.page-topics .hero {
  padding-block: var(--space-6) var(--space-6);
  border-block-end: var(--border-thick) solid var(--color-ink);
}

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

.page-topics .hero__inner {
  display: grid;
  gap: var(--space-3);
  margin-block-start: var(--space-2);
}

.page-topics .hero__title {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-display);
  font-weight: var(--weight-heading);
  line-height: 0.88;
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

.page-topics .hero__lede {
  margin: 0;
  max-width: 48ch;
  color: var(--color-ink-soft);
}

.page-topics .hero__slash {
  margin-block-start: var(--space-2);
  padding: var(--space-4) var(--space-4) calc(var(--space-6) + var(--space-2));
  background: var(--color-primary);
  color: var(--color-primary-ink);
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 30px), 0 100%);
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-3);
}

.page-topics .hero__fig {
  display: flex;
  flex-direction: column;
  gap: var(--space-1);
}

.page-topics .hero__fig-num {
  font-family: var(--font-mono);
  font-size: var(--text-figure);
  font-weight: var(--weight-heading);
  line-height: 0.9;
  letter-spacing: -0.02em;
}

.page-topics .hero__fig-label {
  color: inherit;
  opacity: 0.88;
}

.page-topics .hero__strip {
  list-style: none;
  margin: var(--space-6) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-2);
}

.page-topics .hero__strip .img-frame {
  aspect-ratio: 4 / 3;
  overflow: hidden;
  background: var(--color-surface-deep);
}

.page-topics .img-frame {
  margin: 0;
}

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

/* 筛选条 */
.page-topics .filter-bar {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: var(--space-2);
  margin-block-start: var(--section-y);
  padding-block: var(--space-3);
  border-block: var(--border-thick) solid var(--color-ink);
}

.page-topics .filter-bar .data-label {
  flex-basis: 100%;
  color: var(--color-ink-muted);
}

.page-topics .filter-btn {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  transition: background-color 150ms ease-out, color 150ms ease-out, border-color 150ms ease-out;
}

.page-topics .filter-btn[aria-pressed="true"] {
  background: var(--color-accent);
  color: var(--color-accent-ink);
  border-color: var(--color-accent);
}

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

.page-topics .filter-count {
  margin-inline-start: auto;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
  font-variant-numeric: tabular-nums;
}

/* 分类区块 */
.page-topics .cat-section {
  margin-block-start: var(--section-y);
}

.page-topics .cat {
  margin-block-start: var(--space-6);
  display: grid;
  gap: var(--space-4);
}

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

.page-topics .cat__intro a {
  color: var(--color-accent);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-topics .cat__media {
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background: var(--color-surface-deep);
}

/* 专题条目 */
.page-topics .topic-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-block-start: var(--border-thick) solid var(--color-ink);
}

.page-topics .topic {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  grid-template-areas:
    "no status"
    "body body";
  gap: var(--space-2);
  padding: var(--space-3) var(--space-2);
  border-block-end: var(--border-thin) solid var(--color-line);
  transition: background-color 150ms ease-out, border-color 150ms ease-out;
}

.page-topics .topic__no {
  grid-area: no;
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-weight: var(--weight-heading);
  letter-spacing: 0.1em;
  color: var(--color-primary);
}

.page-topics .topic__status {
  grid-area: status;
  justify-self: end;
  transition: background-color 150ms ease-out, color 150ms ease-out, border-color 150ms ease-out;
}

.page-topics .topic__body {
  grid-area: body;
}

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

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

.page-topics .topic:hover {
  background: var(--color-primary-soft);
}

.page-topics .topic:hover .topic__status {
  background: var(--color-contrast-surface);
  border-color: var(--color-contrast-surface);
  color: var(--color-contrast-accent);
}

/* 子页与引用 */
.page-topics .sub {
  margin-block-start: var(--section-y-lg);
}

.page-topics .sub__title {
  margin: 0 0 var(--space-6);
  color: var(--color-contrast-ink);
}

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

.page-topics .sub__lead p {
  margin: 0 0 var(--space-4);
  max-width: 46ch;
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-contrast-ink);
}

.page-topics .sub__lead a {
  color: var(--color-contrast-accent);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-topics .sub__rules {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--space-3);
}

.page-topics .sub__rules li {
  padding-block-start: var(--space-2);
  border-block-start: var(--border-thin) solid var(--color-contrast-line);
  font-size: var(--text-sm);
  line-height: var(--leading-body);
  color: var(--color-contrast-ink);
}

.page-topics .sub__rules strong {
  color: var(--color-contrast-accent);
  font-weight: var(--weight-heading);
  letter-spacing: 0.08em;
}

.page-topics .sub__rules a {
  color: var(--color-contrast-accent);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-topics .sub__rules a:focus-visible {
  outline: var(--border-thick) solid var(--color-contrast-accent);
  outline-offset: 2px;
}

/* 更宽的屏幕 */
@media (min-width: 680px) {
  .page-topics .hero__strip {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-topics .topic {
    grid-template-columns: 92px minmax(0, 1fr) auto;
    grid-template-areas: "no .page-topics status";
    align-items: baseline;
    column-gap: var(--space-3);
    padding-inline: var(--space-3);
  }
}

@media (min-width: 900px) {
  .page-topics .hero__inner {
    grid-template-columns: minmax(0, 7fr) minmax(0, 3fr);
    column-gap: var(--space-6);
    row-gap: var(--space-3);
    align-items: stretch;
  }

  .page-topics .hero__title {
    grid-column: 1;
    grid-row: 1;
  }

  .page-topics .hero__lede {
    grid-column: 1;
    grid-row: 2;
    align-self: end;
  }

  .page-topics .hero__slash {
    grid-column: 2;
    grid-row: 1 / span 2;
    margin-block-start: 0;
    align-content: center;
    padding: var(--space-6) var(--space-6) calc(var(--space-8) + var(--space-2));
  }

  .page-topics .cat {
    grid-template-columns: repeat(7, minmax(0, 1fr));
    column-gap: var(--gutter);
    row-gap: var(--space-6);
  }

  .page-topics .cat__intro {
    grid-column: span 2;
  }

  .page-topics .cat__media {
    grid-column: span 5;
  }

  .page-topics .topic-list {
    grid-column: 1 / -1;
  }

  .page-topics .sub__cols {
    grid-template-columns: repeat(7, minmax(0, 1fr));
    column-gap: var(--gutter);
  }

  .page-topics .sub__lead {
    grid-column: span 3;
  }

  .page-topics .sub__rules {
    grid-column: span 4;
  }
}