:root {
  color-scheme: dark;
  --bg: #07111f;
  --surface: rgba(13, 27, 45, .88);
  --surface-strong: #0d1b2c;
  --edge: rgba(145, 185, 226, .18);
  --text: #f3f7fc;
  --muted: #93a9bf;
  --accent: #73c7ff;
  --accent-soft: rgba(73, 168, 229, .15);
  --youtube-red: #ff0033;
  --green: #67d6a6;
  --radius: 20px;
}

* { box-sizing: border-box; }
html { min-height: 100%; background: var(--bg); }
body {
  min-height: 100%;
  margin: 0;
  color: var(--text);
  background:
    radial-gradient(circle at 15% -10%, rgba(33, 126, 188, .22), transparent 30rem),
    radial-gradient(circle at 100% 10%, rgba(65, 84, 194, .14), transparent 32rem),
    var(--bg);
  font-family: "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
}
button, select { font: inherit; }
button, a { -webkit-tap-highlight-color: transparent; }

.topbar {
  position: sticky;
  z-index: 20;
  top: 0;
  display: grid;
  grid-template-columns: 44px 1fr 44px;
  align-items: center;
  gap: 10px;
  min-height: calc(64px + env(safe-area-inset-top));
  padding: env(safe-area-inset-top) max(16px, env(safe-area-inset-right)) 0 max(16px, env(safe-area-inset-left));
  border-bottom: 1px solid rgba(154, 191, 226, .13);
  background: rgba(6, 16, 29, .76);
  backdrop-filter: blur(22px) saturate(145%);
  -webkit-backdrop-filter: blur(22px) saturate(145%);
}
.topbar-title { min-width: 0; text-align: center; }
.topbar-title span { display: block; font-size: 16px; font-weight: 700; }
.topbar-title small { display: block; margin-top: 2px; color: var(--muted); font-size: 11px; }
.icon-button {
  display: grid;
  place-items: center;
  width: 40px;
  height: 40px;
  padding: 0;
  border: 1px solid var(--edge);
  border-radius: 13px;
  color: var(--text);
  background: rgba(20, 42, 66, .5);
  text-decoration: none;
  cursor: pointer;
}
.icon-button:active { transform: scale(.96); }
.icon-button svg {
  width: 21px;
  height: 21px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.icon-button.is-loading svg { animation: spin .8s linear infinite; }
@keyframes spin { to { transform: rotate(360deg); } }

.page-shell {
  width: min(1380px, 100%);
  margin: 0 auto;
  padding: 22px max(18px, env(safe-area-inset-right)) max(42px, env(safe-area-inset-bottom)) max(18px, env(safe-area-inset-left));
}
.panel {
  border: 1px solid var(--edge);
  border-radius: var(--radius);
  background: linear-gradient(145deg, rgba(20, 43, 68, .72), rgba(9, 22, 38, .88));
  box-shadow: 0 22px 50px rgba(0, 6, 15, .2);
}
.course-head {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
  margin-bottom: 18px;
  padding: 24px 26px;
}
.eyebrow {
  margin: 0 0 7px;
  color: var(--accent);
  font-size: 10px;
  font-weight: 800;
  letter-spacing: .18em;
}
.course-head h1 {
  margin: 0;
  font-size: clamp(22px, 3.2vw, 36px);
  line-height: 1.2;
}
.course-head p:last-child {
  margin: 9px 0 0;
  color: var(--muted);
  font-size: 13px;
}
.course-progress {
  flex: none;
  min-width: 122px;
  text-align: right;
  color: var(--muted);
  font-size: 12px;
}
.course-progress strong { color: var(--accent); font-size: 30px; }

.learning-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(330px, 390px);
  align-items: start;
  gap: 18px;
}
.player-column { display: grid; gap: 18px; min-width: 0; }
.player-panel { overflow: hidden; }
.video-frame {
  position: relative;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: #000;
  user-select: none;
  -webkit-user-select: none;
  touch-action: none;
}
.video-title-overlay {
  position: absolute;
  z-index: 7;
  top: 0;
  right: 0;
  left: 0;
  display: grid;
  gap: 2px;
  padding: 18px 20px 44px;
  color: #fff;
  background: linear-gradient(rgba(0, 0, 0, .72), transparent);
  opacity: 1;
  pointer-events: none;
  transition: opacity .22s ease;
}
.video-title-overlay[hidden] { display: none; }
.video-title-overlay span {
  color: rgba(255, 255, 255, .72);
  font-size: 11px;
}
.video-title-overlay strong {
  overflow: hidden;
  font-size: 16px;
  font-weight: 600;
  line-height: 1.35;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.video-frame.controls-hidden .video-title-overlay { opacity: 0; }
.video-frame video {
  display: block;
  width: 100%;
  height: 100%;
  background: #000;
  filter: brightness(var(--video-brightness, 1));
  object-fit: contain;
}
.video-frame video::-webkit-media-controls-fullscreen-button { display: none !important; }
.video-frame video::cue {
  color: #fff;
  background: rgba(0, 0, 0, .76);
  font-family: "PingFang SC", "Microsoft YaHei", sans-serif;
}
.subtitle-overlay {
  position: absolute;
  z-index: 4;
  right: 5%;
  bottom: var(--subtitle-height-offset, 0%);
  left: 5%;
  transform: translateY(var(--subtitle-height-offset, 0%));
  display: none;
  color: #fff;
  font-size: clamp(14px, 2.2vw, 22px);
  font-weight: 650;
  line-height: 1.48;
  text-align: center;
  white-space: pre-line;
  text-shadow: 0 1px 3px #000, 0 2px 10px #000;
  pointer-events: none;
}
.subtitle-overlay.is-visible { display: block; }
.subtitle-overlay span {
  display: table;
  margin: 3px auto 0;
  padding: .12em .38em;
  border-radius: .28em;
  background: rgba(0, 0, 0, .72);
  -webkit-text-stroke: 1.2px #000;
  paint-order: stroke fill;
  text-shadow:
    -1px -1px 0 #000,
    1px -1px 0 #000,
    -1px 1px 0 #000,
    1px 1px 0 #000;
  box-decoration-break: clone;
  -webkit-box-decoration-break: clone;
}
.subtitle-overlay span:first-child { margin-top: 0; }
.subtitle-overlay .is-chinese-line { white-space: nowrap; }
.subtitle-overlay[data-style="outline"] span {
  padding: 0;
  border-radius: 0;
  background: transparent;
}
.subtitle-overlay[data-font="system"] {
  font-family: "PingFang SC", "Microsoft YaHei", system-ui, sans-serif;
}
.subtitle-overlay[data-font="serif"] {
  font-family: "Songti SC", "SimSun", "Noto Serif CJK SC", serif;
}
.subtitle-overlay[data-font="mono"] {
  font-family: "SFMono-Regular", "Cascadia Mono", "Consolas", monospace;
}

.video-dimmer {
  position: absolute;
  z-index: 2;
  inset: 0;
  pointer-events: none;
}
.visual-overlay-layer {
  position: absolute;
  z-index: 3;
  display: block;
  width: 0;
  height: 0;
  pointer-events: none;
}
.gesture-surface {
  position: absolute;
  z-index: 5;
  inset: 0 0 58px;
  outline: none;
  cursor: pointer;
  touch-action: none;
  -webkit-tap-highlight-color: transparent;
}
.video-frame.controls-hidden .gesture-surface { bottom: 0; }
.video-center-play {
  position: absolute;
  z-index: 9;
  top: 50%;
  left: 50%;
  display: grid;
  place-items: center;
  width: 64px;
  height: 46px;
  padding: 0;
  transform: translate(-50%, -50%);
  border: 0;
  border-radius: 12px;
  color: #fff;
  background: rgba(24, 24, 24, .88);
  box-shadow: 0 6px 24px rgba(0, 0, 0, .28);
  cursor: pointer;
  transition: background .18s ease, transform .18s ease;
}
.video-center-play[hidden] { display: none; }
.video-center-play:hover,
.video-center-play:focus-visible { background: var(--youtube-red); }
.video-center-play:active { transform: translate(-50%, -50%) scale(.95); }
.video-center-play svg {
  width: 34px;
  height: 34px;
  fill: currentColor;
}
.gesture-hud {
  position: absolute;
  z-index: 12;
  top: 50%;
  left: 50%;
  display: grid;
  place-items: center;
  min-width: 106px;
  padding: 14px 18px;
  transform: translate(-50%, -50%);
  border: 1px solid rgba(255, 255, 255, .24);
  border-radius: 16px;
  color: #fff;
  background: rgba(2, 8, 15, .76);
  box-shadow: 0 12px 35px rgba(0, 0, 0, .3);
  backdrop-filter: blur(14px);
  -webkit-backdrop-filter: blur(14px);
  pointer-events: none;
}
.gesture-hud[hidden] { display: none; }
.gesture-hud .hud-icon {
  display: none;
  width: 22px;
  height: 22px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.gesture-hud[data-kind="seek"] .hud-icon-seek,
.gesture-hud[data-kind="volume"] .hud-icon-volume,
.gesture-hud[data-kind="brightness"] .hud-icon-brightness,
.gesture-hud[data-kind="speed"] .hud-icon-speed {
  display: block;
}
.gesture-hud strong {
  margin-top: 7px;
  font-size: 14px;
  letter-spacing: .02em;
}

.autoplay-overlay {
  position: absolute;
  z-index: 15;
  inset: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-content: center;
  align-items: center;
  gap: 16px 28px;
  padding: clamp(24px, 6vw, 72px);
  color: #fff;
  background: rgba(0, 0, 0, .84);
  backdrop-filter: blur(6px);
  -webkit-backdrop-filter: blur(6px);
}
.autoplay-overlay[hidden] { display: none; }
.autoplay-next-copy {
  display: grid;
  gap: 6px;
  min-width: 0;
}
.autoplay-next-copy span {
  color: rgba(255, 255, 255, .68);
  font-size: 12px;
}
.autoplay-next-copy strong {
  overflow: hidden;
  font-size: clamp(18px, 3vw, 28px);
  line-height: 1.3;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.autoplay-countdown {
  display: grid;
  place-items: center;
  width: 58px;
  height: 58px;
  border: 3px solid rgba(255, 255, 255, .22);
  border-top-color: var(--youtube-red);
  border-radius: 50%;
  font-size: 20px;
  font-weight: 700;
  animation: autoplay-spin 1s linear infinite;
}
.autoplay-countdown span { animation: autoplay-counter-spin 1s linear infinite; }
@keyframes autoplay-spin { to { transform: rotate(360deg); } }
@keyframes autoplay-counter-spin { to { transform: rotate(-360deg); } }
.autoplay-actions {
  grid-column: 1 / -1;
  display: flex;
  gap: 10px;
}
.autoplay-actions button {
  min-height: 38px;
  padding: 0 18px;
  border: 1px solid rgba(255, 255, 255, .34);
  border-radius: 3px;
  color: #fff;
  background: transparent;
  font-weight: 700;
  cursor: pointer;
}
.autoplay-actions button:last-child {
  border-color: var(--youtube-red);
  background: var(--youtube-red);
}

.video-control-bar {
  position: absolute;
  z-index: 10;
  right: 0;
  bottom: 0;
  left: 0;
  padding: 0 12px max(7px, env(safe-area-inset-bottom));
  color: #fff;
  background: linear-gradient(transparent, rgba(0, 0, 0, .92) 56%);
  opacity: 1;
  transform: translateY(0);
  transition: opacity .22s ease, transform .22s ease;
}
.video-control-bar[hidden] { display: none; }
.video-control-bar.is-hidden {
  opacity: 0;
  transform: translateY(14px);
  pointer-events: none;
}
.video-progress {
  --progress-ratio: 0%;
  appearance: none;
  -webkit-appearance: none;
  display: block;
  width: 100%;
  height: 15px;
  margin: 0;
  background: transparent;
  cursor: pointer;
  touch-action: pan-x;
}
.video-progress::-webkit-slider-runnable-track {
  height: 3px;
  border-radius: 3px;
  background: linear-gradient(
    to right,
    var(--youtube-red) 0 var(--progress-ratio),
    rgba(255, 255, 255, .38) var(--progress-ratio) 100%
  );
}
.video-progress::-webkit-slider-thumb {
  appearance: none;
  -webkit-appearance: none;
  width: 12px;
  height: 12px;
  margin-top: -4.5px;
  border: 0;
  border-radius: 50%;
  background: var(--youtube-red);
}
.video-progress::-moz-range-track {
  height: 3px;
  border: 0;
  border-radius: 3px;
  background: rgba(255, 255, 255, .38);
}
.video-progress::-moz-range-progress {
  height: 3px;
  border-radius: 3px;
  background: var(--youtube-red);
}
.video-progress::-moz-range-thumb {
  width: 12px;
  height: 12px;
  border: 0;
  border-radius: 50%;
  background: var(--youtube-red);
}
.video-controls-row {
  display: flex;
  align-items: center;
  min-height: 42px;
  gap: 1px;
}
.video-control-button {
  position: relative;
  display: grid;
  place-items: center;
  width: 38px;
  height: 38px;
  padding: 0;
  border: 0;
  border-radius: 3px;
  color: #fff;
  background: transparent;
  cursor: pointer;
  -webkit-tap-highlight-color: transparent;
}
.video-control-button:hover,
.video-control-button:focus-visible,
.video-control-button[aria-expanded="true"] {
  color: #fff;
  background: rgba(255, 255, 255, .14);
}
.video-control-button:disabled {
  opacity: .36;
  background: transparent;
  cursor: default;
}
.video-control-button svg {
  width: 21px;
  height: 21px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.video-control-button .icon-play { fill: currentColor; stroke: none; }
.video-control-button .icon-pause { display: none; }
.video-frame.is-playing .video-control-button .icon-play { display: none; }
.video-frame.is-playing .video-control-button .icon-pause { display: block; }
.video-control-button[aria-pressed="false"] {
  color: rgba(255, 255, 255, .58);
}
.video-control-button[aria-pressed="false"]::after {
  position: absolute;
  width: 24px;
  height: 1.5px;
  transform: rotate(-42deg);
  border-radius: 2px;
  background: currentColor;
  content: "";
}
.video-time {
  padding-left: 3px;
  font-variant-numeric: tabular-nums;
  font-size: 11px;
  white-space: nowrap;
}
.video-controls-spacer { flex: 1; }
.video-volume-control {
  display: flex;
  align-items: center;
}
.video-volume-control .icon-muted { display: none; }
.video-volume-control.is-muted .icon-volume { display: none; }
.video-volume-control.is-muted .icon-muted { display: block; }
#video-volume-slider {
  appearance: none;
  -webkit-appearance: none;
  width: 0;
  height: 28px;
  opacity: 0;
  background: transparent;
  transition: width .2s ease, opacity .2s ease;
  cursor: pointer;
}
.video-volume-control:hover #video-volume-slider,
.video-volume-control:focus-within #video-volume-slider {
  width: 70px;
  opacity: 1;
}
#video-volume-slider::-webkit-slider-runnable-track {
  height: 3px;
  border-radius: 3px;
  background: rgba(255, 255, 255, .55);
}
#video-volume-slider::-webkit-slider-thumb {
  appearance: none;
  -webkit-appearance: none;
  width: 11px;
  height: 11px;
  margin-top: -4px;
  border: 0;
  border-radius: 50%;
  background: #fff;
}
#video-volume-slider::-moz-range-track {
  height: 3px;
  border-radius: 3px;
  background: rgba(255, 255, 255, .55);
}
#video-volume-slider::-moz-range-thumb {
  width: 11px;
  height: 11px;
  border: 0;
  border-radius: 50%;
  background: #fff;
}
.video-autoplay-toggle {
  position: relative;
  width: 34px;
  height: 20px;
  margin: 0 5px;
  padding: 0;
  border: 0;
  border-radius: 12px;
  background: rgba(255, 255, 255, .38);
  cursor: pointer;
}
.video-autoplay-toggle span {
  position: absolute;
  top: 3px;
  left: 3px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: #fff;
  transition: transform .18s ease;
}
.video-autoplay-toggle[aria-pressed="true"] {
  background: var(--youtube-red);
}
.video-autoplay-toggle[aria-pressed="true"] span {
  transform: translateX(14px);
}

.video-frame:fullscreen,
.video-frame:-webkit-full-screen {
  width: 100vw;
  height: 100vh;
  aspect-ratio: auto;
  background: #000;
}
.video-frame:fullscreen .subtitle-overlay,
.video-frame:-webkit-full-screen .subtitle-overlay {
  font-size: clamp(18px, 3vw, 34px);
}
.video-frame:fullscreen .gesture-surface,
.video-frame:-webkit-full-screen .gesture-surface {
  bottom: max(66px, calc(env(safe-area-inset-bottom) + 58px));
}
.video-frame:fullscreen .video-control-bar,
.video-frame:-webkit-full-screen .video-control-bar {
  padding-right: max(16px, env(safe-area-inset-right));
  padding-left: max(16px, env(safe-area-inset-left));
}
.player-empty {
  position: absolute;
  z-index: 5;
  inset: 0;
  display: grid;
  place-content: center;
  justify-items: center;
  gap: 12px;
  color: var(--muted);
  background:
    radial-gradient(circle at 50% 45%, rgba(38, 109, 155, .18), transparent 32%),
    #040b13;
  font-size: 13px;
  pointer-events: none;
}
.player-empty[hidden] { display: none; }
.player-empty svg {
  width: 52px;
  height: 52px;
  fill: none;
  stroke: var(--accent);
  stroke-width: 1.3;
  stroke-linecap: round;
  stroke-linejoin: round;
}
.player-info {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 18px 20px 20px;
}
.lesson-heading { min-width: 0; }
.lesson-heading span { color: var(--accent); font-size: 11px; font-weight: 800; }
.lesson-heading h2 {
  overflow: hidden;
  margin: 5px 0 0;
  font-size: 18px;
  line-height: 1.35;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.player-settings {
  position: absolute;
  z-index: 11;
  right: 12px;
  bottom: 66px;
  left: auto;
  width: min(360px, calc(100% - 24px));
  max-height: calc(100% - 78px);
  overflow: auto;
  padding: 7px 10px;
  border: 1px solid rgba(255, 255, 255, .16);
  border-radius: 8px;
  background: rgba(28, 28, 28, .97);
  box-shadow: 0 18px 48px rgba(0, 0, 0, .42);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  overscroll-behavior: contain;
  touch-action: pan-y;
}
.player-settings[hidden] { display: none; }
.settings-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
}
.setting-field {
  display: grid;
  grid-template-columns: minmax(88px, 1fr) minmax(120px, 1.15fr);
  align-items: center;
  gap: 12px;
  min-height: 44px;
  padding: 4px 7px;
  border-bottom: 1px solid rgba(255, 255, 255, .09);
  color: rgba(255, 255, 255, .78);
  font-size: 12px;
}
.setting-field:last-child { border-bottom: 0; }
.setting-field select {
  width: 100%;
  height: 34px;
  padding: 0 28px 0 9px;
  border: 0;
  border-radius: 3px;
  color: #fff;
  background: rgba(255, 255, 255, .1);
}
.setting-range > div {
  display: grid;
  grid-template-columns: 1fr 42px;
  align-items: center;
  gap: 8px;
  min-height: 40px;
}
.setting-range input {
  width: 100%;
  accent-color: var(--youtube-red);
}
.setting-range output {
  color: var(--text);
  font-size: 11px;
  text-align: right;
}
.setting-toggle-row {
  grid-template-columns: 1fr auto auto;
}
.setting-toggle-row input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
}
.setting-toggle-row i {
  position: relative;
  width: 34px;
  height: 20px;
  border-radius: 12px;
  background: rgba(255, 255, 255, .3);
  cursor: pointer;
}
.setting-toggle-row i::after {
  position: absolute;
  top: 3px;
  left: 3px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: #fff;
  transition: transform .18s ease;
  content: "";
}
.setting-toggle-row input:checked + i { background: var(--youtube-red); }
.setting-toggle-row input:checked + i::after { transform: translateX(14px); }
.setting-toggle-row input:focus-visible + i { outline: 2px solid #fff; outline-offset: 2px; }
.resume-note {
  margin: -7px 20px 18px;
  padding: 9px 12px;
  border-radius: 10px;
  color: #cfeeff;
  background: var(--accent-soft);
  font-size: 12px;
}

.lesson-panel {
  position: sticky;
  top: calc(82px + env(safe-area-inset-top));
  overflow: hidden;
  max-height: calc(100dvh - 104px - env(safe-area-inset-top));
}
.section-title {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 20px;
  border-bottom: 1px solid rgba(145, 185, 226, .12);
}
.section-title h2 { margin: 0; font-size: 17px; }
.section-title > span { color: var(--muted); font-size: 11px; }
.history-controls {
  display: flex;
  align-items: center;
  gap: 12px;
}
.history-controls > span { color: var(--muted); font-size: 11px; }
.switch-control {
  display: flex;
  align-items: center;
  gap: 8px;
  color: var(--muted);
  font-size: 11px;
  cursor: pointer;
}
.switch-control input {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
}
.switch-control i {
  position: relative;
  width: 38px;
  height: 22px;
  border: 1px solid var(--edge);
  border-radius: 999px;
  background: rgba(80, 107, 135, .34);
  transition: background .18s, border-color .18s;
}
.switch-control i::after {
  position: absolute;
  top: 3px;
  left: 3px;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: #d8e6f4;
  content: "";
  transition: transform .18s, background .18s;
}
.switch-control input:checked + i {
  border-color: rgba(115, 199, 255, .5);
  background: rgba(63, 166, 229, .45);
}
.switch-control input:checked + i::after {
  background: var(--accent);
  transform: translateX(16px);
}
.switch-control input:focus-visible + i {
  outline: 2px solid var(--accent);
  outline-offset: 2px;
}
.continue-button {
  padding: 8px 11px;
  border: 0;
  border-radius: 10px;
  color: #04111d;
  background: var(--accent);
  font-size: 12px;
  font-weight: 800;
  cursor: pointer;
}
.lesson-list {
  display: grid;
  gap: 6px;
  max-height: calc(100dvh - 195px - env(safe-area-inset-top));
  padding: 10px;
  overflow-y: auto;
  overscroll-behavior: contain;
}
.lesson-item {
  position: relative;
  display: grid;
  grid-template-columns: 38px 1fr auto;
  align-items: center;
  gap: 10px;
  min-width: 0;
  padding: 12px 10px;
  border: 1px solid transparent;
  border-radius: 14px;
  color: var(--text);
  background: transparent;
  text-align: left;
  cursor: pointer;
}
.lesson-item:hover { background: rgba(86, 155, 205, .08); }
.lesson-item.is-active {
  border-color: rgba(115, 199, 255, .3);
  background: var(--accent-soft);
}
.lesson-index {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  border-radius: 11px;
  color: var(--accent);
  background: rgba(93, 169, 221, .1);
  font-size: 11px;
  font-weight: 800;
}
.lesson-copy { min-width: 0; }
.lesson-copy strong {
  display: block;
  overflow: hidden;
  font-size: 13px;
  font-weight: 650;
  line-height: 1.45;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.lesson-copy small { display: block; margin-top: 4px; color: var(--muted); font-size: 10px; }
.lesson-status {
  width: 9px;
  height: 9px;
  border: 1px solid rgba(145, 185, 226, .4);
  border-radius: 50%;
}
.lesson-status.is-started { border-color: var(--accent); background: var(--accent); }
.lesson-status.is-complete { border-color: var(--green); background: var(--green); }
.lesson-meter {
  position: absolute;
  right: 10px;
  bottom: 4px;
  left: 58px;
  height: 2px;
  overflow: hidden;
  border-radius: 99px;
  background: rgba(135, 173, 209, .12);
}
.lesson-meter i { display: block; height: 100%; background: var(--accent); }

.history-panel { overflow: hidden; }
.history-list { display: grid; }
.history-list[hidden] { display: none; }
.history-item {
  display: grid;
  grid-template-columns: 42px 1fr auto;
  align-items: center;
  gap: 12px;
  padding: 13px 20px;
  border: 0;
  border-bottom: 1px solid rgba(145, 185, 226, .09);
  color: var(--text);
  background: transparent;
  text-align: left;
  cursor: pointer;
}
.history-item:last-child { border-bottom: 0; }
.history-item:hover { background: rgba(86, 155, 205, .07); }
.history-index { color: var(--accent); font-size: 12px; font-weight: 800; }
.history-copy { min-width: 0; }
.history-copy strong {
  display: block;
  overflow: hidden;
  font-size: 12px;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.history-copy small, .history-position { color: var(--muted); font-size: 10px; }
.empty-copy { margin: 0; padding: 28px 20px; color: var(--muted); font-size: 12px; text-align: center; }
.skeleton {
  height: 61px;
  border-radius: 14px;
  background: linear-gradient(90deg, rgba(255,255,255,.025), rgba(255,255,255,.07), rgba(255,255,255,.025));
  background-size: 200% 100%;
  animation: shimmer 1.4s linear infinite;
}
@keyframes shimmer { to { background-position: -200% 0; } }

.toast {
  position: fixed;
  z-index: 40;
  right: 18px;
  bottom: max(18px, env(safe-area-inset-bottom));
  max-width: min(360px, calc(100% - 36px));
  padding: 11px 14px;
  border: 1px solid var(--edge);
  border-radius: 12px;
  opacity: 0;
  color: var(--text);
  background: #10243a;
  box-shadow: 0 16px 38px rgba(0,0,0,.34);
  font-size: 12px;
  pointer-events: none;
  transform: translateY(10px);
  transition: opacity .2s, transform .2s;
}
.toast.is-visible { opacity: 1; transform: none; }

@media (max-width: 900px) {
  .learning-layout { grid-template-columns: 1fr; }
  .lesson-panel { position: static; max-height: none; }
  .lesson-list { max-height: none; }
}
@media (max-width: 560px) {
  .page-shell { padding-top: 14px; }
  .course-head { align-items: center; padding: 18px; }
  .course-progress { min-width: 82px; }
  .course-progress strong { font-size: 24px; }
  .player-info { padding: 15px; }
  .lesson-heading h2 { white-space: normal; }
  .player-settings {
    right: 8px;
    bottom: 58px;
    left: 8px;
    width: auto;
    padding: 6px 8px;
  }
  .setting-field { gap: 8px; min-height: 40px; font-size: 11px; }
  .setting-field select { height: 32px; }
  .setting-range > div { min-height: 36px; }
  .resume-note { margin-right: 15px; margin-left: 15px; }
  .section-title { padding: 17px 15px; }
  .history-item { padding-right: 15px; padding-left: 15px; }
  .subtitle-overlay {
    right: 3%;
    left: 3%;
    font-size: 14px;
  }
  .video-control-bar { padding-right: 8px; padding-left: 8px; }
  .video-control-button { width: 36px; height: 36px; }
  .video-time { font-size: 10px; }
  .video-volume-control { display: none; }
  .video-title-overlay { padding: 12px 14px 36px; }
  .video-title-overlay strong { font-size: 14px; }
  .video-center-play { width: 58px; height: 42px; }
  .autoplay-overlay {
    grid-template-columns: minmax(0, 1fr) auto;
    gap: 12px 18px;
    padding: 22px;
  }
  .autoplay-next-copy strong { font-size: 17px; }
  .autoplay-countdown { width: 48px; height: 48px; font-size: 17px; }
  .autoplay-actions button { min-height: 34px; padding: 0 14px; font-size: 12px; }
}
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { scroll-behavior: auto !important; animation: none !important; transition: none !important; }
}