function centerDiv(div){
	var el = $(div);
	return ((document.body.offsetHeight-(parseInt(el.getStyle("height"))))/2);
}

window.addEvent("domready", function(){
	$('mainDiv').setStyles({'opacity':0,'top': centerDiv('mainDiv')});
});

window.addEvent("load", function(){
	$('mainDiv').makeAnim({opacity:1}, 'easeOutExpo', 2000);
});


window.addEvent("resize", function(){
	$('mainDiv').makeAnim({top:centerDiv('mainDiv').round()}, 'easeOutExpo', 1600);
});