.thumbnail{
position: relative;
z-index: 0;
}

:hover.thumbnail{
background-color: transparent;
z-index: 50;
}

.thumbnail span{ /*CSS for enlarged image*/
position: absolute;
background-color: #f0f0f0;
padding: 2px;
left: -0px;
border: 1px dashed gray;
visibility: hidden;
color: black;
text-decoration: none;
}

.thumbnail span img{ /*CSS for enlarged image*/
border-width: 0;
padding: 2px;
}

:hover.thumbnail span{ /*CSS for enlarged image on hover*/
visibility: visible;
top: 0;
left: 60px; 
position:absolute
}