Simple CSS media detection

gistfile1.css

/* portrait screen width */
@media screen and (max-device-width: 480px) {
   .portrait {
   }

   .landscape {
      display:none;
   }

}

/* landscape device widths */
@media screen and (min-device-width: 481px) {
   .portrait {
      display:none;
   }

   .landscape {
   }
}