window.onload=centerDiv;
function centerDiv(){
	 var d = document.getElementById('mainPage');
	 	var mp = document.getElementById('mpContainer');
	 	var mpWidth = mp.offsetWidth;
		var mpHeight = mp.offsetHeight;
		mp.style.display='block';
		var offWidth = d.offsetWidth;
	 	var offHeight = d.offsetHeight;
	 	d.style.margin = '-' + (offHeight / 2 ) + 'px ' + '0px ' + '0px ' + '-' + (offWidth / 2 ) + 'px';
		}