.page-about {
  --about-hair: rgba(11, 31, 51, 0.14);
  --about-hair-soft: rgba(11, 31, 51, 0.07);
  --about-hair-dark: rgba(207, 227, 238, 0.22);
  --about-index-w: 96px;
  --about-radius: 2px;
  padding-inline: var(--gutter);
  max-width: 1440px;
  margin-inline: auto;
  padding-bottom: clamp(48px, 8vw, 110px);
  background: var(--ice);
  color: var(--ink);
  font-family: var(--font-body);
  overflow-x: clip;
}

.page-about .breadcrumb {
  padding-block: 18px 4px;
  font-size: 13px;
}

.page-about .breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  color: var(--stone);
}

.page-about .breadcrumb-list li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--ice-line);
}

.page-about .breadcrumb-list a {
  color: var(--polar-800);
  text-decoration: none;
  border-bottom: 1px solid var(--ice-line);
}

.page-about .breadcrumb-list a:hover {
  border-bottom-color: var(--orange);
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  display: grid;
  gap: clamp(28px, 5vw, 56px);
  padding-block: clamp(28px, 5vw, 56px) clamp(32px, 6vw, 72px);
  align-items: end;
}

.page-about .about-kicker {
  margin: 0 0 18px;
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--clay);
}

.page-about .about-hero h1 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(34px, 7.4vw, 76px);
  line-height: 1.02;
  letter-spacing: -0.02em;
  color: var(--polar-900);
}

.page-about .about-lede {
  margin: 22px 0 0;
  max-width: 60ch;
  font-size: clamp(16px, 1.8vw, 18px);
  line-height: 1.78;
  color: #2c3a44;
}

.page-about .about-hero__facts {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 30px;
  margin: 26px 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-hero__facts li {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding-bottom: 4px;
  border-bottom: 1px solid var(--about-hair);
  font-size: 13px;
  color: var(--stone);
}

.page-about .about-hero__facts .mono {
  font-family: var(--font-mono);
  font-size: 20px;
  font-weight: 600;
  color: var(--polar-800);
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.page-about .about-hero__media {
  position: relative;
  margin: 0;
  border: 1px solid var(--about-hair);
  background: var(--polar-800);
}

.page-about .about-hero__media img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 5 / 4;
  object-fit: cover;
}

.page-about .about-hero__media::after {
  content: "";
  position: absolute;
  right: -1px;
  bottom: -1px;
  width: 46%;
  height: 6px;
  background: var(--orange);
}

/* ---------- 章节索引 ---------- */

.page-about .chapter-index {
  position: sticky;
  top: 0;
  z-index: 6;
  display: flex;
  gap: 6px;
  margin-inline: calc(var(--gutter) * -1);
  padding: 10px var(--gutter);
  overflow-x: auto;
  background: var(--paper);
  border-block: 1px solid rgba(11, 31, 51, 0.1);
  scrollbar-width: none;
}

.page-about .chapter-index::-webkit-scrollbar {
  display: none;
}

.page-about .chapter-link {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: baseline;
  gap: 7px;
  padding: 6px 12px;
  border: 1px solid transparent;
  font-size: 13px;
  color: var(--moss);
  text-decoration: none;
  white-space: nowrap;
  transition: color 180ms ease, border-color 180ms ease, background-color 180ms ease;
}

.page-about .chapter-link .mono {
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--stone);
}

.page-about .chapter-link:hover {
  border-color: var(--about-hair);
  color: var(--polar-900);
}

.page-about .chapter-link[data-active] {
  background: var(--polar-900);
  border-color: var(--polar-900);
  color: var(--ice);
}

.page-about .chapter-link[data-active] .mono {
  color: var(--cyan);
}

/* ---------- 通用章节 ---------- */

.page-about .about-section {
  display: grid;
  gap: clamp(14px, 2.4vw, 32px);
  padding-block: clamp(40px, 6vw, 76px);
  border-bottom: 1px solid var(--about-hair-soft);
}

.page-about .about-section__index {
  display: flex;
  align-items: baseline;
  gap: 10px;
  font-family: var(--font-mono);
}

.page-about .about-section__index .mono {
  font-size: 13px;
  font-weight: 600;
  color: var(--orange);
}

.page-about .about-section__index-label {
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--stone);
}

.page-about .about-section h2 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(25px, 4vw, 42px);
  line-height: 1.12;
  letter-spacing: -0.015em;
  color: var(--polar-900);
}

.page-about .about-section__lead {
  margin: 16px 0 0;
  max-width: 62ch;
  font-size: 16px;
  line-height: 1.78;
  color: #35434d;
}

.page-about .about-columns {
  display: grid;
  gap: 18px;
  margin-top: 22px;
}

.page-about .about-columns p {
  margin: 0;
  font-size: 16px;
  line-height: 1.82;
  color: #2c3a44;
}

/* ---------- 路线图 ---------- */

.page-about .route-map {
  position: relative;
  margin-top: 28px;
  padding: clamp(20px, 3.6vw, 44px);
  background: var(--polar-900);
  color: var(--ice);
  overflow: hidden;
}

.page-about .route-map__bg {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.16;
  filter: saturate(0.5) contrast(1.1);
  pointer-events: none;
}

.page-about .route-map__list {
  position: relative;
  z-index: 1;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .route-node {
  position: relative;
  padding-left: 34px;
  padding-block: 8px;
}

.page-about .route-node::before {
  content: "";
  position: absolute;
  left: 8px;
  top: 0;
  bottom: 0;
  width: 1px;
  background: var(--about-hair-dark);
}

.page-about .route-node:first-child::before {
  top: 22px;
}

.page-about .route-node:last-child::before {
  bottom: calc(100% - 22px);
}

.page-about .route-node::after {
  content: "";
  position: absolute;
  left: 3px;
  top: 17px;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: var(--polar-900);
  border: 2px solid var(--stone);
}

.page-about .route-node.is-current::after {
  background: var(--orange);
  border-color: var(--orange);
  box-shadow: 0 0 0 4px rgba(255, 107, 44, 0.18);
}

.page-about .route-node details {
  border-bottom: 1px solid rgba(207, 227, 238, 0.12);
  padding-bottom: 10px;
}

.page-about .route-node summary {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 6px 14px;
  padding-block: 6px 4px;
  cursor: pointer;
  list-style: none;
  color: var(--ice);
}

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

.page-about .route-node summary::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 16px;
  color: var(--cyan);
  transition: transform 200ms ease;
}

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

.page-about .route-node__idx {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 600;
  color: var(--cyan);
}

.page-about .route-node__title {
  flex: 1 1 220px;
  font-family: var(--font-display);
  font-size: clamp(16px, 2vw, 20px);
  font-weight: 700;
  line-height: 1.4;
}

.page-about .route-node__year {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--stone);
  letter-spacing: 0.06em;
}

.page-about .route-node.is-current .route-node__year {
  color: var(--orange);
}

.page-about .route-node details > p {
  margin: 10px 0 0;
  max-width: 66ch;
  font-size: 15px;
  line-height: 1.8;
  color: #b9cbd8;
}

/* ---------- 更新节奏 ---------- */

.page-about .about-update {
  display: grid;
  gap: clamp(20px, 3vw, 36px);
  margin-top: 28px;
}

.page-about .about-update__media {
  margin: 0;
  border: 1px solid var(--about-hair);
  background: var(--paper);
}

.page-about .about-update__media img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
}

.page-about .about-role {
  padding-block: 18px;
  border-top: 1px solid var(--about-hair);
}

.page-about .about-role h3 {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-size: clamp(17px, 2vw, 21px);
  font-weight: 700;
  color: var(--polar-900);
}

.page-about .about-role h3 .mono {
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 600;
  color: var(--clay);
}

.page-about .about-role p {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.82;
  color: #33424c;
}

.page-about .about-update__note {
  margin: 6px 0 0;
  padding: 14px 16px;
  background: var(--paper);
  border-left: 3px solid var(--moss);
  font-size: 14.5px;
  line-height: 1.75;
  color: #2f3d46;
}

/* ---------- 服务版图 ---------- */

.page-about .about-services {
  display: grid;
  gap: 0;
  margin: 26px 0 0;
  padding: 0;
  list-style: none;
  border-top: 1px solid var(--about-hair);
}

.page-about .about-service a {
  display: grid;
  grid-template-columns: auto 1fr auto;
  align-items: baseline;
  gap: 6px 16px;
  padding: 20px 4px;
  border-bottom: 1px solid var(--about-hair);
  text-decoration: none;
  color: inherit;
  transition: background-color 180ms ease, padding-left 180ms ease;
}

.page-about .about-service a:hover {
  background: rgba(207, 227, 238, 0.35);
  padding-left: 12px;
}

.page-about .about-service__idx {
  grid-row: span 2;
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 600;
  color: var(--clay);
}

.page-about .about-service__title {
  font-family: var(--font-display);
  font-size: clamp(17px, 2.1vw, 21px);
  font-weight: 700;
  color: var(--polar-900);
}

.page-about .about-service__desc {
  grid-column: 2;
  font-size: 14.5px;
  line-height: 1.75;
  color: var(--stone);
}

.page-about .about-service .route-arrow {
  grid-row: 1 / span 2;
  align-self: center;
  font-family: var(--font-mono);
  font-size: 18px;
  color: var(--stone);
  transition: color 180ms ease, transform 180ms ease;
}

.page-about .about-service a:hover .route-arrow {
  color: var(--orange);
  transform: translateX(4px);
}

.page-about .about-services__foot {
  margin: 18px 0 0;
  font-size: 15px;
  line-height: 1.7;
  color: var(--stone);
}

.page-about .about-services__foot a {
  color: var(--polar-800);
  text-decoration: none;
  border-bottom: 1px solid var(--orange);
  padding-bottom: 1px;
}

/* ---------- 品牌数字 ---------- */

.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin-top: 28px;
  background: var(--about-hair);
  border: 1px solid var(--about-hair);
}

.page-about .about-stat {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 20px 16px;
  background: var(--ice);
  transition: background-color 200ms ease;
}

.page-about .about-stat:hover {
  background: var(--polar-900);
}

.page-about .about-stat:hover .about-stat__num {
  color: var(--cyan);
}

.page-about .about-stat:hover .about-stat__label {
  color: var(--ice-line);
}

.page-about .about-stat__num {
  font-family: var(--font-mono);
  font-size: clamp(24px, 3.6vw, 34px);
  font-weight: 600;
  line-height: 1.1;
  color: var(--polar-900);
  letter-spacing: -0.01em;
  transition: color 200ms ease;
}

.page-about .about-stat__label {
  font-size: 13px;
  letter-spacing: 0.04em;
  color: var(--stone);
  transition: color 200ms ease;
}

/* ---------- 直达优先 ---------- */

.page-about .about-reasons {
  display: grid;
  gap: 22px;
  margin-top: 26px;
}

.page-about .about-reason {
  padding-top: 18px;
  border-top: 2px solid var(--polar-900);
}

.page-about .about-reason:nth-child(2) {
  border-top-color: var(--moss);
}

.page-about .about-reason:nth-child(3) {
  border-top-color: var(--clay);
}

.page-about .about-reason h3 {
  margin: 0 0 10px;
  font-family: var(--font-display);
  font-size: clamp(17px, 2vw, 20px);
  font-weight: 700;
  color: var(--polar-900);
}

.page-about .about-reason p {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.82;
  color: #33424c;
}

/* ---------- 结尾入口 ---------- */

.page-about .about-cta {
  margin-top: clamp(36px, 5vw, 64px);
  padding: clamp(28px, 5vw, 56px);
  background: var(--polar-800);
  color: var(--ice);
  position: relative;
  overflow: hidden;
}

.page-about .about-cta::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 78px;
  height: 4px;
  background: var(--orange);
}

.page-about .about-cta__kicker {
  margin: 0 0 12px;
  font-size: 12px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--cyan);
}

.page-about .about-cta h2 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(24px, 4vw, 40px);
  line-height: 1.15;
  letter-spacing: -0.015em;
  color: var(--ice);
}

.page-about .about-cta p {
  margin: 16px 0 0;
  max-width: 58ch;
  font-size: 15.5px;
  line-height: 1.8;
  color: #c3d5e2;
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 24px;
}

.page-about .about-cta__meta {
  margin-top: 22px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--stone);
  word-break: break-word;
}

/* ---------- 交互与响应式 ---------- */

@media (prefers-reduced-motion: reduce) {
  .page-about .chapter-link,
  .page-about .about-service a,
  .page-about .about-service .route-arrow,
  .page-about .about-stat,
  .page-about .route-node summary::after {
    transition: none;
  }
}

@media (min-width: 760px) {
  .page-about .about-columns {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 26px 40px;
  }

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

  .page-about .about-update {
    grid-template-columns: minmax(0, 5fr) minmax(0, 7fr);
    align-items: start;
  }

  .page-about .about-update__media {
    position: sticky;
    top: calc(var(--header-height) + 64px);
  }

  .page-about .about-reasons {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 28px;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    align-items: start;
  }

  .page-about .about-hero__media {
    margin-top: clamp(24px, 4vw, 56px);
  }

  .page-about .about-section {
    grid-template-columns: var(--about-index-w) minmax(0, 1fr);
    gap: clamp(20px, 3vw, 44px);
  }

  .page-about .about-section__index {
    position: sticky;
    top: calc(var(--header-height) + 72px);
    display: block;
    align-self: start;
    padding-top: 6px;
  }

  .page-about .about-section__index .mono {
    display: block;
    font-size: 30px;
    line-height: 1;
    letter-spacing: -0.02em;
  }

  .page-about .about-section__index-label {
    display: block;
    margin-top: 8px;
    font-size: 11px;
    letter-spacing: 0.16em;
    color: var(--stone);
    writing-mode: horizontal-tb;
  }
}

@media (min-width: 1180px) {
  .page-about .about-hero {
    grid-template-columns: minmax(0, 8fr) minmax(0, 4fr);
    gap: 64px;
  }

  .page-about .about-services {
    border-top-width: 2px;
    border-top-color: var(--polar-900);
  }

  .page-about .about-cta {
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto;
    align-items: end;
    gap: 40px;
  }

  .page-about .about-cta h2,
  .page-about .about-cta p,
  .page-about .about-cta__kicker {
    grid-column: 1;
  }

  .page-about .about-cta__actions {
    grid-column: 2;
    grid-row: 1 / span 3;
    align-self: center;
    margin-top: 0;
  }

  .page-about .about-cta__meta {
    grid-column: 1 / -1;
    margin-top: 8px;
  }
}