function main () {
	update ();
}
function update () {
	var x = (document.body.clientWidth  - 294 ) / 2 + document.body.scrollLeft;
	var y = (document.body.clientHeight - 294 ) / 2 + document.body.scrollTop;
	document.body.style.backgroundPosition = x+"px "+y+"px";
	document.body.style.backgroundImage = "url('/img/cross.jpg')";
	setTimeout ( "update()", 100 );
}