var W = screen.width;
if (W == 800) document.body.background = "";
else if (W == 1024) document.body.background = "/images/1024.jpg";
else if (W == 1152) document.body.background = "/images/1024.jpg";
else if (W == 1280) document.body.background = "/images/1280.jpg";
else if (W == 1366) document.body.background = "/images/1280.jpg";
else if (W == 1440) document.body.background = "/images/1280.jpg";
else if (W == 1600) document.body.background = "/images/1280.jpg";
else if (W == 1680) document.body.background = "/images/1280.jpg";
else document.body.background = "";
document.body.style.backgroundRepeat = "no-repeat";