function position()
{
	var ua = navigator.userAgent.toLowerCase();

	if (ua.indexOf('msie') != -1) {
	var content_height=document.documentElement.clientHeight-140;
	if (content_height<1) content_height=1;
	document.getElementById('main').style.height=content_height;
	}
	else if (ua.indexOf('msie 7') >= -1) {
	var content_height=window.innerHeight-140;
	if (content_height<1) content_height=1;
	document.getElementById('main').style.height=content_height+"px";
	}

}