.thumbnail
{
  position: relative;
  z-index: 0;
}
.thumbnail:hover
{
  background-color: transparent;
  z-index: 50;
}
/* CSS for enlarged image*/
.thumbnail span
{ 
  position: absolute;
  background-color: #E9E9E9;
  padding: 5px;
  left: -1000px;
  border: 1px dashed #000000;
  visibility: hidden;
  color: black;
  text-decoration: none;
}
/* CSS for enlarged image*/
.thumbnail span img
{
  border-width: 0;
  padding: 2px;
}
/* CSS for enlarged image on hover*/
.thumbnail:hover span
{
  visibility: visible;
  top: -150px;
  /* position where enlarged image should offset horizontally */
  left: 10px;
}