#main-iframe {
    width: 920px;
    height: 480px;
    border: 2px solid #fff;
    border-radius: 10px;
}

#fullscreen-button {
    display: block;
    margin: 10px auto;
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
    text-align: center;
}