body {
  background: white url(../graphics/face_nmr.jpg) no-repeat top left;
}

div#links {
  font-family: "Helvetica", "Verdana", "Arial", sans-serif;
  font-size: large;
  position: absolute; top: 250px; left: 50px; width: 600px; z-index: 100;
}

div#links a {
  text-decoration: none;

  color: #13C;
}

div#links a:hover {
  color: #FC3;
}

div#links a span {
  display: none;
}


div#links a:hover span {
   display: block;
   position: absolute; top: 50px; left: 200px; width: 200px;
   padding: 5px; margin: 10px; z-index: 100;
   color: black; background: transparent;
   font: small "Helvetica", "Verdana", "Arial", sans-serif; text-align: center;
}