#classroom[hidden]{display:none!important}
@media(max-width:600px){body[data-course] header nav{display:block;width:100%;font-size:.9rem;padding-top:.6rem}body[data-course] header{height:auto;gap:.4rem}}

.b80-lesson-video{display:block;width:100%;max-width:960px;aspect-ratio:16/9;object-fit:contain;background:#101828;border-radius:12px}.b80-video-note{font-size:.9rem;color:#d9b565}