function centerDiv(divId){
	var scrennWidth = 0;
	var screenHeight = 0;
	var divWidth = 0;
	var divHeight = 0;
	var div = document.getElementById(divId);
	var dw = new String(div.style.width);
	var dh = new String(div.style.height);
	divWidth = parseInt(dw.substring(0,(dw.length-2)));
	divHeight = parseInt(dh.substring(0,(dw.length-2)));

	if (navigator.userAgent.indexOf("MSIE") > 0){
		screenWidth = document.documentElement.clientWidth/2;
		screenHeight = document.documentElement.clientHeight/2;
		div.style.top = (screenHeight - (divHeight/2)) + 'px' ;
		div.style.left = (screenWidth - (divWidth/2)) + 'px' ;
		div.style.width = divWidth + 'px';
		div.style.height = divHeight + 'px';
	}
	
	else {
		screenWidth = window.innerWidth/2;
		screenHeight = window.innerHeight/2;
		div.style.top = (screenHeight - (divHeight/2)) + 'px' ;
		div.style.left = (screenWidth - (divWidth/2)) + 'px' ;
		div.style.width = divWidth + 'px';
		div.style.height = divHeight + 'px';
	}

}
window.onresize = function (){
	centerDiv("main");
}