:root {
  color-scheme: light;
  --navy: #123369;
  --ink: #192f51;
  --blue: #2d62d8;
  --muted: #65758d;
  --line: #d8e3f1;
  --paper: #ffffff;
  --sky: #edf4fc;
  font-family: "PingFang SC", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  font-size: 16px;
  background: var(--sky);
  color: var(--ink);
}
* { box-sizing: border-box; }
body { margin: 0; }
button, input { font: inherit; }
button { cursor: pointer; -webkit-tap-highlight-color: transparent; }
button:focus-visible, a:focus-visible { outline: 3px solid #e29a27; outline-offset: 4px; }
.page { --sidebar-width: 220px; --column-gap: 32px; max-width: 820px; margin: auto; padding: 28px 32px max(24px, env(safe-area-inset-bottom)); }
.header, .watch-layout, .viewer-actions, .footer { max-width: calc(var(--sidebar-width) + var(--column-gap) + min(40.5svh, 405px)); margin-inline: auto; }
.header { padding: 0 0 24px; }
.brand { color: var(--navy); font-size: .875rem; font-weight: 600; margin-bottom: 9px; }
h1 { margin: 0; font-size: 1.625rem; line-height: 1.4; font-weight: 700; }
.guide-picker { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); gap: 12px; margin-top: 20px; }
.guide-button { min-width: 0; min-height: 70px; padding: 12px 16px; border: 1px solid var(--line); border-radius: 8px; background: var(--paper); color: var(--muted); text-align: left; }
.guide-button span { display: block; font-size: 1.0625rem; line-height: 1.5; font-weight: 700; }
.guide-button small { display: block; margin-top: 3px; font-size: .8125rem; line-height: 1.5; }
.guide-button[aria-pressed="true"] { border-color: var(--navy); background: var(--navy); color: white; }
.watch-layout { display: grid; grid-template-columns: var(--sidebar-width) minmax(0, 1fr); gap: var(--column-gap); align-items: start; }
.player-panel { min-width: 0; }
.video-stage { background: #d9e6f5; border: 1px solid #c7d8ed; border-radius: 12px; overflow: hidden; }
video { display: block; width: 100%; height: auto; aspect-ratio: 9 / 16; background: #d9e6f5; object-fit: contain; }
.playback-caption { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding-top: 13px; font-size: .9375rem; font-weight: 600; }
.duration { color: var(--muted); font-size: .875rem; font-variant-numeric: tabular-nums; font-weight: 400; }
.status { font-size: .875rem; line-height: 1.5; color: var(--muted); margin: 6px 0 0; }
.status:empty { display: none; }
.chapter-panel { min-width: 0; padding-top: 5px; }
.chapter-heading h2 { margin: 0; font-size: 1.25rem; line-height: 1.4; }
.chapter-heading p { margin: 7px 0 18px; font-size: .9375rem; color: var(--muted); }
.chapters { display: grid; grid-template-columns: minmax(0, 1fr); gap: 9px; }
.chapter-button { position: relative; display: flex; align-items: center; justify-content: space-between; gap: 10px; min-height: 60px; padding: 13px 15px; border: 1px solid var(--line); border-radius: 8px; background: var(--paper); color: var(--ink); text-align: left; }
.chapter-label { font-size: 1.0625rem; line-height: 1.5; font-weight: 600; }
.chapter-time { flex-shrink: 0; font-size: .875rem; line-height: 1.5; color: var(--muted); font-variant-numeric: tabular-nums; }
.chapter-button[aria-current="true"] { border-color: var(--blue); color: var(--navy); background: #e0ecff; box-shadow: inset 3px 0 0 var(--blue); }
.chapter-button[aria-current="true"] .chapter-time { color: var(--navy); }
.viewer-actions { display: grid; grid-template-columns: minmax(0, 1fr) minmax(0, 1fr); align-items: start; gap: 16px; margin-top: 22px; }
.watch-all { min-height: 46px; padding: 11px 14px; border: 1px solid #c7d8ed; border-radius: 7px; color: var(--navy); font-size: .875rem; line-height: 1.5; background: white; }
.share-block { min-width: 0; }
.share-button { width: 100%; min-height: 46px; border: 0; border-radius: 7px; background: var(--navy); color: white; font-size: .9375rem; font-weight: 600; padding: 11px 16px; }
.share-button:disabled { cursor: default; background: #65758d; }
.share-status { margin: 9px 0 0; color: var(--muted); font-size: .875rem; line-height: 1.5; }
.manual-link { width: 100%; margin-top: 9px; padding: 10px; border: 1px solid var(--line); border-radius: 5px; background: white; font-size: .875rem; }
.footer { margin-top: 30px; border-top: 1px solid var(--line); padding-top: 18px; }
.contact { margin: 0 0 14px; font-size: .9375rem; line-height: 1.7; }
.contact a { color: var(--navy); font-weight: 700; text-decoration: none; }
.contact span { margin-left: 12px; color: var(--muted); white-space: nowrap; font-size: .875rem; }
.risk { margin: 0; color: #596b85; font-size: .875rem; line-height: 1.85; }
@media (max-width: 650px) {
  .page { --sidebar-width: 136px; --column-gap: 20px; padding: 18px 16px max(20px, env(safe-area-inset-bottom)); }
  .header { padding-bottom: 17px; }
  .brand { font-size: .875rem; margin-bottom: 5px; }
  h1 { font-size: 1.3125rem; }
  .guide-picker { gap: 10px; margin-top: 14px; }
  .guide-button { min-height: 64px; padding: 10px 12px; }
  .guide-button span { font-size: .9375rem; }
  .guide-button small { font-size: .75rem; }
  .chapter-panel { padding-top: 0; }
  .chapter-heading h2 { font-size: 1rem; }
  .chapter-heading p { margin: 4px 0 12px; font-size: .8125rem; }
  .chapters { gap: 7px; }
  .chapter-button { flex-direction: column; align-items: flex-start; justify-content: center; gap: 0; padding: 7px 10px; min-height: 56px; }
  .chapter-label { font-size: .9375rem; }
  .chapter-time { font-size: .75rem; }
  .video-stage { border-radius: 9px; }
  .playback-caption { padding-top: 9px; flex-wrap: wrap; gap: 3px 8px; font-size: .8125rem; }
  .duration { font-size: .75rem; }
  .viewer-actions { gap: 10px; margin-top: 18px; }
  .watch-all, .share-button { font-size: .8125rem; padding: 10px; }
  .watch-all-hint { display: block; font-size: .75rem; white-space: nowrap; }
  .share-status { font-size: .75rem; }
  .footer { margin-top: 22px; }
  .contact span { display: block; margin-left: 0; }
}
@media (max-width: 480px) {
  .page { --sidebar-width: 104px; --column-gap: 12px; padding-inline: 12px; }
  .chapter-heading h2 { font-size: .9375rem; }
  .chapter-heading p { font-size: .75rem; }
  .chapter-button { padding-inline: 8px; }
  .chapter-label { font-size: .875rem; }
}
@media (prefers-reduced-motion: no-preference) {
  .chapter-button, .guide-button { transition: background-color .15s ease, border-color .15s ease; }
}
@media (max-width: 360px) {
  .page { --sidebar-width: 96px; --column-gap: 10px; }
  .chapter-button { min-height: 52px; }
}