.page-about {
  --about-sticky-offset: calc(var(--mast-h) + 24px);
  background: var(--space);
  color: var(--text);
  overflow-x: hidden;
}

/* ---------- 首屏 ---------- */
.page-about .story-hero {
  position: relative;
  overflow: hidden;
  padding-top: calc(var(--mast-h) + 44px);
  padding-bottom: 56px;
  border-bottom: 1px solid var(--hairline);
}
.page-about .story-hero::before {
  content: "";
  position: absolute;
  inset: -30% -12% auto -12%;
  height: 640px;
  background:
    radial-gradient(58% 52% at 16% 32%, rgba(52, 229, 255, 0.16), transparent 70%),
    radial-gradient(48% 48% at 84% 18%, rgba(139, 92, 246, 0.2), transparent 72%),
    radial-gradient(30% 30% at 62% 78%, rgba(255, 200, 87, 0.08), transparent 74%);
  pointer-events: none;
}
.page-about .story-hero::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(154, 166, 196, 0.07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(154, 166, 196, 0.07) 1px, transparent 1px);
  background-size: 72px 72px;
  -webkit-mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.75), transparent 88%);
  mask-image: linear-gradient(180deg, rgba(0, 0, 0, 0.75), transparent 88%);
  pointer-events: none;
}
.page-about .story-hero__inner {
  position: relative;
  z-index: 1;
}
.page-about .story-hero .crumbs {
  margin-bottom: 36px;
}

.page-about .story-hero__kicker {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  margin: 0 0 22px;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.2em;
  text-transform: uppercase;
  color: var(--cyan);
}
.page-about .story-hero__kicker::before {
  content: "";
  width: 30px;
  height: 1px;
  background: linear-gradient(90deg, var(--cyan), transparent);
}

.page-about .story-hero__title {
  margin: 0;
  font-family: var(--font-title);
  font-weight: 200;
  font-size: clamp(2.1rem, 7vw, 5.2rem);
  line-height: 1.04;
  letter-spacing: -0.025em;
  color: var(--white);
}
.page-about .story-hero__title-line {
  display: block;
}
.page-about .story-hero__title-line--accent {
  font-weight: 300;
  background: linear-gradient(96deg, var(--cyan) 0%, var(--violet) 62%, var(--gold) 100%);
  -webkit-background-clip: text;
  background-clip: text;
  color: transparent;
}

.page-about .story-hero__lede {
  max-width: 62ch;
  margin: 26px 0 0;
  font-size: 1.0625rem;
  line-height: 1.85;
  color: var(--text);
}

.page-about .story-hero__facts {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 40px 0 0;
  padding: 0;
  background: var(--hairline);
  border: 1px solid var(--hairline);
}
.page-about .fact {
  background: rgba(10, 16, 36, 0.74);
  padding: 16px 16px 18px;
}
.page-about .fact__k {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.625rem;
  letter-spacing: 0.16em;
  color: var(--muted);
}
.page-about .fact__v {
  margin: 8px 0 0;
  font-family: var(--font-mono);
  font-size: 1.375rem;
  font-weight: 500;
  line-height: 1.1;
  color: var(--gold);
}

/* ---------- 章节索引 ---------- */
.page-about .story-index {
  position: sticky;
  top: var(--mast-h);
  z-index: 20;
  background: rgba(10, 16, 36, 0.9);
  border-bottom: 1px solid var(--hairline);
}
.page-about .story-index__shell {
  padding-left: 0;
  padding-right: 0;
}
.page-about .story-index__list {
  display: flex;
  margin: 0;
  padding: 0;
  list-style: none;
  overflow-x: auto;
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
}
.page-about .story-index__list::-webkit-scrollbar {
  display: none;
}
.page-about .story-index__item {
  flex: 0 0 auto;
}
.page-about .story-index__link {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 15px 16px;
  font-size: 0.8125rem;
  color: var(--muted);
  text-decoration: none;
  white-space: nowrap;
  border-right: 1px solid var(--hairline);
  transition: color 0.2s ease, background-color 0.2s ease;
}
.page-about .story-index__link:hover {
  color: var(--white);
  background: rgba(52, 229, 255, 0.07);
}
.page-about .story-index__link:focus-visible {
  outline: 1px solid var(--cyan);
  outline-offset: -2px;
  color: var(--white);
}
.page-about .story-index__num {
  font-family: var(--font-mono);
  font-size: 0.625rem;
  letter-spacing: 0.1em;
  color: var(--ember);
}
.page-about .story-index__label {
  letter-spacing: 0.02em;
}

/* ---------- 章节通用 ---------- */
.page-about .chapter {
  border-bottom: 1px solid var(--hairline);
}
.page-about .chapter__shell {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 20px;
  padding: 52px 0;
}
.page-about .chapter__aside {
  display: flex;
  align-items: baseline;
  gap: 14px;
}
.page-about .chapter__num {
  font-family: var(--font-mono);
  font-weight: 200;
  font-size: clamp(2.1rem, 9vw, 3.2rem);
  line-height: 0.85;
  letter-spacing: -0.04em;
  color: var(--ember);
}
.page-about .chapter__label {
  font-family: var(--font-mono);
  font-size: 0.625rem;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
}

.page-about .chapter__title {
  margin: 0 0 18px;
  font-family: var(--font-title);
  font-weight: 300;
  font-size: clamp(1.5rem, 4.4vw, 2.4rem);
  line-height: 1.18;
  letter-spacing: -0.015em;
  color: var(--white);
}
.page-about .chapter__text {
  max-width: 66ch;
  margin: 0 0 18px;
  font-size: 1rem;
  line-height: 1.9;
  color: var(--text);
}
.page-about .chapter__text:last-child {
  margin-bottom: 0;
}

.page-about .inline-link {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(52, 229, 255, 0.42);
  transition: color 0.2s ease, border-color 0.2s ease;
}
.page-about .inline-link:hover {
  color: var(--white);
  border-bottom-color: var(--white);
}
.page-about .inline-link:focus-visible {
  outline: 1px solid var(--cyan);
  outline-offset: 2px;
}

/* ---------- 时间轴 ---------- */
.page-about .timeline {
  position: relative;
  margin: 32px 0 0;
  padding: 0 0 0 28px;
  list-style: none;
}
.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: linear-gradient(180deg, var(--ember) 0%, var(--cyan) 48%, var(--violet) 100%);
  opacity: 0.6;
}
.page-about .timeline__item {
  position: relative;
  padding: 0 0 26px;
}
.page-about .timeline__item:last-child {
  padding-bottom: 0;
}
.page-about .timeline__item::before {
  content: "";
  position: absolute;
  left: -28px;
  top: 6px;
  width: 11px;
  height: 11px;
  background: var(--space);
  border: 1px solid var(--ember);
  transition: background-color 0.2s ease, border-color 0.2s ease;
}
.page-about .timeline__item:hover::before {
  background: var(--ember);
  border-color: var(--gold);
}
.page-about .timeline__title {
  margin: 0 0 6px;
  font-family: var(--font-title);
  font-size: 1rem;
  font-weight: 700;
  letter-spacing: 0.02em;
  color: var(--white);
}
.page-about .timeline__text {
  max-width: 60ch;
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.85;
  color: var(--text);
}

/* ---------- 数据卡组 ---------- */
.page-about .flow-cards {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin: 32px 0 0;
  background: var(--hairline);
  border: 1px solid var(--hairline);
}
.page-about .panel {
  background: rgba(18, 28, 61, 0.55);
  padding: 20px 18px;
  transition: background-color 0.22s ease, box-shadow 0.22s ease;
}
.page-about .panel:hover {
  background: rgba(18, 28, 61, 0.92);
  box-shadow: inset 0 0 0 1px var(--hairline-cyan);
}
.page-about .panel__index {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 0.625rem;
  letter-spacing: 0.16em;
  color: var(--cyan);
}
.page-about .panel__title {
  margin: 0 0 8px;
  font-size: 1rem;
  font-weight: 700;
  color: var(--white);
}
.page-about .panel__text {
  margin: 0;
  font-size: 0.875rem;
  line-height: 1.8;
  color: var(--text);
}

/* ---------- 版本迭代清单 ---------- */
.page-about .releases {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  margin: 32px 0 0;
  padding: 0;
  list-style: none;
  background: var(--hairline);
  border: 1px solid var(--hairline);
}
.page-about .release {
  background: rgba(18, 28, 61, 0.42);
  padding: 18px 16px;
  transition: background-color 0.22s ease;
}
.page-about .release:hover {
  background: rgba(18, 28, 61, 0.9);
}
.page-about .release__tag {
  display: inline-block;
  margin-bottom: 10px;
  padding: 3px 7px;
  font-family: var(--font-mono);
  font-size: 0.5625rem;
  letter-spacing: 0.16em;
  color: var(--violet-soft);
  border: 1px solid rgba(139, 92, 246, 0.42);
}
.page-about .release__title {
  margin: 0 0 6px;
  font-size: 0.9375rem;
  font-weight: 700;
  color: var(--white);
}
.page-about .release__text {
  margin: 0;
  font-size: 0.8125rem;
  line-height: 1.8;
  color: var(--text);
}

/* ---------- 指标区 ---------- */
.page-about .stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 32px 0 26px;
  background: var(--hairline);
  border: 1px solid var(--hairline);
}
.page-about .stat {
  background: rgba(10, 16, 36, 0.62);
  padding: 20px 16px;
}
.page-about .stat__num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.5rem, 5.4vw, 2.1rem);
  font-weight: 500;
  line-height: 1;
  color: var(--gold);
}
.page-about .stat__unit {
  margin-left: 4px;
  font-size: 0.75rem;
  font-weight: 400;
  color: var(--muted);
}
.page-about .stat__label {
  display: block;
  margin-top: 10px;
  font-size: 0.75rem;
  letter-spacing: 0.03em;
  color: var(--muted);
}

/* ---------- 备案清单 ---------- */
.page-about .legal-list {
  margin: 32px 0 24px;
  border-top: 1px solid var(--hairline);
}
.page-about .legal-list__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 4px;
  padding: 14px 0;
  border-bottom: 1px solid var(--hairline);
}
.page-about .legal-list__k {
  font-family: var(--font-mono);
  font-size: 0.625rem;
  letter-spacing: 0.16em;
  color: var(--muted);
}
.page-about .legal-list__v {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.7;
  color: var(--white);
  word-break: break-word;
}

/* ---------- 联系纸卡 ---------- */
.page-about .contact-cards {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 14px;
  margin: 30px 0 22px;
}
.page-about .paper {
  background: var(--cream);
  color: var(--ink);
  padding: 22px 20px;
  border-left: 3px solid var(--ember);
}
.page-about .paper__label {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 0.625rem;
  letter-spacing: 0.16em;
  color: var(--ember);
}
.page-about .paper__title {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 1rem;
  font-weight: 600;
  line-height: 1.4;
  color: var(--ink);
  word-break: break-all;
}
.page-about .paper__text {
  margin: 0;
  font-size: 0.8125rem;
  line-height: 1.8;
  color: #4A3A2C;
}

/* ---------- 图片 ---------- */
.page-about .figure {
  margin: 36px 0 0;
}
.page-about .figure__frame {
  position: relative;
  overflow: hidden;
  background: var(--panel);
  border: 1px solid var(--hairline);
}
.page-about .figure__frame--wide {
  aspect-ratio: 3 / 2;
}
.page-about .figure__frame--square {
  aspect-ratio: 1 / 1;
}
.page-about .figure__img {
  display: block;
  width: 100%;
  height: 100%;
  max-width: 100%;
  object-fit: cover;
}
.page-about .figure__caption {
  margin: 12px 0 0;
  font-family: var(--font-mono);
  font-size: 0.6875rem;
  letter-spacing: 0.06em;
  line-height: 1.7;
  color: var(--muted);
}

/* ---------- 收束 ---------- */
.page-about .story-outro {
  padding: 60px 0 72px;
  background: linear-gradient(180deg, transparent, rgba(52, 229, 255, 0.05));
}
.page-about .story-outro__inner {
  border-top: 1px solid var(--hairline-cyan);
  padding-top: 42px;
}
.page-about .story-outro__text {
  max-width: 58ch;
  margin: 0 0 26px;
  font-size: 1.0625rem;
  line-height: 1.9;
  color: var(--white);
}
.page-about .story-outro__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- 断点 ---------- */
@media (min-width: 720px) {
  .page-about .story-hero {
    padding-top: calc(var(--mast-h) + 68px);
    padding-bottom: 72px;
  }
  .page-about .story-hero__facts {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .page-about .fact {
    padding: 20px 20px 22px;
  }
  .page-about .flow-cards {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .releases {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .stats {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .contact-cards {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .story-index__link {
    padding: 16px 20px;
  }
}

@media (min-width: 900px) {
  .page-about .chapter__shell {
    grid-template-columns: minmax(0, 3fr) minmax(0, 9fr);
    gap: 60px;
    padding: 84px 0;
    align-items: start;
  }
  .page-about .chapter--flip .chapter__shell {
    grid-template-columns: minmax(0, 9fr) minmax(0, 3fr);
  }
  .page-about .chapter--flip .chapter__aside {
    order: 2;
  }
  .page-about .chapter--flip .chapter__body {
    order: 1;
  }
  .page-about .chapter__aside {
    position: sticky;
    top: var(--about-sticky-offset);
    flex-direction: column;
    align-items: flex-start;
    gap: 18px;
  }
  .page-about .chapter__num {
    font-size: clamp(4.2rem, 7.5vw, 6.8rem);
  }
  .page-about .chapter__label {
    font-size: 0.6875rem;
  }
  .page-about .legal-list__row {
    grid-template-columns: 190px minmax(0, 1fr);
    gap: 24px;
    align-items: baseline;
  }
  .page-about .story-hero__lede {
    font-size: 1.125rem;
  }
  .page-about .figure {
    margin-top: 44px;
  }
}

@media (min-width: 1180px) {
  .page-about .releases {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .page-about .release {
    padding: 22px 20px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .panel,
  .page-about .release,
  .page-about .timeline__item::before,
  .page-about .story-index__link {
    transition: none;
  }
}
</main>