function cssPreloadImages() { 
	var i, j, img; 
	for (i=0; i<document.styleSheets.length; i++) { 
		var pos = document.styleSheets[i].href.lastIndexOf("/"); 
		var cssDir = (pos != -1) ? document.styleSheets[i].href.substring(0, pos + 1) : ""; 
		var rules = document.styleSheets[i].cssRules ? document.styleSheets[i].cssRules : document.styleSheets[i].rules; 
		for (j=0; j<rules.length; j++) { 
			var style = rules[j].style; 
			if (style.backgroundImage.toLowerCase().substr(0,4) == "url(") { 
				var filename = style.backgroundImage.substring(4, style.backgroundImage.length - 1); 
				if (filename.indexOf("http://") != 0 && filename.indexOf("/") != 0) 
					filename = cssDir + filename; 
				var img = new Image(); 
				img.src = filename; 
			} 
		}
	}
} 

if (window.attachEvent) {
	// IE 
	window.attachEvent("onload", cssPreloadImages); 

} else { 
	// DOM 
	window.addEventListener("load", cssPreloadImages, false); 
}