.footer {
    position: absolute;
    bottom: 0;
    width: 100%;
    margin-top: 4em;
    padding: 20px 0;
    background-color: white;
}

.social {
    height: 21px;
    margin-top: 8px;
    float: right;
}

.footer .social .img {
    background-repeat: no-repeat;
    background-size: 21px 21px;
    width: 21px;
    height: 21px;
    display: inline-block;
}

.footer .social .twitter-icon .img {
    background-image: url(//media.mongodb.org.s3.amazonaws.com/social-twitter.png);
}

.footer .social .youtube-icon .img {
    background-image: url(//media.mongodb.org.s3.amazonaws.com/social-youtube.png);
}

.footer .social .facebook-icon .img {
    background-image: url(//media.mongodb.org.s3.amazonaws.com/social-facebook.png);
}

.footer .social .gplus-icon .img {
    background-image: url(//media.mongodb.org.s3.amazonaws.com/social-gplus.png);
}

@media only screen and (-webkit-min-device-pixel-ratio: 2) {
    .footer .social .twitter-icon .img {
        background-image: url(//media.mongodb.org.s3.amazonaws.com/social-twitter@2x.png);
    }

    .footer .social .youtube-icon .img {
        background-image: url(//media.mongodb.org.s3.amazonaws.com/social-youtube@2x.png);
    }

    .footer .social .facebook-icon .img {
        background-image: url(//media.mongodb.org.s3.amazonaws.com/social-facebook@2x.png);
    }

    .footer .social .gplus-icon .img {
        background-image: url(//media.mongodb.org.s3.amazonaws.com/social-gplus@2x.png);
    }
}
