html,
body {
    height: 100%;
    margin: 0;
    padding: 0;

    display: flex;
    justify-content: center;
    align-items: center;
    flex-direction: column;

    background-color: #000;
    font-family: sans-serif;

    overflow: hidden;
    touch-action: manipulation;
}

/* book container */
#flipbook {
    margin: 0 auto;

    /* ✅ This dark background becomes the "left blank page" next to cover */
    background: #222;

    box-shadow: 0 10px 30px rgba(0, 0, 0, 0.6);
}

/* normal pages stay white */
#flipbook .page,
#flipbook .turn-page {
    background: #fff;
    margin: 0 !important;
    padding: 0 !important;

    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
}

/* optional ending blank page */
#flipbook .page.blank {
    background: #222 !important;
}

/* do not force transforms on wrappers */
#flipbook .page-wrapper,
#flipbook .turn-page-wrapper {
    background: transparent !important;
    box-shadow: none !important;
    border: none !important;
}

/* images */
#flipbook img {
    width: 100%;
    height: 100%;
    object-fit: contain;
    display: block;

    user-select: none;
    -webkit-user-drag: none;
}