<div id="demo_div"></div>
<style> #demo_div{ left: 0; position: fixed; bottom: 0; width: 100%; } </style>
<div id="demo_div"></div>
<style> #demo_div{ left: 0; position: fixed; bottom: 0; width: 100%; } </style>
原文：http://www.cnblogs.com/BearLee/p/8109871.html