function Mostrar_capa() {
   var i, visStr, args, theObj;
   args = Mostrar_capa.arguments;
   for (i=0; i<(args.length-2); i+=3) {
      visStr   = args[i+2];
      if (navigator.appName == 'Netscape' && document.layers != null) {
         theObj = eval(args[i]);
         if (theObj) theObj.visibility = visStr;
      }
      else if (document.all != null) {
         if (visStr == 'show') visStr = 'visible';
         if (visStr == 'hide') visStr = 'hidden';
         theObj = eval(args[i+1]);
         if (theObj) theObj.style.visibility = visStr;
      }
   }
}
function posiciondelborde() {
   var ancho = screen.width
   var alto = screen.height
   if (ancho==800||alto==600) {
      Mostrar_capa('document.layers[\'Layer1\']','document.all[\'Layer1\']','show');
   }
   if (ancho==640||alto==480) {
      Mostrar_capa('document.layers[\'Layer2\']','document.all[\'Layer2\']','show');
   }
   if (ancho==1024||alto==768) {
      Mostrar_capa('document.layers[\'Layer3\']','document.all[\'Layer3\']','show');
   }
   else {
      Mostrar_capa('document.layers[\'Layer4\']','document.all[\'Layer4\']','show');
   }
}