---
title: margin-top
slug: Web/CSS/margin-top
translation_of: Web/CSS/margin-top
---
<div>{{CSSRef}}</div>

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

<p><img alt="The effect of the CSS margin-top property on the element box" src="/files/4101/margin-top.svg" style="border-style: solid; border-width: 1px; float: left; margin-bottom: 2em; margin-right: 1em;"><span class="seoSummary"> <strong><code>margin-top</code></strong> 属性用来设置元素的顶部外边距，你也可以使用负值。</span></p>

<p><span class="seoSummary">这个属性对于不可替换的inline元素没有效果,比如 {{HTMLElement("tt")}} 或者 {{HTMLElement("span")}}.</span></p>

<p>{{cssinfo}}</p>

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

<pre class="brush:css">/* &lt;length&gt; values */
margin-top: 10px;        /* 绝对长度 */
margin-top: 1em;         /*相对于字体大小 */
margin-top: 5%;          /*相对于最相邻的父级元素块（block）的宽度*/

/* Keyword values */
margin-top: auto;

/* Global values */
margin-top: inherit;
margin-top: initial;
margin-top: unset;
</pre>

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

<dl>
 <dt><code>&lt;length&gt;</code></dt>
 <dd>设置固定长度 参考{{cssxref("&lt;length&gt;")}} 来查看合适的值.</dd>
 <dt><code>&lt;percentage&gt;</code></dt>
 <dd>百分比值{{cssxref("&lt;percentage&gt;")}} 总是相对于 父元素块的宽度</dd>
 <dt><code>auto</code></dt>
 <dd>参考 {{cssxref("margin")}}.</dd>
</dl>

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

{{csssyntax}}

<h2 id="Examples" name="Examples">示例</h2>

<pre class="brush:css;">.content { margin-top:   5%; }
.sidebox { margin-top: 10px; }
.logo    { margin-top: -5px; }
#footer  { margin-top:  1em; }
</pre>

<h2 id="Specifications" name="Specifications">说明</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 Box', '#the-margin', 'margin-top')}}</td>
   <td>{{Spec2('CSS3 Box')}}</td>
   <td>无改动</td>
  </tr>
  <tr>
   <td>{{SpecName('CSS3 Transitions', '#animatable-css', 'margin-top')}}</td>
   <td>{{Spec2('CSS3 Transitions')}}</td>
   <td>定义 <code>margin-top</code> 为可动画的属性.</td>
  </tr>
  <tr>
   <td>{{SpecName('CSS2.1', 'box.html#margin-properties', 'margin-top')}}</td>
   <td>{{Spec2('CSS2.1')}}</td>
   <td>去除了在inline元素的效果。</td>
  </tr>
  <tr>
   <td>{{SpecName('CSS1', '#margin-top', 'margin-top')}}</td>
   <td>{{Spec2('CSS1')}}</td>
   <td>最初定义了该属性</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_Compatibility" name="Browser_Compatibility">浏览器兼容性</h2>

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

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari (WebKit)</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>1.0</td>
   <td>{{CompatGeckoDesktop("1")}}</td>
   <td>3.0</td>
   <td>3.5</td>
   <td>1.0 (85)</td>
  </tr>
  <tr>
   <td><code>auto</code> value</td>
   <td>1.0</td>
   <td>{{CompatGeckoDesktop("1")}}</td>
   <td>6.0 (strict mode)</td>
   <td>3.5</td>
   <td>1.0 (85)</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>IE Phone</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>1.0</td>
   <td>{{CompatGeckoMobile("1")}}</td>
   <td>6.0</td>
   <td>6.0</td>
   <td>1.0</td>
  </tr>
 </tbody>
</table>
</div>