{cssxref("&lt;percentage&gt;")}}</td>
   <td>1.0</td>
   <td>{{ CompatGeckoDesktop("1") }}</td>
   <td>4.0</td>
   <td>3.5</td>
   <td>1.0 (85)</td>
  </tr>
  <tr>
   <td>Four-value syntax (support for offset from any edge) {{ experimental_inline() }}</td>
   <td>{{ CompatNo() }} {{ webkitbug("37514") }}</td>
   <td>{{ CompatGeckoDesktop("13.0") }}</td>
   <td>{{ CompatNo() }}</td>
   <td>10.5</td>
   <td>{{ CompatNo() }} {{ webkitbug("37514") }}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>特性</th>
   <th>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>{{ CompatVersionUnknown() }}</td>
   <td>{{ CompatGeckoMobile("1") }}</td>
   <td>{{ CompatVersionUnknown() }}</td>
   <td>{{ CompatVersionUnknown() }}</td>
   <td>{{ CompatVersionUnknown() }}</td>
  </tr>
  <tr>
   <td>Combination of a keyword and a {{cssxref("&lt;length&gt;")}}, or {{cssxref("&lt;percentage&gt;")}}</td>
   <td>{{ CompatVersionUnknown() }}</td>
   <td>{{ CompatGeckoMobile("1") }}</td>
   <td>{{ CompatVersionUnknown() }}</td>
   <td>{{ CompatVersionUnknown() }}</td>
   <td>{{ CompatVersionUnknown() }}</td>
  </tr>
  <tr>
   <td>Four-value syntax (support for offset from any edge) {{ experimental_inline() }}</td>
   <td>{{ CompatNo() }}</td>
   <td>{{ CompatGeckoMobile("13.0") }}</td>
   <td>{{ CompatUnknown() }}</td>
   <td>{{ CompatUnknown() }}</td>
   <td>{{ CompatNo() }}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="sect1"> </h2>