.page-about {
  --about-rail-w: 244px;
  --about-num: clamp(1.9rem, 4.6vw, 3.2rem);
  display: block;
}

.page-about .about-shell {
  width: min(100% - (var(--gut) * 2), var(--w));
  margin-inline: auto;
  padding-block: clamp(20px, 3vw, 34px) clamp(56px, 9vw, 110px);
}

.page-about .about-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(36px, 6vw, 60px);
  margin-top: clamp(18px, 2.6vw, 30px);
}

.page-about .about-main {
  position: relative;
  min-width: 0;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding-bottom: clamp(28px, 4vw, 46px);
  border-bottom: 1px solid var(--line);
}

.page-about .about-hero__title {
  margin: 14px 0 0;
  font-size: clamp(1.85rem, 5.2vw, 3.3rem);
  line-height: 1.2;
  letter-spacing: -0.02em;
  font-weight: 800;
  max-width: 18ch;
  color: var(--text);
}

.page-about .about-hero__lead {
  margin-top: clamp(16px, 2.4vw, 24px);
  max-width: 62ch;
  color: var(--muted);
  font-size: 16.5px;
  line-height: 1.8;
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(22px, 3vw, 32px);
}

/* ---------- 章节骨架 ---------- */
.page-about .about-sec {
  padding-top: clamp(44px, 6.4vw, 84px);
}

.page-about .sec-head {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  column-gap: clamp(14px, 2vw, 26px);
  row-gap: 6px;
  align-items: baseline;
  border-top: 1px solid var(--line);
  padding-top: 18px;
  margin-bottom: clamp(20px, 3vw, 32px);
}

.page-about .sec-head__no {
  grid-row: 1 / 3;
  align-self: start;
  font-family: var(--mono);
  font-size: var(--about-num);
  font-weight: 700;
  line-height: 0.95;
  letter-spacing: 0.01em;
  background: var(--pulse);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.page-about .sec-head__title {
  margin: 0;
  font-size: clamp(1.22rem, 2.6vw, 1.7rem);
  line-height: 1.4;
  letter-spacing: -0.01em;
  font-weight: 800;
  color: var(--text);
}

.page-about .sec-head__note {
  margin: 0;
  font-size: 15px;
  line-height: 1.72;
  color: var(--muted);
}

.page-about .sec-body {
  max-width: 68ch;
  font-size: 16.5px;
  line-height: 1.82;
  color: var(--text);
}

.page-about .sec-body p {
  margin: 0;
}

.page-about .sec-body p + p {
  margin-top: 1.15em;
}

.page-about .sec-body a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(53, 230, 210, 0.4);
  transition: border-color 180ms var(--ease), color 180ms var(--ease);
}

.page-about .sec-body a:hover,
.page-about .sec-body a:focus-visible {
  color: var(--text);
  border-bottom-color: var(--cyan);
}

/* ---------- 四组分工 ---------- */
.page-about .crew-list {
  list-style: none;
  margin: clamp(24px, 3.4vw, 36px) 0 0;
  padding: 0;
  display: grid;
  gap: 0;
  border-top: 1px solid var(--line);
}

.page-about .crew-item {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: 14px;
  padding: 18px 14px 18px 0;
  border-bottom: 1px solid var(--line);
  border-left: 2px solid var(--line);
  padding-left: 16px;
  transition: background 200ms var(--ease), border-left-color 200ms var(--ease);
}

.page-about .crew-item:hover,
.page-about .crew-item:focus-within {
  background: var(--hull);
  border-left-color: var(--cyan);
}

.page-about .crew-item__no {
  font-family: var(--mono);
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--orange);
  line-height: 1.7;
}

.page-about .crew-item__name {
  margin: 0;
  font-size: 16px;
  font-weight: 700;
  letter-spacing: 0.01em;
  color: var(--text);
}

.page-about .crew-item__desc {
  margin: 6px 0 0;
  font-size: 15px;
  line-height: 1.78;
  color: var(--muted);
}

/* ---------- 折叠组 ---------- */
.page-about .about-fold {
  margin-top: clamp(24px, 3.4vw, 34px);
  border: 1px solid var(--line);
  background: var(--hull);
}

.page-about .about-fold .group__head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 14px 16px;
}

.page-about .about-fold .group__title {
  margin: 0;
  font-size: 15px;
  font-weight: 700;
  color: var(--text);
  letter-spacing: 0.01em;
}

.page-about .about-fold .group__toggle {
  flex: none;
  appearance: none;
  border: 1px solid var(--line);
  background: transparent;
  color: var(--cyan);
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  padding: 6px 12px;
  border-radius: var(--rad);
  cursor: pointer;
  transition: border-color 180ms var(--ease), background 180ms var(--ease), color 180ms var(--ease);
}

.page-about .about-fold .group__toggle:hover,
.page-about .about-fold .group__toggle:focus-visible {
  border-color: var(--cyan);
  background: rgba(53, 230, 210, 0.08);
}

.page-about .about-fold .group__body {
  padding: 0 16px 18px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--muted);
  border-top: 1px solid var(--line);
  padding-top: 16px;
}

/* 未启用脚本时内容始终可见；启用后由 data-open 控制展开 */
.page-about .about-fold .group__body > p {
  margin: 0;
}

.page-about .js-on .about-fold .group__body {
  display: none;
}

.page-about .js-on .about-fold[data-open] .group__body {
  display: block;
}

/* ---------- 图文 ---------- */
.page-about .about-figure {
  margin: clamp(26px, 3.8vw, 42px) 0 0;
}

.page-about .about-figure .media__frame {
  border: 1px solid var(--line);
  border-radius: var(--rad);
  overflow: hidden;
  background: var(--hull);
  aspect-ratio: 2 / 1;
}

.page-about .about-figure--square .media__frame {
  aspect-ratio: 10 / 7;
}

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

.page-about .about-figure .media__cap {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.68;
  color: var(--muted);
  max-width: 62ch;
}

/* ---------- 长期理由 ---------- */
.page-about .reason-list {
  display: grid;
  gap: 0;
  border-top: 1px solid var(--line);
}

.page-about .reason-item {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 8px;
  padding: clamp(20px, 3vw, 28px) 0;
  border-bottom: 1px solid var(--line);
}

.page-about .reason-item__name {
  margin: 0;
  font-size: 16px;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--cyan);
}

.page-about .reason-item__desc {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.8;
  color: var(--muted);
  max-width: 62ch;
}

.page-about .about-cta {
  margin-top: clamp(30px, 4.4vw, 48px);
  padding: clamp(22px, 3vw, 30px);
  border: 1px solid var(--line);
  border-left: 3px solid transparent;
  border-image: var(--pulse) 1;
  background: var(--hull);
}

.page-about .about-cta__text {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.78;
  color: var(--text);
  max-width: 56ch;
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 18px;
}

/* ---------- 右侧索引带 ---------- */
.page-about .about-rail {
  display: grid;
  gap: clamp(24px, 3vw, 34px);
  align-content: start;
  padding-top: clamp(6px, 1.4vw, 14px);
}

.page-about .rail-label {
  margin: 0 0 12px;
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--muted);
}

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

.page-about .rail-nav__link {
  display: grid;
  grid-template-columns: 24px minmax(0, 1fr);
  align-items: baseline;
  gap: 10px;
  padding: 8px 10px;
  border-left: 2px solid transparent;
  font-size: 13.5px;
  line-height: 1.5;
  color: var(--muted);
  text-decoration: none;
  transition: color 180ms var(--ease), border-left-color 180ms var(--ease), background 180ms var(--ease);
}

.page-about .rail-nav__link:hover,
.page-about .rail-nav__link:focus-visible {
  color: var(--text);
  border-left-color: var(--cyan);
  background: var(--hull);
}

.page-about .rail-nav__no {
  font-family: var(--mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--cyan);
  opacity: 0.75;
}

.page-about .rail-facts {
  display: grid;
  gap: 16px;
  border-top: 1px solid var(--line);
  padding-top: 20px;
}

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

.page-about .rail-fact__num {
  display: block;
  font-family: var(--mono);
  font-size: clamp(1.5rem, 3vw, 1.85rem);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: 0.01em;
  background: var(--pulse);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.page-about .rail-fact__unit {
  font-size: 0.5em;
  margin-left: 4px;
  letter-spacing: 0.06em;
  -webkit-text-fill-color: currentColor;
}

.page-about .rail-fact__label {
  display: block;
  margin-top: 6px;
  font-size: 12px;
  line-height: 1.62;
  color: var(--muted);
  transition: opacity 200ms var(--ease), transform 200ms var(--ease);
}

/* ---------- 中等屏幕 ---------- */
@media (min-width: 720px) {
  .page-about .reason-item {
    grid-template-columns: 168px minmax(0, 1fr);
    align-items: start;
    gap: clamp(18px, 3vw, 36px);
  }

  .page-about .about-cta {
    display: flex;
    align-items: center;
    justify-content: space-between;
    gap: 24px;
    flex-wrap: wrap;
  }

  .page-about .about-cta__actions {
    margin-top: 0;
  }
}

/* ---------- 桌面端：左重右轻 + 吸附索引 ---------- */
@media (min-width: 1024px) {
  .page-about .about-layout {
    grid-template-columns: minmax(0, 1fr) var(--about-rail-w);
    gap: clamp(44px, 5vw, 84px);
    align-items: start;
  }

  .page-about .about-main::before {
    content: "";
    position: absolute;
    top: 0;
    bottom: 0;
    left: calc(-1 * clamp(20px, 2.6vw, 42px));
    width: 1px;
    background: linear-gradient(180deg, transparent 0, var(--cyan) 6%, var(--line) 20%, var(--line) 88%, transparent 100%);
    opacity: 0.7;
    pointer-events: none;
  }

  .page-about .about-rail {
    position: sticky;
    top: calc(var(--hdr) + 26px);
    align-self: start;
    padding-top: 4px;
  }

  .page-about .rail-fact__label {
    opacity: 0;
    transform: translateY(-4px);
  }

  .page-about .rail-fact:hover .rail-fact__label,
  .page-about .rail-fact:focus-within .rail-fact__label {
    opacity: 1;
    transform: none;
  }
}

@media (min-width: 1240px) {
  .page-about .about-hero__lead {
    font-size: 17px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .crew-item,
  .page-about .rail-nav__link,
  .page-about .about-fold .group__toggle,
  .page-about .rail-fact__label,
  .page-about .sec-body a {
    transition: none;
  }
}
<<<END>>>