#flashScreen {
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: #a8a8a8;
    /* Dark background */
    z-index: 10000;
    /* High z-index to cover everything */
    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;
    transition: opacity 0.5s ease-in-out, visibility 0.5s ease-in-out;
    opacity: 1;
    visibility: visible;
}

#flashScreen.hidden {
    opacity: 0;
    visibility: hidden;
}