function ie_height() 
{
	var mainHeight = document.documentElement.clientHeight;
	var elem = document.getElementById('obj').offsetHeight;
	if (elem <= mainHeight) {
		document.getElementById('obj').style.top = "-50%";
		document.getElementById('middle').style.top = "50%";
	}
}
if (window.attachEvent && !window.opera)
{
	window.attachEvent("onload", ie_height);
}