.page-about {
  --about-rail: 74px;
  --about-measure: 64ch;
  --about-text: rgba(232, 226, 210, .82);
  padding: clamp(16px, 2.6vw, 30px) 0 clamp(48px, 7vw, 88px);
}

.page-about .breadcrumb {
  margin-bottom: clamp(14px, 2.4vw, 26px);
}

/* ---------- 首屏 ---------- */
.page-about .about-masthead {
  padding: 0 0 clamp(24px, 4vw, 42px);
  border-bottom: 1px solid var(--line);
}

.page-about .about-masthead .eyebrow {
  color: var(--cyan);
}

.page-about .about-masthead h1 {
  margin: 12px 0 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(31px, 6vw, 58px);
  line-height: 1.05;
  letter-spacing: -.02em;
  color: var(--warm);
  text-wrap: balance;
}

.page-about .about-masthead h1 .hl {
  color: var(--cyan);
}

.page-about .about-masthead .lede {
  margin: 18px 0 0;
  max-width: 56ch;
  font-size: clamp(15px, 1.6vw, 17px);
  line-height: 1.82;
  color: var(--about-text);
}

.page-about .masthead-stats {
  display: flex;
  flex-wrap: wrap;
  gap: 16px 0;
  margin: 28px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .masthead-stats li {
  flex: 1 1 140px;
  min-width: 0;
  padding: 2px 16px;
  border-left: 1px solid var(--line);
}

.page-about .masthead-stats li:first-child {
  padding-left: 0;
  border-left: 0;
}

.page-about .masthead-stats .num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(19px, 2.6vw, 26px);
  line-height: 1.1;
  letter-spacing: -.01em;
  color: var(--orange);
}

.page-about .masthead-stats .label {
  display: block;
  margin-top: 5px;
  font-size: 11px;
  letter-spacing: .16em;
  text-transform: uppercase;
  color: var(--rock);
}

/* ---------- 章节骨架与纵向刻度 ---------- */
.page-about .chapter {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 10px;
  padding: clamp(30px, 5vw, 58px) 0;
  border-bottom: 1px solid var(--line-soft);
}

.page-about .chapter-rail {
  display: flex;
  align-items: baseline;
  gap: 12px;
}

.page-about .chapter-num {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--cyan);
}

.page-about .chapter-tag {
  font-size: 10.5px;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--rock);
}

.page-about .chapter-body {
  max-width: var(--about-measure);
  min-width: 0;
}

.page-about .chapter-body--wide {
  max-width: 100%;
}

.page-about .chapter h2 {
  margin: 0 0 16px;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(22px, 3.4vw, 33px);
  line-height: 1.2;
  letter-spacing: -.01em;
  color: var(--warm);
  text-wrap: balance;
}

.page-about .chapter p {
  margin: 0 0 14px;
  font-size: 15.5px;
  line-height: 1.86;
  color: var(--about-text);
}

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

/* ---------- 01 品牌路径 ---------- */
.page-about .split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(20px, 3vw, 32px);
  margin-top: 6px;
}

.page-about .split-text p {
  max-width: 62ch;
}

.page-about .about-figure {
  margin: 0;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: auto;
  border: 1px solid var(--line);
  background: var(--panel);
  object-fit: cover;
}

.page-about .about-figure figcaption {
  margin-top: 9px;
  font-size: 11.5px;
  line-height: 1.65;
  letter-spacing: .05em;
  color: var(--rock);
}

/* ---------- 02 四步流程 ---------- */
.page-about .flow {
  margin: 22px 0 26px;
  padding: 0;
  list-style: none;
  display: grid;
  gap: 12px;
}

.page-about .flow-step {
  padding: 16px 18px;
  border-left: 2px solid var(--moss);
  background: linear-gradient(90deg, rgba(63, 93, 78, .34), rgba(63, 93, 78, .03) 82%);
  transition: border-color .18s ease;
}

.page-about .flow-step:hover {
  border-left-color: var(--cyan);
}

.page-about .flow-step h3 {
  margin: 0 0 8px;
  font-size: 15.5px;
  line-height: 1.5;
  font-weight: 700;
  color: var(--warm);
}

.page-about .flow-step h3 .num {
  display: inline-block;
  margin-right: 10px;
  font-family: var(--font-mono);
  font-size: 12.5px;
  letter-spacing: .08em;
  color: var(--orange);
}

.page-about .flow-step p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.78;
}

/* ---------- 03 团队与班次 ---------- */
.page-about .tabs {
  margin-top: 22px;
}

.page-about .tablist {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.page-about .tab {
  font-family: var(--font-body);
  font-size: 13px;
  letter-spacing: .05em;
  padding: 10px 15px;
  color: var(--cream);
  background: rgba(63, 93, 78, .22);
  border: 1px solid var(--line);
  border-radius: 2px;
  cursor: pointer;
  transition: background-color .16s ease, color .16s ease, border-color .16s ease;
}

.page-about .tab:hover {
  border-color: var(--cyan);
  color: var(--cyan);
}

.page-about .tab[aria-selected="true"] {
  background: var(--cyan);
  border-color: var(--cyan);
  color: var(--ink);
  font-weight: 700;
}

.page-about .tab:focus-visible {
  outline: 2px solid var(--orange);
  outline-offset: 2px;
}

.page-about .tabpanel {
  margin-top: 14px;
  padding: 18px 20px;
  background: var(--panel);
  border: 1px solid var(--line-soft);
}

.page-about .tabpanel .role-count {
  display: block;
  margin-bottom: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--cyan);
}

.page-about .tabpanel h3 {
  margin: 0 0 10px;
  font-size: 15.5px;
  line-height: 1.5;
  font-weight: 700;
  color: var(--warm);
}

.page-about .tabpanel p {
  margin: 0;
  font-size: 14.5px;
  line-height: 1.8;
}

.page-about .rhythm-note {
  margin-top: 22px;
  padding-left: 16px;
  border-left: 2px solid var(--clay);
  font-size: 15px;
}

/* ---------- 04 版本时间线 ---------- */
.page-about .timeline {
  margin: 24px 0 0;
  padding: 0 0 0 16px;
  list-style: none;
}

.page-about .timeline li {
  position: relative;
  display: grid;
  grid-template-columns: 58px minmax(0, 1fr);
  gap: 14px;
  padding-bottom: 30px;
}

.page-about .timeline li::before {
  content: "";
  position: absolute;
  left: -16px;
  top: 9px;
  bottom: -4px;
  width: 1px;
  background: var(--line);
}

.page-about .timeline li::after {
  content: "";
  position: absolute;
  left: -20px;
  top: 8px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--orange);
}

.page-about .timeline li:last-child {
  padding-bottom: 4px;
}

.page-about .timeline li:last-child::before {
  display: none;
}

.page-about .timeline-year {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: .06em;
  line-height: 1.9;
  color: var(--cyan);
}

.page-about .timeline-body h3 {
  margin: 0 0 8px;
  font-size: 16px;
  line-height: 1.5;
  font-weight: 700;
  color: var(--warm);
}

.page-about .timeline-body p {
  margin: 0;
  font-size: 14.8px;
  line-height: 1.82;
}

.page-about .timeline-strip {
  margin-top: 26px;
}

/* ---------- 05 覆盖规模 ---------- */
.page-about .stat-board {
  margin-top: 26px;
  padding: clamp(20px, 3.4vw, 34px);
  background: var(--warm);
  border-left: 3px solid var(--orange);
}

.page-about .stat-board .board-title {
  margin: 0 0 18px;
  font-size: 11px;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--clay);
}

.page-about .stat-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px 20px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .stat-grid .num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(21px, 2.8vw, 29px);
  line-height: 1.12;
  letter-spacing: -.02em;
  color: var(--ink);
}

.page-about .stat-grid .label {
  display: block;
  margin-top: 6px;
  font-size: 11.5px;
  letter-spacing: .07em;
  color: #52615a;
}

/* ---------- 下一步 ---------- */
.page-about .next-steps {
  margin-top: clamp(32px, 5vw, 56px);
  padding-top: clamp(22px, 3vw, 34px);
  border-top: 1px solid var(--line);
}

.page-about .next-steps h2 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(20px, 2.6vw, 26px);
  letter-spacing: -.01em;
  color: var(--warm);
}

.page-about .next-links {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 10px;
  margin: 18px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .next-links a {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 14px 16px;
  text-decoration: none;
  color: var(--warm);
  font-size: 14.5px;
  line-height: 1.5;
  background: rgba(15, 42, 35, .62);
  border: 1px solid var(--line);
  transition: border-color .16s ease, color .16s ease;
}

.page-about .next-links a:hover,
.page-about .next-links a:focus-visible {
  border-color: var(--cyan);
  color: var(--cyan);
}

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

/* ---------- 响应式 ---------- */
@media (min-width: 700px) {
  .page-about .next-links {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .stat-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 880px) {
  .page-about .chapter {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: clamp(20px, 3vw, 38px);
  }

  .page-about .chapter-rail {
    position: sticky;
    top: calc(var(--rail-h) + 22px);
    align-self: start;
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
    padding: 2px 0 2px 18px;
  }

  .page-about .chapter-rail::before {
    content: "";
    position: absolute;
    left: 3px;
    top: 8px;
    bottom: -8px;
    width: 1px;
    background: var(--line);
  }

  .page-about .chapter-rail::after {
    content: "";
    position: absolute;
    left: -1px;
    top: 6px;
    width: 8px;
    height: 8px;
    border-radius: 50%;
    background: var(--cyan);
  }

  .page-about .split {
    grid-template-columns: minmax(0, 1.05fr) minmax(0, .95fr);
    align-items: start;
  }

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

  .page-about .timeline li {
    grid-template-columns: 64px minmax(0, 1fr);
    gap: 18px;
  }
}

@media (min-width: 1080px) {
  .page-about .about-masthead h1 {
    max-width: 20ch;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .flow-step,
  .page-about .tab,
  .page-about .next-links a {
    transition: none;
  }
}