Site={
	backgroundimage:document.getElement('#backgroundimage img'),

	set:function(v){
		if(Site.s&&((v=window.getSize()).x!=Site.x||v.y!=Site.y||Site.backgroundimage.src!=Site.s.src)){
			var s=$(Site.s),width=Math.round(v.y*(s.width/s.height));Site.x=v.x;Site.y=v.y;
			Site.backgroundimage.setStyles({width:(s.width>s.height&&v.x>width)?'50%':width,height:'auto'}).set('src',s.get('src'));
		}
	},
}

$extend(new Image(),{onload:function(){Site.set(Site.s=this)},src:Site.backgroundimage.get('src')});

window.addEvents({resize:Site.set.bind(Site)})