.art_image img {
    width: 10em;
    padding: .5em;
}

.desc {
    visibility: hidden;
    font-family: "Open Sans", sans-serif;
    color: black;
    font-weight: 800px;
    line-height: 1.53em;
    position: absolute;
    background-color: Snow;
    padding: .5em;
    justify-self: left;
}

.art_image:hover .desc {
    visibility: visible;
}