.page-topics-index {
  --pl-h1: clamp(27px, 5.4vw, var(--text-xl));
  --pl-h2: clamp(21px, 2.8vw, var(--text-lg));
  --pl-figure: clamp(33px, 5.2vw, var(--text-figure));
  --pl-rule: var(--border-thin) solid var(--color-line);
  --pl-rule-dark: var(--border-thin) solid var(--color-contrast-line);
}

/* ---------- 面包屑条 ---------- */
.page-topics-index .pl-crumb {
  background: var(--color-surface-alt);
  border-bottom: var(--pl-rule);
}

.page-topics-index .pl-crumb .breadcrumbs {
  padding: var(--space-2) 0;
}

/* ---------- 开篇深色面板 ---------- */
.page-topics-index .pl-open {
  position: relative;
  overflow: hidden;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-bottom: var(--border-thick) solid var(--color-accent);
}

.page-topics-index .pl-open__bg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: center 40%;
  opacity: 0.58;
}

.page-topics-index .pl-open__scrim {
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
}

.page-topics-index .pl-open__inner {
  position: relative;
  z-index: 1;
  padding: var(--space-8) 0 var(--space-8);
}

.page-topics-index .pl-open__eyebrow {
  color: var(--color-contrast-accent);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  margin: 0 0 var(--space-2);
}

.page-topics-index .pl-open h1 {
  margin: 0;
  font-family: var(--font-heading);
  font-weight: var(--weight-heading);
  font-size: var(--pl-h1);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  max-width: 24ch;
}

.page-topics-index .pl-open__h1line {
  display: block;
  color: var(--color-contrast-accent);
}

.page-topics-index .pl-open__lead {
  margin: var(--space-3) 0 0;
  max-width: 58ch;
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-contrast-ink);
  opacity: 0.88;
}

.page-topics-index .pl-open__meta {
  margin: var(--space-6) 0 0;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-4);
  border-top: var(--pl-rule-dark);
  padding-top: var(--space-3);
}

.page-topics-index .pl-open__metaitem {
  min-width: 120px;
}

.page-topics-index .pl-open__metaitem dt {
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
  opacity: 0.66;
  margin-bottom: 4px;
}

.page-topics-index .pl-open__metaitem dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-base);
  color: var(--color-contrast-ink);
}

/* ---------- 小节目录 ---------- */
.page-topics-index .pl-toc {
  border-bottom: var(--pl-rule);
}

.page-topics-index .pl-toc__inner {
  display: flex;
  align-items: center;
  gap: var(--space-3);
  padding: var(--space-2) 0;
  overflow-x: auto;
}

.page-topics-index .pl-toc__label {
  flex: none;
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
  letter-spacing: 0.08em;
}

.page-topics-index .pl-toc__list {
  display: flex;
  gap: var(--space-3);
  list-style: none;
  margin: 0;
  padding: 0;
  white-space: nowrap;
}

.page-topics-index .pl-toc__list a {
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  text-decoration: none;
  padding-bottom: 2px;
  border-bottom: var(--border-thick) solid transparent;
}

.page-topics-index .pl-toc__list a:hover,
.page-topics-index .pl-toc__list a:focus-visible {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

/* ---------- 01 口径范围 ---------- */
.page-topics-index .pl-scope__head {
  margin-bottom: var(--space-4);
}

.page-topics-index .pl-scope__body {
  margin-bottom: var(--space-6);
}

.page-topics-index .pl-scope__body a {
  color: var(--color-primary);
  text-decoration: underline;
  text-underline-offset: 3px;
}

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

.page-topics-index .pl-scope__item {
  border-top: var(--border-thick) solid var(--color-primary);
  padding-top: var(--space-2);
}

.page-topics-index .pl-scope__item h3 {
  margin: 0 0 var(--space-1);
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
  letter-spacing: 0.02em;
}

.page-topics-index .pl-scope__item p {
  margin: 0;
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

/* ---------- 02 两组对照 ---------- */
.page-topics-index .pl-split__intro {
  margin-bottom: var(--space-6);
}

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

.page-topics-index .pl-split__col {
  background: var(--color-surface);
  border: var(--pl-rule);
  padding: var(--space-4);
}

.page-topics-index .pl-split__tag {
  display: inline-block;
  margin: 0 0 var(--space-2);
  font-size: var(--text-sm);
  letter-spacing: 0.14em;
  color: var(--color-accent-ink);
  background: var(--color-accent);
  padding: 2px var(--space-1);
}

.page-topics-index .pl-split__title {
  margin: 0 0 var(--space-2);
  font-family: var(--font-heading);
  font-size: var(--pl-h2);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
}

.page-topics-index .pl-split__desc {
  margin: 0 0 var(--space-3);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink);
}

.page-topics-index .pl-split__spec {
  margin: 0;
  border-top: var(--pl-rule);
}

.page-topics-index .pl-split__spec dt {
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
  padding-top: var(--space-1);
}

.page-topics-index .pl-split__spec dd {
  margin: 2px 0 var(--space-1);
  font-size: var(--text-base);
  color: var(--color-ink);
  border-bottom: var(--pl-rule);
  padding-bottom: var(--space-1);
}

.page-topics-index .pl-split__spec dd:last-child {
  border-bottom: 0;
}

.page-topics-index .pl-split__spec dd.mono {
  font-family: var(--font-mono);
  color: var(--color-accent);
  font-weight: var(--weight-heading);
}

.page-topics-index .pl-split__rule {
  display: none;
}

/* ---------- 03 关键数字 ---------- */
.page-topics-index .pl-numbers {
  position: relative;
  overflow: hidden;
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
  border-top: var(--border-thick) solid var(--color-primary);
}

.page-topics-index .pl-numbers__bg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.28;
}

.page-topics-index .pl-numbers__scrim {
  position: absolute;
  inset: 0;
  background: var(--overlay-scrim);
}

.page-topics-index .pl-numbers__inner {
  position: relative;
  z-index: 1;
  padding: var(--section-y) 0;
}

.page-topics-index .section-head__num--on-dark {
  color: var(--color-contrast-accent);
}

.page-topics-index .pl-numbers__title {
  margin: 0 0 var(--space-6);
  font-family: var(--font-heading);
  font-size: var(--pl-h2);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  max-width: 22ch;
}

.page-topics-index .pl-numbers__grid {
  display: grid;
  gap: var(--space-4);
  border-top: var(--pl-rule-dark);
  padding-top: var(--space-4);
}

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

.page-topics-index .pl-num__value {
  font-family: var(--font-mono);
  font-size: var(--pl-figure);
  font-weight: var(--weight-heading);
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--color-contrast-accent);
}

.page-topics-index .pl-num:nth-child(1) .pl-num__value {
  color: var(--color-contrast-ink);
}

.page-topics-index .pl-num__unit {
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
  opacity: 0.72;
}

.page-topics-index .pl-numbers__note {
  margin: var(--space-4) 0 0;
  font-size: var(--text-sm);
  color: var(--color-contrast-ink);
  opacity: 0.6;
  max-width: 60ch;
}

/* ---------- 通栏图 ---------- */
.page-topics-index .pl-band {
  margin: 0;
  border-bottom: var(--border-thick) solid var(--color-accent);
}

.page-topics-index .pl-band img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
}

/* ---------- 04 记录字段 ---------- */
.page-topics-index .pl-fields__head {
  margin-bottom: var(--space-4);
}

.page-topics-index .pl-fields__list {
  border-top: var(--border-thick) solid var(--color-ink);
}

.page-topics-index .pl-fields__item {
  border-bottom: var(--pl-rule);
}

.page-topics-index .pl-fields__item summary {
  display: flex;
  align-items: baseline;
  gap: var(--space-2);
  padding: var(--space-2) 0;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
  color: var(--color-ink);
}

.page-topics-index .pl-fields__item summary::-webkit-details-marker {
  display: none;
}

.page-topics-index .pl-fields__item summary::after {
  content: "+";
  margin-left: auto;
  flex: none;
  font-family: var(--font-mono);
  font-size: var(--text-lg);
  line-height: 1;
  color: var(--color-accent);
}

.page-topics-index .pl-fields__item[open] summary::after {
  content: "−";
}

.page-topics-index .pl-fields__item[open] summary {
  color: var(--color-primary);
}

.page-topics-index .pl-fields__idx {
  flex: none;
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

.page-topics-index .pl-fields__item p {
  margin: 0 0 var(--space-3);
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
  max-width: var(--measure);
}

/* ---------- 05 情形拆解 ---------- */
.page-topics-index .pl-cases__head {
  margin-bottom: var(--space-6);
}

.page-topics-index .pl-cases__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--space-4);
}

.page-topics-index .pl-case {
  display: grid;
  grid-template-columns: auto 1fr;
  gap: var(--space-2) var(--space-3);
  background: var(--color-surface);
  border-left: var(--border-thick) solid var(--color-primary);
  padding: var(--space-3);
}

.page-topics-index .pl-case__idx {
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  color: var(--color-accent);
  letter-spacing: 0.06em;
  padding-top: 4px;
}

.page-topics-index .pl-case__body h3 {
  margin: 0 0 var(--space-1);
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
  letter-spacing: 0.01em;
}

.page-topics-index .pl-case__body p {
  margin: 0;
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-ink-soft);
}

/* ---------- 06 修订说明 ---------- */
.page-topics-index .pl-revise__head {
  margin-bottom: var(--space-4);
}

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

.page-topics-index .pl-revise__col h3 {
  margin: 0 0 var(--space-2);
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
  border-left: var(--border-thick) solid var(--color-accent);
  padding-left: var(--space-2);
}

.page-topics-index .pl-revise__col a {
  color: var(--color-primary);
  text-decoration: underline;
  text-underline-offset: 3px;
}

/* ---------- 07 相邻主题 ---------- */
.page-topics-index .pl-next__inner {
  padding: var(--section-y) 0;
}

.page-topics-index .pl-next .section-head__title {
  margin-bottom: var(--space-4);
}

.page-topics-index .pl-next__list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: var(--pl-rule);
}

.page-topics-index .pl-next__item a {
  display: grid;
  grid-template-columns: 1fr;
  gap: 2px;
  padding: var(--space-2) 0;
  border-bottom: var(--pl-rule);
  text-decoration: none;
  color: var(--color-ink);
}

.page-topics-index .pl-next__item a:hover .pl-next__name,
.page-topics-index .pl-next__item a:focus-visible .pl-next__name {
  color: var(--color-primary);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-topics-index .pl-next__name {
  font-family: var(--font-heading);
  font-size: var(--text-base);
  font-weight: var(--weight-heading);
}

.page-topics-index .pl-next__desc {
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
}

.page-topics-index .pl-next__note {
  margin: var(--space-4) 0 0;
  font-size: var(--text-sm);
  color: var(--color-ink-soft);
  max-width: var(--measure);
}

/* ---------- 返回顶部 ---------- */
.page-topics-index .pl-topwrap {
  padding: var(--space-4) 0 var(--space-6);
}

.page-topics-index .pl-topwrap__btn {
  text-decoration: none;
}

/* ---------- 桌面栅格 ---------- */
@media (min-width: 800px) {
  .page-topics-index .pl-open__inner {
    padding: var(--section-y-lg) 0 var(--space-8);
  }

  .page-topics-index .pl-scope__list {
    grid-template-columns: repeat(3, 1fr);
    gap: var(--space-4);
  }

  .page-topics-index .pl-split {
    grid-template-columns: 1fr 1fr;
    gap: 0;
  }

  .page-topics-index .pl-split__col {
    border-color: transparent;
    background: transparent;
    padding: 0 var(--space-6) 0 0;
  }

  .page-topics-index .pl-split__rule {
    display: block;
    grid-column: 2;
    grid-row: 1;
    justify-self: stretch;
    width: 1px;
    background: var(--color-line);
    margin: 0 auto;
  }

  .page-topics-index .pl-split__col + .pl-split__col {
    padding: 0 0 0 var(--space-6);
    grid-column: 3;
    grid-row: 1;
  }

  .page-topics-index .pl-split {
    grid-template-columns: 1fr 1px 1fr;
  }

  .page-topics-index .pl-numbers__grid {
    grid-template-columns: 1.4fr 1fr 1fr;
    gap: var(--space-6);
  }

  .page-topics-index .pl-cases__list {
    grid-template-columns: 1fr 1fr;
    gap: var(--space-4);
  }

  .page-topics-index .pl-revise__grid {
    grid-template-columns: 1fr 1fr;
    gap: var(--space-8);
  }

  .page-topics-index .pl-next__item a {
    grid-template-columns: minmax(160px, 240px) 1fr;
    gap: var(--space-3);
    align-items: baseline;
    padding: var(--space-2) 0;
  }
}

@media (min-width: 1100px) {
  .page-topics-index .pl-open h1 {
    max-width: 20ch;
  }

  .page-topics-index .pl-scope__inner {
    display: grid;
    grid-template-columns: minmax(0, 1fr) minmax(0, 2fr);
    gap: var(--space-8);
    align-items: start;
  }

  .page-topics-index .pl-scope__head {
    margin-bottom: 0;
    position: sticky;
    top: var(--space-8);
  }

  .page-topics-index .pl-scope__list {
    grid-template-columns: 1fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-topics-index [data-reveal] {
    transition: none;
  }
}
</main>