CSS3 drop shadows with gradients

drop shadows with gradients
  height: 8em;
  width: 15em;
  padding: 2em;
  border-radius: 2em;
  background: 
   radial-gradient(right bottom, rgba(255,255,255,0.0), black 2em), 
   linear-gradient(left, black, rgba(255,255,255,0.0) 2em, rgba(255,255,255,0.0) 19em, rgba(255,255,255,0.0)), 
   linear-gradient(top, black, rgba(255,255,255,0.0) 2em, rgba(255,255,255,0.0) 10em, rgba(255,255,255,0.0));
  background-color: white;
  background-size: 2em 2em, 20em 10em, 17em 10em;
  background-position: top left, left 2em, 2em top;
  background-repeat: no-repeat;