方法一：
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css">
body{
margin:0;
padding:0;
min-width:600px;
}
.main{
float:left;
width:100%;
}
.main_body{
margin:0 210px;
background:#888;
height:200px;
}
.left,.right{
float:left;
width:200px;
height:200px;
background:#F60;
}
.left{
margin-left:-100%;
}
.right{
margin-left:-200px;
}
</style>
</head>
<body>
<div class="main">
<div class="main_body">Main</div>
</div>
<div class="left">Left</div>
<div class="right">Right</div>
</body>
</html>方法二：
<!doctype html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
<style type="text/css">
*{
border:0;
margin:0;
padding:0;
}
</style>
</head>
<body>
<div style="float:left;width:200px;height:200px;background:#444;">zuo</div>
<div style="float:right;width:200px;height:200px;background:#444;">you</div>
<div style="height:200px;margin-left:200px;margin-right:200px;background:#999;">zhong</div>
</body>
</html>