.page-topics {
  --topics-num-col: 42px;
  --topics-dot-line: color-mix(in srgb, var(--color-line) 78%, transparent);
  --topics-hair: color-mix(in srgb, var(--color-primary) 42%, transparent);
  --topics-accent-hair: color-mix(in srgb, var(--color-accent) 40%, transparent);
}

/* ---------- 首屏 ---------- */

.page-topics .topics-hero {
  position: relative;
  padding-block: var(--section-y-lg) var(--section-y);
  background:
    radial-gradient(940px 460px at 84% -8%, color-mix(in srgb, var(--color-primary) 13%, transparent), transparent 68%),
    radial-gradient(620px 380px at 4% 108%, color-mix(in srgb, var(--color-accent) 8%, transparent), transparent 70%),
    linear-gradient(180deg, var(--color-surface-alt) 0%, var(--color-surface) 66%);
  border-bottom: var(--border-thin) solid var(--color-line);
  overflow: hidden;
}

.page-topics .breadcrumb {
  margin-bottom: var(--space-4);
}

.page-topics .topics-hero__grid {
  display: grid;
  gap: var(--space-6);
}

.page-topics .topics-hero__lead {
  min-width: 0;
}

.page-topics .topics-hero__title {
  margin: var(--space-2) 0 var(--space-4);
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 0.94;
  letter-spacing: -0.022em;
  color: var(--color-ink);
}

.page-topics .topics-hero__lede {
  margin: 0;
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-topics .lane-tags {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  margin: var(--space-4) 0 0;
  padding: 0;
  list-style: none;
}

.page-topics .lane-tags__item {
  padding: 5px var(--space-2);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-sm);
  background: color-mix(in srgb, var(--color-surface-alt) 72%, transparent);
  color: var(--color-ink-soft);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
}

.page-topics .lane-tags__item--a {
  color: var(--color-primary);
  border-color: var(--topics-hair);
}

.page-topics .lane-tags__item--b {
  color: var(--color-ink);
}

.page-topics .lane-tags__item--c {
  color: var(--color-accent);
  border-color: var(--topics-accent-hair);
}

.page-topics .lane-tags__item--d {
  color: var(--color-ink-muted);
}

/* 缩略索引 */
.page-topics .topics-hero__mini {
  min-width: 0;
  padding: var(--space-3);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-surface-alt);
}

.page-topics .topics-hero__mini-title {
  margin: 0 0 var(--space-2);
  padding-bottom: var(--space-2);
  border-bottom: var(--border-thin) dotted var(--color-line);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}

.page-topics .mini-index {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 2px var(--space-2);
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-topics .mini-index__row a {
  display: flex;
  align-items: baseline;
  gap: var(--space-1);
  padding: 3px var(--space-1);
  border-radius: var(--radius-sm);
  font-size: var(--text-xs);
  color: var(--color-ink-soft);
  text-decoration: none;
}

.page-topics .mini-index__num {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  color: var(--color-primary);
  letter-spacing: 0.04em;
}

.page-topics .mini-index__name {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.page-topics .mini-index__row a:hover,
.page-topics .mini-index__row a:focus-visible {
  background: var(--color-primary-soft);
  color: var(--color-ink);
}

/* 首屏图片 */
.page-topics .topics-hero__figure {
  margin: var(--space-6) 0 0;
}

.page-topics .topics-hero__media {
  aspect-ratio: 16 / 9;
  overflow: hidden;
}

.page-topics .topics-hero__media img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* 数字带 */
.page-topics .hero-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--border-thin);
  margin: var(--space-6) 0 0;
  padding: 0;
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-md);
  background: var(--color-line);
  overflow: hidden;
}

.page-topics .hero-stats__cell {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
  padding: var(--space-3);
  background: var(--color-surface-alt);
}

.page-topics .hero-stats__label {
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

.page-topics .hero-stats__value {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-3xl);
  font-weight: var(--weight-heading);
  line-height: 1;
  color: var(--color-primary);
}

/* ---------- 筛选带 ---------- */

.page-topics .topics-bar {
  padding-block: var(--space-6);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.page-topics .topics-bar__row {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-2) var(--space-4);
  margin-bottom: var(--space-3);
}

.page-topics .topics-bar__index {
  margin: 0;
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  color: var(--color-primary);
}

.page-topics .topics-bar__note {
  margin: 0;
  max-width: var(--measure);
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

.page-topics .filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  padding-top: var(--space-3);
  border-top: var(--border-thin) dotted var(--color-line);
}

.page-topics .filter-btn {
  padding: 6px var(--space-2);
  border: var(--border-thin) solid var(--color-line);
  border-radius: var(--radius-pill);
  background: var(--color-surface-alt);
  color: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.4;
  cursor: pointer;
}

.page-topics .filter-btn:hover {
  color: var(--color-ink);
  border-color: var(--color-surface-deep);
}

.page-topics .filter-btn:focus-visible {
  outline: var(--border-thin) solid var(--color-focus);
  outline-offset: 2px;
}

.page-topics .filter-btn.is-active {
  background: var(--color-primary-soft);
  color: var(--color-primary);
  border-color: var(--topics-hair);
}

.page-topics .topics-bar__empty {
  margin: var(--space-3) 0 0;
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

.page-topics .topics-bar__empty[hidden] {
  display: none;
}

/* ---------- 专题分组 ---------- */

.page-topics .topic-index {
  display: block;
}

.page-topics .topic-group {
  padding-block: var(--section-y);
  border-bottom: var(--border-thin) dotted var(--color-line);
}

.page-topics .topic-group:not(:has(.topic-item:not(.is-filtered-out))) {
  display: none;
}

.page-topics .topic-head {
  display: grid;
  gap: var(--space-4);
  align-items: end;
  margin-bottom: var(--space-4);
  padding-bottom: var(--space-4);
  border-bottom: var(--border-thin) solid var(--color-line);
}

.page-topics .topic-head__index {
  margin: 0;
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-ink-muted);
}

.page-topics .topic-head__title {
  margin: var(--space-1) 0 var(--space-2);
  font-family: var(--font-heading);
  font-size: var(--text-3xl);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

.page-topics .topic-head__note {
  margin: 0;
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-topics .topic-head__figure {
  margin: 0;
  min-width: 0;
}

.page-topics .topic-head__figure .figure-media {
  aspect-ratio: 3 / 2;
  overflow: hidden;
}

.page-topics .topic-head__figure img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* ---------- 条目 ---------- */

.page-topics .topic-list {
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-topics .topic-item {
  display: grid;
  grid-template-columns: var(--topics-num-col) minmax(0, 1fr);
  gap: var(--space-2);
  padding: var(--space-3) 0;
  border-top: var(--border-thin) dotted var(--topics-dot-line);
  scroll-margin-top: 96px;
}

.page-topics .topic-list > .topic-item:first-child {
  border-top: 0;
}

.page-topics .topic-item__num {
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  line-height: 1.2;
  letter-spacing: 0.06em;
  color: var(--color-primary);
  padding-top: 1px;
}

.page-topics .topic-item__body {
  min-width: 0;
}

.page-topics .topic-item__top {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: var(--space-2);
}

.page-topics .topic-item__name {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  color: var(--color-ink);
}

.page-topics .topic-item__desc {
  margin: var(--space-2) 0 0;
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-topics .topic-item__detail {
  margin: var(--space-2) 0 0;
  max-width: var(--measure);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.04em;
  color: var(--color-ink-muted);
}

.page-topics .topic-state {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
}

.page-topics .status-dot {
  display: inline-block;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--color-primary);
  animation: topics-pulse 1.6s ease-in-out infinite;
}

.page-topics .topic-state--archived .status-dot {
  background: var(--color-ink-muted);
  animation: none;
}

@keyframes topics-pulse {
  0%, 100% { opacity: 1; }
  50% { opacity: 0.32; }
}

@media (prefers-reduced-motion: reduce) {
  .page-topics .status-dot {
    animation: none;
  }
}

/* ---------- 结尾指引 ---------- */

.page-topics .topics-guide {
  padding-block: var(--section-y-lg);
  background: var(--color-surface-alt);
  border-top: var(--border-thin) solid var(--color-line);
}

.page-topics .topics-guide__grid {
  display: grid;
  gap: var(--space-6);
}

.page-topics .topics-guide__index {
  margin: 0 0 var(--space-2);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  color: var(--color-primary);
}

.page-topics .topics-guide__title {
  margin: 0 0 var(--space-3);
  font-family: var(--font-heading);
  font-size: var(--text-2xl);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  color: var(--color-ink);
}

.page-topics .topics-guide__text {
  margin: 0;
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-topics .read-path {
  margin: 0;
  padding: 0;
  list-style: none;
  border-top: var(--border-thin) solid var(--color-line);
}

.page-topics .read-path__item {
  display: grid;
  grid-template-columns: 78px minmax(0, 1fr);
  gap: var(--space-2);
  padding: var(--space-3) 0;
  border-bottom: var(--border-thin) dotted var(--topics-dot-line);
}

.page-topics .read-path__step {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-accent);
  padding-top: 3px;
}

.page-topics .read-path__text {
  margin: 0;
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink);
}

.page-topics .topics-guide__note {
  margin: var(--space-6) 0 0;
  padding-top: var(--space-4);
  border-top: var(--border-thin) dotted var(--color-line);
  max-width: var(--measure);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

.page-topics .topics-guide__note a {
  color: var(--color-primary);
  text-decoration: underline;
  text-decoration-style: dotted;
  text-underline-offset: 3px;
}

.page-topics .topics-guide__note a:hover,
.page-topics .topics-guide__note a:focus-visible {
  color: var(--color-focus);
}

/* ---------- 响应式 ---------- */

@media (min-width: 760px) {
  .page-topics .hero-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-topics .topics-hero__mini-title {
    letter-spacing: 0.14em;
  }

  .page-topics .mini-index {
    grid-template-columns: minmax(0, 1fr);
  }
}

@media (min-width: 900px) {
  .page-topics .topics-hero__grid {
    grid-template-columns: minmax(0, 1.9fr) minmax(0, 1fr);
    gap: var(--space-8);
    align-items: start;
  }

  .page-topics .topic-head {
    grid-template-columns: minmax(0, 1fr) 300px;
    gap: var(--space-8);
  }

  .page-topics .topic-head--flip {
    grid-template-columns: 300px minmax(0, 1fr);
  }

  .page-topics .topic-head--flip .topic-head__text {
    order: 2;
  }

  .page-topics .topic-head--flip .topic-head__figure {
    order: 1;
  }

  .page-topics .topics-guide__grid {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.15fr);
    gap: var(--space-8);
    align-items: start;
  }

  .page-topics .topic-item__num {
    font-size: var(--text-xl);
  }

  .page-topics .topic-item__detail {
    max-height: 0;
    margin-top: 0;
    overflow: hidden;
    opacity: 0;
    transition: max-height 160ms ease, opacity 160ms ease, margin-top 160ms ease;
  }

  .page-topics .topic-item:hover .topic-item__detail,
  .page-topics .topic-item:focus-within .topic-item__detail {
    max-height: 48px;
    margin-top: var(--space-2);
    opacity: 1;
  }
}

@media (min-width: 1180px) {
  .page-topics .topics-hero__mini {
    padding: var(--space-4);
  }
}