iframe {
    position: fixed;
    top: 0;
    left: 0;
    right: 0;
    bottom: 0;
    width: 100%;
    height: 100%;
}

img.first-page-button {
    position: fixed;
    bottom: 10px;
    right: 10px;
    z-index: 1000;
    width: 65px;
    color: white;
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
    border-radius: 5px;
}