Outer shadow
.shadow {
  -moz-box-shadow: 5px 5px 5px #ccc;
  -webkit-box-shadow: 5px 5px 5px #ccc;
  box-shadow: 5px 5px 5px #ccc;
}

Inner shadow
.shadow {
   -moz-box-shadow:inset 0 0 10px #000000;
   -webkit-box-shadow:inset 0 0 10px #000000;
   box-shadow:inset 0 0 10px #000000;
}