.hoverbox {
    position: relative;
    padding: 1em 0 2em 1em;
    font-size: 80%;
    font-family: Verdana, Arial, sans-serif;
/*Add a height attribute and set to largest image's height to prevent overlaying*/
}
.thumbnail img {
    border: 5px solid #EBEBEB;
    margin: 0 1em 1em 0;
}
.thumbnail:hover img {
    border: 5px solid #EBEBEB;
}
.thumbnail span { /*CSS for enlarged image*/
    position: absolute;
    background-color: #FFFFFF;
    padding: 5px;
    left: -1000px;
    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: -30px;
    left: 100px; /*position where enlarged image should offset horizontally */
    z-index: 50;
}