<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
<style type="text/css">
div
{
width:100px; height:100px;position:absolute; top:10px;
filter: Alpha(Opacity=50); /* 针对IE*/
background-color: rgba(0, 0, 0, 0.5); /*针对其他浏览器*/
}
</style>
</head> <body>
<h1>hello</h1>
<div></div>
</body>
</html>
div块覆盖在hello上，依然是透明的