#bg {
    position: fixed;
    top: 0;
    left: 0;
    z-index: -2;
    width: 100%;
    height: 100%;
    background: linear-gradient(to bottom, #1d1d1d 0%, #ba9 100%);
}

/* date-specific easter egg styles! */
#bg.at1225 {
    background: linear-gradient(to bottom, #660000 0%, #005403 100%)
}