---
title: mask-border-width
slug: Web/CSS/mask-border-width
translation_of: Web/CSS/mask-border-width
---
<div>{{CSSRef}}{{SeeCompatTable}}</div>

<div><code><strong>mask-border-width</strong></code> <a href="/zh-CN/docs/Web/CSS">CSS</a> 属性设置元素的 <a href="/zh-CN/docs/Web/CSS/mask-border">mask border</a>的宽度</div>

<h2 id="语法">语法</h2>

<pre class="brush:css no-line-numbers">/* Keyword value */
mask-border-width: auto;

/* &lt;length&gt; value */
mask-border-width: 1rem;

/* &lt;percentage&gt; value */
mask-border-width: 25%;

/* &lt;number&gt; value */
mask-border-width: 3;

/* vertical | horizontal */
mask-border-width: 2em 3em;

/* top | horizontal | bottom */
mask-border-width: 5% 15% 10%;

/* top | right | bottom | left */
mask-border-width: 5% 2em 10% auto;

/* Global values */
mask-border-width: inherit;
mask-border-width: initial;
mask-border-width: unset;
</pre>

<p>可以使用从下面的值列表中选择的一个，两个，三个或四个值来指定<code>mask-border-width</code>属性。</p>

<ul>
 <li>指定一个值时，即对应四条边的宽度；</li>
 <li>指定两个值时，第一个值对应上下边框的宽度，第二个值对应左右边框的宽度；</li>
 <li>指定三个值时，第一个值对应上边框的宽度，第二个值对应左右边框的宽度，第三个值对应底部边框的宽度；</li>
 <li>指定四个值时，按顺时针方向，分别对应上，右，下，左边框的宽度。</li>
</ul>

<h3 id="值">值</h3>

<dl>
 <dt><code>&lt;length-percentage&gt;</code></dt>
 <dd><code>mask</code>边框宽度指定一个值或者百分比，设定百分比时，是相对于<code>mask</code>的长度和宽度。不能为负数。</dd>
 <dt><font face="consolas, Liberation Mono, courier, monospace"><span style="background-color: rgba(220, 220, 220, 0.5);">&lt;number&gt;</span></font></dt>
 <dd>mask边框宽度为元素<code>border-width</code>的倍数。不能为负数。</dd>
 <dt><code>auto</code></dt>
 <dd>使<code>mask-border</code>的宽度等于相应<a href="https://developer.mozilla.org/en-US/docs/Web/CSS/mask-border-slice" title="The mask-border-slice CSS property divides the image set by mask-border-source into regions. These regions are used to form the components of an element's mask border."><code>mask-border-slice</code></a>的固有宽度或高度（以适用者为准），如果图像没有所需的固有尺寸，则使用相应的边框宽度。</dd>
</dl>

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

<pre class="syntaxbox">{{csssyntax}}</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("CSS Masks", "#propdef-mask-border-width", "mask-border-width")}}</td>
   <td>{{Spec2("CSS Masks")}}</td>
   <td>Initial definition</td>
  </tr>
 </tbody>
</table>

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

<h2 id="浏览器兼容性">浏览器兼容性</h2>

<p>待定</p>