body, html {
    margin: 0;
    padding: 0;
    overflow: hidden;
}
#overlay {
    position: fixed;
    inset: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    background: rgba(0, 0, 0, 0.8);
    color: #fff;
    font-family: sans-serif;
    font-size: 2em;
    z-index: 9999;
    cursor: pointer;
}