<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/ html4/strict.dtd">
<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"><title>CSS伪元素</title></head><style type="text/css">p:first-child:first-letter {color: #ff0000;font-size: xx-large;}p:first-child:first-line {color: #0000ff;font-variant: small-caps;}div:first-line{color: #0000ff;font-variant: small-caps;}h1:before {content: url(./book.png);}h2:after {content: url(./book.png);}</style><body><p>北京欢迎你</p><p>北京欢迎你</p><div>北京欢迎你<br/>北京欢迎你</div><h1>百度</h1><h2>百度</h2></body>
</html>
运行结果
 MongoDB介绍及安装)
