页脚绝对定位

<style type="text/css">
*{margin: 0;padding: 0;}
.min_nav_bg_new {
width: 100%;
position: fixed;
_position: absolute;
_top: expression(documentElement.scrollTop + documentElement.clientHeight-offsetHeight);
height: 46px;
bottom: 0;
z-index: 50;
}
.min_nav_new {
width: 1000px;
margin: 0 auto;
height: 46px;
}
</style>
<div class="min_nav_bg_new">
<div class="min_nav_new">
</div>
</div>