.page-about {
  --about-note-gap: 20px;
  background: var(--ink);
  color: var(--mist);
  font-family: var(--f-body);
  overflow-x: clip;
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding: 40px 0 0;
  border-bottom: 1px solid var(--grid);
  overflow: hidden;
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: -12% -18% 0;
  background-image:
    linear-gradient(to right, rgba(27, 58, 49, .85) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(27, 58, 49, .85) 1px, transparent 1px);
  background-size: 88px 88px;
  -webkit-mask-image: radial-gradient(120% 92% at 22% 0%, #000 0%, transparent 70%);
  mask-image: radial-gradient(120% 92% at 22% 0%, #000 0%, transparent 70%);
  pointer-events: none;
}

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

.page-about .hero-grid {
  display: grid;
  gap: 28px;
  margin-top: 28px;
}

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

.page-about .hero-title {
  margin: 14px 0 0;
  font-family: var(--f-display);
  font-weight: 900;
  font-size: clamp(2rem, 8.2vw, 4.5rem);
  line-height: 1.02;
  letter-spacing: -.02em;
  text-align: left;
  color: var(--mist);
  text-shadow: 0 0 0 transparent;
}

.page-about .hero-title::after {
  content: "";
  display: block;
  width: 72px;
  height: 3px;
  margin-top: 20px;
  border-radius: var(--r-pill);
  background: var(--accent);
}

.page-about .hero-lede {
  margin-top: 20px;
  max-width: 34em;
  font-size: 1rem;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .hero-aside {
  display: flex;
  align-items: center;
  gap: 16px;
  flex-wrap: wrap;
}

.page-about .hero-side-note {
  margin: 0;
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: .26em;
  color: var(--muted);
  text-transform: uppercase;
}

.page-about .hero-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin-top: 36px;
  border-top: 1px solid var(--grid);
}

.page-about .stat {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 18px 12px 20px;
  border-bottom: 1px solid var(--grid);
}

.page-about .stat:first-child {
  padding-left: 0;
}

.page-about .stat-num {
  font-family: var(--f-mono);
  font-weight: 600;
  font-size: 1.5rem;
  line-height: 1.1;
  color: var(--mist);
}

.page-about .stat:first-child .stat-num {
  color: var(--accent);
}

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

/* ---------- 章节骨架 ---------- */
.page-about .about-body {
  padding-bottom: 32px;
}

.page-about .chapter {
  display: grid;
  grid-template-columns: 1fr;
  gap: 18px;
  padding: 52px 0;
  border-top: 1px solid var(--grid);
}

.page-about .chapter:first-child {
  border-top: 0;
}

.page-about .chapter-rail {
  display: flex;
  align-items: center;
  gap: 14px;
}

.page-about .chapter-index {
  font-family: var(--f-mono);
  font-weight: 600;
  font-size: 1.375rem;
  line-height: 1;
  color: var(--accent);
  letter-spacing: .04em;
}

.page-about .chapter-side {
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: .28em;
  color: var(--muted);
  text-transform: uppercase;
}

.page-about .chapter-body {
  min-width: 0;
}

.page-about .chapter-title {
  margin: 0 0 18px;
  font-family: var(--f-display);
  font-weight: 800;
  font-size: clamp(1.375rem, 4.4vw, 2.125rem);
  line-height: 1.24;
  letter-spacing: -.01em;
  color: var(--mist);
}

.page-about .chapter-body p {
  max-width: 34em;
  margin: 0 0 16px;
  font-size: .968rem;
  line-height: 1.85;
  color: var(--muted);
}

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

/* ---------- 阅读顺序三步 ---------- */
.page-about .read-steps {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
}

.page-about .step {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 2px 14px;
  padding: 18px 0;
  border-top: 1px solid var(--grid);
}

.page-about .step:last-child {
  border-bottom: 1px solid var(--grid);
}

.page-about .step-num {
  grid-row: 1 / span 2;
  font-family: var(--f-mono);
  font-weight: 600;
  font-size: .875rem;
  line-height: 1.7;
  color: var(--accent);
}

.page-about .step-title {
  margin: 0;
  font-family: var(--f-display);
  font-weight: 700;
  font-size: 1.0625rem;
  letter-spacing: .01em;
  color: var(--mist);
}

.page-about .step p {
  margin: 4px 0 0;
  max-width: 32em;
  font-size: .9375rem;
  line-height: 1.8;
  color: var(--muted);
}

/* ---------- 图片 ---------- */
.page-about .about-figure,
.page-about .about-break {
  margin: 26px 0 30px;
}

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

.page-about .fig-cap {
  margin-top: 12px;
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: .16em;
  color: var(--muted);
}

.page-about .about-break {
  border-top: 1px solid var(--grid);
  padding-top: 32px;
}

.page-about .about-break .media-frame {
  max-width: 720px;
}

/* ---------- 团队与时间轴 ---------- */
.page-about .team-list,
.page-about .timeline {
  margin-top: 26px;
  border-top: 1px solid var(--grid);
}

.page-about .team-list .disclosure,
.page-about .timeline .disclosure {
  border-bottom: 1px solid var(--grid);
}

.page-about .team-list .disclosure-head,
.page-about .timeline .disclosure-head {
  background: transparent;
  border: 0;
  width: 100%;
  text-align: left;
  cursor: pointer;
  font-family: inherit;
}

.page-about .timeline .disclosure-index {
  color: var(--amber);
  letter-spacing: .06em;
}

.page-about .team-list .disclosure-inner p,
.page-about .timeline .disclosure-inner p {
  max-width: 34em;
  margin: 0;
  font-size: .9375rem;
  line-height: 1.8;
  color: var(--muted);
}

.page-about .timeline::before {
  content: none;
}

/* ---------- 下一步入口 ---------- */
.page-about .about-next {
  padding: 56px 0 72px;
  border-top: 1px solid var(--grid);
}

.page-about .next-title {
  margin: 0 0 20px;
  font-family: var(--f-display);
  font-weight: 800;
  font-size: 1.25rem;
  letter-spacing: .02em;
  color: var(--mist);
}

.page-about .next-grid {
  display: grid;
  gap: 10px;
}

.page-about .next-link {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 18px 20px;
  border-radius: var(--r-md);
  background: var(--panel);
  color: var(--mist);
  text-decoration: none;
  transition: background var(--dur) var(--ease), transform var(--dur) var(--ease);
}

.page-about .next-link:hover,
.page-about .next-link:focus-visible {
  background: var(--zone-soft);
  transform: translateX(3px);
}

.page-about .next-text {
  display: flex;
  align-items: baseline;
  gap: 14px;
  min-width: 0;
}

.page-about .next-label {
  font-family: var(--f-mono);
  font-size: 12px;
  color: var(--accent);
  letter-spacing: .08em;
}

.page-about .next-name {
  font-size: .968rem;
  line-height: 1.5;
}

.page-about .next-arrow {
  flex: none;
  font-family: var(--f-mono);
  color: var(--muted);
  transition: color var(--dur) var(--ease);
}

.page-about .next-link:hover .next-arrow,
.page-about .next-link:focus-visible .next-arrow {
  color: var(--accent);
}

/* ---------- 平板 ---------- */
@media (min-width: 720px) {
  .page-about .about-hero {
    padding-top: 56px;
  }

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

  .page-about .stat {
    border-bottom: 0;
    border-left: 1px solid var(--grid);
    padding: 22px 18px 26px;
  }

  .page-about .stat:first-child {
    border-left: 0;
    padding-left: 0;
  }

  .page-about .stat-num {
    font-size: 1.75rem;
  }

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

  .page-about .chapter-body p {
    font-size: 1rem;
  }
}

/* ---------- 桌面：左窄栏 + 右主内容 ---------- */
@media (min-width: 900px) {
  .page-about .about-hero {
    padding-top: 72px;
  }

  .page-about .hero-grid {
    grid-template-columns: minmax(0, 1fr) 176px;
    align-items: end;
    gap: 40px;
    margin-top: 36px;
  }

  .page-about .hero-aside {
    flex-direction: column;
    align-items: flex-start;
    gap: 22px;
    padding-bottom: 8px;
  }

  .page-about .hero-side-note {
    writing-mode: vertical-rl;
    transform: rotate(180deg);
    letter-spacing: .34em;
    padding-left: 4px;
    border-left: 1px solid var(--grid);
  }

  .page-about .chapter {
    grid-template-columns: 128px minmax(0, 1fr);
    gap: 32px;
    padding: 80px 0;
  }

  .page-about .chapter-rail {
    flex-direction: column;
    align-items: flex-start;
    gap: 20px;
    position: sticky;
    top: calc(var(--hdr-min) + 28px);
    align-self: start;
  }

  .page-about .chapter-side {
    writing-mode: vertical-rl;
    transform: rotate(180deg);
    letter-spacing: .34em;
    padding-left: 4px;
    border-left: 1px solid var(--grid);
  }

  .page-about .chapter-body {
    position: relative;
    border-left: 1px solid var(--grid);
    padding-left: clamp(22px, 3vw, 48px);
  }

  .page-about .chapter-body::before {
    content: "";
    position: absolute;
    left: -5px;
    top: 10px;
    width: 9px;
    height: 9px;
    border-radius: 50%;
    background: var(--accent);
    box-shadow: 0 0 0 4px rgba(61, 255, 168, .14);
  }

  .page-about .chapter-title {
    font-size: clamp(1.625rem, 2.4vw, 2.25rem);
  }

  .page-about .about-break {
    margin: 0 0 0 128px;
    padding-left: 32px;
    padding-top: 48px;
  }

  .page-about .about-break .media-frame {
    max-width: 640px;
  }

  .page-about .about-next {
    padding: 72px 0 96px;
  }
}

/* ---------- 大屏收窄主体 ---------- */
@media (min-width: 1280px) {
  .page-about .hero-lede {
    font-size: 1.0625rem;
  }

  .page-about .chapter-body p,
  .page-about .step p,
  .page-about .team-list .disclosure-inner p,
  .page-about .timeline .disclosure-inner p {
    max-width: 600px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .next-link,
  .page-about .next-arrow {
    transition: opacity var(--dur) var(--ease);
  }

  .page-about .next-link:hover,
  .page-about .next-link:focus-visible {
    transform: none;
  }
}