$(document).ready(function() {
	var bgImg = $("#background");

	function resizeImg() 
	{
		var imgwidth = bgImg.width();
		var imgheight = bgImg.height();
		
		var winwidth = $(window).width();
		var winheight = $(window).height();
		
		var widthratio = winwidth / imgwidth;
		var heightratio = winheight / imgheight;
		
		var widthdiff = heightratio * imgwidth;
		var heightdiff = widthratio * imgheight;
	
		if(heightdiff>winheight) {
			bgImg.css({
				width: winwidth+'px',
				height: heightdiff+'px',
				"z-index": "-10"
			});
		} else {
			bgImg.css({
				width: widthdiff+'px',
				height: winheight+'px',
				"z-index": "-50"
			});		
		}
	}
		 
	resizeImg(bgImg);
	
	$(window).load(function () {
  		resizeImg(bgImg);
	});
		
	$(window).resize(function() {
		resizeImg(bgImg);
	});
});