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

.thumbnail img{
margin:0 auto;
padding:0;
}

.thumbnail:hover{
background-color: transparent;

}

.thumbnail:hover img{
 border:none;

}

.thumbnail span{ /*CSS for enlarged image*/
position: absolute;
padding: 5px;
left: -1000px;

visibility: hidden;
color: black;
text-decoration: none;
bottom:0px;
}

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

}

.thumbnail:hover span{ /*CSS for enlarged image*/
visibility: visible;
top: 139px;
left:260.5px; /*position where enlarged image should offset horizontally */
z-index: 250;
bottom:0px;
}