CSS_Layout三分栏__左右两栏宽度固定,中间自适应

body{
min-width:800px;
}
h1,
h2,
div p{
margin:0;
padding:10px;
}
/*#wrapper{*/
/*width:90%;*/
/*margin:0 auto;*/
/*background:#ddd;*/
/*}*/
#content{
background:#ff6;
}
#left,
#right{
width:200px;
float:left;
background:#fc0;
}
#middle{
float:left;
width:100%;
margin:0 -200px;
}
#middle .inner{
margin:0 200px;
background:#ccc;
}
#right{
float:right;
}
#footer{
clear:both;
}
/* Clearfix */
.clearfix:after{content:".";display:block;height:0;clear:both;visibility:hidden;}
.clearfix{display:inline-table;}
/* Hides from IE-mac /*/
* html .clearfix{height:1%;}
.clearfix{display:block;}
/* End hide from IE-mac */
*+html .clearfix{min-height:1%;}/* IE7 */

<div id="wrapper">
<div id="content" class="clearfix">
<div id="left">
<h2>Left</h2>
<p>左边栏宽度固定为200px</p>
</div>
<div id="middle">
<div class="inner">
<h2>Middle</h2>
<p>中间栏宽度可以自适应</p>
<p><b>原理：</b>利用margin的负值错别固定的宽度</p>
</div>
</div>
<div id="right">
<h2>Right</h2>
<p>右边栏宽度固定为200px</p>
</div>
</div>
<div id="footer">
<h1>Footer</h1>
</div>
</div>