.page-about {
  --about-rail: 300px;
  --about-gap: clamp(24px, 3.2vw, 48px);
}

/* 面包屑 */
.page-about .about-crumb {
  margin: clamp(20px, 3vw, 36px) auto 0;
}
.page-about .about-crumb ol {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--muted);
}
.page-about .about-crumb li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--line);
}
.page-about .about-crumb a {
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color .18s ease, border-color .18s ease;
}
.page-about .about-crumb a:hover,
.page-about .about-crumb a:focus-visible {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}
.page-about .about-crumb [aria-current="page"] {
  color: var(--white);
}

/* 首屏 */
.page-about .about-hero {
  padding: clamp(28px, 5vw, 56px) 0 clamp(44px, 6vw, 80px);
  border-bottom: 1px solid var(--line);
}
.page-about .about-hero-grid {
  display: grid;
  gap: clamp(28px, 3.6vw, 52px);
}
.page-about .about-h1 {
  margin: 14px 0 20px;
  font-size: clamp(34px, 6.2vw, 78px);
  font-weight: 900;
  line-height: 1.04;
  letter-spacing: -.01em;
  color: var(--white);
}
.page-about .about-hero-copy .lede {
  max-width: 62ch;
}
.page-about .about-keynums {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  list-style: none;
  margin: clamp(26px, 3.4vw, 40px) 0 0;
  padding: 0;
  background: var(--line);
  border: 1px solid var(--line);
}
.page-about .about-keynums li {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 16px 18px;
  background: var(--panel);
}
.page-about .about-kn-num {
  font-size: clamp(22px, 2.6vw, 30px);
  font-weight: 700;
  line-height: 1;
  color: var(--cyan);
}
.page-about .about-kn-label {
  font-size: 13px;
  line-height: 1.4;
  color: var(--muted);
}
.page-about .about-hero-media {
  margin: 0;
  align-self: end;
}
.page-about .about-hero-media img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 14 / 9;
  object-fit: cover;
  filter: saturate(1.05) contrast(1.02);
}

/* 主体布局：左索引 + 右叙事 */
.page-about .about-layout {
  display: grid;
  gap: var(--about-gap);
  padding-top: clamp(40px, 6vw, 76px);
  padding-bottom: clamp(40px, 6vw, 80px);
}
.page-about .about-rail {
  display: none;
}
.page-about .about-toc {
  list-style: none;
  margin: 18px 0 0;
  padding: 0;
  border-left: 1px solid var(--line);
}
.page-about .about-toc li {
  border-bottom: 1px solid var(--line);
}
.page-about .about-toc a {
  display: flex;
  align-items: baseline;
  gap: 12px;
  padding: 12px 14px;
  font-size: 14px;
  line-height: 1.4;
  color: var(--muted);
  text-decoration: none;
  border-left: 2px solid transparent;
  transition: color .18s ease, background-color .18s ease, border-color .18s ease;
}
.page-about .about-toc a .mono {
  color: var(--cyan);
  font-size: 12px;
}
.page-about .about-toc a:hover,
.page-about .about-toc a:focus-visible {
  color: var(--white);
  background: var(--mist-soft);
  border-left-color: var(--cyan);
}
.page-about .about-toc a[aria-current="true"],
.page-about .about-toc a.is-active {
  color: var(--white);
  background: var(--mist-soft);
  border-left-color: var(--lava);
}
.page-about .about-rail-note {
  margin: 0;
  font-size: 11px;
  letter-spacing: .16em;
  color: var(--cyan);
}
.page-about .about-rail-foot {
  margin: 20px 0 0;
  padding: 12px 14px;
  font-size: 11px;
  letter-spacing: .1em;
  line-height: 1.7;
  color: var(--muted);
  background: var(--panel);
  border: 1px solid var(--line);
}

/* 章节骨架 */
.page-about .about-sec {
  padding: 0 0 clamp(48px, 6vw, 84px);
  margin-bottom: clamp(32px, 4vw, 52px);
  border-bottom: 1px solid var(--line);
  scroll-margin-top: 96px;
}
.page-about .about-sec:last-of-type {
  border-bottom: 0;
}
.page-about .about-sec-head {
  position: relative;
  padding-left: 0;
  margin-bottom: clamp(22px, 3vw, 34px);
}
.page-about .about-sec-idx {
  margin: 0 0 10px;
  font-size: 13px;
  letter-spacing: .22em;
  color: var(--cyan);
}
.page-about .about-sec-head .h2 {
  margin: 0;
  max-width: 20ch;
}
.page-about .about-mark {
  display: none;
}
.page-about .about-block-title {
  margin: 0 0 12px;
  font-size: 12px;
  letter-spacing: .16em;
  color: var(--muted);
}
.page-about .about-fineprint {
  margin: 16px 0 0;
  font-size: 13px;
  line-height: 1.75;
  color: var(--muted);
}

/* 分栏 */
.page-about .about-split {
  display: grid;
  gap: clamp(24px, 3vw, 40px);
}

/* 项目标签 */
.page-about .about-taglist {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0;
}

/* 使用场景 */
.page-about .about-uses {
  display: grid;
  gap: 1px;
  margin-top: clamp(26px, 3.4vw, 40px);
  background: var(--line);
  border: 1px solid var(--line);
}
.page-about .about-use {
  padding: 20px 20px 22px;
  background: var(--panel);
  border-top: 2px solid transparent;
  transition: background-color .2s ease, border-color .2s ease;
}
.page-about .about-use:hover {
  background: var(--panel-hi);
  border-top-color: var(--cyan);
}
.page-about .about-use .h3 {
  margin: 0 0 8px;
}
.page-about .about-use .prose {
  margin: 0;
}

/* 历程图 */
.page-about .about-chart {
  margin: 0 0 clamp(26px, 3.4vw, 40px);
}
.page-about .about-chart img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 10 / 7;
  object-fit: cover;
}

/* 版本时间轴 */
.page-about .about-timeline {
  list-style: none;
  margin: 0;
  padding: 0 0 0 clamp(22px, 3vw, 34px);
  position: relative;
}
.page-about .about-timeline::before {
  content: "";
  position: absolute;
  left: 0;
  top: 10px;
  bottom: 20px;
  width: 1px;
  background: linear-gradient(180deg, var(--cyan) 0%, var(--line) 55%, var(--line) 100%);
}
.page-about .about-tl-item {
  position: relative;
  padding-bottom: clamp(28px, 3.6vw, 44px);
}
.page-about .about-tl-item:last-child {
  padding-bottom: 0;
}
.page-about .about-tl-item::before {
  content: "";
  position: absolute;
  left: calc(-1 * clamp(22px, 3vw, 34px) - 4px);
  top: 7px;
  width: 9px;
  height: 9px;
  background: var(--ink);
  border: 1px solid var(--cyan);
}
.page-about .about-tl-item:first-child::before {
  background: var(--cyan);
}
.page-about .about-tl-ver {
  margin: 0 0 8px;
  font-size: 12px;
  letter-spacing: .14em;
  color: var(--muted);
  transition: color .18s ease;
}
.page-about .about-tl-item:hover .about-tl-ver,
.page-about .about-tl-item:focus-within .about-tl-ver {
  color: var(--lava);
}
.page-about .about-tl-item .h3 {
  margin: 0 0 10px;
}
.page-about .about-tl-item .prose {
  margin: 0;
  max-width: 60ch;
}

/* 团队与流程 */
.page-about .about-flow {
  list-style: none;
  margin: clamp(22px, 3vw, 32px) 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}
.page-about .about-flow li {
  position: relative;
  padding: 18px 18px 18px 58px;
  background: var(--panel);
}
.page-about .about-flow-idx {
  position: absolute;
  left: 18px;
  top: 18px;
  font-size: 14px;
  font-weight: 700;
  color: var(--neon);
}
.page-about .about-flow .h3 {
  margin: 0 0 6px;
}
.page-about .about-flow .prose {
  margin: 0;
}
.page-about .about-flow-media {
  margin: 0;
  align-self: start;
}
.page-about .about-flow-media img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
}

/* 展开阅读 */
.page-about .about-details {
  margin-top: clamp(24px, 3vw, 34px);
  border: 1px solid var(--line);
  background: var(--panel);
}
.page-about .about-details summary {
  cursor: pointer;
  padding: 16px 18px;
  font-size: 15px;
  font-weight: 700;
  color: var(--white);
  list-style: none;
  display: flex;
  align-items: center;
  gap: 10px;
}
.page-about .about-details summary::-webkit-details-marker {
  display: none;
}
.page-about .about-details summary::before {
  content: "+";
  font-family: var(--mono);
  font-size: 16px;
  color: var(--cyan);
}
.page-about .about-details[open] summary::before {
  content: "−";
  color: var(--lava);
}
.page-about .about-details summary:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: -2px;
}
.page-about .about-details .prose {
  margin: 0;
  padding: 0 18px 20px;
  border-top: 1px solid var(--line);
  padding-top: 16px;
}

/* 合作生态 */
.page-about .about-partner-cards {
  display: grid;
  gap: 14px;
}
.page-about .about-partner-card {
  padding: 20px;
  background: var(--panel);
}
.page-about .about-partner-card .card-title {
  margin: 14px 0 8px;
}
.page-about .about-partner-card .prose {
  margin: 0;
}

/* 规模条 */
.page-about .about-scale-bar {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
  border-top: 3px solid var(--lava);
  margin-bottom: clamp(26px, 3.4vw, 40px);
}
.page-about .about-scale-cell {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: clamp(18px, 2.4vw, 28px);
  background: var(--panel);
}
.page-about .about-scale-num {
  font-size: clamp(28px, 4vw, 46px);
  font-weight: 700;
  line-height: 1;
  color: var(--white);
}
.page-about .about-scale-label {
  font-size: 13px;
  color: var(--muted);
}
.page-about .about-quote-panel {
  padding: 24px 22px;
  background: var(--deep);
  border: 1px solid var(--line);
  border-left: 3px solid var(--cyan);
}
.page-about .about-quote {
  margin: 0 0 14px;
  font-size: clamp(15px, 1.7vw, 18px);
  line-height: 1.7;
  color: var(--white);
}
.page-about .about-quote-from {
  margin: 0;
  font-size: 12px;
  letter-spacing: .08em;
  color: var(--muted);
}

/* 去向卡片 */
.page-about .about-next {
  padding-top: clamp(34px, 4vw, 52px);
  border-top: 1px solid var(--line);
}
.page-about .about-next .h2 {
  margin: 0 0 clamp(20px, 2.6vw, 30px);
}
.page-about .about-next-grid {
  display: grid;
  gap: 14px;
}
.page-about .about-next-card {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 20px;
  background: var(--panel);
  border: 1px solid var(--line);
  text-decoration: none;
  transition: border-color .18s ease, background-color .18s ease;
}
.page-about .about-next-card:hover,
.page-about .about-next-card:focus-visible {
  border-color: var(--cyan);
  background: var(--mist-soft);
}
.page-about .about-next-idx {
  font-size: 12px;
  letter-spacing: .2em;
  color: var(--cyan);
}
.page-about .about-next-title {
  font-size: 19px;
  font-weight: 800;
  line-height: 1.25;
  color: var(--white);
}
.page-about .about-next-desc {
  font-size: 14px;
  line-height: 1.65;
  color: var(--muted);
}

/* 平板 */
@media (min-width: 720px) {
  .page-about .about-keynums {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .page-about .about-uses {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .about-scale-bar {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
  .page-about .about-partner-cards {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .about-next-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .about-flow {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

/* 桌面：左索引 + 右叙事 */
@media (min-width: 1000px) {
  .page-about .about-hero-grid {
    grid-template-columns: 5fr 7fr;
    align-items: end;
  }
  .page-about .about-layout {
    grid-template-columns: minmax(240px, 4fr) minmax(0, 8fr);
    gap: clamp(32px, 4vw, 64px);
    align-items: start;
  }
  .page-about .about-rail {
    display: block;
    position: sticky;
    top: 104px;
    align-self: start;
  }
  .page-about .about-sec-head {
    padding-right: 44px;
    min-height: 92px;
  }
  .page-about .about-mark {
    display: block;
    position: absolute;
    right: 0;
    top: 4px;
    font-size: 11px;
    letter-spacing: .28em;
    color: var(--line);
  }
  .page-about .about-split--5-7 {
    grid-template-columns: 5fr 7fr;
  }
  .page-about .about-split--7-5 {
    grid-template-columns: 7fr 5fr;
  }
  .page-about .about-sec--scale .about-split--7-5 {
    align-items: center;
  }
}