层固定在底部
<style type="text/css">
#bottomNav
{
background-color: red;
z-index: 999;
position: fixed;
bottom: 0px;
left: 0px;
width: 100%;
_position: absolute; /* for IE6 */
_top: expression(documentElement.scrollTop + documentElement.clientHeight-this.offsetHeight); /* for IE6 */
overflow: visible;
}
</style>
<div id="bottomNav">
漂浮层</div>