.thumbnail{
        position: relative;
        z-index: 0;
}

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

.thumbnail span{
        position: absolute;
        background-color: lightyellow;
        padding: 5px;
        left: -1000px;
        border: 1px gray;
        visibility: hidden;
        color: black;
        text-decoration: none;
}

.thumbnail span img{
        border-width: 0;
        padding: 2px;
}

.thumbnail:hover span{
        visibility: visible;
        top: -80px;
        left: 20px;
}