.page-about {
  --about-rail: 208px;
  --about-note: 248px;
  --about-dash: rgba(18, 24, 26, 0.16);
  --about-shadow: 0 22px 46px -34px rgba(14, 31, 26, 0.75);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  background: var(--ink-green);
  color: var(--paper);
  padding: 22px 0 56px;
  overflow: hidden;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 3px;
  background: var(--orange);
}

.page-about .about-hero .breadcrumb ol {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  list-style: none;
  margin: 0 0 26px;
  padding: 0;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--stand-blue);
}

.page-about .about-hero .breadcrumb li + li::before {
  content: "/";
  margin-right: 8px;
  color: rgba(143, 166, 184, 0.6);
}

.page-about .about-hero .breadcrumb a {
  color: var(--stand-blue);
  text-decoration: none;
}

.page-about .about-hero .breadcrumb a:hover {
  color: var(--orange);
}

.page-about .about-hero .breadcrumb li[aria-current="page"] {
  color: var(--paper);
}

.page-about .hero-split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 30px;
}

.page-about .about-hero .eyebrow {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--orange);
}

.page-about .hero-copy h1 {
  margin: 14px 0 18px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(32px, 5.4vw, 60px);
  line-height: 1.06;
  letter-spacing: -0.012em;
  color: var(--paper);
}

.page-about .hero-lede {
  margin: 0;
  max-width: 46ch;
  font-size: 15px;
  line-height: 1.78;
  color: rgba(244, 241, 232, 0.84);
}

.page-about .hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 26px;
}

/* 记分牌视觉 */
.page-about .hero-board {
  background: var(--pitch-green);
  border: 1px solid var(--hair-dark);
  padding: 18px 18px 16px;
  box-shadow: var(--about-shadow);
}

.page-about .board-head {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--hair-dark);
  font-size: 11px;
  letter-spacing: 0.16em;
  color: var(--stand-blue);
}

.page-about .board-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
}

.page-about .board-cell {
  padding: 18px 0 14px;
  border-bottom: 1px solid var(--hair-dark);
}

.page-about .board-cell:nth-child(odd) {
  padding-right: 14px;
  border-right: 1px solid var(--hair-dark);
}

.page-about .board-cell:nth-child(even) {
  padding-left: 14px;
}

.page-about .board-num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(26px, 3.6vw, 38px);
  line-height: 1;
  color: var(--paper);
}

.page-about .board-label {
  display: block;
  margin-top: 8px;
  font-size: 12px;
  letter-spacing: 0.05em;
  color: var(--stand-blue);
}

.page-about .board-foot {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding-top: 14px;
}

/* ---------- 三栏骨架 ---------- */
.page-about .about-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 28px;
  padding-top: 34px;
  padding-bottom: 64px;
}

/* 左侧章节索引：移动端横向条 */
.page-about .about-rail {
  position: sticky;
  top: 0;
  z-index: 6;
  margin: 0 calc(var(--gutter) * -1);
  padding: 8px var(--gutter) 0;
  background: var(--paper);
  border-bottom: 1px solid var(--hair-ink);
}

.page-about .rail-title {
  display: none;
  margin: 0 0 10px;
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--muted);
}

.page-about .about-rail ol {
  display: flex;
  gap: 20px;
  margin: 0;
  padding: 0;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: none;
}

.page-about .about-rail ol::-webkit-scrollbar {
  display: none;
}

.page-about .about-rail a {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 0;
  white-space: nowrap;
  font-size: 13px;
  color: var(--muted);
  text-decoration: none;
  border-bottom: 2px solid transparent;
  transition: color 0.24s var(--ease), border-color 0.24s var(--ease);
}

.page-about .rail-no {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--stand-blue);
}

.page-about .about-rail a:hover {
  color: var(--ink);
}

.page-about .about-rail a[aria-current="true"] {
  color: var(--orange-deep);
  border-bottom-color: var(--orange);
}

.page-about .about-rail a[aria-current="true"] .rail-no {
  color: var(--orange);
}

/* ---------- 章节 ---------- */
.page-about .about-sec {
  padding-top: 24px;
  margin-bottom: 52px;
  border-top: 1px solid var(--hair-ink);
  scroll-margin-top: 92px;
}

.page-about .about-eyebrow {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--orange-deep);
}

.page-about .about-eyebrow--light {
  color: var(--orange);
}

.page-about .about-sec h2,
.page-about .about-next h2 {
  margin: 0 0 18px;
  font-family: var(--font-body);
  font-weight: 700;
  font-size: clamp(23px, 3.2vw, 32px);
  line-height: 1.28;
  letter-spacing: -0.01em;
  color: var(--ink);
}

.page-about .about-sec p {
  margin: 0 0 14px;
  line-height: 1.78;
  color: var(--body-text);
}

.page-about .about-sec p:last-child {
  margin-bottom: 0;
}

.page-about .sec-lede {
  max-width: 60ch;
  color: var(--muted);
}

.page-about .figure {
  margin: 0;
  background: var(--paper-warm);
}

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

.page-about .figure__caption {
  padding: 10px 12px 12px;
  font-family: var(--font-mono);
  font-size: 11.5px;
  line-height: 1.6;
  color: var(--muted);
  border-top: 1px solid var(--hair-ink);
}

/* 起点 */
.page-about .origin-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 24px;
}

.page-about .origin-figure {
  border: 1px solid var(--hair-ink);
}

/* 方法四步 */
.page-about .method-wrap {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 26px;
  margin-top: 22px;
}

.page-about .steps {
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .step {
  border-top: 1px solid var(--about-dash);
}

.page-about .step:last-child {
  border-bottom: 1px solid var(--about-dash);
}

.page-about .step > summary {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr) 16px;
  align-items: start;
  gap: 12px;
  padding: 16px 0;
  cursor: pointer;
  list-style: none;
}

.page-about .step > summary::-webkit-details-marker {
  display: none;
}

.page-about .step-no {
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
  color: var(--paper);
  background: var(--pitch-green);
  padding: 3px 5px;
  text-align: center;
}

.page-about .step[open] .step-no {
  background: var(--orange);
}

.page-about .step-text {
  display: block;
  min-width: 0;
}

.page-about .step-title {
  display: block;
  font-weight: 700;
  font-size: 16.5px;
  line-height: 1.45;
  color: var(--ink);
}

.page-about .step-hint {
  display: block;
  margin-top: 4px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--muted);
}

.page-about .step-mark {
  position: relative;
  width: 12px;
  height: 12px;
  margin-top: 7px;
}

.page-about .step-mark::before,
.page-about .step-mark::after {
  content: "";
  position: absolute;
  background: var(--orange-deep);
  transition: transform 0.24s var(--ease), opacity 0.24s var(--ease);
}

.page-about .step-mark::before {
  left: 0;
  top: 5px;
  width: 12px;
  height: 2px;
}

.page-about .step-mark::after {
  left: 5px;
  top: 0;
  width: 2px;
  height: 12px;
}

.page-about .step[open] .step-mark::after {
  transform: scaleY(0);
  opacity: 0;
}

.page-about .step-body {
  padding: 0 0 20px 46px;
  border-left: 1px dashed var(--about-dash);
  margin-left: 17px;
}

.page-about .step-body p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.78;
  color: var(--body-text);
}

.page-about .method-figure {
  border: 1px solid var(--hair-ink);
}

/* 团队 */
.page-about .team-figure {
  margin-bottom: 22px;
}

.page-about .team-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 14px;
  margin-top: 22px;
}

.page-about .team-card {
  background: var(--white);
  border-top: 3px solid var(--pitch-green);
  padding: 18px 16px 20px;
  box-shadow: var(--about-shadow);
}

.page-about .team-card--accent {
  border-top-color: var(--orange);
}

.page-about .team-num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 30px;
  line-height: 1;
  color: var(--ink-green);
}

.page-about .team-card--accent .team-num {
  color: var(--orange-deep);
}

.page-about .team-card h3 {
  margin: 10px 0 8px;
  font-size: 15.5px;
  font-weight: 700;
  color: var(--ink);
}

.page-about .team-card p {
  margin: 0;
  font-size: 14px;
  line-height: 1.72;
  color: var(--muted);
}

/* 四条主张 */
.page-about .belief-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
}

.page-about .belief {
  padding: 18px 16px 20px;
  background: var(--white);
  border: 1px solid var(--hair-ink);
  border-left: 3px solid var(--orange);
}

.page-about .belief-k {
  display: inline-block;
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.14em;
  color: var(--orange-deep);
}

.page-about .belief h3 {
  margin: 8px 0 8px;
  font-size: 15.5px;
  font-weight: 700;
  color: var(--ink);
}

.page-about .belief p {
  margin: 0;
  font-size: 14px;
  line-height: 1.72;
  color: var(--muted);
}

/* 平板端 */
.page-about .about-sec--band {
  border-top: 0;
}

.page-about .tablet-band {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 24px;
  padding: 28px 20px 30px;
  background: var(--ink-green);
  color: var(--paper);
}

.page-about .tablet-band h2 {
  margin: 0 0 16px;
  font-family: var(--font-body);
  font-weight: 700;
  font-size: clamp(22px, 3vw, 30px);
  line-height: 1.3;
  color: var(--paper);
}

.page-about .tablet-band p {
  margin: 0 0 14px;
  font-size: 14.5px;
  line-height: 1.8;
  color: rgba(244, 241, 232, 0.84);
}

.page-about .tablet-band p:last-child {
  margin-bottom: 0;
}

.page-about .entry-map {
  border: 1px solid var(--hair-dark);
  background: var(--pitch-green);
}

.page-about .entry-row {
  display: grid;
  grid-template-columns: 96px minmax(0, 1fr);
  gap: 10px;
  align-items: center;
  padding: 13px 14px;
  border-bottom: 1px solid var(--hair-dark);
}

.page-about .entry-row:last-child {
  border-bottom: 0;
}

.page-about .entry-row--key {
  background: rgba(255, 106, 19, 0.12);
  border-left: 3px solid var(--orange);
  padding-left: 11px;
}

.page-about .entry-key {
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--orange);
}

.page-about .entry-val {
  font-size: 13.5px;
  line-height: 1.5;
  color: var(--paper);
}

/* 时间线 */
.page-about .tl {
  margin: 8px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .tl-item {
  position: relative;
  padding: 0 0 26px 26px;
  border-left: 1px solid var(--about-dash);
}

.page-about .tl-item:last-child {
  padding-bottom: 4px;
}

.page-about .tl-item::before {
  content: "";
  position: absolute;
  left: -4px;
  top: 6px;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background: var(--stand-blue);
}

.page-about .tl-item--key::before {
  left: -5px;
  width: 9px;
  height: 9px;
  background: var(--orange);
}

.page-about .tl-year {
  display: block;
  font-size: 12.5px;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--muted);
}

.page-about .tl-item--key .tl-year {
  color: var(--orange-deep);
}

.page-about .tl-item h3 {
  margin: 6px 0 6px;
  font-size: 15.5px;
  font-weight: 700;
  color: var(--ink);
}

.page-about .tl-item p {
  margin: 0;
  max-width: 54ch;
  font-size: 14px;
  line-height: 1.72;
  color: var(--muted);
}

/* 延伸入口 */
.page-about .about-next {
  padding-top: 26px;
  border-top: 3px solid var(--ink-green);
}

.page-about .next-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 10px;
}

.page-about .next-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 15px 16px;
  background: var(--white);
  border: 1px solid var(--hair-ink);
  font-size: 14.5px;
  line-height: 1.5;
  color: var(--ink);
  text-decoration: none;
  transition: border-color 0.24s var(--ease), transform 0.24s var(--ease);
}

.page-about .next-card:hover,
.page-about .next-card:focus-visible {
  border-color: var(--orange);
  transform: translateX(2px);
}

.page-about .next-arrow {
  flex: none;
  font-family: var(--font-mono);
  color: var(--orange-deep);
}

/* 旁注列 */
.page-about .about-margin {
  display: grid;
  gap: 12px;
}

.page-about .note {
  padding: 14px 16px;
  background: var(--paper-warm);
  border-left: 3px solid var(--orange);
  font-size: 13px;
  line-height: 1.68;
  color: var(--body-text);
}

.page-about .note b {
  display: block;
  margin-bottom: 6px;
  font-family: var(--font-mono);
  font-size: 11px;
  font-weight: 700;
  letter-spacing: 0.1em;
  color: var(--orange-deep);
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .team-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .belief-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .next-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 860px) {
  .page-about .hero-split {
    grid-template-columns: 5fr 7fr;
    gap: 48px;
    align-items: center;
  }

  .page-about .about-hero {
    padding: 26px 0 66px;
  }

  .page-about .origin-grid {
    grid-template-columns: minmax(0, 1fr) 320px;
    gap: 32px;
    align-items: start;
  }

  .page-about .method-wrap {
    grid-template-columns: minmax(0, 1fr) 300px;
    gap: 32px;
    align-items: start;
  }

  .page-about .tablet-band {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
    gap: 36px;
    padding: 36px 32px 38px;
    align-items: start;
  }
}

@media (min-width: 1040px) {
  .page-about .about-shell {
    grid-template-columns: var(--about-rail) minmax(0, 1fr) var(--about-note);
    gap: 40px;
    align-items: start;
    padding-top: 44px;
  }

  .page-about .about-rail {
    position: sticky;
    top: 96px;
    margin: 0;
    padding: 0;
    background: none;
    border-bottom: 0;
  }

  .page-about .rail-title {
    display: block;
  }

  .page-about .about-rail ol {
    display: grid;
    gap: 2px;
    overflow: visible;
  }

  .page-about .about-rail a {
    display: flex;
    padding: 9px 0 9px 12px;
    white-space: normal;
    line-height: 1.45;
    border-bottom: 0;
    border-left: 2px solid var(--about-dash);
  }

  .page-about .about-rail a[aria-current="true"] {
    border-bottom-color: transparent;
    border-left-color: var(--orange);
    background: linear-gradient(90deg, rgba(255, 106, 19, 0.1), transparent 70%);
  }

  .page-about .about-margin {
    position: sticky;
    top: 96px;
  }

  .page-about .about-sec {
    scroll-margin-top: 110px;
  }
}

@media (min-width: 1240px) {
  .page-about .belief {
    padding: 22px 20px 24px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .next-card,
  .page-about .step-mark::before,
  .page-about .step-mark::after {
    transition: none;
  }

  .page-about .next-card:hover,
  .page-about .next-card:focus-visible {
    transform: none;
  }
}