/**
 * OVERLAY
 */
.overlay {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: -1;
    background: rgba(0,0,0,.5);
    filter: alpha(opacity=0);
    opacity: 0;
    transition: opacity .5s;
}

.overlay.active {
    filter: alpha(opacity=50);
    opacity: 1;
    z-index: 9;
}