.page-about {
  --about-rail: 92px;
  --about-toc: 216px;
  background: var(--ink);
  color: var(--mist);
  font-family: var(--font-body);
  overflow-x: hidden;
}

/* 首屏 */
.page-about .about-hero {
  position: relative;
  padding: clamp(24px, 4vw, 48px) 0 clamp(32px, 5vw, 64px);
  border-bottom: 1px solid var(--line-d);
  background-image:
    repeating-linear-gradient(90deg, var(--line-d-soft) 0 1px, transparent 1px 96px),
    repeating-linear-gradient(0deg, var(--line-d-soft) 0 1px, transparent 1px 96px);
}

.page-about .about-hero__grid {
  display: grid;
  gap: clamp(20px, 3vw, 36px);
  margin-top: clamp(18px, 3vw, 34px);
}

.page-about .about-hero__title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(44px, 10vw, 108px);
  line-height: 0.92;
  letter-spacing: -0.02em;
  text-transform: uppercase;
  margin: 14px 0 0;
  color: var(--mist);
}

.page-about .about-hero__lead p {
  margin: 0 0 1em;
  font-size: clamp(15px, 1.6vw, 17px);
  line-height: 1.8;
  color: var(--mist-dim);
  max-width: 54ch;
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 22px;
}

.page-about .about-figures {
  display: grid;
  gap: 1px;
  margin: clamp(28px, 4vw, 48px) 0 0;
  border-top: 1px solid var(--line-d);
  background: var(--line-d-soft);
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.page-about .about-figures__item {
  padding: 16px 12px 14px 0;
  background: var(--ink);
}

.page-about .about-figures__item dt {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--grid);
}

.page-about .about-figures__item dd {
  margin: 8px 0 0;
  color: var(--mist);
}

.page-about .about-figures__item .num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(26px, 4vw, 40px);
  line-height: 1;
  color: var(--signal);
}

.page-about .about-figures__unit {
  font-size: 12px;
  margin-left: 6px;
  color: var(--mist-dim);
}

/* 主体网格 */
.page-about .about-body {
  display: grid;
  gap: clamp(24px, 3vw, 40px);
  padding-top: clamp(28px, 4vw, 56px);
  padding-bottom: clamp(44px, 6vw, 88px);
}

/* 章节目录 */
.page-about .about-toc {
  border-top: 2px solid var(--signal);
  padding-top: 14px;
}

.page-about .about-toc__list {
  list-style: none;
  margin: 12px 0 0;
  padding: 0;
}

.page-about .about-toc__list li {
  border-bottom: 1px solid var(--line-d-soft);
}

.page-about .about-toc__list a {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 10px 0;
  color: var(--mist-dim);
  text-decoration: none;
  font-size: 14px;
  transition: color 0.18s ease, padding-left 0.18s ease;
}

.page-about .about-toc__list a .mono {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 11px;
  color: var(--grid);
}

.page-about .about-toc__list a:hover,
.page-about .about-toc__list a:focus-visible {
  color: var(--signal);
  padding-left: 4px;
}

.page-about .about-toc__list a.is-active,
.page-about .about-toc__list a[aria-current] {
  color: var(--signal);
}

.page-about .about-toc__list a.is-active .mono,
.page-about .about-toc__list a[aria-current] .mono {
  color: var(--flash);
}

.page-about .about-toc__note {
  margin: 16px 0 0;
  font-size: 12px;
  line-height: 1.7;
  color: var(--grid);
}

/* 堆叠画板 */
.page-about .about-stack {
  display: grid;
  gap: clamp(18px, 2.6vw, 32px);
}

.page-about .board {
  position: relative;
  display: grid;
  gap: clamp(14px, 2vw, 26px);
  padding: clamp(20px, 3vw, 38px);
  border: 1px solid var(--line-d);
  border-radius: var(--radius);
  background: var(--ink2);
  box-shadow: 8px 8px 0 0 rgba(5, 7, 8, 0.55);
}

.page-about .board--light {
  background: var(--mist);
  color: var(--ink);
  border-color: var(--line-l);
}

.page-about .board--signal {
  background: var(--signal);
  color: var(--ink);
  border-color: var(--signal);
}

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

.page-about .board__num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(30px, 5vw, 54px);
  line-height: 1;
  color: var(--signal);
}

.page-about .board--signal .board__num {
  color: var(--ink);
}

.page-about .board__tag {
  font-family: var(--font-mono);
  font-size: 10px;
  letter-spacing: 0.3em;
  text-transform: uppercase;
  color: var(--grid);
}

.page-about .board__cols {
  display: grid;
  gap: 16px;
  margin-top: 14px;
}

.page-about .board__main {
  max-width: 68ch;
}

.page-about .board__main p {
  margin: 0 0 1em;
  font-size: 16px;
  line-height: 1.78;
}

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

.page-about .board__aside {
  padding-left: 12px;
  border-left: 2px solid var(--signal);
}

.page-about .board__aside--ink {
  border-left-color: var(--ink);
}

.page-about .aside-note {
  margin: 0;
  font-size: 12.5px;
  line-height: 1.75;
  color: var(--grid);
}

.page-about .aside-note--ink {
  color: var(--ink-dim);
}

/* 要点列表 */
.page-about .point-list {
  list-style: none;
  margin: 18px 0 0;
  padding: 0;
  border-top: 1px solid var(--line-l-soft);
}

.page-about .point-list li {
  padding: 12px 0;
  border-bottom: 1px solid var(--line-l-soft);
  font-size: 15px;
  line-height: 1.7;
  color: var(--ink-dim);
}

.page-about .point-list li strong {
  display: inline-block;
  min-width: 8.5em;
  color: var(--ink);
  font-weight: 700;
}

/* 图片 */
.page-about .about-figure {
  margin: 20px 0 0;
}

.page-about .about-figure--inset {
  margin-top: 24px;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--line-d);
}

.page-about .board--light .about-figure img {
  border-color: var(--line-l);
}

.page-about .about-figure figcaption {
  margin-top: 8px;
  font-size: 12px;
  line-height: 1.7;
  color: var(--grid);
}

.page-about .board--light .about-figure figcaption {
  color: var(--ink-dim);
}

/* 版本时间线 */
.page-about .tl {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line-d);
  border: 1px solid var(--line-d);
}

.page-about .tl__item {
  position: relative;
  padding: 18px 16px 20px;
  background: var(--ink);
}

.page-about .tl__item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 100%;
  height: 3px;
  background: var(--grid);
}

.page-about .tl__item--now::before {
  background: var(--signal);
}

.page-about .tl__ver {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 13px;
  letter-spacing: 0.12em;
  color: var(--flash);
}

.page-about .tl__name {
  margin: 8px 0 8px;
  font-family: var(--font-display);
  font-size: 20px;
  line-height: 1.2;
  letter-spacing: -0.01em;
  color: var(--mist);
}

.page-about .tl__item p {
  margin: 0;
  font-size: 13.5px;
  line-height: 1.7;
  color: var(--mist-dim);
}

/* 索引标签矩阵 */
.page-about .idx-grid {
  display: grid;
  gap: 1px;
  margin-top: 24px;
  background: var(--line-l);
  border: 1px solid var(--line-l);
}

.page-about .idx {
  background: var(--mist);
  padding: 0;
}

.page-about .idx > summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  padding: 14px 16px;
  cursor: pointer;
  list-style: none;
  border-left: 3px solid var(--ink);
}

.page-about .idx > summary::-webkit-details-marker {
  display: none;
}

.page-about .idx > summary:hover {
  background: rgba(7, 20, 27, 0.04);
}

.page-about .idx[open] > summary {
  border-left-color: var(--signal);
}

.page-about .idx__meta {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 11.5px;
  color: var(--ink-dim);
  white-space: nowrap;
}

.page-about .idx p {
  margin: 0;
  padding: 0 16px 16px;
  font-size: 14px;
  line-height: 1.75;
  color: var(--ink-dim);
}

/* 团队分工 */
.page-about .team {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line-d);
  border: 1px solid var(--line-d);
}

.page-about .team__cell {
  background: var(--ink);
  padding: 16px 14px;
}

.page-about .team__num {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(26px, 4vw, 40px);
  line-height: 1;
  color: var(--signal);
}

.page-about .team__label {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  color: var(--mist-dim);
}

/* 合作生态 */
.page-about .eco {
  list-style: none;
  margin: 24px 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line-l);
  border-top: 2px solid var(--ink);
  border-bottom: 1px solid var(--line-l);
}

.page-about .eco__item {
  padding: 16px 4px;
  background: var(--mist);
}

.page-about .eco__num {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(30px, 5vw, 46px);
  line-height: 1;
  color: var(--ink);
}

.page-about .eco__label {
  display: block;
  margin-top: 6px;
  font-size: 13px;
  color: var(--ink-dim);
}

/* 结尾 */
.page-about .about-next__text {
  margin: 14px 0 0;
  max-width: 62ch;
  font-size: 15.5px;
  line-height: 1.8;
  color: var(--ink);
}

.page-about .about-next__links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 22px;
}

.page-about .board--signal .btn--light {
  background: var(--ink);
  color: var(--mist);
  border-color: var(--ink);
}

.page-about .board--signal .btn--light:hover,
.page-about .board--signal .btn--light:focus-visible {
  background: transparent;
  color: var(--ink);
}

/* 平板以上 */
@media (min-width: 640px) {
  .page-about .about-figures {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

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

  .page-about .eco {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .eco__item {
    padding: 18px 16px;
  }
}

/* 桌面：左侧目录跟随 + 章节画板错位 */
@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    align-items: end;
  }

  .page-about .about-body {
    grid-template-columns: var(--about-toc) minmax(0, 1fr);
    align-items: start;
  }

  .page-about .about-toc {
    position: sticky;
    top: calc(var(--header-h) + 20px);
  }

  .page-about .board {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: clamp(18px, 2.4vw, 32px);
  }

  .page-about .board__rail {
    flex-direction: column;
    align-items: flex-start;
    gap: 14px;
    border-right: 1px solid var(--line-d);
    padding-right: 10px;
  }

  .page-about .board--light .board__rail {
    border-right-color: var(--line-l);
  }

  .page-about .board--signal .board__rail {
    border-right-color: rgba(7, 20, 27, 0.28);
  }

  .page-about .board__tag {
    writing-mode: vertical-rl;
    transform: rotate(180deg);
    letter-spacing: 0.34em;
  }

  .page-about .about-stack > .board:nth-child(even) {
    margin-left: clamp(0px, 1.8vw, 26px);
  }

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

@media (min-width: 1120px) {
  .page-about .board__cols {
    grid-template-columns: minmax(0, 1fr) minmax(0, 250px);
    gap: clamp(20px, 3vw, 40px);
    align-items: start;
  }

  .page-about .board__aside {
    padding-left: 16px;
  }

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

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

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

@media (prefers-reduced-motion: reduce) {
  .page-about .about-toc__list a {
    transition: none;
  }
}
<<<END>>>