.loading {
    position: fixed;
    z-index: 999;
    height: 2em;
    width: 2em;
    overflow: show;
    margin: auto;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    visibility: hidden;
}

/* Transparent Overlay */
.loading:before {
    content: '';
    display: block;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background: radial-gradient(rgba(20, 20, 20, .8), rgba(0, 0, 0, .8));

    background: -webkit-radial-gradient(rgba(20, 20, 20, .8), rgba(0, 0, 0, .8));
}