window.onload = getMarginTop;
window.onresize = getMarginTop;

function getMarginTop(){
	if(document.documentElement.clientHeight){
		var top = (document.documentElement.clientHeight - document.getElementById('container').clientHeight)/2 + "px";
	}else{
		var top = "200px";
	}
	document.getElementById('container').style.marginTop = top;
}