<!DOCTYPE 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>已知宽高度DIV垂直水平居</title>   
<style type="text/css">   
<!--  
.main{ position:absolute; top:50%; left:50%; width:821px; height:392px; margin:-196px 0 0 -410.5px; background:#C8EDFB}  
-->   
</style>   
</head>   
<body>   
<div class="main">已知宽高度DIV垂直水平居</div>   
</div>   
</body>   
</html>   

 

 
 
说明:
width:821px; height:392px
margin的取值为高和宽的一半