》》HTML
<div class="zg_city">
<div class="zg_left"></div>
<div class="zg_right"></div
</div>
》》css
.zg_city{ width:100%; height:100%; background-color:#f8f8f8}
.zg_city:after { visibility: hidden; clear: both; display: block; height: 0px; content: "."; }
原文：http://www.cnblogs.com/Greenzgz/p/4447931.html