$(document).ready(function(){
	setBgPosition();
						
	$(window).resize(function(){
		setBgPosition();
	});					   
})
function setBgPosition(){
	var _t = $('#mainpage');
	var offset = _t.offset();
	bg_x = _t.width() + offset.left - 1068;
	bg_y = _t.height() + offset.top - 686;
	$("body").css("background-position",bg_x + "px "+ bg_y + "px");	
}