<!DOCTYPE html>
<html>
<head>
<meta charset="{CHARSET}">
<title></title>
<style type="text/css">
#a{
border: 5px solid blue;
width: 100px;
height: 100px;
margin: 10px;
background-color: #ADFF2F;
position: fixed;
}
#aa{
border: 5px solid blue;
width: 100px;
height: 100px;
margin: 10px;
background-color: #ADFF2F;
left: 20px;
top: 50px;
position: relative;
}
</style>
</head>
<body>
<div id="a">a
</div>
<div id="aa">aa
</div>
</body>
</html>
原文：http://www.cnblogs.com/sglq/p/7192742.html