<!DOCTYPE html>
<html>
<meta name="name" content="content" charset='utf-8'>
<head>
<title></title>
</head>
<style type="text/css" media="screen">
.by{padding-left:180px;padding-right: 200px;}
.main{width: 100%;height: 400px;background: red;float: left;}
.left{width: 180px;float: left;background: green;height: 300px;position: relative;margin-left: -100%;right: 180px;overflow: hidden;}
.right{width: 200px;float: left;background: blue;height: 300px;position: relative;margin-right: -200px;}
</style>
<body>
<div class="by">
<div class="main">
</div>
<div class="left">
</div>
<div class="right">
</div>
</div>
</body>
<script type="text/javascript" charset="utf-8" async defer>
</script>
</html>
