RUNOOB.COM
源代码：
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<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>电脑学习网教程(runoob.com)</title> <style> h1:after {content:url(smiley.gif);} </style> </head> <body> <h1>This is a heading</h1> <p>The :after pseudo-element inserts content after an element.</p> <h1>This is a heading</h1> <p><b>注意:</b>仅当!DOCTYPE 已经声明 IE8支持这个内容属性.</p> </body> </html>
运行结果