jQuery(document).ready( function() {
	var
	viewportHeight = $(window).height(),
	$body = $('body'),
	$window = $(window);
	$window.bind('resize', function() {
		var offset = $('#fullheightcontainer').offset();
		$('#backdrop').css('width', $body.width());
		$('#backdrop').css('left', -offset.left);

		var pos = $body.height() + ( -parseFloat($('#backdrop').css('bottom')) );
		if( pos >= $('#wrapper').height() ) {
			pos = 0;
			$('#backdrop').css('bottom', 0);
		}

		pos = $body.height() + ( -parseFloat($('#backdrop').css('bottom')) );

	});
	$window.bind('scroll', function() {
		var pos = 0;
		if( $body.height() < $('#wrapper').height() ) {
			// anpassen
			pos = - $window.scrollTop();
		} else if( $body.height() >= $('#wrapper').height() ) {
			// nicht anpassen
			pos = 0;
		}

		$('#backdrop').css('bottom', pos);

		var pos = $body.height() + parseFloat($('#backdrop').css('bottom'));
		if( pos >= $('#wrapper').height() ) {
			$('#backdrop').css('bottom', 0);
		}
	});
	$window.resize();
});