if (screen.width <= 1024) {
	  var $file = "bg1024.jpg";
  }
  else if (screen.width <= 1280) {
	  var $file = "bg1280.jpg";
  }
  else if (screen.width <= 1920) {
	  var $file = "bg1920.jpg";
  }
  else {
    var $file = "bg2272.jpg";
  }

  document.write("<style type=\"text/css\">");
  document.write("body { background-image: url('/img/"+$file+"'); )");
  document.write("</style>");