.thumbnail{position: relative;z-index: 0; color: #00A020;}

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

.thumbnail span{ /*CSS for enlarged image*/
position: absolute;
background-color: lightyellow;
padding: 5px;
left: -1000px;
border: 1px dashed gray;
visibility: hidden;
color: black;
text-decoration: none;
}

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

.thumbnail:hover span{ /*CSS for enlarged image on hover*/
visibility: visible;
top: 20px;
left: 30px; /*position where enlarged image should offset horizontally */
width: 120px;
}