根据窗口大小自动调整元素大小

<!--[if IE]>
<script>
var objmain = document.getElementById("main");

function updatesize(){
var bodyw = window.document.body.offsetWidth;
if(bodyw <= 790) objmain.style.width="772px";
else if(bodyw >= 1016) objmain.style.width="996px";
else objmain.style.width="100%";
}
updatesize();
window.onresize = updatesize;

</script>
<![endif]-->