if (screen.width <= 800)
  {
   var window_width = Math.ceil(screen.width * 0.985);
   var window_height = Math.ceil(screen.height * 0.87);
  }
else
  {
   var window_width = Math.ceil(800 * 1.10);
   var window_height = Math.ceil(600 * 1.10);
   window_left = Math.ceil((screen.width - window_width) / 2);
   window_top = Math.ceil((screen.height - window_height) / 2);
  }

if (document.layers)
  {
   window_width = Math.ceil(window_width * 0.985);
   window_height = Math.ceil(window_height * 0.735);
  }