.lesson-player {
  --lesson-space: clamp(0.75rem, 2.5vw, 1.5rem);
  box-sizing: border-box;
  color: #172033;
  inline-size: 100%;
  max-inline-size: 72rem;
  margin-inline: auto;
  overflow-wrap: anywhere;
}

.lesson-player *, .lesson-player *::before, .lesson-player *::after { box-sizing: inherit; }
.lesson-player__page { display: grid; gap: var(--lesson-space); min-inline-size: 0; }
.lesson-player__page--two_column { grid-template-columns: repeat(2, minmax(0, 1fr)); }
.lesson-player__page--two_column .lesson-player__title { grid-column: 1 / -1; }
.lesson-player__block { min-inline-size: 0; overflow: hidden; }
.lesson-player__block img, .lesson-player__block video, .lesson-player__block iframe {
  display: block;
  block-size: auto;
  max-inline-size: 100%;
}
.lesson-player__block-error { padding: 1rem; border: 1px solid #d8a72d; border-radius: 0.5rem; background: #fff8df; }
.lesson-player__navigation { display: grid; grid-template-columns: 1fr auto 1fr; align-items: center; gap: 0.75rem; margin-block-start: 1.25rem; }
.lesson-player__navigation button { min-block-size: 44px; padding-inline: 1rem; }
.lesson-player__navigation button:last-child { justify-self: end; }
.lesson-player__status { text-align: center; font-variant-numeric: tabular-nums; }

@media (max-width: 480px) {
  .lesson-player { padding-inline: 0.75rem; }
  .lesson-player__page--two_column, .lesson-player__page--content_question { grid-template-columns: minmax(0, 1fr); }
  .lesson-player__navigation { grid-template-columns: 1fr 1fr; }
  .lesson-player__status { grid-column: 1 / -1; grid-row: 1; }
}

@media (prefers-reduced-motion: reduce) {
  .lesson-player * { scroll-behavior: auto !important; transition-duration: 0.01ms !important; }
}

/* Toàn màn hình (xem thử và học sinh): thật (:fullscreen) hoặc giả (.is-pseudo-fullscreen) */
.lesson-fullscreen-lock{overflow:hidden}
.is-pseudo-fullscreen{position:fixed!important;inset:0!important;width:100vw!important;height:100dvh!important;max-width:none!important;max-height:none!important;margin:0!important;border-radius:0!important;z-index:2147483000}
.lesson-fs-target:fullscreen{width:100vw;height:100vh;max-width:none;max-height:none;margin:0;border-radius:0;overflow:auto;background:var(--fs-bg,#f5f8fc)}
.lesson-fs-target:fullscreen::backdrop{background:var(--fs-bg,#f5f8fc)}
.lesson-fs-target:fullscreen .lesson-player,.lesson-fs-target.is-pseudo-fullscreen .lesson-player{max-width:min(1280px,100%);margin-inline:auto;font-size:clamp(1rem,1.1vw + .6rem,1.5rem)}
.lesson-fs-target.is-pseudo-fullscreen{overflow:auto;background:var(--fs-bg,#f5f8fc)}
.lesson-fs-button{white-space:nowrap}
.il-session-tools{display:flex;justify-content:flex-end;margin-bottom:8px}
.il-button--ghost{background:#fff;color:#17304f;border:1px solid #c9d6e8}
.preview-header .lesson-fs-button{margin-left:auto;margin-right:12px}
.lesson-fs-target:fullscreen .il-session-tools,.lesson-fs-target.is-pseudo-fullscreen .il-session-tools{position:sticky;top:0;z-index:2;padding:8px 12px}
.lesson-figure{margin:0;text-align:center}
.lesson-figure__art{display:flex;justify-content:center}
.lesson-figure__art svg{width:100%;max-width:560px;height:auto;max-height:60vh;color:inherit}
.lesson-figure figcaption{margin-top:6px;font-size:.9em;color:#667085}