function checkBackgroundPosition() {
	var size = Position.windowSize();
	var width = size[0] - 1004;
	if (size[0] < 1004) { size[0] = 1004; }
	size[0] = size[0] - 16;
	//size[0] = size[0] - 20;
	var offset = (size[0] / 2) - 800;
	
	$$("Body")[0].setStyle({ backgroundPosition: offset + "px 0px" });
}