#modalpopup_Background{
display:none;
position:absolute; /* hack for internet explorer 6*/
height:expression(document.documentElement.clientHeight + 'px');
width:100%;
top:0;
left:0;
background:#000000;
border:0;
z-index:1;
}
body > #modalpopup_Background {
	position: fixed;
	height:100%;
}