为什么margin:10 200px 10 300px 相对定位的结果那么奇怪？
<!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">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>o代表垂直距离，auto代表水平距离</title>
<style type="text/css">
body{margin:0;padding:0}
.top{height:100px;width:300px;background:blue;position:absolute;left:0;top:0}
.main{height:300px;background:#ccc;margin:10 200px 10 300px}
.foot{height:100px;background:#900;width:200px;position:absolute;right:0;top:0}
</style>
</head>
<body>
<div class="top"></div>
<div class="main"></div>
<div class="foot"></div>
</body>
</html>
结果麻烦老师们自己运行一下，求解答
