​x
 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head>
<style type="text/css">
h1:after {content:url(/i/w3school_logo_white.gif)}
</style>
</head>
​
<body>
<h1>This is a heading</h1>
<p>The :before pseudo-element inserts content before an element.</p>
<h1>This is a heading</h1>
<p><b>注释：</b>如果已规定 !DOCTYPE，那么 Internet Explorer 8 （以及更高版本）支持 content 属性。
</body>
</html>
​