.gallerycontainer{
position: relative;
/* Add a height attribute and set to largest image's height to prevent overlaying */
}

.thumbnail img{
border: 1px solid silver;
margin: 0 5px 5px 0;
}

.thumbnail:hover{
background-color: transparent;
}

.thumbnail:hover img{
border: 1px solid silver;
}

.thumbnail span{ /* CSS for enlarged image */
position: absolute;
background-color: transparent;
padding: 0px;
left: -1000px;
border: 1px none;
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 */
visibility: visible;
top: 0;
left: 180px; /* horizontal offset for displayed image */
z-index: 50;
}

</style>