css的田字格布局
利用清除浮动
<!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" xml:lang="en"><head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
<title>Document</title>
<style>
div{
margin: 10px;
width: 300px;
height: 300px;
background: blue;
float: left;
}
#s{
clear: left;
}
</style>
</head>
<body>
<div></div>
<div></div>
<div id="s"></div>
<div></div>
</body>
</html>