code fond

$(function(){

var bg= "(http://img99.xooimage.com/files/a/c/a/fond-2000-40861dc.jpg)";

if(screen.width < 801) bg="http://img99.xooimage.com/files/7/f/6/fond-800-408619a.jpg";
else if(screen.width < 1025) bg="http://img99.xooimage.com/files/a/e/e/fond-1024-40861ae.jpg";
else if(screen.width < 1281) bg="http://img98.xooimage.com/files/0/3/7/fond-1280-40861bc.jpg";
else if(screen.width < 1601) bg="http://img97.xooimage.com/files/c/0/5/fond-1600-40861cd.jpg";

document.body.style.backgroundImage="url(\""+bg+"\")";

});