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css.cascade.html
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css.cascade.html
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<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>CSS 层叠与集成</title>
<link rel="stylesheet" type="text/css" href="http://fonts.googleapis.com/css?family=Graduate|Numans">
<link rel="stylesheet" type="text/css" href="/assets/lib/prism.css">
<link rel="stylesheet" type="text/css" href="/assets/style/site.css">
<script src="/assets/lib/prism.js" defer></script>
<script src="/assets/elements/elements.bundle.js"></script>
</head>
<body>
<div class="page-loading">
<div class="loading-bar"></div>
</div>
<script>
!function(){
var s = 'page-loading';
window.addEventListener('load', function() {
setTimeout(function() {
document.querySelector('.' + s).classList.remove(s);
}, 500);
});
}();
</script>
<x-menu></x-menu>
<div class="content">
<h1 class="header">CSS 层叠与集成</h1>
<x-table-of-content root=".article" content=".content"></x-table-of-content>
<article class="article single-column">
<div class="wrap">
<p><a href="http://www.w3.org/TR/css3-cascade">规范地址(2013-10-3)</a></p>
<h2><code class="language-javascript">@import</code> 规则</h2>
<p>从其他样式表中导入规则。</p>
<p><code class="language-javascript">@import</code> 必须放在所有 at 规则(除了 <code class="language-javascript">@charset</code>)前面。</p>
<h2>速记属性(shorthand properties)</h2>
<p>速记属性中确实的声明部分,默认会使用它的初始值来声明。</p>
<h3><code class="language-javascript">all</code> 属性</h3>
<p>是所有属性(除了 <code class="language-javascript">direction</code> 和 <code class="language-javascript">unicode-bidi</code>)的速记方式,可以设置 <code class="language-javascript">inherit</code>,<code class="language-javascript">initial</code> 和 <code class="language-javascript">unset</code>。</p>
<p>Firefox 从 27 开始支持。</p>
<h2>值处理</h2>
<p>获取 CSS 属性的最终值需要经过诸多步骤:</p>
<ol><li>收集元素的所有声明值(declared value)。</li><li>层叠产生层叠值(cascaded value)。</li><li>缺省化产生指定值(specified value)。</li><li>解析值的依赖产生计算值(computed value)。</li><li>格式化文档产生使用值(used value)。</li><li>最终,使用值基于显示环境的限制转为实际值(actual value)。</li></ol>
</div>
</article>
</div>
<x-progressbar root=".content"></x-progressbar>
<x-go-top root=".content"></x-go-top>
</body>
</html>