div.overlay {
    display: none;
    position: absolute;
    z-index: 1;
    top: 0;
    left: 0;
    width: 100%; height: 100%;
    background: white; /* fallback */
    background: rgba(0,0,0,0.3);
}

div.overlay > div {
    margin: 5em 3em;
    background: white; /* fallback */
    background: rgba(255,255,255,0.95);
    padding: 1em;
    box-shadow: 4px 4px 12px rgba(0,0,0,0.33);
    /*border-radius: 5px;*/
}