2列布局中再3列布局搞不了
<!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">
.sd{height:300px;width:45%;background:#379;float:left;}
.ds{height:300px;width:55%;background:#F06;float:right;}
.ab{width:100px;height:300px;top:0;left:0; background:#00C; float:left;position:absolute;}
.ac{height:300px;margin:0 120px 0 100px;}
.ad{width:120px;height:300px; top:0;right:0;background:#00C; float:right;position:absolute;}
</style>
</head>
<div class="sd">5</div>
<div class="ds">
<div class="ab"></div>
<div class="ac"></div>
<div class="ad"></div>
</div>
<body>
</body>
</html>