.course button,
.back-button {
  margin-top: 12px;
  border: 0;
  border-radius: 8px;
  background: #17684a;
  color: #fff;
  padding: 9px 13px;
  cursor: pointer;
}
.course-heading {
  display: flex;
  justify-content: space-between;
  align-items: end;
  margin: 18px 0;
}
.course-heading h2 {
  margin: 5px 0;
}
.course-heading small {
  color: #17684a;
}
.course-heading span {
  font-variant-numeric: tabular-nums;
  font-size: 20px;
}
.learning-room {
  display: grid;
  grid-template-columns: minmax(0, 1.55fr) minmax(330px, 0.75fr);
  gap: 18px;
  align-items: start;
}
.player-column {
  min-width: 0;
}
.video-player {
  background: #101713;
  border-radius: 14px;
  padding: 16px;
  color: #fff;
}
.video-placeholder {
  aspect-ratio: 16/9;
  background: linear-gradient(135deg, #172b22, #263b31);
  display: grid;
  place-content: center;
  text-align: center;
  border-radius: 10px;
  gap: 8px;
}

.video-placeholder[hidden],
#courseVideo[hidden],
[hidden] {
  display: none !important;
}
.video-placeholder span {
  font-size: 44px;
}
.video-placeholder small {
  color: #aebcb5;
}
.video-player > input {
  width: 100%;
  accent-color: #50bd8b;
  margin-top: 15px;
}
.player-controls {
  display: flex;
  align-items: center;
  gap: 15px;
  font-size: 12px;
  color: #adbbb4;
}
.player-controls button {
  border: 0;
  border-radius: 7px;
  background: #fff;
  color: #17231e;
  padding: 8px 13px;
}

.player-controls .learning-fullscreen-button {
  color: #fff !important;
  background: #315fe8 !important;
}

.learning-room:fullscreen {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(320px, 390px);
  gap: 18px;
  width: 100vw;
  height: 100vh;
  padding: 18px;
  overflow: hidden;
  background: #eef4fc;
}

.learning-room:fullscreen .player-column {
  display: grid;
  height: 100%;
  min-height: 0;
}

.learning-room:fullscreen .player-column > :not(.video-player) {
  display: none !important;
}

.learning-room:fullscreen .video-player {
  display: flex;
  height: 100%;
  min-height: 0;
  flex-direction: column;
}

.learning-room:fullscreen #courseVideo,
.learning-room:fullscreen .video-placeholder {
  min-height: 0;
  flex: 1;
  object-fit: contain;
}

.learning-room:fullscreen .tutor-panel {
  position: static;
  display: flex;
  height: 100%;
  min-height: 0;
  flex-direction: column;
}

.learning-room:fullscreen .chat-messages {
  min-height: 0;
  flex: 1;
}

@media (max-width: 850px) {
  .learning-room:fullscreen {
    grid-template-columns: 1fr;
    overflow: auto;
  }

  .learning-room:fullscreen .video-player,
  .learning-room:fullscreen .tutor-panel {
    min-height: 70vh;
  }
}
.lesson-note {
  background: #fff;
  border: 1px solid #e2e8e4;
  border-radius: 12px;
  margin-top: 14px;
  padding: 18px;
}
.tutor-panel {
  position: sticky;
  top: 20px;
  background: #fff;
  border: 1px solid #dce7e0;
  border-radius: 14px;
  padding: 14px;
  display: block;
  height: auto;
}
.tutor-head {
  display: flex;
  justify-content: space-between;
  align-items: center;
}
.tutor-head div {
  display: grid;
  gap: 3px;
}
.tutor-head small {
  color: #748079;
}
.tutor-head b {
  font-size: 12px;
  color: #17684a;
}
.tutor-panel .stagebar {
  font-size: 11px;
  margin: 12px 0;
}
.tutor-panel .chat-messages {
  height: 390px;
  min-height: 0;
  border: 0;
  background: #f6f8f6;
  padding: 10px;
}
.tutor-panel #chatForm {
  border: 0;
  padding: 10px 0 0;
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 8px;
}
.tutor-panel #chatForm textarea {
  min-width: 0;
  resize: none;
}
.tutor-panel #chatForm button {
  grid-column: auto;
}
.tutor-panel .secondary {
  width: 100%;
}
.back-button {
  background: #e8f2ec;
  color: #17684a;
}
@media (max-width: 900px) {
  .learning-room {
    grid-template-columns: 1fr;
  }
  .tutor-panel {
    position: static;
  }
  .tutor-panel .chat-messages {
    height: 320px;
  }
}
@media (max-width: 600px) {
  .course-heading {
    align-items: start;
  }
  .learning-room {
    gap: 10px;
  }
  .tutor-panel #chatForm {
    grid-template-columns: 1fr;
  }
  .tutor-panel #chatForm button {
    grid-column: 1;
  }
}