如何在混合布局中设置子列间的间隙？
在单列布局中我们可以用
<style type="text/css">
body{ margin:0; padding:0; font-size:50px; font-weight:bold}
div{ text-align:center; line-height:50px}
.main{ margin:0 auto}
.left{width:200px;height:500px;background:#090;position:absolute;left:0;right:0;}
.middle{height:500px;background:#C6C;margin:0 310px 0 210px}
.right{width:300px;height:500px;background:#03C;position:absolute;right:0;top:0;}
</style>
</head>
<body>
<div class="main">
<div class="left">200px</div>
<div class="middle">我是松鼠我爱吃玉米玉米玉米玉米玉米 啊啊！！！！！！</div>
<div class="right">300px</div>
</div>
</body>
那么在混合布局中如何设置子列间的间隙，相对的距离的参考是哪一个
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>混合布局</title>
<style>
body{ margin:0; padding:0; font-size:30px; font-weight:bold}
div{ text-align:center; line-height:50px}
.top{ height:100px;background:#9CF}
.head,.main{ width:960px;margin:0 auto}
.head{ height:100px; background:#F90}
.left{ width:220px; height:300px; background:#ccc; float:left}
.right{ width:740px; height:300px;background:#FCC; float:right}
.r_sub_left{ width:540px; height:300px; background:#9C3; float:left}
.r_sub_right{ width:200px; height:300px; background:#9FC;float:right}
.footer{height:100px; background:#9F9;clear:both}
</style>
</head>
<body>
<div class="top">
<div class="head">head</div>
</div>
<div class="main">
<div class="left">left</div>
<div class="right">
<div class="r_sub_left">sub_left
</div>
<div class=" r_sub_right">sub_right
</div>
</div>
</div>
<div class="footer">footer</div>
</body>
