.page-about .breadcrumb {
  padding-top: var(--space-4);
}

.page-about .about-hero {
  padding-bottom: var(--space-8);
}

.page-about .about-hero__title {
  margin: var(--space-2) 0 var(--space-3);
  max-width: 20ch;
  font-family: var(--font-heading);
  font-size: var(--text-4xl);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  letter-spacing: var(--tracking-heading);
  color: var(--color-ink);
}

.page-about .about-hero__lead {
  max-width: 58ch;
  color: var(--color-ink-soft);
}

.page-about .about-hero__meta {
  margin-top: var(--space-3);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  color: var(--color-ink-muted);
  line-height: 1.5;
}

.page-about .about-hero__figure {
  margin-top: var(--space-6);
}

.page-about .media-frame {
  margin: 0;
}

.page-about .media-frame img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border-radius: var(--radius-lg);
}

.page-about .about-intro {
  max-width: 62ch;
  margin-top: var(--space-3);
  color: var(--color-ink-soft);
  font-size: var(--text-base);
  line-height: 1.75;
}

/* ---------- 长段落 + 页边批注 ---------- */

.page-about .about-note-split {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-6);
  margin-top: var(--space-6);
}

.page-about .about-body p {
  max-width: var(--measure);
}

.page-about .about-pull {
  margin: var(--space-4) 0;
  padding-left: var(--space-3);
  border-left: 3px solid var(--color-primary);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-style: normal;
  font-weight: var(--weight-heading);
  line-height: 1.55;
  color: var(--color-ink);
}

.page-about .about-notes {
  display: grid;
  gap: var(--space-3);
  align-self: start;
}

.page-about .margin-note {
  padding: var(--space-3);
  background: var(--color-surface-alt);
  border-left: 2px solid var(--color-primary);
  border-radius: 0 var(--radius-md) var(--radius-md) 0;
  transition: background-color 240ms ease-out;
}

.page-about .margin-note:hover,
.page-about .margin-note:focus {
  background: var(--color-surface-deep);
  outline: 1px solid var(--color-focus);
  outline-offset: 2px;
}

.page-about .margin-note__label {
  margin: 0 0 var(--space-1);
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  color: var(--color-accent);
}

.page-about .margin-note__text {
  margin: 0;
  font-size: var(--text-base);
  line-height: 1.6;
  color: var(--color-ink);
}

.page-about .margin-note__more {
  max-height: 0;
  margin-top: 0;
  overflow: hidden;
  opacity: 0;
  font-size: var(--text-sm);
  line-height: 1.7;
  color: var(--color-ink-soft);
  transition: max-height 260ms ease-out, opacity 260ms ease-out, margin-top 260ms ease-out;
}

.page-about .margin-note:hover .margin-note__more,
.page-about .margin-note:focus .margin-note__more,
.page-about .margin-note:focus-within .margin-note__more {
  max-height: 14em;
  margin-top: var(--space-2);
  opacity: 1;
}

@media (hover: none) {
  .page-about .margin-note__more {
    max-height: none;
    margin-top: var(--space-2);
    opacity: 1;
  }
}

/* ---------- 阶段节点图 ---------- */

.page-about .about-phase-map__scroll {
  margin-top: var(--space-6);
  overflow-x: auto;
  overflow-y: hidden;
}

.page-about .about-phase-map {
  display: block;
  width: max(100%, 620px);
  height: auto;
}

.page-about .about-phase-map__axis {
  stroke: var(--color-line);
  stroke-width: 1;
}

.page-about .about-phase-map__node circle {
  fill: var(--color-surface);
  stroke: var(--color-primary);
  stroke-width: 2;
}

.page-about .about-phase-map__node--current circle {
  fill: var(--color-accent);
  stroke: var(--color-accent);
}

.page-about .about-phase-map__node text {
  fill: var(--color-ink-soft);
  font-family: var(--font-mono);
  font-size: 16px;
}

.page-about .about-phase-map__node--current text {
  fill: var(--color-accent);
}

/* ---------- 历程 ---------- */

.page-about .about-history__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-6);
  margin-top: var(--space-6);
}

.page-about .about-phases {
  margin: 0;
  padding: 0 0 0 var(--space-4);
  list-style: none;
  border-left: 1px solid var(--color-line);
}

.page-about .about-phase {
  position: relative;
  padding-bottom: var(--space-6);
}

.page-about .about-phase::before {
  content: "";
  position: absolute;
  left: calc(-1 * var(--space-4) - 5px);
  top: 6px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--color-surface);
  box-shadow: var(--shadow-1);
}

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

.page-about .about-phase__tag {
  margin: 0;
  font-size: var(--text-sm);
  letter-spacing: 0.08em;
  color: var(--color-ink-muted);
  line-height: 1.4;
}

.page-about .about-phase__title {
  margin: var(--space-1) 0 var(--space-2);
  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 .about-phase__body {
  max-width: 58ch;
  margin: 0;
  color: var(--color-ink-soft);
  font-size: var(--text-base);
  line-height: 1.75;
}

.page-about .about-phase__stats {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-3) var(--space-6);
  margin: var(--space-3) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-phase__stats li {
  display: flex;
  align-items: baseline;
  gap: var(--space-1);
}

.page-about .about-stat {
  font-family: var(--font-mono);
  font-size: var(--text-2xl);
  font-weight: 700;
  line-height: 1;
  color: var(--color-accent);
  text-decoration: none;
  border-bottom: 2px solid var(--color-primary);
  transition: color 200ms ease-out, border-color 200ms ease-out;
}

.page-about .about-stat:hover,
.page-about .about-stat:focus-visible {
  color: var(--color-focus);
  border-bottom-color: var(--color-focus);
}

.page-about .about-stat__label {
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

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

/* ---------- 边界 ---------- */

.page-about .about-limits {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-6);
  margin-top: var(--space-6);
}

.page-about .about-limit__head {
  margin: 0;
  padding-bottom: var(--space-2);
  border-bottom: 1px solid var(--color-line);
  font-size: var(--text-sm);
  letter-spacing: 0.1em;
  color: var(--color-accent);
}

.page-about .about-limit--alt .about-limit__head {
  color: var(--color-ink-muted);
}

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

.page-about .about-limit__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: var(--space-2);
  padding: var(--space-3) 0;
  border-bottom: 1px solid var(--color-line);
  font-size: var(--text-base);
  line-height: 1.65;
  color: var(--color-ink);
}

.page-about .about-limit--alt .about-limit__item {
  color: var(--color-ink-soft);
}

.page-about .about-limit__idx {
  padding-top: 3px;
  font-size: var(--text-sm);
  color: var(--color-ink-muted);
}

/* ---------- 原则（强对比区块） ---------- */

.page-about .about-principles {
  margin-top: var(--space-6);
  padding: var(--space-6) var(--space-4);
  background: var(--color-contrast-surface);
  border-radius: var(--radius-lg);
  color: var(--color-contrast-ink);
}

.page-about .about-principles__grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--space-6);
}

.page-about .about-principle__num {
  margin: 0;
  font-size: var(--text-sm);
  letter-spacing: 0.12em;
  color: var(--color-contrast-accent);
}

.page-about .about-principle__title {
  margin: var(--space-2) 0 var(--space-2);
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  color: var(--color-contrast-ink);
}

.page-about .about-principle__text {
  margin: 0;
  font-size: var(--text-base);
  line-height: 1.72;
  color: color-mix(in srgb, var(--color-contrast-ink) 84%, var(--color-contrast-surface));
}

.page-about .about-principles__foot {
  margin: var(--space-6) 0 0;
  padding-top: var(--space-3);
  border-top: 1px solid var(--color-contrast-line);
  font-size: var(--text-sm);
  letter-spacing: 0.04em;
  color: var(--color-contrast-accent);
}

.page-about .about-principle-figure {
  margin: var(--space-6) 0 0;
}

/* ---------- 继续阅读入口 ---------- */

.page-about .about-next {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0;
  margin: var(--space-6) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-next__item {
  border-top: 1px solid var(--color-line);
}

.page-about .about-next__link {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  grid-template-areas:
    "idx label"
    "idx desc";
  gap: 2px var(--space-3);
  padding: var(--space-3) 0;
  text-decoration: none;
  color: inherit;
}

.page-about .about-next__idx {
  grid-area: idx;
  padding-top: 4px;
  font-size: var(--text-sm);
  color: var(--color-primary);
}

.page-about .about-next__label {
  grid-area: label;
  font-family: var(--font-heading);
  font-size: var(--text-lg);
  font-weight: var(--weight-heading);
  line-height: var(--leading-heading);
  color: var(--color-ink);
  transition: color 200ms ease-out;
}

.page-about .about-next__desc {
  grid-area: desc;
  font-size: var(--text-sm);
  line-height: 1.55;
  color: var(--color-ink-muted);
}

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

/* ---------- 断点 ---------- */

@media (min-width: 720px) {
  .page-about .about-hero__title {
    font-size: var(--text-4xl);
  }

  .page-about .about-next {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 0 var(--space-8);
  }

  .page-about .about-principles {
    padding: var(--space-8) var(--space-6);
  }
}

@media (min-width: 820px) {
  .page-about .about-limits {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: var(--space-8);
  }

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

@media (min-width: 900px) {
  .page-about .about-note-split {
    grid-template-columns: minmax(0, 7fr) minmax(0, 4fr);
    gap: var(--space-8);
    align-items: start;
  }

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

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

@media (prefers-reduced-motion: reduce) {
  .page-about .margin-note,
  .page-about .margin-note__more,
  .page-about .about-stat,
  .page-about .about-next__label {
    transition: none;
  }
}
<<<END>>>