.page-about {
  --about-grain: radial-gradient(rgba(11, 61, 46, 0.05) 1px, transparent 1px);
  --about-line: rgba(168, 159, 145, 0.5);
  --about-orange-glow: rgba(255, 107, 0, 0.16);
  background: var(--c-stone-100);
  overflow-x: hidden;
}

/* ===== Hero 首屏 ===== */
.page-about__hero {
  position: relative;
  background: var(--c-green-900);
  color: var(--c-stone-100);
  padding: 40px 0 48px;
  overflow: hidden;
}
.page-about__hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image: radial-gradient(rgba(245, 240, 230, 0.03) 1px, transparent 1px);
  background-size: 4px 4px;
  pointer-events: none;
}
.page-about__hero::after {
  content: '';
  position: absolute;
  top: 0;
  right: -12%;
  width: 52%;
  height: 100%;
  background: linear-gradient(135deg, transparent 58%, var(--about-orange-glow) 100%);
  transform: skewX(-14deg);
  pointer-events: none;
}
.page-about__hero-frame {
  position: relative;
  padding: 28px 20px 24px;
  background: rgba(255, 255, 255, 0.02);
  z-index: 1;
}
.page-about__hero-grid {
  display: flex;
  flex-direction: column;
  gap: 32px;
  padding-top: 32px;
}
.page-about__hero-main {
  max-width: 720px;
}
.page-about__kicker {
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--c-orange-300);
  margin-bottom: 16px;
}
.page-about__title {
  font-family: var(--f-display);
  font-size: clamp(30px, 6vw, 52px);
  line-height: 1.12;
  font-weight: 700;
  color: var(--c-stone-100);
  margin: 0 0 18px;
}
.page-about__lead {
  font-size: 16px;
  line-height: 1.75;
  color: rgba(245, 240, 230, 0.82);
  margin: 0;
  max-width: 560px;
}
.page-about__hero-side {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  border-left: 2px solid var(--c-orange-500);
  padding-left: 20px;
}
.page-about__version-block {
  display: flex;
  align-items: baseline;
  position: relative;
}
.page-about__version-main {
  font-family: var(--f-display);
  font-size: 64px;
  line-height: 1;
  color: var(--c-orange-500);
}
.page-about__version-sub {
  font-family: var(--f-display);
  font-size: 28px;
  line-height: 1;
  color: var(--c-stone-100);
  margin-left: 2px;
}
.page-about__version-label {
  display: block;
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.22em;
  color: var(--c-stone-400);
  margin-top: 10px;
}
.page-about__version-note {
  font-size: 14px;
  line-height: 1.65;
  color: rgba(245, 240, 230, 0.72);
  margin: 16px 0 0;
}

/* ===== TOC 层叠目录 ===== */
.page-about__toc {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(245, 240, 230, 0.94);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--c-stone-400);
  padding: 14px 0;
}
.page-about__toc-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 28px;
  list-style: none;
  margin: 0;
  padding: 0;
}
.page-about__toc-list a {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 14px;
  font-weight: 700;
  color: var(--c-green-900);
  text-decoration: none;
  padding: 4px 0;
  border-bottom: 2px solid transparent;
  transition: border-color 0.2s var(--ease), color 0.2s var(--ease);
}
.page-about__toc-list span {
  font-family: var(--f-mono);
  font-size: 12px;
  color: var(--c-clay);
}
.page-about__toc-list a:hover {
  color: var(--c-orange-500);
  border-bottom-color: var(--c-orange-500);
}

/* ===== 通用章节 ===== */
.page-about__section {
  position: relative;
  padding: 56px 0;
}
.page-about__section-tag {
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--c-clay);
  margin-bottom: 12px;
}
.page-about__section-tag--light {
  color: var(--c-orange-300);
}
.page-about__section-title {
  font-family: var(--f-display);
  font-size: clamp(28px, 4vw, 40px);
  line-height: 1.18;
  font-weight: 700;
  color: var(--c-green-900);
  margin: 0 0 24px;
}
.page-about__prose {
  color: var(--c-ink);
  font-size: 15px;
  line-height: 1.8;
}
.page-about__prose p {
  margin-top: 0;
  margin-bottom: 16px;
}
.page-about__note {
  margin-top: 28px;
  padding: 16px 18px;
  border-left: 3px solid var(--c-stone-400);
  background: rgba(168, 159, 145, 0.1);
}
.page-about__note-label {
  display: block;
  font-family: var(--f-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--c-clay);
  margin-bottom: 8px;
}
.page-about__note p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--c-ink);
}

/* ===== Figure 图片 ===== */
.page-about__figure {
  position: relative;
  margin: 0;
  overflow: hidden;
}
.page-about__figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  filter: contrast(1.08) saturate(0.9) sepia(0.08);
}
.page-about__figure::after {
  content: '';
  position: absolute;
  inset: 0;
  background-image: radial-gradient(rgba(11, 61, 46, 0.06) 1px, transparent 1px);
  background-size: 3px 3px;
  opacity: 0.45;
  pointer-events: none;
}
.page-about__figure figcaption {
  font-family: var(--f-mono);
  font-size: 12px;
  line-height: 1.5;
  color: var(--c-stone-400);
  padding-top: 12px;
  border-bottom: 1px solid var(--c-stone-400);
  padding-bottom: 12px;
}
.page-about__figure--early {
  max-width: 600px;
}
.page-about__figure--team {
  max-width: 700px;
}

/* ===== 里程碑 ===== */
.page-about__section--milestones {
  background-color: var(--c-stone-100);
  background-image:
    linear-gradient(rgba(11, 61, 46, 0.04) 1px, transparent 1px),
    linear-gradient(90deg, rgba(11, 61, 46, 0.04) 1px, transparent 1px);
  background-size: 32px 32px;
  border-top: 1px solid var(--c-stone-400);
  border-bottom: 1px solid var(--c-stone-400);
}
.page-about__milestone-lead {
  font-size: 16px;
  line-height: 1.7;
  color: var(--c-ink);
  max-width: 640px;
  margin: 0 0 40px;
}

/* 时间线 */
.page-about__timeline {
  position: relative;
  margin-top: 16px;
}
.page-about__timeline::before {
  content: '';
  position: absolute;
  left: 32px;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(to bottom, var(--c-stone-400) 0%, var(--c-stone-400) 82%, transparent 100%);
  z-index: 0;
}
.page-about__tl-item {
  position: relative;
  display: grid;
  grid-template-columns: 64px minmax(0, 1fr);
  gap: 16px;
  padding-bottom: 48px;
  z-index: 1;
}
.page-about__tl-item:last-child {
  padding-bottom: 0;
}
.page-about__tl-marker {
  position: relative;
  text-align: center;
  z-index: 1;
}
.page-about__tl-dot {
  display: block;
  width: 16px;
  height: 16px;
  margin: 0 auto;
  border-radius: 50%;
  background: var(--c-orange-500);
  border: 3px solid var(--c-stone-100);
  box-shadow: 0 0 0 2px var(--c-orange-500), 0 0 12px rgba(255, 107, 0, 0.3);
  transition: transform 0.3s var(--ease), box-shadow 0.3s var(--ease);
}
.page-about__tl-item:hover .page-about__tl-dot {
  transform: scale(1.35);
  box-shadow: 0 0 0 3px var(--c-orange-500), 0 0 20px rgba(255, 107, 0, 0.45);
}
.page-about__tl-year {
  display: block;
  font-family: var(--f-mono);
  font-size: 12px;
  color: var(--c-clay);
  margin-top: 8px;
  letter-spacing: 0.04em;
  transition: color 0.3s var(--ease);
}
.page-about__tl-item:hover .page-about__tl-year {
  color: var(--c-orange-500);
}
.page-about__tl-flag {
  display: inline-block;
  font-family: var(--f-mono);
  font-size: 10px;
  letter-spacing: 0.14em;
  color: var(--c-stone-100);
  background: var(--c-orange-500);
  padding: 3px 8px;
  border-radius: 2px;
  margin-top: 8px;
}
.page-about__tl-card {
  background: #ffffff;
  border-left: 3px solid var(--c-orange-500);
  padding: 20px 20px 22px;
  box-shadow: var(--shadow-sm);
  position: relative;
  transition: box-shadow 0.3s var(--ease), transform 0.3s var(--ease);
}
.page-about__tl-card:hover {
  box-shadow: var(--shadow-md);
  transform: translateY(-3px);
}
.page-about__tl-card .bs-tag {
  margin-bottom: 12px;
}
.page-about__tl-card h3 {
  font-family: var(--f-display);
  font-size: 20px;
  line-height: 1.25;
  font-weight: 700;
  color: var(--c-green-900);
  margin: 0 0 10px;
}
.page-about__tl-card p {
  font-size: 14px;
  line-height: 1.75;
  color: var(--c-ink);
  margin: 0;
}
.page-about__tl-details {
  margin-top: 14px;
  border-top: 1px dashed var(--c-stone-400);
  padding-top: 12px;
}
.page-about__tl-details summary {
  font-family: var(--f-mono);
  font-size: 13px;
  color: var(--c-green-900);
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 4px 0;
  transition: color 0.2s var(--ease);
}
.page-about__tl-details summary:hover,
.page-about__tl-details[open] summary {
  color: var(--c-orange-500);
}
.page-about__tl-details ul {
  margin: 10px 0 0;
  padding-left: 20px;
}
.page-about__tl-details li {
  font-size: 14px;
  line-height: 1.75;
  color: var(--c-ink);
}

/* 增长图 */
.page-about__growth {
  position: relative;
  margin: 56px 0 0;
  overflow: hidden;
}
.page-about__growth img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  filter: contrast(1.08) saturate(0.92) sepia(0.06);
}
.page-about__growth figcaption {
  font-family: var(--f-mono);
  font-size: 12px;
  line-height: 1.5;
  color: var(--c-stone-400);
  padding-top: 12px;
  border-bottom: 1px solid var(--c-stone-400);
  padding-bottom: 12px;
}

/* ===== 数据哲学 ===== */
.page-about__philosophy {
  position: relative;
  background: var(--c-green-900);
  color: var(--c-stone-100);
  padding: 56px 0;
  overflow: hidden;
}
.page-about__philosophy::before {
  content: '';
  position: absolute;
  inset: 0;
  background-image: radial-gradient(rgba(245, 240, 230, 0.035) 1px, transparent 1px);
  background-size: 4px 4px;
  pointer-events: none;
}
.page-about__philosophy-title {
  font-family: var(--f-display);
  font-size: clamp(28px, 4vw, 40px);
  line-height: 1.18;
  font-weight: 700;
  color: var(--c-stone-100);
  margin: 0 0 16px;
}
.page-about__philosophy-lead {
  font-size: 16px;
  line-height: 1.7;
  color: rgba(245, 240, 230, 0.78);
  margin: 0 0 44px;
  max-width: 620px;
}
.page-about__metric-grid {
  row-gap: 32px;
}
.page-about__metric {
  border-top: 1px solid rgba(245, 240, 230, 0.14);
  padding-top: 20px;
}
.page-about__metric-label {
  display: block;
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--c-orange-300);
  margin-bottom: 12px;
}
.page-about__metric-value {
  display: block;
  font-family: var(--f-display);
  font-size: 56px;
  line-height: 1;
  font-weight: 700;
  color: var(--c-stone-100);
}
.page-about__metric-unit {
  font-size: 22px;
  margin-left: 4px;
  color: var(--c-orange-500);
}
.page-about__metric p {
  font-size: 14px;
  line-height: 1.7;
  color: rgba(245, 240, 230, 0.7);
  margin: 14px 0 0;
}

/* ===== 团队与生态 ===== */
.page-about__section--team {
  padding-top: 64px;
}

/* ===== 品牌CTA ===== */
.page-about__cta {
  position: relative;
  background: var(--c-green-900);
  color: var(--c-stone-100);
  padding: 72px 0;
  overflow: hidden;
}
.page-about__cta::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  height: 4px;
  background: linear-gradient(90deg, var(--c-orange-500) 0%, transparent 72%);
}
.page-about__cta::after {
  content: '';
  position: absolute;
  bottom: 0;
  right: -10%;
  width: 40%;
  height: 100%;
  background: linear-gradient(315deg, transparent 60%, rgba(255, 107, 0, 0.12) 100%);
  transform: skewX(-16deg);
  pointer-events: none;
}
.page-about__cta-inner {
  position: relative;
  z-index: 1;
  max-width: 780px;
  margin: 0 auto;
  text-align: center;
}
.page-about__cta-kicker {
  font-family: var(--f-mono);
  font-size: 12px;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--c-orange-300);
  margin-bottom: 14px;
}
.page-about__cta-title {
  font-family: var(--f-display);
  font-size: clamp(30px, 5vw, 48px);
  line-height: 1.15;
  font-weight: 700;
  color: var(--c-stone-100);
  margin: 0 0 18px;
}
.page-about__cta-text {
  font-size: 16px;
  line-height: 1.75;
  color: rgba(245, 240, 230, 0.8);
  margin: 0 auto 36px;
  max-width: 560px;
}
.page-about__cta-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 20px 32px;
  justify-content: center;
  align-items: center;
}
.page-about__cta-link {
  color: var(--c-stone-100);
  text-decoration: none;
  font-size: 15px;
  font-weight: 700;
  border-bottom: 1px solid rgba(245, 240, 230, 0.4);
  padding-bottom: 3px;
  transition: color 0.2s var(--ease), border-color 0.2s var(--ease);
}
.page-about__cta-link span {
  display: inline-block;
  margin-left: 4px;
  transition: transform 0.2s var(--ease);
}
.page-about__cta-link:hover {
  color: var(--c-orange-300);
  border-color: var(--c-orange-300);
}
.page-about__cta-link:hover span {
  transform: translateX(4px);
}

/* ===== 响应式：桌面端 ===== */
@media (min-width: 900px) {
  .page-about__hero {
    padding: 56px 0 72px;
  }
  .page-about__hero-frame {
    padding: 40px 40px 32px;
  }
  .page-about__hero-grid {
    display: grid;
    grid-template-columns: 1.2fr 0.8fr;
    gap: 64px;
    align-items: end;
    padding-top: 44px;
  }
  .page-about__hero-side {
    align-items: flex-start;
    justify-content: flex-end;
    padding-left: 28px;
  }
  .page-about__version-main {
    font-size: 88px;
  }
  .page-about__version-sub {
    font-size: 36px;
  }

  .page-about__section {
    padding: 88px 0;
  }

  .page-about__section--origin .bs-grid__col--5 {
    padding-top: 20px;
  }
  .page-about__section--origin .bs-grid__col--6 {
    padding-top: 40px;
  }
  .page-about__section--milestones {
    padding-top: 96px;
  }
  .page-about__milestone-lead {
    margin-bottom: 56px;
  }

  .page-about__tl-item {
    grid-template-columns: 100px minmax(0, 1fr);
    gap: 40px;
  }
  .page-about__timeline::before {
    left: 50px;
  }
  .page-about__tl-year {
    font-size: 13px;
  }
  .page-about__tl-card {
    padding: 24px 28px 26px;
  }

  .page-about__growth {
    margin-top: 72px;
  }

  .page-about__philosophy {
    padding: 88px 0;
  }
  .page-about__metric-grid {
    margin-top: 8px;
  }

  .page-about__section--team {
    padding-top: 96px;
  }
  .page-about__section--team .bs-grid__col--6 {
    padding-top: 24px;
  }

  .page-about__cta {
    padding: 96px 0;
  }
}