$(document).ready(function(){
	var theWindow        = $(window),
	$bg              = $("#background"),
	aspectRatio      = $bg.width() / $bg.height();

	function resizeBg() {

			if ( (theWindow.width() / theWindow.height()) < aspectRatio ) {
				$bg
					.removeClass()
					.addClass('bgheight');
			} else {
				$bg
					.removeClass()
					.addClass('bgwidth');
			}
	}

	theWindow.resize(function() {
			resizeBg();
	}).trigger("resize");
});