var i,
res = [2560,1920,1600,1440,1280,1152,1024];
for (i=0; i<res.length; i++) {
if (screen.width >= res[i]) {
document.body.style.backgroundImage = 'url(http://www.leia.se/wp-content/themes/child/images/bakgrunder/bg' + res[i] + '.jpg)';
	    break;
	  }
	}