CSS 置底浮動footer

#bottombar {
background-color: #efefec;
position: fixed; !important;
width: 100%;
bottom: 0;
z-index: 5; 
height: 34px;		
border: 1px solid #999999;		
background-repeat:repeat-x;
color:#FFFFFF;
_position:absolute;
_top:expression(document.body.scrollTop+document.body.clientHeight-this.clientHeight);
}