MooTools Full Screen Background - Asset.image

<style>
#bg{position:fixed !important;position:absolute;bottom:0}
</stylev

<script>
window.addEvent('load', function() {resize();});
window.addEvent('resize',function(){resize();});

function resize(){
	win= window.getSize();
	
	if($('bg') !=null){$('bg').dispose();}
	
	var bg = new Element('div',{id:'bg'}).inject(document.body,'top');
	bg.setStyles({'overflow':'hidden','top':0,'left':0,'width':win.x,'height':win.y,'display':'block'});
	var image = 'bg1.jpg';
	var loader = new Asset.images(image, {
		onComplete: function() {
			var imgL = new Element('img',{src:image});
			imgL.setStyles({'opacity':0});
			imgL.inject(bg);
			imgW = imgL.getSize().x;
			imgH = imgL.getSize().y;
			if(imgW/imgH>win.x/win.y){n_imgH = win.y; n_imgW = (win.y/imgH)*imgW;}
			else {n_imgH = (win.x/imgW)*imgH; n_imgW = win.x;}
			imgL.setStyles({'width':n_imgW ,'height':n_imgH,'display':'block','opacity':1});
		}
});};
</script>