html,
body {
    margin: 0;
    width: 100%;
    height: 100%;
    overflow: hidden;
    background: #000;
}

#mainVideo {
    width: 100vw;
    height: 100vh;
    object-fit: cover;
    display: block;
    background: #000;

    opacity: 1;
    transition: opacity 0.5s ease;
}

#mainVideo.fade-out {
    opacity: 0;
}