.page-about {
  --about-index-w: 96px;
  --about-measure: 62ch;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
}

/* 首屏 */
.page-about .about-hero {
  position: relative;
  background: var(--felt);
  color: var(--paper);
  padding-block: clamp(72px, 10vw, 128px) clamp(48px, 7vw, 88px);
  overflow: hidden;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  right: -140px;
  top: -120px;
  width: 420px;
  height: 420px;
  border-radius: 50%;
  background: radial-gradient(circle, rgba(216, 165, 68, 0.18), transparent 68%);
  pointer-events: none;
}

.page-about .about-hero__inner {
  position: relative;
  z-index: 1;
  display: grid;
  gap: clamp(18px, 2.6vw, 26px);
}

.page-about .about-hero__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(38px, 7.2vw, 92px);
  line-height: 1.06;
  letter-spacing: -0.02em;
  max-width: 10em;
  color: var(--paper);
}

.page-about .about-hero__lede {
  margin: 0;
  max-width: var(--about-measure);
  font-size: clamp(16px, 1.6vw, 19px);
  line-height: 1.8;
  color: rgba(245, 242, 233, 0.9);
}

.page-about .about-hero__sub {
  margin: 0;
  max-width: 56ch;
  font-size: 15px;
  line-height: 1.78;
  color: var(--mist);
}

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

.page-about .about-hero .about-kicker,
.page-about .about-block--deep .about-kicker {
  color: var(--gold-soft);
}

/* 首屏数字条 */
.page-about .hero-stats {
  list-style: none;
  margin: clamp(28px, 4vw, 52px) 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line-mist);
  border-block: 1px solid var(--line-mist);
}

.page-about .hero-stats > li {
  background: var(--felt);
  padding: 18px 16px 20px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  min-width: 0;
}

.page-about .hero-stats__num {
  font-family: var(--font-mono);
  font-size: clamp(24px, 3.4vw, 34px);
  letter-spacing: 0.02em;
  color: var(--gold-soft);
  line-height: 1.1;
}

.page-about .hero-stats__label {
  font-size: 13px;
  line-height: 1.6;
  color: var(--mist);
}

/* 首屏图 */
.page-about .about-hero__figure {
  margin: clamp(36px, 5vw, 68px) 0 0;
}

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

.page-about .about-hero__figure figcaption {
  margin-top: 12px;
  font-size: 13px;
  line-height: 1.6;
  color: var(--mist);
}

/* 主体区 */
.page-about .about-main {
  background: var(--paper);
  padding-block: clamp(48px, 7vw, 96px);
}

.page-about .about-shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(32px, 5vw, 56px);
}

.page-about .about-content {
  display: grid;
  gap: clamp(44px, 6.5vw, 84px);
  min-width: 0;
}

.page-about .about-block {
  min-width: 0;
}

.page-about .about-block + .about-block {
  border-top: 1px solid var(--line-ink);
  padding-top: clamp(36px, 5.5vw, 68px);
}

.page-about .about-h2 {
  margin: 14px 0 0;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(25px, 3.4vw, 42px);
  line-height: 1.24;
  letter-spacing: -0.02em;
  color: var(--ink);
  max-width: 20em;
}

.page-about .about-body {
  margin-top: 20px;
  max-width: var(--about-measure);
}

.page-about .about-body p {
  margin: 0 0 1.1em;
  font-size: 16px;
  line-height: 1.78;
  color: var(--ink);
}

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

.page-about .about-lead {
  margin: 18px 0 0;
  max-width: 56ch;
  font-size: 15px;
  line-height: 1.8;
  color: var(--stone);
}

/* 左侧索引列 */
.page-about .about-index {
  display: none;
}

.page-about .about-index__head {
  margin: 0 0 16px;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--stone);
}

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

.page-about .about-index__list a {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 9px 0 9px 13px;
  margin-left: -1px;
  border-left: 1px solid var(--line-ink);
  font-size: 13px;
  line-height: 1.4;
  color: var(--stone);
  text-decoration: none;
  transition: color 180ms var(--ease), border-color 180ms var(--ease);
}

.page-about .about-index__list a:hover,
.page-about .about-index__list a:focus-visible {
  color: var(--felt);
  border-left-color: var(--gold);
}

.page-about .about-index__list .mono {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.08em;
  color: var(--gold);
}

/* 分类对比 */
.page-about .taxo {
  display: grid;
  gap: 16px;
  margin-top: clamp(24px, 4vw, 36px);
  max-width: var(--about-measure);
}

.page-about .taxo__col {
  display: grid;
  gap: 14px;
  padding: 20px 18px 18px;
  background: var(--paper-2);
  border: 1px solid var(--line-ink);
}

.page-about .taxo__col--new {
  background: var(--felt);
  border-color: var(--line-gold);
}

.page-about .taxo__label {
  margin: 0;
  font-size: 13px;
  letter-spacing: 0.04em;
  color: var(--ink);
}

.page-about .taxo__col--new .taxo__label {
  color: var(--paper);
}

.page-about .taxo__label .mono {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  margin-right: 10px;
  color: var(--coral);
}

.page-about .taxo__col--new .taxo__label .mono {
  color: var(--gold);
}

.page-about .taxo__lattice {
  --cell-w: 34px;
  height: 96px;
  border: 1px solid var(--line-ink);
  background-image:
    repeating-linear-gradient(to right, rgba(21, 31, 28, 0.16) 0 1px, transparent 1px var(--cell-w)),
    repeating-linear-gradient(to bottom, rgba(21, 31, 28, 0.16) 0 1px, transparent 1px 24px);
}

.page-about .taxo__lattice--old {
  --cell-w: 40px;
}

.page-about .taxo__lattice--new {
  --cell-w: 21px;
  border-color: var(--line-gold);
  background-image:
    repeating-linear-gradient(to right, rgba(216, 165, 68, 0.34) 0 1px, transparent 1px var(--cell-w)),
    repeating-linear-gradient(to bottom, rgba(216, 165, 68, 0.34) 0 1px, transparent 1px 15px);
}

.page-about .taxo__note {
  margin: 0;
  font-size: 13px;
  line-height: 1.65;
  color: var(--stone);
}

.page-about .taxo__col--new .taxo__note {
  color: var(--mist);
}

/* 图文 */
.page-about .about-figure {
  margin: clamp(26px, 4vw, 44px) 0 0;
}

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

.page-about .about-figure figcaption {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.65;
  color: var(--stone);
}

/* 深色块 */
.page-about .about-block--deep {
  background: var(--felt);
  border: 1px solid var(--line-gold);
  padding: clamp(26px, 4vw, 48px);
  color: var(--paper);
}

.page-about .about-block--deep .about-h2 {
  color: var(--paper);
}

.page-about .about-block--deep .about-body p {
  color: rgba(245, 242, 233, 0.88);
}

.page-about .about-block--deep .about-figure figcaption {
  color: var(--mist);
}

.page-about .about-steps {
  list-style: none;
  margin: clamp(22px, 4vw, 34px) 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
  max-width: var(--about-measure);
}

.page-about .about-steps li {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 14px;
  align-items: start;
  padding: 14px 16px;
  background: var(--felt-deep);
  border-left: 1px solid var(--gold);
  font-size: 15px;
  line-height: 1.72;
  color: rgba(245, 242, 233, 0.9);
}

.page-about .about-steps__n {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--gold-soft);
}

/* 时间线 */
.page-about .timeline {
  position: relative;
  margin-top: clamp(22px, 4vw, 40px);
  padding-left: 22px;
  max-width: var(--about-measure);
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 12px;
  bottom: 12px;
  width: 1px;
  background: linear-gradient(to bottom, var(--gold), var(--line-ink));
}

.page-about .tl-node {
  border-bottom: 1px solid var(--line-ink);
}

.page-about .tl-node:first-child {
  border-top: 1px solid var(--line-ink);
}

.page-about .tl-summary {
  position: relative;
  display: grid;
  grid-template-columns: 88px minmax(0, 1fr);
  gap: 12px;
  align-items: baseline;
  padding: 18px 0;
  cursor: pointer;
  list-style: none;
}

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

.page-about .tl-summary::before {
  content: "";
  position: absolute;
  left: -22px;
  top: 24px;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--paper);
  border: 1px solid var(--gold);
  transition: background 180ms var(--ease);
}

.page-about .tl-node[open] .tl-summary::before {
  background: var(--gold);
}

.page-about .tl-year {
  font-family: var(--font-mono);
  font-size: clamp(22px, 3vw, 30px);
  letter-spacing: 0.02em;
  line-height: 1;
  color: var(--gold);
}

.page-about .tl-title {
  font-family: var(--font-display);
  font-size: 17px;
  line-height: 1.4;
  color: var(--ink);
}

.page-about .tl-node[open] .tl-title {
  color: var(--felt);
}

.page-about .tl-body {
  padding: 0 0 20px;
}

.page-about .tl-body p {
  margin: 0;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.8;
  color: var(--ink);
}

/* 服务范围数字 */
.page-about .about-reach {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin-top: clamp(22px, 4vw, 36px);
  max-width: 720px;
  background: var(--line-ink);
  border: 1px solid var(--line-ink);
}

.page-about .about-reach__item {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 18px 16px;
  background: var(--paper);
  min-width: 0;
}

.page-about .about-reach__num {
  font-family: var(--font-mono);
  font-size: clamp(24px, 3vw, 32px);
  line-height: 1.1;
  color: var(--felt);
}

.page-about .about-reach__txt {
  font-size: 13px;
  line-height: 1.6;
  color: var(--stone);
}

/* 行动链接行 */
.page-about .about-link-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: clamp(20px, 3vw, 30px) 0 0;
}

/* 收尾 */
.page-about .about-cta {
  background: var(--felt-deep);
  color: var(--paper);
  padding-block: clamp(48px, 7vw, 88px);
  border-top: 1px solid var(--line-gold);
}

.page-about .about-cta__inner {
  display: grid;
  gap: 16px;
}

.page-about .about-cta__title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(25px, 3.6vw, 44px);
  line-height: 1.2;
  letter-spacing: -0.02em;
  color: var(--paper);
}

.page-about .about-cta__text {
  margin: 0;
  max-width: 56ch;
  font-size: 15px;
  line-height: 1.8;
  color: var(--mist);
}

/* 中屏 */
@media (min-width: 720px) {
  .page-about .taxo {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 20px;
  }

  .page-about .about-reach {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .hero-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

/* 桌面：固定索引列 + 时间线错位 */
@media (min-width: 1024px) {
  .page-about .about-shell {
    grid-template-columns: var(--about-index-w) minmax(0, 1fr);
    column-gap: clamp(40px, 5vw, 80px);
    align-items: start;
  }

  .page-about .about-index {
    display: block;
  }

  .page-about .about-index__inner {
    position: sticky;
    top: calc(var(--header-h) + 40px);
  }

  .page-about .timeline {
    padding-left: 26px;
    margin-left: -16px;
  }

  .page-about .timeline::before {
    left: 5px;
  }

  .page-about .tl-summary::before {
    left: -26px;
  }

  .page-about .about-block + .about-block {
    padding-top: clamp(48px, 5.5vw, 72px);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-index__list a,
  .page-about .tl-summary::before {
    transition: none;
  }
}