<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>div+css</title>
<style type="text/css">
.out{
border:solid 1px red;
width: 960px;
height: 400px;
margin: 0 auto;
}
.left{
width: 300px;
height: 400px;
background-color: red;
float: left;
}
.right{
width: 660px;
height: 400px;
background-color: blue ;
float: left;
}
.rup{
width: 660px;
height: 200px;
background-color: yellow;
}
</style>
</head>
<body>
<div class="out">
<div class="left"></div>
<div class="right">
<div class="rup"></div>
<div class="down"></div>
</div>
</div>
</body>
</html>
原文：https://www.cnblogs.com/zhangqianxi/p/13941067.html