样式表：

body{margin:0;padding:0px;text-align:center;}
#wrap{margin:0 auto;text-align:left; width:100%;}

/*左边栏，固定宽度*/
.wrap_l{float:left;background:#FF0000;margin-right:-150px;width:150px;}
/*中间栏，自适应宽度*/
.wrap_m{width:auto;background:#00FF00;margin:0 140px 0 150px;}
/*右边栏，固定宽度*/
.wrap_r{float:right;background:#0000FF;margin-left:-140px;width:140px;}

.wrap_inner_l{float:left;background:#00FFFF;margin-right:-200px;width:200px;}
.wrap_inner_m{width:auto;background:#FFFF00;margin:0 0 0 200px;}



html代码
<div id="wrap">
<div class="wrap_l">左边栏</div>
<div class="wrap_r">右边栏</div>
<div class="wrap_m">中间栏</div>
</div>