function center() {
			var myMaxH = document.documentElement.clientHeight;
				
			if(myMaxH > 450){	
				myMaxH = myMaxH - 250;
			} else {
				myMaxH = 133;
			}
			
			document.getElementById('delta').style.height = myMaxH+"px";
			
			var footerTop = document.getElementById('delta').style.top + document.getElementById('delta').style.height;
			document.getElementById('footer').style.top = footerTop+"px";
		}