var height = 1607;

$(document).ready(function() {
	background();
	$(window).resize(function() { background(); }).scroll(function() { background(); });
});

function background() {
	var body_height = $("body").height();
	var max_scroll = height-$("#background-helper").height();
	if($(window).scrollTop()>max_scroll) {
		$("body").css({'background-attachment': 'fixed', 'background-position': 'center bottom'});
	} else {
		$("body").css({'background-attachment': 'scroll', 'background-position': 'center top'});
	}
}