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

.bg {
    /* The image used */
/*    background-image: url(../images/access_denied.jpg);*/

    /* Full height */
    height: 100%;

    /* Center and scale the image nicely */
    background-position: center;
    background-repeat: no-repeat;
    background-size: cover;
}