.thumbnail{ position: relative; z-index: 0; }
.thumbnail:hover{ background-color: transparent; z-index: 50; }
.thumbnail span{
position: absolute; background-color: #767c6b; padding: 5px; left: -1000px;
border: 1px solid #767c6b; visibility: hidden; color: #FFFFFF; text-decoration: none;
}
.thumbnail span img{ border-width: 0; padding: 2px; }
.thumbnail:hover span{ visibility: visible; top: -50px; left: -200px; }