/* 复用首页的字体、背景和页头，只为视频页面补充布局。 */
.chemistry-page {
  --chemistry-ink: #57416d;
  --chemistry-muted: #776187;
  --chemistry-line: #ddd1e5;
}

.chemistry-shell { max-width: 1180px; }
.home-wordmark { text-decoration: none; }

.back-link {
  display: inline-flex;
  align-items: center;
  flex-shrink: 0;
  gap: 8px;
  padding-block: 12px;
  color: var(--muted);
  font-size: 14px;
  text-decoration: none;
}

.chemistry-intro { padding-block: 60px 30px; }
.chemistry-intro .eyebrow { color: var(--chemistry-muted); }
.chemistry-intro .eyebrow > span { background: #a88abd; }
.chemistry-dot { color: #b99aca; }

.chemistry-lead {
  margin: 24px 0 20px;
  color: var(--muted);
  font-size: 17px;
  line-height: 1.9;
}

.collection-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  margin: 0;
  color: var(--chemistry-muted);
  font-size: 14px;
}

.topic-nav {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 34px;
}

.topic-nav a {
  padding: 10px 17px;
  border: 1px solid var(--chemistry-line);
  border-radius: 24px;
  color: var(--chemistry-ink);
  background: #f2edf5;
  font-size: 13px;
  text-decoration: none;
  transition: background-color 180ms ease;
}

.video-collection {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px;
}

.video-card {
  display: flex;
  flex-direction: column;
  min-width: 0;
  padding: 18px;
  border: 1px solid var(--chemistry-line);
  border-radius: 18px;
  background: #fffdf9;
  scroll-margin-top: 24px;
}

/* 固定画幅避免点击播放时跳动；保留完整视频，横竖比例不同时留边。 */
.video-player {
  overflow: hidden;
  aspect-ratio: 16 / 9;
  border-radius: 10px;
  background: #1d1921;
}

.video-player video {
  display: block;
  width: 100%;
  height: 100%;
  aspect-ratio: 16 / 9;
  object-fit: contain;
}

.video-content {
  display: flex;
  flex: 1;
  flex-direction: column;
  padding: 23px 6px 4px;
}

.video-meta {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px 16px;
  margin-bottom: 14px;
  color: var(--chemistry-muted);
  font-size: 12px;
  letter-spacing: 0.03em;
}

.video-duration { white-space: nowrap; }

.video-content h2 {
  margin: 0;
  color: var(--chemistry-ink);
  font-size: clamp(23px, 2vw, 28px);
  font-weight: 620;
  line-height: 1.45;
  letter-spacing: -0.035em;
  overflow-wrap: anywhere;
}

.video-description {
  margin: 15px 0 18px;
  color: #626465;
  font-size: 15px;
  line-height: 1.9;
}

.observation {
  margin: auto 0 22px;
  padding-left: 12px;
  border-left: 2px solid #cdb5dc;
  color: var(--chemistry-muted);
  font-size: 14px;
  line-height: 1.8;
}

.observation > span {
  display: block;
  color: var(--chemistry-ink);
  font-size: 12px;
  font-weight: 600;
}

.video-source {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: space-between;
  gap: 8px 18px;
  padding-top: 16px;
  border-top: 1px solid #e6dfea;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.8;
}

.video-source a {
  padding-block: 4px;
  color: var(--chemistry-ink);
  text-underline-offset: 4px;
}

.video-source a > span { margin-left: 4px; }

.video-featured {
  display: grid;
  grid-column: 1 / -1;
  grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr);
  align-items: center;
  gap: 30px;
  padding: 24px;
  background: #f0e9f4;
}

.video-featured .video-content { padding: 6px 2px; }
.video-featured h2 { font-size: clamp(26px, 2.5vw, 32px); }
.video-featured .observation { margin-top: 0; }
.video-featured .video-source { border-top-color: #d9cce3; }

.recommendation {
  color: var(--chemistry-ink);
  font-weight: 600;
}

.chemistry-page a:focus-visible,
.chemistry-page video:focus-visible {
  outline: 3px solid #79538f;
  outline-offset: 5px;
}

.chemistry-footer { padding-top: 34px; }
.chemistry-footer > :last-child > span { color: #a083b3; }

@media (hover: hover) {
  .topic-nav a:hover { background: #e8ddef; }
  .back-link:hover { color: var(--chemistry-ink); }
  .video-source a:hover { text-decoration-thickness: 2px; }
}

@media (max-width: 1000px) {
  .video-featured { grid-template-columns: 1fr; gap: 0; padding: 20px; }
  .video-featured .video-content { padding: 24px 6px 4px; }
  .video-featured h2 { font-size: 30px; }
}

@media (max-width: 760px) {
  .chemistry-page .site-header { gap: 14px; }
  .chemistry-page .wordmark { gap: 8px; font-size: 10px; }
  .chemistry-page .site-mark { width: 23px; height: 23px; }
  .back-link { gap: 5px; font-size: 12px; }
  .chemistry-intro { padding-block: 42px 24px; }
  .chemistry-lead { margin-block: 20px 17px; font-size: 15px; }
  .chemistry-lead br { display: none; }
  .collection-meta { font-size: 13px; }
  .topic-nav { gap: 8px; margin-bottom: 26px; }
  .topic-nav a { padding: 10px 14px; font-size: 12px; }
  .video-collection { grid-template-columns: 1fr; gap: 20px; }
  .video-card, .video-featured { padding: 12px; border-radius: 15px; }
  .video-content, .video-featured .video-content { padding: 20px 6px 6px; }
  .video-content h2, .video-featured h2 { font-size: 24px; }
  .video-meta { margin-bottom: 12px; }
  .video-description { margin-block: 13px 18px; }
  .observation { margin-bottom: 18px; }
}

@media (max-width: 360px) {
  .chemistry-page .wordmark-domain { display: none; }
  .video-content h2, .video-featured h2 { font-size: 22px; }
}