.page-about {
  --about-rail-w: 268px;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--font-body);
  overflow-x: clip;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  background: var(--ink);
  color: var(--paper);
  padding-block: clamp(18px, 3vw, 28px) clamp(44px, 7vw, 84px);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(220, 230, 242, .07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(220, 230, 242, .07) 1px, transparent 1px);
  background-size: 64px 64px;
  pointer-events: none;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  top: -22%;
  right: -12%;
  width: min(620px, 82vw);
  height: min(620px, 82vw);
  background: radial-gradient(circle, rgba(200, 255, 77, .2), rgba(95, 212, 255, .1) 45%, transparent 68%);
  pointer-events: none;
}

.page-about .about-hero > .shell {
  position: relative;
  z-index: 1;
}

.page-about .about-hero .breadcrumb {
  color: rgba(220, 230, 242, .66);
  font-size: .78rem;
}

.page-about .about-hero .breadcrumb a {
  color: var(--ice);
  text-decoration: none;
}

.page-about .about-hero__frame {
  margin-top: clamp(22px, 3.6vw, 36px);
  padding: clamp(18px, 3.4vw, 44px);
  border: 1px solid rgba(220, 230, 242, .22);
  border-radius: var(--radius-lg);
  background: linear-gradient(152deg, rgba(22, 35, 58, .92), rgba(5, 16, 30, .58));
  box-shadow: var(--shadow-card);
  display: grid;
  gap: clamp(22px, 4vw, 44px);
}

.page-about .about-hero .eyebrow {
  margin: 0;
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--signal);
}

.page-about .about-hero h1 {
  margin: 14px 0 0;
  font-family: var(--font-head);
  font-weight: 900;
  font-size: clamp(1.85rem, 5.4vw, 3.4rem);
  line-height: 1.08;
  letter-spacing: -.02em;
  color: #fff;
}

.page-about .about-hero .lede {
  margin: 16px 0 0;
  max-width: 46ch;
  font-size: clamp(.96rem, 1.7vw, 1.06rem);
  line-height: 1.78;
  color: rgba(245, 248, 252, .78);
}

.page-about .about-hero__facts {
  list-style: none;
  margin: clamp(22px, 3vw, 30px) 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .about-hero__facts li {
  border-left: 2px solid var(--signal);
  padding-left: 12px;
  font-size: .86rem;
  line-height: 1.5;
  color: rgba(220, 230, 242, .82);
}

.page-about .about-hero__num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.4rem, 3.4vw, 1.9rem);
  font-weight: 700;
  line-height: 1.1;
  color: var(--signal);
}

.page-about .about-hero__figure {
  margin: 0;
  border-radius: var(--radius-md);
  overflow: hidden;
  border: 1px solid rgba(220, 230, 242, .2);
  background: linear-gradient(160deg, var(--graphite), var(--ink-deep));
}

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

/* ---------- 主体分栏 ---------- */
.page-about .about-body {
  display: grid;
  gap: clamp(26px, 4vw, 48px);
  padding-block: clamp(36px, 6vw, 76px) clamp(56px, 8vw, 104px);
  align-items: start;
}

/* ---------- 左侧目录时间线 ---------- */
.page-about .about-rail__label {
  margin: 0 0 12px;
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--slate);
}

.page-about .about-nav {
  display: flex;
  gap: 8px;
  overflow-x: auto;
  padding-bottom: 10px;
  -webkit-overflow-scrolling: touch;
}

.page-about .about-nav__link {
  flex: 0 0 auto;
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  border-radius: var(--radius-pill);
  border: 1px solid var(--mint);
  background: #fff;
  color: var(--ink);
  font-size: .84rem;
  line-height: 1.3;
  text-decoration: none;
  white-space: nowrap;
  transition: background .2s var(--ease), border-color .2s var(--ease), color .2s var(--ease);
}

.page-about .about-nav__dot {
  font-family: var(--font-mono);
  font-size: .68rem;
  color: var(--slate);
}

.page-about .about-nav__link:hover {
  border-color: var(--ice);
  background: #fff;
}

.page-about .about-nav__link[aria-current="true"] {
  background: var(--signal-soft);
  border-color: var(--signal);
}

/* ---------- 右侧叙事 ---------- */
.page-about .about-flow {
  display: grid;
  gap: clamp(38px, 5vw, 66px);
  min-width: 0;
}

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

.page-about .about-section + .about-section,
.page-about .about-section + .about-board {
  padding-top: clamp(32px, 5vw, 54px);
}

.page-about .about-section + .about-section::before,
.page-about .about-section + .about-board::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 1px;
  background: linear-gradient(90deg, var(--ice), var(--mint) 42%, rgba(220, 230, 242, 0));
}

.page-about .about-section h2,
.page-about .about-board h2 {
  position: relative;
  margin: 0 0 18px;
  padding-left: 22px;
  font-family: var(--font-head);
  font-weight: 900;
  font-size: clamp(1.4rem, 3.4vw, 2.05rem);
  line-height: 1.22;
  letter-spacing: -.02em;
  color: var(--ink);
}

.page-about .about-section h2::before,
.page-about .about-board h2::before {
  content: "";
  position: absolute;
  left: 0;
  top: .16em;
  width: 12px;
  height: .96em;
  border-radius: 6px;
  background: var(--signal);
}

.page-about .about-section h3 {
  margin: 0;
  font-family: var(--font-head);
  font-weight: 800;
  font-size: 1.02rem;
  line-height: 1.4;
  letter-spacing: -.01em;
  color: var(--ink);
}

.page-about .about-section .prose p {
  color: var(--slate);
  line-height: 1.78;
}

.page-about .about-section .prose a,
.page-about .about-tier__hint a {
  color: var(--ink);
  text-decoration: underline;
  text-decoration-color: var(--ice);
  text-decoration-thickness: 2px;
  text-underline-offset: 3px;
}

.page-about .about-section .prose a:hover,
.page-about .about-tier__hint a:hover {
  text-decoration-color: var(--signal);
}

/* ---------- 演进阶段 ---------- */
.page-about .about-phases {
  list-style: none;
  margin: clamp(20px, 3vw, 28px) 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .about-phase {
  display: grid;
  gap: 8px 20px;
  padding: clamp(16px, 2.4vw, 22px) clamp(16px, 2.4vw, 24px);
  border-radius: var(--radius-md);
  border: 1px solid var(--mint);
  background: #fff;
  box-shadow: 0 14px 34px -30px rgba(5, 16, 30, .7);
}

.page-about .about-phase__head {
  display: flex;
  align-items: baseline;
  gap: 10px;
  flex-wrap: wrap;
}

.page-about .about-phase__num {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 1.45rem;
  line-height: 1;
  color: var(--ice);
}

.page-about .about-phase__tag {
  font-family: var(--font-mono);
  font-size: .66rem;
  letter-spacing: .12em;
  padding: 3px 10px;
  border-radius: var(--radius-pill);
  background: var(--signal-soft);
  color: var(--ink);
}

.page-about .about-phase__body p {
  margin: 8px 0 0;
  font-size: .94rem;
  line-height: 1.74;
  color: var(--slate);
}

/* ---------- 插图 ---------- */
.page-about .about-figure {
  margin: clamp(22px, 3.5vw, 32px) 0 0;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: auto;
  border-radius: var(--radius-lg);
  border: 1px solid var(--mint);
  object-fit: cover;
  background: linear-gradient(150deg, var(--graphite), var(--ink));
}

.page-about .about-figure figcaption {
  margin-top: 10px;
  font-size: .84rem;
  line-height: 1.6;
  color: var(--slate);
}

/* ---------- 三条生产线 ---------- */
.page-about .about-crews {
  display: grid;
  gap: 16px;
  margin-top: clamp(20px, 3vw, 28px);
}

.page-about .about-crew {
  position: relative;
  padding: clamp(20px, 2.6vw, 26px);
  border-radius: var(--radius-md);
  border: 1px solid var(--mint);
  background: #fff;
  transition: transform .22s var(--ease), border-color .22s var(--ease);
}

.page-about .about-crew:hover {
  transform: translateY(-4px);
  border-color: var(--signal);
}

.page-about .about-crew__badge {
  display: inline-block;
  margin-bottom: 12px;
  padding: 4px 12px;
  border-radius: var(--radius-pill);
  background: var(--ink);
  color: var(--signal);
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .1em;
}

.page-about .about-crew p {
  margin: 10px 0 0;
  font-size: .92rem;
  line-height: 1.74;
  color: var(--slate);
}

/* ---------- 数字看板 ---------- */
.page-about .about-board {
  position: relative;
  overflow: hidden;
  padding: clamp(24px, 4vw, 42px);
  border-radius: var(--radius-lg);
  background: var(--signal);
  color: var(--ink);
}

.page-about .about-board::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image: repeating-linear-gradient(90deg, rgba(10, 26, 47, .09) 0 1px, transparent 1px 36px);
  pointer-events: none;
}

.page-about .about-board > * {
  position: relative;
  z-index: 1;
}

.page-about .about-board h2 {
  color: var(--ink);
  margin-bottom: 12px;
}

.page-about .about-board h2::before {
  background: var(--ink);
}

.page-about .about-board__intro {
  margin: 0;
  max-width: 52ch;
  font-size: .94rem;
  line-height: 1.72;
  color: rgba(10, 26, 47, .74);
}

.page-about .about-board__grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: clamp(16px, 2.6vw, 26px);
  margin-top: clamp(20px, 3vw, 30px);
}

.page-about .about-board__item {
  padding-top: 12px;
  border-top: 2px solid rgba(10, 26, 47, .28);
}

.page-about .about-board__num {
  display: block;
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: clamp(1.4rem, 3.6vw, 2.1rem);
  line-height: 1.05;
  letter-spacing: -.02em;
}

.page-about .about-board__cap {
  display: block;
  margin-top: 6px;
  font-size: .8rem;
  line-height: 1.4;
  color: rgba(10, 26, 47, .72);
}

.page-about .about-board__figure {
  margin: clamp(22px, 3vw, 30px) 0 0;
  border-radius: var(--radius-md);
  overflow: hidden;
  border: 1px solid rgba(10, 26, 47, .2);
}

.page-about .about-board__figure img {
  display: block;
  width: 100%;
  aspect-ratio: 1200 / 900;
  max-height: 300px;
  object-fit: cover;
}

/* ---------- 会员档位 ---------- */
.page-about .about-tiers {
  list-style: none;
  margin: clamp(20px, 3vw, 28px) 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
  counter-reset: tier;
}

.page-about .about-tier {
  padding: clamp(18px, 2.6vw, 24px);
  border-radius: var(--radius-md);
  border: 1px solid var(--mint);
  border-left: 6px solid var(--mint);
  background: #fff;
}

.page-about .about-tier--mid {
  border-left-color: var(--ice);
  background: linear-gradient(120deg, #fff, rgba(233, 255, 184, .34));
}

.page-about .about-tier__head {
  display: flex;
  align-items: baseline;
  gap: 12px;
  flex-wrap: wrap;
}

.page-about .about-tier__name {
  font-family: var(--font-head);
  font-weight: 900;
  font-size: 1.18rem;
  letter-spacing: -.01em;
  color: var(--ink);
}

.page-about .about-tier__fit {
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .06em;
  color: var(--slate);
}

.page-about .about-tier p {
  margin: 10px 0 0;
  font-size: .93rem;
  line-height: 1.76;
  color: var(--slate);
}

.page-about .about-tier__hint {
  margin: 16px 0 0;
  font-size: .9rem;
  line-height: 1.7;
  color: var(--slate);
}

/* ---------- 合作与纠错 ---------- */
.page-about .about-paths {
  display: grid;
  gap: 14px;
  margin-top: clamp(18px, 3vw, 26px);
}

.page-about .about-path {
  padding: clamp(18px, 2.6vw, 24px);
  border-radius: var(--radius-md);
  border: 1px solid var(--mint);
  background: #fff;
}

.page-about .about-path p {
  margin: 8px 0 0;
  font-size: .92rem;
  line-height: 1.76;
  color: var(--slate);
}

.page-about .about-path a {
  color: var(--ink);
  text-decoration: underline;
  text-decoration-color: var(--ice);
  text-decoration-thickness: 2px;
  text-underline-offset: 3px;
}

.page-about .about-path a:hover {
  text-decoration-color: var(--signal);
}

.page-about .about-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(20px, 3vw, 28px);
}

.page-about .about-cta .btn {
  text-decoration: none;
}

/* ---------- 窄屏保险 ---------- */
.page-about .about-flow,
.page-about .about-section,
.page-about .about-board {
  max-width: 100%;
}

.page-about .about-flow img {
  max-width: 100%;
  height: auto;
}

@media (min-width: 620px) {
  .page-about .about-hero__facts {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (min-width: 720px) {
  .page-about .about-hero__frame {
    padding: clamp(26px, 3.4vw, 44px);
  }

  .page-about .about-phase {
    grid-template-columns: 112px minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-phase__head {
    flex-direction: column;
    align-items: flex-start;
    gap: 8px;
  }

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

  .page-about .about-paths {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .about-paths .about-path:first-child {
    grid-column: 1 / -1;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero__frame {
    grid-template-columns: 1.12fr .88fr;
    align-items: center;
  }

  .page-about .about-crews {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 22px;
    align-items: start;
  }

  .page-about .about-crew:nth-child(2) {
    margin-top: 22px;
  }

  .page-about .about-crew:nth-child(3) {
    margin-top: 44px;
  }

  .page-about .about-crew:not(:first-child)::before {
    content: "";
    position: absolute;
    left: -22px;
    top: 40px;
    width: 22px;
    border-top: 2px dashed var(--ice);
  }
}

@media (min-width: 960px) {
  .page-about .about-body {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: clamp(36px, 5vw, 72px);
  }

  .page-about .about-rail {
    position: sticky;
    top: calc(var(--header-h) + 24px);
  }

  .page-about .about-nav {
    flex-direction: column;
    overflow: visible;
    gap: 0;
    padding-bottom: 0;
  }

  .page-about .about-nav__link {
    position: relative;
    display: grid;
    grid-template-columns: 44px minmax(0, 1fr);
    align-items: center;
    gap: 12px;
    padding: 12px 0;
    border: 0;
    border-radius: 0;
    background: none;
    white-space: normal;
    font-size: .9rem;
    color: var(--slate);
  }

  .page-about .about-nav__link::before {
    content: "";
    position: absolute;
    left: 15px;
    top: 0;
    bottom: 0;
    width: 2px;
    background: var(--mint);
  }

  .page-about .about-nav__link:first-child::before {
    top: 50%;
  }

  .page-about .about-nav__link:last-child::before {
    bottom: 50%;
  }

  .page-about .about-nav__dot {
    position: relative;
    z-index: 1;
    display: grid;
    place-items: center;
    width: 32px;
    height: 32px;
    border-radius: 50%;
    border: 2px solid var(--mint);
    background: #fff;
    font-size: .64rem;
    color: var(--slate);
    transition: background .2s var(--ease), border-color .2s var(--ease), color .2s var(--ease);
  }

  .page-about .about-nav__link:hover {
    background: none;
    color: var(--ink);
  }

  .page-about .about-nav__link[aria-current="true"] {
    background: none;
    color: var(--ink);
  }

  .page-about .about-nav__link:hover .about-nav__dot,
  .page-about .about-nav__link[aria-current="true"] .about-nav__dot {
    background: var(--signal);
    border-color: var(--signal);
    color: var(--ink);
  }

  .page-about .about-nav__text {
    line-height: 1.42;
  }
}

@media (min-width: 1100px) {
  .page-about {
    --about-rail-w: 292px;
  }

  .page-about .about-board {
    padding: clamp(32px, 3.6vw, 50px);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-crew,
  .page-about .about-nav__link,
  .page-about .about-nav__dot {
    transition: none;
  }

  .page-about .about-crew:hover {
    transform: none;
  }
}