body, html {
    margin: 0;
    padding: 0;
    width: 100vw;
    height: 100vh;
    background-color: #1a1a1a;
    overflow: hidden;
    font-family: 'Poppins', Arial, sans-serif; 
}

._df_book {
    width: 100vw !important;
    height: 100vh !important;
    position: absolute !important;
    top: 0 !important;
    left: 0 !important;
    background-color: #1a1a1a !important;
}

._df_book .df-book-wrapper, 
._df_book canvas, 
._df_book iframe {
    margin: auto !important;
    position: absolute !important;
    top: 0 !important;
    bottom: 0 !important;
    left: 0 !important;
    right: 0 !important;
}

.btn-regresar-blog {
    position: fixed;
    top: 20px;
    left: 20px;
    z-index: 2147483647 !important;
    background-color: #be0303;
    color: white;
    padding: 10px 22px;
    border-radius: 30px;
    text-decoration: none;
    font-weight: bold;
    font-family: 'Poppins', Arial, sans-serif; 
    display: flex;
    align-items: center;
    gap: 8px;
    box-shadow: 0 4px 15px rgba(0, 0, 0, 0.4);
    transition: all 0.3s ease;
}

.btn-regresar-blog:hover {
    background-color: #004687;
    color: white;
    transform: scale(1.05);
}