html,
body {
    height: 100%;
    margin:0;
}

img {
    max-width: 100%;
}

/* cover */

#cover {
    background:#222 url('img/dice.jpg') center center  no-repeat;
    background-size:cover;
    color: black;
    height: 100%;
    text-align: center;
    display: flex;
    align-items: center;
}

#cover-caption {
    width: 100%;
}