.page-about {
  --about-rail-width: calc(var(--space-8) * 2);
  --about-note-gap: var(--space-6);
  display: block;
}

/* ---------- 面包屑与首屏 ---------- */

.page-about .about-crumb {
  margin-bottom: var(--space-3);
}

.page-about .about-crumb__list {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-1);
  margin: 0;
  padding: 0;
  list-style: none;
  font-size: var(--text-xs);
  color: var(--color-ink-muted);
}

.page-about .about-crumb__list li + li::before {
  content: "/";
  margin-inline-end: var(--space-1);
  color: var(--color-line);
}

.page-about .about-crumb__list a {
  color: var(--color-primary);
  text-decoration: none;
}

.page-about .about-crumb__list a:hover,
.page-about .about-crumb__list a:focus-visible {
  text-decoration: underline;
}

.page-about .about-intro {
  padding-block: var(--space-8) var(--space-6);
  background: var(--color-surface);
}

.page-about .about-intro__grid {
  display: grid;
  gap: var(--space-4);
  padding-block-start: var(--space-4);
  border-top: var(--border-thin) solid var(--color-line);
}

.page-about h1 {
  margin: 0;
  font-family: var(--font-heading);
  font-size: var(--text-3xl);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
  max-width: 15ch;
  text-wrap: balance;
}

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

.page-about .meta-line {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  line-height: 1.7;
  color: var(--color-ink-muted);
}

.page-about .about-intro__figure {
  margin: var(--space-6) auto 0;
  max-width: var(--container);
  padding-inline: var(--gutter);
}

.page-about .about-intro__figure img,
.page-about .about-history__figure img,
.page-about .about-team__figure img {
  display: block;
  inline-size: 100%;
  block-size: auto;
  object-fit: cover;
  border-radius: var(--radius-lg);
  background: var(--color-surface-deep);
}

.page-about .about-intro__figure img {
  aspect-ratio: 12 / 7;
}

.page-about .about-history__figure img,
.page-about .about-team__figure img {
  aspect-ratio: 8 / 5;
}

.page-about .media-caption {
  margin-block-start: var(--space-2);
  font-size: var(--text-xs);
  line-height: 1.7;
  color: var(--color-ink-muted);
}

/* ---------- 通用分区 ---------- */

.page-about .section {
  padding-block: var(--section-y);
}

.page-about .section--alt {
  background: var(--color-surface-alt);
}

.page-about .section--deep {
  background: var(--color-contrast-surface);
  color: var(--color-contrast-ink);
}

.page-about h2 {
  margin: 0 0 var(--space-4);
  font-family: var(--font-heading);
  font-size: var(--text-2xl);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
  max-width: 20ch;
}

.page-about h3 {
  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);
  color: var(--color-ink);
}

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

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

.page-about .prose a,
.page-about .about-contact__foot a {
  color: var(--color-primary);
  text-decoration: none;
  border-bottom: var(--border-thin) solid color-mix(in srgb, var(--color-primary) 45%, transparent);
}

.page-about .prose a:hover,
.page-about .prose a:focus-visible,
.page-about .about-contact__foot a:hover,
.page-about .about-contact__foot a:focus-visible {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

.page-about .eyebrow {
  margin: 0 0 var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.12em;
  text-transform: uppercase;
  color: var(--color-primary);
}

/* ---------- 正文 + 旁注 ---------- */

.page-about .about-block {
  display: grid;
  gap: var(--space-6);
}

.page-about .about-note__box {
  border-radius: var(--radius-md);
  background: var(--color-primary-soft);
  box-shadow: var(--shadow-1);
  padding: var(--space-3);
}

.page-about .about-note__box summary {
  cursor: pointer;
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-primary);
  list-style: none;
}

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

.page-about .about-note__box summary::after {
  content: " +";
  color: var(--color-ink-muted);
}

.page-about .about-note__box[open] summary::after {
  content: " −";
}

.page-about .about-note__box p {
  margin: var(--space-2) 0 0;
  font-size: var(--text-sm);
  line-height: 1.75;
  color: var(--color-ink-soft);
}

/* ---------- 时间线 ---------- */

.page-about .about-history {
  display: grid;
  gap: var(--space-6);
}

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

.page-about .about-timeline__item {
  position: relative;
  padding-inline-start: var(--space-4);
  padding-block-end: var(--space-6);
  border-inline-start: var(--border-thin) solid var(--color-line);
}

.page-about .about-timeline__item:last-child {
  padding-block-end: 0;
  border-inline-start-color: transparent;
}

.page-about .about-timeline__tick {
  position: absolute;
  inset-block-start: calc(var(--space-2) * 0.6);
  inset-inline-start: calc(var(--space-1) * -0.5);
  inline-size: var(--space-1);
  block-size: var(--space-1);
  border-radius: var(--radius-pill);
  background: var(--color-line);
}

.page-about .about-timeline__item.is-current .about-timeline__tick {
  background: var(--color-accent);
}

.page-about .about-timeline__year {
  margin: 0 0 var(--space-1);
  font-family: var(--font-mono);
  font-size: var(--text-sm);
  font-variant-numeric: tabular-nums;
  letter-spacing: 0.06em;
  color: var(--color-ink-muted);
}

.page-about .about-timeline__item.is-current .about-timeline__year {
  color: var(--color-accent);
}

.page-about .about-timeline__item p {
  margin: 0;
  font-size: var(--text-sm);
  line-height: 1.8;
  color: var(--color-ink-soft);
  max-width: 52ch;
}

/* ---------- 能力边界 ---------- */

.page-about .about-limits {
  display: grid;
  gap: var(--space-6);
}

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

.page-about .about-list li {
  position: relative;
  padding-block: var(--space-2);
  padding-inline-start: var(--space-4);
  border-block-end: var(--border-thin) solid var(--color-line);
  font-size: var(--text-sm);
  line-height: 1.85;
  color: var(--color-ink-soft);
}

.page-about .about-list li::before {
  content: "";
  position: absolute;
  inset-inline-start: 0;
  inset-block-start: calc(var(--space-3) * 0.85);
  inline-size: var(--space-2);
  block-size: var(--border-thin);
  background: var(--color-primary);
}

.page-about .about-limits__col--stop .about-list li::before {
  background: var(--color-ink-muted);
}

.page-about .about-list a {
  color: var(--color-primary);
  text-decoration: none;
}

.page-about .about-list a:hover,
.page-about .about-list a:focus-visible {
  color: var(--color-accent);
  text-decoration: underline;
}

/* ---------- 引号强调块 ---------- */

.page-about .about-quote {
  margin: var(--space-6) 0 0;
  padding: var(--space-3) var(--space-4);
  border-inline-start: var(--border-thin) solid var(--color-accent);
  border-radius: var(--radius-sm);
  background: var(--color-highlight);
}

.page-about .about-quote summary {
  cursor: pointer;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  color: var(--color-ink);
  list-style: none;
  text-indent: 0;
}

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

.page-about .about-quote summary::after {
  content: " 展开说明";
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  font-weight: var(--weight-body);
  letter-spacing: 0.06em;
  color: var(--color-accent);
}

.page-about .about-quote[open] summary::after {
  content: "";
}

.page-about .about-quote p {
  margin: var(--space-3) 0 0;
  font-size: var(--text-sm);
  line-height: 1.85;
  color: var(--color-ink-soft);
  max-width: var(--measure);
}

/* ---------- 团队 ---------- */

.page-about .about-team {
  display: grid;
  gap: var(--space-6);
}

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

.page-about .about-roles {
  margin: 0 0 var(--space-4);
  padding: 0;
  list-style: none;
}

.page-about .about-roles li {
  padding-block: var(--space-3);
  border-block-end: var(--border-thin) solid var(--color-line);
}

.page-about .about-roles li:first-child {
  padding-block-start: 0;
}

.page-about .about-roles p {
  margin: 0;
  font-size: var(--text-sm);
  line-height: 1.8;
  color: var(--color-ink-soft);
  max-width: 56ch;
}

.page-about .about-team__note {
  margin: 0;
  padding-inline-start: var(--space-4);
  border-inline-start: var(--border-thin) solid var(--color-primary);
  font-size: var(--text-sm);
  line-height: 1.8;
  color: var(--color-ink-muted);
  max-width: var(--measure);
}

/* ---------- 联系（深底） ---------- */

.page-about .about-contact h2,
.page-about .about-contact h3 {
  color: var(--color-contrast-ink);
}

.page-about .about-contact .eyebrow {
  color: var(--color-contrast-accent);
}

.page-about .about-contact__grid {
  display: grid;
  gap: var(--space-6);
}

.page-about .about-contact__lead p {
  margin: 0;
  font-size: var(--text-base);
  line-height: var(--leading-body);
  color: var(--color-contrast-ink);
  max-width: var(--measure);
}

.page-about .about-contact__list {
  margin: 0;
  display: grid;
  gap: var(--space-2);
}

.page-about .about-contact__row {
  display: grid;
  gap: calc(var(--space-1) / 2);
  padding-block-end: var(--space-2);
  border-block-end: var(--border-thin) solid var(--color-contrast-line);
}

.page-about .about-contact__row dt {
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-contrast-accent);
}

.page-about .about-contact__row dd {
  margin: 0;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: var(--color-contrast-ink);
  word-break: break-word;
}

.page-about .about-contact__foot {
  margin-block-start: var(--space-6);
  padding-block-start: var(--space-4);
  border-block-start: var(--border-thin) solid var(--color-contrast-line);
}

.page-about .about-contact__foot p {
  margin: 0;
  font-size: var(--text-sm);
  line-height: 1.85;
  color: var(--color-contrast-ink);
  max-width: var(--measure);
}

.page-about .about-contact__foot a {
  color: var(--color-contrast-accent);
  text-decoration: none;
  border-bottom: var(--border-thin) solid color-mix(in srgb, var(--color-contrast-accent) 50%, transparent);
}

.page-about .about-contact__foot a:hover,
.page-about .about-contact__foot a:focus-visible {
  color: var(--color-contrast-ink);
  border-bottom-color: var(--color-contrast-ink);
}

/* ---------- 侧边章节轨道 ---------- */

.page-about .about-rail {
  display: none;
}

.page-about .about-rail__label {
  margin: 0 0 var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--text-xs);
  letter-spacing: 0.1em;
  color: var(--color-ink-muted);
}

.page-about .about-rail__list {
  margin: 0;
  padding: 0;
  list-style: none;
  display: grid;
  gap: var(--space-1);
}

.page-about .about-rail__list a {
  display: block;
  font-size: var(--text-xs);
  line-height: 1.5;
  color: var(--color-ink-muted);
  text-decoration: none;
  transition: color 140ms cubic-bezier(0.22, 0.61, 0.36, 1);
}

.page-about .about-rail__list a:hover,
.page-about .about-rail__list a:focus-visible {
  color: var(--color-accent);
}

.page-about:has(#sec-position:target) .about-rail__list a[href="#sec-position"],
.page-about:has(#sec-history:target) .about-rail__list a[href="#sec-history"],
.page-about:has(#sec-limits:target) .about-rail__list a[href="#sec-limits"],
.page-about:has(#sec-principles:target) .about-rail__list a[href="#sec-principles"],
.page-about:has(#sec-team:target) .about-rail__list a[href="#sec-team"],
.page-about:has(#sec-contact:target) .about-rail__list a[href="#sec-contact"] {
  color: var(--color-accent);
}

/* ---------- 断点 ---------- */

@media (min-width: 720px) {
  .page-about .about-intro {
    padding-block: var(--space-8) var(--section-y);
  }

  .page-about .about-intro__grid {
    grid-template-columns: minmax(0, 1fr);
    gap: var(--space-4);
  }

  .page-about h1 {
    font-size: var(--text-4xl);
  }

  .page-about h2 {
    font-size: var(--text-3xl);
  }

  .page-about .about-limits {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: var(--space-6);
  }

  .page-about .about-contact__grid {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    gap: var(--space-8);
    align-items: start;
  }
}

@media (min-width: 900px) {
  .page-about .section {
    padding-block: var(--section-y-lg);
  }

  .page-about .about-intro__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    gap: var(--space-8);
    align-items: start;
  }

  .page-about .about-block {
    grid-template-columns: minmax(0, 1fr) minmax(220px, 0.36fr);
    gap: var(--about-note-gap);
    align-items: start;
  }

  .page-about .about-note {
    position: sticky;
    top: var(--space-6);
  }

  .page-about .about-history {
    grid-template-columns: minmax(0, 1.25fr) minmax(0, 0.75fr);
    gap: var(--space-8);
    align-items: start;
  }

  .page-about .about-history__figure {
    position: sticky;
    top: var(--space-6);
  }

  .page-about .about-team {
    grid-template-columns: minmax(0, 0.85fr) minmax(0, 1.15fr);
    gap: var(--space-8);
    align-items: start;
  }
}

@media (min-width: 1440px) {
  .page-about .about-rail {
    display: block;
    position: fixed;
    inset-block-start: 50%;
    inset-inline-end: var(--space-4);
    transform: translateY(-50%);
    inline-size: var(--about-rail-width);
    z-index: 6;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-rail__list a {
    transition: none;
  }
}
<<<END>>>