.page-about {
  --about-rail-w: 190px;
  --about-space: clamp(72px, 10vw, 120px);
  position: relative;
  overflow-x: clip;
  background: var(--ink-900);
  color: var(--bone-100);
  padding-bottom: clamp(64px, 10vw, 120px);
}

/* 面包屑 */
.page-about .about-crumbs {
  padding-top: clamp(20px, 4vw, 36px);
}
.page-about .about-crumbs .breadcrumbs__list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: var(--fs-13);
  letter-spacing: 0.06em;
  color: var(--mist-300);
}
.page-about .about-crumbs .breadcrumbs__item + .breadcrumbs__item::before {
  content: "/";
  margin-right: 10px;
  color: var(--line);
}
.page-about .about-crumbs a {
  color: var(--mist-300);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.page-about .about-crumbs a:hover,
.page-about .about-crumbs a:focus-visible {
  color: var(--lime-400);
  border-bottom-color: var(--lime-400);
}
.page-about .about-crumbs [aria-current="page"] {
  color: var(--bone-100);
}

/* 首屏 */
.page-about .about-hero {
  position: relative;
  padding: clamp(40px, 7vw, 76px) 0 clamp(48px, 7vw, 88px);
}
.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0 0 auto;
  height: 100%;
  pointer-events: none;
  background-image:
    linear-gradient(to right, rgba(42, 58, 52, 0.75) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(42, 58, 52, 0.75) 1px, transparent 1px);
  background-size: 88px 88px;
  opacity: 0.5;
  -webkit-mask-image: linear-gradient(to bottom, #000 0%, transparent 82%);
  mask-image: linear-gradient(to bottom, #000 0%, transparent 82%);
}
.page-about .about-hero > * {
  position: relative;
}
.page-about .about-hero__eyebrow {
  margin: 0;
  font-size: var(--fs-13);
  letter-spacing: 0.22em;
  color: var(--lime-400);
  text-transform: uppercase;
  padding-left: 14px;
  border-left: 2px solid var(--lime-400);
}
.page-about .about-hero__title {
  margin: clamp(20px, 3vw, 32px) 0 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(2.1rem, 6vw, 4rem);
  line-height: 1;
  letter-spacing: -0.02em;
  max-width: 20ch;
}
.page-about .about-hero__lede {
  margin: clamp(20px, 3vw, 28px) 0 0;
  max-width: 52ch;
  font-size: var(--fs-body);
  line-height: 1.8;
  color: var(--mist-300);
}
.page-about .about-hero__facts {
  display: flex;
  flex-wrap: wrap;
  gap: 14px 26px;
  margin: clamp(28px, 4vw, 44px) 0 0;
  padding: 0;
  list-style: none;
  font-family: var(--font-mono);
  font-size: var(--fs-13);
  letter-spacing: 0.06em;
  color: var(--mist-300);
}
.page-about .about-hero__facts li {
  display: inline-flex;
  align-items: baseline;
  gap: 8px;
  padding-left: 12px;
  border-left: 1px solid var(--line);
}
.page-about .about-hero__fact-num {
  font-size: 1.25rem;
  color: var(--lime-400);
}

/* 主体布局 */
.page-about .about-layout {
  display: grid;
  gap: clamp(32px, 5vw, 48px);
  margin-top: clamp(36px, 6vw, 72px);
}

/* 左侧章节导航 */
.page-about .about-rail {
  border-top: 1px solid var(--line);
  padding-top: 16px;
}
.page-about .about-rail__label {
  margin: 0 0 12px;
  font-size: 11px;
  letter-spacing: 0.24em;
  color: var(--mist-300);
  text-transform: uppercase;
}
.page-about .about-rail__list {
  display: flex;
  flex-wrap: wrap;
  gap: 6px 20px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.page-about .about-rail__link {
  position: relative;
  display: inline-flex;
  align-items: baseline;
  gap: 9px;
  padding: 6px 0;
  font-family: var(--font-mono);
  font-size: var(--fs-13);
  letter-spacing: 0.06em;
  color: var(--mist-300);
  text-decoration: none;
  transition: color var(--dur) var(--ease);
}
.page-about .about-rail__num {
  color: var(--amber-500);
  font-size: 11px;
  letter-spacing: 0.12em;
}
.page-about .about-rail__link::after {
  content: "";
  position: absolute;
  left: -12px;
  top: 50%;
  width: 8px;
  height: 1px;
  background: var(--amber-500);
  transform: translateY(-50%) scaleX(0);
  transform-origin: left center;
  transition: transform var(--dur) var(--ease);
}
.page-about .about-rail__link:hover,
.page-about .about-rail__link:focus-visible {
  color: var(--bone-100);
}
.page-about .about-rail__link:hover::after,
.page-about .about-rail__link:focus-visible::after {
  transform: translateY(-50%) scaleX(1);
}

/* 区块与排版 */
.page-about .about-body {
  min-width: 0;
}
.page-about .about-body > .about-block + .about-block {
  margin-top: var(--about-space);
}
.page-about .about-block {
  position: relative;
  padding-top: clamp(28px, 4vw, 44px);
  border-top: 1px solid var(--line);
  scroll-margin-top: calc(var(--header-h) + 24px);
}
.page-about .about-body > .about-block:first-child {
  padding-top: 0;
  border-top: 0;
}
.page-about .about-block__num {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-weight: 100;
  font-size: clamp(3rem, 7vw, 5.5rem);
  line-height: 0.82;
  letter-spacing: -0.03em;
  color: var(--mist-300);
  opacity: 0.3;
  user-select: none;
}
.page-about .about-block__title {
  margin: 0 0 clamp(16px, 2.4vw, 24px);
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(1.55rem, 3.4vw, 2.4rem);
  line-height: 1.06;
  letter-spacing: -0.01em;
  max-width: 24ch;
}
.page-about .about-prose p {
  margin: 0 0 1.2em;
  max-width: 62ch;
  font-size: var(--fs-body);
  line-height: 1.82;
  color: var(--bone-100);
}
.page-about .about-prose p:last-child {
  margin-bottom: 0;
}
.page-about .about-prose a {
  color: var(--lime-400);
  text-decoration: none;
  border-bottom: 1px solid var(--line);
  transition: border-color var(--dur) var(--ease);
}
.page-about .about-prose a:hover,
.page-about .about-prose a:focus-visible {
  border-bottom-color: var(--lime-400);
}

/* 图片 */
.page-about .about-figure {
  margin: clamp(32px, 5vw, 56px) 0 0;
}
.page-about .about-body > .about-figure {
  margin-top: clamp(40px, 6vw, 80px);
}
.page-about .about-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--line);
  filter: saturate(0.78) contrast(1.04);
}
.page-about .about-figure figcaption {
  margin-top: 12px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--mist-300);
}
.page-about .about-figure--tall img {
  max-width: 420px;
}

/* 时间轴 */
.page-about .about-timeline__hint {
  margin: 0 0 clamp(24px, 3vw, 36px);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--amber-500);
}
.page-about .about-timeline__list {
  display: grid;
  gap: 26px;
  margin: 0;
  padding: 0;
  list-style: none;
}
.page-about .about-timeline__item {
  position: relative;
  padding-top: 26px;
  border-top: 1px solid var(--line);
}
.page-about .about-timeline__dot {
  position: absolute;
  top: -5px;
  left: 0;
  width: 9px;
  height: 9px;
  background: var(--ink-900);
  border: 1px solid var(--mist-300);
  transition: background var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.page-about .about-timeline__node {
  display: block;
  text-decoration: none;
  color: inherit;
}
.page-about .about-timeline__year {
  display: block;
  margin-bottom: 8px;
  font-size: var(--fs-13);
  letter-spacing: 0.14em;
  color: var(--amber-500);
  transition: color var(--dur) var(--ease);
}
.page-about .about-timeline__name {
  display: block;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(1.05rem, 2vw, 1.3rem);
  line-height: 1.2;
  max-width: 18ch;
}
.page-about .about-timeline__more {
  display: inline-block;
  margin-top: 10px;
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--mist-300);
  border-bottom: 1px solid var(--line);
  padding-bottom: 2px;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.page-about .about-timeline__item:hover .about-timeline__dot,
.page-about .about-timeline__item:focus-within .about-timeline__dot {
  background: var(--lime-400);
  border-color: var(--lime-400);
}
.page-about .about-timeline__item:hover .about-timeline__year,
.page-about .about-timeline__item:focus-within .about-timeline__year {
  color: var(--lime-400);
}
.page-about .about-timeline__item:hover .about-timeline__more,
.page-about .about-timeline__item:focus-within .about-timeline__more {
  color: var(--lime-400);
  border-bottom-color: var(--lime-400);
}
.page-about .about-timeline__detail {
  display: none;
  margin-top: 16px;
  padding-left: 14px;
  border-left: 2px solid var(--lime-400);
  font-size: var(--fs-13);
  line-height: 1.78;
  color: var(--mist-300);
}
.page-about .about-timeline__detail p {
  margin: 0;
}
.page-about .about-timeline__detail:target {
  display: block;
}

/* 内容准则 */
.page-about .about-rules {
  margin: clamp(24px, 4vw, 40px) 0 0;
  padding: 0;
  list-style: none;
}
.page-about .about-rules__item {
  position: relative;
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 14px;
  padding: 20px 0 20px 16px;
  border-top: 1px solid var(--line);
}
.page-about .about-rules__item:last-child {
  border-bottom: 1px solid var(--line);
}
.page-about .about-rules__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--lime-400);
  transform: scaleY(0);
  transform-origin: top center;
  transition: transform var(--dur) var(--ease);
}
.page-about .about-rules__item:hover::before,
.page-about .about-rules__item:focus-within::before {
  transform: scaleY(1);
}
.page-about .about-rules__num {
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--amber-500);
  padding-top: 4px;
}
.page-about .about-rules__title {
  margin: 0 0 8px;
  font-family: var(--font-body);
  font-size: var(--fs-18);
  font-weight: 600;
  line-height: 1.4;
  color: var(--bone-100);
}
.page-about .about-rules__body p {
  margin: 0;
  max-width: 58ch;
  font-size: var(--fs-13);
  line-height: 1.8;
  color: var(--mist-300);
}

/* 合作生态 */
.page-about .about-coop {
  display: grid;
  gap: clamp(20px, 3vw, 32px);
  margin-top: clamp(20px, 3vw, 32px);
  padding: clamp(22px, 4vw, 40px);
  background: var(--charcoal-800);
  border: 1px solid var(--line);
  border-left: 2px solid var(--lime-400);
}
.page-about .about-coop__figure {
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.page-about .about-coop__num {
  font-family: var(--font-display);
  font-weight: 900;
  font-size: clamp(3rem, 8vw, 4.6rem);
  line-height: 0.84;
  letter-spacing: -0.03em;
  color: var(--lime-400);
}
.page-about .about-coop__unit {
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--mist-300);
}
.page-about .about-coop__text p {
  margin: 0 0 1em;
  max-width: 56ch;
  font-size: var(--fs-body);
  line-height: 1.8;
  color: var(--bone-100);
}
.page-about .about-coop__text p:last-child {
  margin-bottom: 0;
}
.page-about .about-coop__text a {
  color: var(--lime-400);
  text-decoration: none;
  border-bottom: 1px solid var(--line);
  transition: border-color var(--dur) var(--ease);
}
.page-about .about-coop__text a:hover,
.page-about .about-coop__text a:focus-visible {
  border-bottom-color: var(--lime-400);
}

/* 行动区 */
.page-about .about-cta {
  padding-top: clamp(32px, 5vw, 52px);
  border-top: 1px solid var(--line);
}
.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(20px, 3vw, 28px);
}
.page-about .about-cta__actions .btn {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  text-decoration: none;
}

/* 平板与桌面 */
@media (min-width: 720px) {
  .page-about .about-timeline__list {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 24px;
  }
  .page-about .about-rules__item {
    grid-template-columns: 44px minmax(0, 1fr);
    gap: 20px;
    padding-left: 20px;
  }
  .page-about .about-coop {
    grid-template-columns: minmax(0, 200px) minmax(0, 1fr);
    align-items: start;
  }
}

@media (min-width: 960px) {
  .page-about .about-layout {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: clamp(48px, 6vw, 96px);
  }
  .page-about .about-rail {
    position: sticky;
    top: calc(var(--header-h) + 32px);
    align-self: start;
    padding-left: 14px;
  }
  .page-about .about-rail__list {
    display: block;
  }
  .page-about .about-rail__list li + li {
    margin-top: 4px;
  }
  .page-about .about-rail__link {
    display: flex;
    width: 100%;
  }
  .page-about .about-block__num {
    position: absolute;
    top: clamp(20px, 3vw, 36px);
    left: 0;
    margin: 0;
    opacity: 0.16;
    font-size: clamp(4rem, 8vw, 6.5rem);
  }
  .page-about .about-block__title {
    padding-top: clamp(28px, 4vw, 48px);
  }
  .page-about .about-body > .about-block:first-child .about-block__num {
    top: 6px;
  }
  .page-about .about-body > .about-block:first-child .about-block__title {
    padding-top: clamp(32px, 4vw, 52px);
  }
}

@media (min-width: 1180px) {
  .page-about .about-figure--tall img {
    max-width: 480px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-rail__link::after,
  .page-about .about-rules__item::before,
  .page-about .about-timeline__dot {
    transition: none;
  }
}
</main>