[CSS] Div 置底

css style如下

<style type="text/css">
.footer { position:fixed !important;
/*for ie*/
top:expression(document.body.clientHeight + offsetParent.scrollTop-this.offsetHeight-5);
/*for ff*/
bottom:15px;
right:15px;
}

</style>

<div style="height: 120px;" id="footer" class="r1">Message</div>