var w=screen.width
var h=screen.height
if (w <= 800) {
	var url = 'url('+baseUrl+'/images/800x600_background.jpg)';
} else if (w <= 1024) {
	var url = 'url('+baseUrl+'/images/1024x768_background.jpg)';
} else if (w <= 1280) {
	var url = 'url('+baseUrl+'/images/1280x960_background.jpg)';
} else if (w <= 1600) {
	var url = 'url('+baseUrl+'/images/1600x1200_background.jpg)';
} else if (w <= 1920) {
	var url = 'url('+baseUrl+'/images/1920x1200_background.jpg)';
} else {
	var url = 'url('+baseUrl+'/images/1920x1200_background.jpg)';
	}
document.body.style.backgroundImage = url;