三列等高布局

<div class="content">
<p class="left">left<br />left<br />left<br /></p>
<p class="center">center</p>
<p class="right">right </p>
</div>

.content{overflow:hidden}
.left,.center,.right{
    margin-bottom:-10000px;
    padding-bottom:10000px;
    width:300px;
    float:left;
    
}
.left{background:#f00;}
.center{background:#0ff}
.right{background:#f0f}

1.上层div设overflow:hidden,隐藏溢出

3.三个p设padding-bottom填充10000px;然后用margin-bottom抵消10000px