.page-about {
  display: block;
  padding-bottom: clamp(36px, 6vw, 80px);
  background: var(--bg);
  color: var(--text);
}

.page-about [id] {
  scroll-margin-top: calc(var(--header-h) + 20px);
}

/* ---------- 栅格 ---------- */
.page-about .grid-12 {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(18px, 3vw, 40px);
}

@media (min-width: 900px) {
  .page-about .grid-12 {
    grid-template-columns: repeat(12, minmax(0, 1fr));
  }
  .page-about .col-rail { grid-column: span 3; }
  .page-about .col-main { grid-column: span 9; }
  .page-about .col-band { grid-column: 1 / -1; }
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding-top: calc(var(--header-h) + clamp(20px, 4vw, 48px));
  padding-bottom: clamp(32px, 5vw, 64px);
  border-bottom: 1px solid var(--border);
}

.page-about .about-hero__grid {
  margin-top: clamp(24px, 4vw, 48px);
}

.page-about .about-hero__rail { order: 2; }
.page-about .about-hero__main { order: 1; }

@media (min-width: 900px) {
  .page-about .about-hero__rail { order: 1; }
  .page-about .about-hero__main { order: 2; }
}

.page-about .about-hero h1 {
  margin: 0 0 clamp(16px, 2.4vw, 26px);
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(2.15rem, 7.4vw, 5rem);
  line-height: 1.02;
  letter-spacing: 0.01em;
  text-wrap: balance;
}

.page-about .about-hero .lede {
  margin: 0;
  max-width: 58ch;
  font-size: clamp(1rem, 1.5vw, 1.125rem);
  line-height: 1.8;
  color: var(--text-soft);
}

.page-about .hero-index {
  list-style: none;
  margin: clamp(14px, 2vw, 24px) 0 0;
  padding: 0;
  border-top: 1px solid var(--border);
}

.page-about .hero-index li { border-bottom: 1px solid var(--border); }

.page-about .hero-index a {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  padding: 11px 2px;
  font-size: 0.9rem;
  color: var(--text-soft);
  text-decoration: none;
  transition: color var(--dur) var(--ease), padding-left var(--dur) var(--ease);
}

.page-about .hero-index a:hover,
.page-about .hero-index a:focus-visible {
  color: var(--key);
  padding-left: 8px;
}

.page-about .hero-index .mono {
  font-size: 0.78rem;
  color: var(--text-dim);
}

.page-about .hero-stats {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1px;
  margin: clamp(26px, 4vw, 52px) 0 0;
  padding: 1px;
  background: var(--border);
  border-radius: var(--radius);
  overflow: hidden;
}

.page-about .hero-stats__item {
  background: var(--surface);
  padding: clamp(16px, 2vw, 24px) clamp(14px, 2vw, 22px);
}

.page-about .hero-stats__label {
  margin: 0 0 8px;
  font-size: 0.78rem;
  letter-spacing: 0.12em;
  color: var(--text-dim);
}

.page-about .hero-stats__value {
  margin: 0;
  font-size: clamp(1.35rem, 2.6vw, 2rem);
  font-weight: 600;
  color: var(--key);
  line-height: 1.1;
}

/* ---------- 章节头 ---------- */
.page-about .section { padding: clamp(44px, 7vw, 92px) 0; }

.page-about .about-head {
  max-width: 100%;
  padding-bottom: clamp(24px, 3.4vw, 44px);
  border-bottom: 1px solid var(--border);
}

.page-about .about-head__title {
  margin: 12px 0 clamp(12px, 1.6vw, 20px);
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(1.8rem, 4.4vw, 3.2rem);
  line-height: 1.08;
  letter-spacing: 0.01em;
}

.page-about .about-head__lede {
  margin: 0;
  max-width: 64ch;
  font-size: clamp(0.98rem, 1.35vw, 1.08rem);
  line-height: 1.8;
  color: var(--text-soft);
}

/* ---------- 图片容器 ---------- */
.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);
  border: 1px solid var(--border);
  background: var(--bg-band);
}

.page-about .media-frame__caption {
  margin-top: 10px;
  font-size: 0.8rem;
  letter-spacing: 0.04em;
  color: var(--text-dim);
}

.page-about .media-frame--wide .media-frame__img { aspect-ratio: 7 / 4; }
.page-about .media-frame--tall .media-frame__img { aspect-ratio: 3 / 4; }

.page-about .about-archive__figure {
  margin: clamp(28px, 4vw, 48px) 0 clamp(32px, 5vw, 60px);
}

.page-about .about-scene {
  max-width: var(--container);
  margin-inline: auto;
  padding-inline: var(--gutter);
  margin-block: clamp(8px, 2vw, 24px);
}

/* ---------- 时间线 ---------- */
.page-about .timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  position: relative;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 9px;
  top: 10px;
  bottom: 18px;
  width: 1px;
  background: linear-gradient(var(--c-earth), var(--border) 78%, transparent);
}

.page-about .timeline__node {
  position: relative;
  padding-left: 38px;
  padding-bottom: clamp(26px, 4vw, 46px);
}

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

.page-about .timeline__node::before {
  content: "";
  position: absolute;
  left: 3px;
  top: 7px;
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: var(--bg);
  border: 2px solid var(--c-earth);
  box-sizing: border-box;
}

.page-about .timeline__node:last-child::before {
  background: var(--key);
  border-color: var(--key);
}

.page-about .timeline__season {
  margin: 0 0 8px;
  font-size: 1rem;
  font-weight: 600;
  letter-spacing: 0.02em;
  color: var(--c-earth);
}

.page-about .timeline__node:last-child .timeline__season { color: var(--key); }

.page-about .timeline__title {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.15rem, 2.2vw, 1.5rem);
  line-height: 1.3;
}

.page-about .timeline__note {
  margin: 0 0 14px;
  max-width: 58ch;
  font-size: 0.98rem;
  line-height: 1.8;
  color: var(--text-soft);
}

.page-about .timeline__stat {
  margin: 0 0 6px;
  font-family: var(--font-mono);
  font-size: 0.86rem;
  letter-spacing: 0.04em;
  color: var(--text-dim);
}

.page-about .timeline__stat .mono--key {
  font-size: 1.5rem;
  margin-right: 8px;
  color: var(--key);
}

.page-about .timeline__more > summary {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 0;
  font-size: 0.84rem;
  letter-spacing: 0.06em;
  color: var(--text-dim);
  cursor: pointer;
  list-style: none;
}

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

.page-about .timeline__more > summary::before {
  content: "+";
  font-family: var(--font-mono);
  color: var(--accent);
}

.page-about .timeline__more[open] > summary::before { content: "−"; }

.page-about .timeline__more p {
  margin: 6px 0 0;
  max-width: 60ch;
  padding-left: 18px;
  border-left: 1px solid var(--border-strong);
  font-size: 0.94rem;
  line-height: 1.8;
  color: var(--text-soft);
}

@media (min-width: 760px) {
  .page-about .timeline::before { left: 100px; }

  .page-about .timeline__node {
    display: grid;
    grid-template-columns: 100px minmax(0, 1fr);
    column-gap: 42px;
    padding-left: 0;
  }

  .page-about .timeline__node::before { left: 94px; top: 9px; }

  .page-about .timeline__season {
    grid-column: 1;
    text-align: right;
    margin: 0;
    padding-right: 22px;
    font-size: 1.1rem;
    padding-top: 2px;
  }

  .page-about .timeline__body { grid-column: 2; }
}

/* ---------- 团队分工 ---------- */
.page-about .duty-grid { margin-top: clamp(28px, 4vw, 48px); }

.page-about .duty-index__panel {
  padding: clamp(16px, 2vw, 22px);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  background: var(--glass);
  backdrop-filter: blur(12px);
}

.page-about .duty-index__panel .kicker { margin: 0 0 12px; }

.page-about .duty-index__list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--border);
}

.page-about .duty-index__list li { border-bottom: 1px solid var(--border); }

.page-about .duty-index__list a {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 10px;
  padding: 10px 2px;
  font-size: 0.9rem;
  color: var(--text-soft);
  text-decoration: none;
  transition: color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}

.page-about .duty-index__list a:hover,
.page-about .duty-index__list a:focus-visible {
  color: var(--key);
  background: var(--surface-2);
}

.page-about .duty-index__list .mono {
  font-size: 0.8rem;
  color: var(--text-dim);
}

.page-about .duty-index__foot {
  margin: 14px 0 0;
  font-size: 0.78rem;
  letter-spacing: 0.08em;
  color: var(--text-dim);
}

.page-about .duty-notes {
  display: flex;
  flex-direction: column;
  gap: clamp(22px, 3vw, 38px);
}

.page-about .duty-note {
  padding-top: clamp(16px, 2vw, 24px);
  border-top: 1px solid var(--border);
}

.page-about .duty-note:first-child { border-top-color: var(--border-strong); }

.page-about .duty-note__title {
  margin: 0 0 6px;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.15rem, 2.1vw, 1.45rem);
}

.page-about .duty-note__meta {
  margin: 0 0 12px;
  font-size: 0.8rem;
  letter-spacing: 0.08em;
  color: var(--text-dim);
}

.page-about .duty-note__text {
  margin: 0 0 12px;
  max-width: 62ch;
  font-size: 0.98rem;
  line-height: 1.82;
  color: var(--text-soft);
}

.page-about .duty-figure { max-width: 460px; }

@media (min-width: 900px) {
  .page-about .duty-index {
    position: sticky;
    top: calc(var(--header-h) + 26px);
    align-self: start;
  }
}

/* ---------- 统计规则 ---------- */
.page-about .about-rules {
  padding: clamp(44px, 7vw, 88px) 0;
  background: var(--c-earth);
  color: var(--c-ink);
}

.page-about .about-rules .about-head { border-bottom-color: rgba(18, 22, 26, 0.24); }
.page-about .about-rules .kicker { color: rgba(18, 22, 26, 0.68); }
.page-about .about-rules .about-head__lede { color: rgba(18, 22, 26, 0.78); }

.page-about .rules-tabs { margin-top: clamp(24px, 3.4vw, 40px); }

.page-about .rules-tabs__nav {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: clamp(18px, 2.6vw, 28px);
}

.page-about .rules-tabs__tab {
  padding: 9px 20px;
  border: 1px solid rgba(18, 22, 26, 0.34);
  border-radius: var(--radius-pill);
  background: rgba(242, 237, 228, 0.22);
  color: var(--c-ink);
  font-family: var(--font-display);
  font-size: 0.9rem;
  letter-spacing: 0.06em;
  cursor: pointer;
  transition: background-color var(--dur) var(--ease), color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}

.page-about .rules-tabs__tab:hover { background: rgba(242, 237, 228, 0.45); }

.page-about .rules-tabs__tab[aria-pressed="true"] {
  background: var(--c-ink);
  border-color: var(--c-ink);
  color: var(--c-paper);
}

.page-about .rules-tabs__tab:focus-visible {
  outline: 2px solid var(--c-alert);
  outline-offset: 2px;
}

.page-about .rules-panel {
  padding: clamp(16px, 2.4vw, 26px) 0;
  border-top: 1px solid rgba(18, 22, 26, 0.26);
}

.page-about .rules-panel__title {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 0.92rem;
  letter-spacing: 0.06em;
  font-weight: 600;
}

.page-about .rules-panel p {
  margin: 0;
  max-width: 66ch;
  font-size: 0.98rem;
  line-height: 1.82;
  color: rgba(18, 22, 26, 0.82);
}

.page-about .rules-cross {
  margin-top: clamp(24px, 3.4vw, 42px);
  padding-top: clamp(18px, 2.4vw, 26px);
  border-top: 2px solid var(--c-ink);
}

.page-about .rules-cross__label {
  margin: 0 0 10px;
  color: rgba(18, 22, 26, 0.68);
}

.page-about .rules-cross__text {
  margin: 0;
  max-width: 70ch;
  font-size: 0.98rem;
  line-height: 1.82;
  color: rgba(18, 22, 26, 0.86);
}

/* ---------- 版本留痕 ---------- */
.page-about .ledger-grid { margin-top: 0; }

.page-about .ledger-rail {
  border-top: 2px solid var(--c-earth);
  padding-top: 14px;
}

.page-about .ledger-rail__big {
  margin: 14px 0 4px;
  font-family: var(--font-mono);
  font-size: clamp(3.4rem, 9vw, 5.6rem);
  font-weight: 400;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--key);
}

.page-about .ledger-rail__cap {
  margin: 0;
  font-size: 0.86rem;
  line-height: 1.7;
  color: var(--text-dim);
}

.page-about .ledger-main .about-head__title { margin-top: 0; }

.page-about .ledger-main .lede {
  margin: 0 0 clamp(20px, 3vw, 32px);
  max-width: 64ch;
  font-size: clamp(0.98rem, 1.35vw, 1.08rem);
  line-height: 1.82;
  color: var(--text-soft);
}

.page-about .ledger-list {
  list-style: none;
  margin: 0 0 clamp(20px, 3vw, 30px);
  padding: 0;
  border-top: 1px solid var(--border-strong);
}

.page-about .ledger-list__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 4px;
  padding: 14px 0;
  border-bottom: 1px solid var(--border);
}

.page-about .ledger-list__ver {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--c-earth);
}

.page-about .ledger-list__time {
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  color: var(--text-dim);
}

.page-about .ledger-list__desc {
  font-size: 0.94rem;
  line-height: 1.7;
  color: var(--text-soft);
}

@media (min-width: 720px) {
  .page-about .ledger-list__row {
    grid-template-columns: 110px 180px minmax(0, 1fr);
    align-items: baseline;
    column-gap: 20px;
  }
}

.page-about .ledger-main__foot {
  margin: 0 0 clamp(20px, 3vw, 30px);
  max-width: 66ch;
  font-size: 0.96rem;
  line-height: 1.82;
  color: var(--text-soft);
}

.page-about .ledger-main__links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 0;
}

/* ---------- 使用场景 ---------- */
.page-about .usecase-list {
  margin-top: clamp(24px, 3.4vw, 40px);
  border-top: 2px solid var(--c-earth);
}

.page-about .usecase-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 12px;
  padding: clamp(18px, 2.6vw, 28px) 0;
  border-bottom: 1px solid var(--border);
}

.page-about .usecase-row__who {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 1.05rem;
  letter-spacing: 0.02em;
  color: var(--c-earth);
}

.page-about .usecase-row__body p {
  margin: 0 0 12px;
  max-width: 68ch;
  font-size: 0.98rem;
  line-height: 1.82;
  color: var(--text-soft);
}

.page-about .usecase-row__link {
  display: inline-block;
  font-size: 0.86rem;
  letter-spacing: 0.04em;
  color: var(--key);
  text-decoration: none;
  border-bottom: 1px solid currentColor;
  padding-bottom: 2px;
}

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

@media (min-width: 820px) {
  .page-about .usecase-row {
    grid-template-columns: 200px minmax(0, 1fr);
    column-gap: 40px;
    align-items: start;
  }
}

/* ---------- 下一步 ---------- */
.page-about .about-next {
  margin-top: clamp(34px, 5vw, 64px);
  padding-top: clamp(20px, 2.6vw, 30px);
  border-top: 1px solid var(--border-strong);
}

.page-about .about-next__list {
  list-style: none;
  margin: 14px 0 0;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .about-next__list a {
  display: block;
  padding: 13px 2px;
  border-bottom: 1px solid var(--border);
  font-size: 0.98rem;
  color: var(--text-soft);
  text-decoration: none;
  transition: color var(--dur) var(--ease), padding-left var(--dur) var(--ease);
}

.page-about .about-next__list a:hover,
.page-about .about-next__list a:focus-visible {
  color: var(--key);
  padding-left: 10px;
}

/* ---------- 无障碍 ---------- */
.page-about a:focus-visible,
.page-about summary:focus-visible {
  outline: 2px solid var(--c-alert);
  outline-offset: 2px;
}
<<<END>>>