.caption {
    position: absolute;
    background-color: rgba(0, 0, 0, .6);
    color: #fff;
    padding: 0.5rem 1rem;
    font-size: 1.2rem;
    right: .5rem;
}
.caption:empty {
    display: none;
}
.caption--bottom {
    bottom: .5rem;
}
.caption--top {
    top: .5rem;
}