<!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">
*{margin:0;padding:0;}
#wrap{width:960px;;margin:0 auto;}
.mainbody{width:100%;height:400px;background:#FC0;overflow:hidden;}
.box1{width:130px;height:50px;background:red;float:left;}
.box2{width:330px; height:150px;background:blue;}
.box3{height:50px;background:purple; }
</style>
</head>
<body>
<div id="wrap">
<div class="mainbody">
<div class="box1">盒子1</div>
<div class="box2">盒子2</div>
<div class="box3">盒子3</div>
</div>
</div>
</body>
</html>