footer {
    position: relative;
    width: 100%;
    height: calc(2.75em + 42px);
    bottom: 0;
    left: 0;
    right: 0;
    text-align: center;
    color: #fff;
    background-color: #212121;
    z-index: 10;
    opacity: 0.9;
}

footer>span {
    width: 100vw;
    height: 2em;
    font-size: 1.1em;
    display: table-cell;
    vertical-align: middle;
}

#contact {
    margin: 1em 0 0 0;
}

button.social {
    cursor: pointer;
    outline: none;
    border-radius: 50%;
    width: 36px;
    height: 36px;
    margin: 3px;
    background-color: transparent;
}

button.social#fb {
    background: url('../icons/fb.png');
    background-size: cover;
}

button.social#tw {
    background: url('../icons/tw.png');
    background-size: cover;
}

button.social#flickr {
    background: url('../icons/flickr.png');
    background-size: cover;
    background-color: #fff;
}

button.social#mail {
    background: url('../icons/mail.png');
    background-size: cover;
}