.page-about {
  background: var(--sand-050);
  color: var(--ink-900);
}

.page-about .about-crumbs {
  padding-top: clamp(18px, 3vw, 34px);
  padding-bottom: clamp(10px, 1.6vw, 18px);
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  padding-top: clamp(6px, 1.6vw, 20px);
  padding-bottom: clamp(30px, 5vw, 68px);
}

.page-about .about-hero__inner {
  display: grid;
  gap: clamp(26px, 4vw, 56px);
  align-items: end;
}

.page-about .about-hero__eyebrow {
  color: var(--ember-700);
  margin: 0 0 14px;
}

.page-about .about-hero__title {
  margin: 0;
  max-width: 18ch;
}

.page-about .about-hero__lede {
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.85;
  color: var(--ink-900);
  max-width: 62ch;
  margin: clamp(16px, 2.4vw, 26px) 0 0;
}

.page-about .about-hero__facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 0;
  background: var(--hair);
  border-top: 1px solid var(--clay-700);
  border-bottom: 1px solid var(--hair);
}

.page-about .fact {
  background: var(--sand-050);
  padding: 14px 16px 16px;
}

.page-about .fact__k {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--ash-500);
  line-height: 1.5;
}

.page-about .fact__v {
  margin: 6px 0 0;
  font-family: var(--font-mono);
  font-size: clamp(22px, 3vw, 34px);
  font-weight: 700;
  letter-spacing: 0.04em;
  line-height: 1.06;
  color: var(--ember-700);
}

/* ---------- 主体两栏 ---------- */

.page-about .about-body {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 4vw, 48px);
  padding-bottom: clamp(56px, 8vw, 112px);
}

.page-about .about-rail {
  border-top: 1px solid var(--clay-700);
  padding-top: 14px;
}

.page-about .about-rail__cap {
  color: var(--ash-500);
  margin: 0 0 12px;
}

.page-about .rail {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 18px;
  overflow-x: auto;
  padding-bottom: 6px;
  scrollbar-width: thin;
}

.page-about .rail__row {
  display: flex;
  align-items: center;
  gap: 8px;
  min-width: max-content;
  position: relative;
  padding: 4px 0;
}

.page-about .rail__year {
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--ink-900);
}

.page-about .rail__dot {
  width: 7px;
  height: 7px;
  flex: none;
  background: var(--sand-050);
  border: 1px solid var(--clay-700);
  transform: rotate(45deg);
  transition: background 180ms ease, border-color 180ms ease, transform 180ms ease;
}

.page-about .rail__note {
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--ash-500);
  white-space: nowrap;
}

.page-about .rail__row:hover .rail__dot {
  background: var(--ember-600);
  border-color: var(--ember-600);
}

.page-about .rail__row:hover .rail__note {
  color: var(--ember-700);
}

.page-about .about-stream {
  min-width: 0;
}

/* ---------- 章节画板 ---------- */

.page-about .dossier {
  position: relative;
}

.page-about .dossier + .dossier {
  margin-top: clamp(40px, 6vw, 84px);
  padding-top: clamp(36px, 5vw, 72px);
  border-top: 1px solid var(--clay-700);
}

.page-about .dossier__head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  margin-bottom: clamp(16px, 2.4vw, 28px);
}

.page-about .dossier__no {
  flex: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--ember-700);
  border: 1px solid currentColor;
  padding: 2px 7px;
  line-height: 1.5;
}

.page-about .dossier__title {
  margin: 0;
  font-size: clamp(24px, 4vw, 40px);
  line-height: 1.14;
  letter-spacing: -0.01em;
}

.page-about .dossier__lede {
  margin-top: 0;
}

.page-about .dossier__foot {
  margin-top: clamp(18px, 2.4vw, 28px);
}

/* 深色画板 */
.page-about .dossier--dark {
  background: var(--pitch-900);
  color: var(--sand-050);
  padding: clamp(24px, 4vw, 52px);
  margin-inline: calc(-1 * clamp(16px, 4vw, 40px));
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 30px), calc(100% - 30px) 100%, 0 100%);
}

.page-about .dossier--dark .dossier__no {
  color: var(--ember-600);
}

.page-about .dossier--dark .dossier__title,
.page-about .dossier--dark .prose,
.page-about .dossier--dark .steps__sum {
  color: var(--sand-050);
}

.page-about .dossier--dark a {
  color: var(--cyan-400);
  text-decoration-color: var(--cyan-400);
}

.page-about .dossier--dark a:hover {
  text-decoration-thickness: 2px;
}

/* 浅色分区画板 */
.page-about .dossier--tint {
  background: var(--sand-100);
  padding: clamp(22px, 3.6vw, 44px);
  margin-inline: calc(-1 * clamp(16px, 4vw, 40px));
  clip-path: polygon(0 0, 100% 0, 100% calc(100% - 24px), calc(100% - 24px) 100%, 0 100%);
}

/* ---------- 三组切换 ---------- */

.page-about .crew {
  margin-top: clamp(20px, 2.6vw, 32px);
}

.page-about .crew__tabs {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 20px;
}

.page-about .crew__tab {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 9px 14px;
  font-size: 14px;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--ink-900);
  background: transparent;
  border: 1px solid var(--clay-700);
  cursor: pointer;
  transition: background 180ms ease, color 180ms ease, border-color 180ms ease;
}

.page-about .crew__tab .num {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--ember-700);
}

.page-about .crew__tab:hover {
  border-color: var(--ember-600);
}

.page-about .crew__tab:hover .num {
  color: var(--ember-600);
}

.page-about .crew__radio:focus-visible + .crew__tabs,
.page-about .crew__radio:focus-visible ~ .crew__tabs {
  outline: 2px solid var(--cyan-400);
  outline-offset: 4px;
}

.page-about #crew-tab-1:checked ~ .crew__tabs [for="crew-tab-1"],
.page-about #crew-tab-2:checked ~ .crew__tabs [for="crew-tab-2"],
.page-about #crew-tab-3:checked ~ .crew__tabs [for="crew-tab-3"] {
  background: var(--ink-900);
  color: var(--sand-050);
  border-color: var(--ink-900);
}

.page-about #crew-tab-1:checked ~ .crew__tabs [for="crew-tab-1"] .num,
.page-about #crew-tab-2:checked ~ .crew__tabs [for="crew-tab-2"] .num,
.page-about #crew-tab-3:checked ~ .crew__tabs [for="crew-tab-3"] .num {
  color: var(--cyan-400);
}

.page-about .crew__panel {
  border-left: 2px solid var(--ochre-500);
  padding-left: clamp(16px, 2.4vw, 26px);
}

.page-about .crew__radio:checked ~ .crew__panels > .crew__panel {
  display: none;
}

.page-about #crew-tab-1:checked ~ .crew__panels > [data-crew="a"],
.page-about #crew-tab-2:checked ~ .crew__panels > [data-crew="b"],
.page-about #crew-tab-3:checked ~ .crew__panels > [data-crew="c"] {
  display: block;
}

.page-about .crew__lead {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 800;
  letter-spacing: -0.01em;
  margin: 0 0 10px;
  color: var(--clay-700);
}

.page-about .crew__list {
  list-style: none;
  margin: 16px 0 0;
  padding: 0;
  display: grid;
  gap: 8px;
}

.page-about .crew__list li {
  position: relative;
  padding-left: 20px;
  font-size: 15px;
  line-height: 1.75;
  color: var(--ink-900);
}

.page-about .crew__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.72em;
  width: 10px;
  height: 1px;
  background: var(--ember-600);
}

/* ---------- 展览标签说明牌 ---------- */

.page-about .plaque {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 10px 14px;
  margin: clamp(22px, 3vw, 34px) 0 0;
  padding: 14px 16px;
  border: 1px solid var(--clay-700);
  background: transparent;
}

.page-about .plaque__tag {
  flex: none;
  color: var(--ember-700);
  border: 1px solid currentColor;
  padding: 1px 6px;
  line-height: 1.5;
}

.page-about .plaque__text {
  font-size: 14px;
  line-height: 1.75;
  color: var(--ash-500);
}

.page-about .dossier--dark .plaque {
  border-color: var(--hair-dark);
}

.page-about .dossier--dark .plaque__text {
  color: var(--sand-100);
}

/* ---------- 评审步骤折叠 ---------- */

.page-about .steps {
  margin-top: clamp(20px, 2.6vw, 30px);
  display: grid;
  gap: 1px;
  background: var(--hair-dark);
  border-top: 1px solid var(--hair-dark);
}

.page-about .steps__item {
  background: var(--pitch-900);
  padding: 4px 0;
}

.page-about .steps__sum {
  display: flex;
  align-items: baseline;
  gap: 12px;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-display);
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.01em;
  padding: 12px 0;
  transition: color 180ms ease;
}

.page-about .steps__sum::-webkit-details-marker {
  display: none;
}

.page-about .steps__sum:hover {
  color: var(--cyan-400);
}

.page-about .steps__no {
  flex: none;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--ember-600);
}

.page-about .steps__item .prose {
  margin: 0 0 12px;
  padding-left: 34px;
  opacity: 0.86;
  transition: opacity 220ms ease;
}

/* ---------- 口径公式 ---------- */

.page-about .formula {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px 12px;
  margin: clamp(24px, 3.2vw, 38px) 0 0;
  padding: 16px 18px;
  border-left: 3px solid var(--ember-600);
  background: var(--pitch-600);
  font-family: var(--font-mono);
  font-size: clamp(14px, 1.8vw, 17px);
  letter-spacing: 0.04em;
  color: var(--sand-050);
}

.page-about .formula__key {
  font-weight: 700;
  color: var(--ember-600);
}

.page-about .formula__var {
  color: var(--cyan-400);
}

.page-about .formula__eq,
.page-about .formula__op,
.page-about .formula__arrow {
  color: var(--ash-500);
}

.page-about .formula__out {
  color: var(--white);
  font-weight: 700;
}

/* ---------- 档案编排三段 ---------- */

.page-about .spec {
  margin-top: clamp(20px, 2.6vw, 32px);
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--hair);
  border-top: 1px solid var(--clay-700);
}

.page-about .spec__block {
  background: var(--sand-050);
  padding: clamp(18px, 2.6vw, 28px) 0;
}

.page-about .spec__kicker {
  color: var(--ash-500);
  margin: 0 0 8px;
}

.page-about .spec__title {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 800;
  letter-spacing: -0.01em;
}

.page-about .spec__block .prose {
  margin: 0;
}

/* ---------- 阅读节奏 ---------- */

.page-about .reading {
  list-style: none;
  margin: clamp(20px, 2.6vw, 30px) 0 0;
  padding: 0;
  display: grid;
  gap: clamp(18px, 2.6vw, 30px);
}

.page-about .reading__row {
  display: grid;
  gap: 10px;
  padding-left: 16px;
  border-left: 1px solid var(--clay-700);
}

.page-about .reading__no {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--ember-700);
}

.page-about .reading__title {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 800;
  letter-spacing: -0.01em;
}

.page-about .reading__row .prose {
  margin: 0;
}

/* ---------- 更新节奏 ---------- */

.page-about .cadence {
  list-style: none;
  margin: clamp(20px, 2.6vw, 30px) 0 0;
  padding: 0;
  border-top: 1px solid var(--hair);
}

.page-about .cadence__row {
  display: grid;
  gap: 6px;
  padding: 15px 0;
  border-bottom: 1px solid var(--hair);
}

.page-about .cadence__when {
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--ember-700);
}

.page-about .cadence__what {
  font-size: 16px;
  line-height: 1.78;
  color: var(--ink-900);
}

/* ---------- 时间轴 ---------- */

.page-about .timeline {
  list-style: none;
  margin: clamp(22px, 3vw, 34px) 0 0;
  padding: 0;
  position: relative;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 6px;
  bottom: 6px;
  width: 1px;
  background: var(--clay-700);
}

.page-about .timeline__node {
  position: relative;
  display: grid;
  gap: 8px;
  padding: 0 0 clamp(24px, 3.4vw, 38px) 28px;
}

.page-about .timeline__node:last-child {
  padding-bottom: 0;
}

.page-about .timeline__node::before {
  content: "";
  position: absolute;
  left: 0;
  top: 6px;
  width: 11px;
  height: 11px;
  background: var(--sand-050);
  border: 1px solid var(--clay-700);
  transform: rotate(45deg);
  transition: background 180ms ease, border-color 180ms ease, box-shadow 220ms ease;
}

.page-about .timeline__node:hover::before {
  background: var(--ember-600);
  border-color: var(--ember-600);
  box-shadow: 0 0 0 6px rgba(226, 85, 31, 0.14);
}

.page-about .timeline__node--now::before {
  background: var(--ochre-500);
  border-color: var(--ochre-500);
}

.page-about .timeline__year {
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.12em;
  color: var(--clay-700);
}

.page-about .timeline__title {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-size: 18px;
  font-weight: 800;
  letter-spacing: -0.01em;
}

.page-about .timeline__body .prose {
  margin: 0;
  font-size: 16px;
}

/* ---------- 图片 ---------- */

.page-about .about-figure {
  margin: clamp(24px, 3.4vw, 40px) 0 0;
}

.page-about .about-figure .figure__frame {
  overflow: hidden;
  border: 1px solid var(--clay-700);
}

.page-about .about-figure .figure__img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .dossier--dark .about-figure .figure__frame {
  border-color: var(--hair-dark);
}

.page-about .figure__cap {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--ash-500);
}

.page-about .dossier--dark .figure__cap {
  color: var(--sand-100);
}

/* ---------- 响应式 ---------- */

@media (min-width: 640px) {
  .page-about .about-hero__facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

  .page-about .spec {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: clamp(18px, 2.6vw, 34px);
    background: transparent;
  }

  .page-about .spec__block {
    padding: 20px 0 0;
    border-top: 2px solid var(--ochre-500);
    background: transparent;
  }

  .page-about .cadence__row {
    grid-template-columns: 110px minmax(0, 1fr);
    align-items: baseline;
    gap: 20px;
  }

  .page-about .reading__row {
    grid-template-columns: 76px minmax(0, 1fr);
    gap: 20px;
    align-items: start;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero__inner {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
  }

  .page-about .about-body {
    grid-template-columns: 172px minmax(0, 1fr);
    gap: clamp(32px, 5vw, 76px);
    align-items: start;
  }

  .page-about .about-rail {
    position: sticky;
    top: 132px;
    border-top: 1px solid var(--clay-700);
  }

  .page-about .rail {
    display: block;
    overflow: visible;
    padding-bottom: 0;
    border-left: 1px solid var(--hair);
    margin-left: 1px;
  }

  .page-about .rail__row {
    display: grid;
    grid-template-columns: minmax(0, 1fr);
    gap: 2px;
    min-width: 0;
    padding: 9px 0 9px 20px;
  }

  .page-about .rail__dot {
    position: absolute;
    left: -4px;
    top: 15px;
  }

  .page-about .rail__note {
    white-space: normal;
  }

  .page-about .formula {
    padding: 20px 24px;
  }
}

@media (min-width: 1180px) {
  .page-about .about-rail {
    top: 148px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .rail__dot,
  .page-about .crew__tab,
  .page-about .steps__sum,
  .page-about .steps__item .prose,
  .page-about .timeline__node::before {
    transition: none;
  }
}