左列定宽，右列自适应布局

利用float+margin实现

.left{float:left;width:100px;}
.right{margin-left:100px;}

利用float+margin（fix）实现

<div class="parent">
    <div class="left"></div>
    <div class="right-fix">
        <div class="right"></div>
    </div>
</div>

.left{width:100px;float:left;}
.right-fix{width:100%;margin-left:-100px;float:right'}
.right{margin-left:100px;}

利用float+overflow实现

.left{width:100px;float:left;}
.right{overflow:hidden;}