.page-about {
  --about-rail-w: 232px;
  --about-rule: var(--sand-gray);
  background: var(--sand-white);
  color: var(--ink);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding: calc(var(--header-h) + 64px) 0 0;
  background: var(--deep-sea);
  color: var(--sand-white);
  overflow: hidden;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  left: 0;
  right: 0;
  bottom: 0;
  height: 1px;
  background: linear-gradient(90deg, transparent, var(--tide-teal) 40%, var(--signal-orange) 100%);
  opacity: .7;
}

.page-about .about-hero-inner {
  display: grid;
  gap: 20px;
  padding-bottom: 52px;
  justify-items: start;
}

.page-about .about-hero .breadcrumb-list {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  list-style: none;
  margin: 0;
  padding: 0;
  font-size: 12px;
  letter-spacing: .14em;
  color: rgba(245, 239, 228, .62);
}

.page-about .about-hero .breadcrumb-list li + li::before {
  content: "/";
  margin-right: 8px;
  color: var(--tide-teal-soft);
}

.page-about .about-hero .breadcrumb-list a {
  color: rgba(245, 239, 228, .78);
  text-decoration: none;
}

.page-about .about-hero .breadcrumb-list a:hover,
.page-about .about-hero .breadcrumb-list a:focus-visible {
  color: var(--tide-teal-soft);
}

.page-about .about-hero .display-title {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(40px, 6.4vw, 84px);
  line-height: .98;
  letter-spacing: .05em;
  text-transform: uppercase;
  font-weight: 800;
}

.page-about .about-hero .eyebrow {
  color: var(--tide-teal-soft);
  letter-spacing: .26em;
  margin: 0;
}

.page-about .about-hero .lede {
  max-width: 660px;
  margin: 0;
  color: rgba(245, 239, 228, .82);
  font-size: 17px;
  line-height: 1.85;
}

.page-about .about-hero-figure {
  margin: 0;
  line-height: 0;
}

.page-about .about-hero-figure img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 6;
  object-fit: cover;
}

/* ---------- 双栏骨架 ---------- */
.page-about .about-layout {
  display: grid;
  grid-template-columns: 1fr;
  gap: 44px;
  padding-top: 56px;
  padding-bottom: 88px;
}

.page-about .about-rail-inner {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.page-about .about-rail-inner > .annotation {
  margin: 0;
  letter-spacing: .28em;
  color: var(--tide-teal);
}

.page-about .about-toc-list {
  list-style: none;
  margin: 0;
  padding: 18px 0 0;
  border-top: 1px solid var(--about-rule);
  display: flex;
  flex-wrap: wrap;
  gap: 6px 22px;
}

.page-about .about-toc-list a {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 5px 0;
  font-size: 14px;
  color: var(--ink);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 220ms var(--ease), border-color 220ms var(--ease);
}

.page-about .about-toc-list a .mono {
  font-size: 11px;
  letter-spacing: .12em;
  color: var(--tide-teal);
}

.page-about .about-toc-list a:hover,
.page-about .about-toc-list a:focus-visible {
  color: var(--signal-orange);
  border-bottom-color: var(--signal-orange);
}

.page-about .about-toc-list a:focus-visible,
.page-about .year-node:focus-visible,
.page-about .about-detail summary:focus-visible {
  outline: 2px solid var(--signal-orange);
  outline-offset: 3px;
}

.page-about .about-rail-mark {
  display: none;
  writing-mode: vertical-rl;
  letter-spacing: .36em;
  color: rgba(18, 166, 160, .55);
  margin: 8px 0 0;
  font-size: 11px;
}

/* ---------- 内容列 ---------- */
.page-about .about-body {
  display: flex;
  flex-direction: column;
  gap: 76px;
  min-width: 0;
}

.page-about .about-section {
  display: grid;
  gap: 24px;
  scroll-margin-top: calc(var(--header-h) + 32px);
}

.page-about .about-section-head {
  display: grid;
  gap: 10px;
  padding-top: 22px;
  border-top: 1px solid var(--about-rule);
}

.page-about .about-section-head .eyebrow {
  margin: 0;
  color: var(--tide-teal);
  letter-spacing: .24em;
}

.page-about .about-section-head .section-title {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(26px, 3.4vw, 42px);
  line-height: 1.12;
  letter-spacing: .03em;
  font-weight: 800;
  color: var(--deep-sea);
}

.page-about .about-section-body {
  display: grid;
  gap: 18px;
}

.page-about .prose {
  max-width: 720px;
  margin: 0;
  font-size: 16px;
  line-height: 1.85;
  color: #2b3742;
}

.page-about .prose a {
  color: var(--tide-teal);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.page-about .prose a:hover,
.page-about .prose a:focus-visible {
  color: var(--signal-orange);
}

/* ---------- 内容分类折叠 ---------- */
.page-about .about-details {
  display: flex;
  flex-direction: column;
  border-top: 1px solid var(--about-rule);
}

.page-about .about-detail {
  border-bottom: 1px solid var(--about-rule);
}

.page-about .about-detail summary {
  display: grid;
  grid-template-columns: 26px minmax(0, 1fr);
  grid-template-areas:
    "idx name"
    ".   meta";
  gap: 4px 14px;
  align-items: baseline;
  padding: 18px 0 18px 0;
  border-left: 3px solid transparent;
  cursor: pointer;
  list-style: none;
  transition: border-color 240ms var(--ease), padding-left 240ms var(--ease), background 240ms var(--ease);
}

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

.page-about .about-detail summary::marker {
  content: "";
}

.page-about .about-detail summary:hover {
  border-left-color: var(--tide-teal);
  padding-left: 14px;
  background: rgba(18, 166, 160, .05);
}

.page-about .about-detail[open] summary {
  border-left-color: var(--signal-orange);
  padding-left: 14px;
}

.page-about .detail-idx {
  grid-area: idx;
  font-size: 12px;
  letter-spacing: .1em;
  color: var(--signal-orange);
}

.page-about .detail-name {
  grid-area: name;
  font-size: 19px;
  font-weight: 700;
  letter-spacing: .02em;
  color: var(--deep-sea);
}

.page-about .detail-meta {
  grid-area: meta;
  font-size: 12px;
  letter-spacing: .08em;
  color: #6b7883;
}

.page-about .detail-body {
  padding: 0 0 22px 14px;
  max-width: 680px;
}

.page-about .detail-body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: #34424d;
}

/* ---------- 分栏（流程 / 归档） ---------- */
.page-about .about-split {
  display: grid;
  gap: 30px;
  align-items: start;
}

.page-about .flow-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .flow-step {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 14px;
  padding: 20px 0;
  border-bottom: 1px solid var(--about-rule);
}

.page-about .flow-step:first-child {
  border-top: 1px solid var(--about-rule);
}

.page-about .flow-num {
  font-size: 13px;
  letter-spacing: .1em;
  color: var(--signal-orange);
  padding-top: 3px;
}

.page-about .flow-title {
  margin: 0 0 6px;
  font-size: 19px;
  font-weight: 700;
  letter-spacing: .02em;
  color: var(--deep-sea);
}

.page-about .flow-content p {
  margin: 0;
  max-width: 520px;
  font-size: 15px;
  line-height: 1.82;
  color: #34424d;
}

.page-about .flow-figure,
.page-about .archive-figure {
  margin: 0;
  position: relative;
  overflow: hidden;
}

.page-about .flow-figure img,
.page-about .archive-figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  transition: transform 600ms var(--ease);
}

.page-about .flow-figure::after {
  content: "";
  position: absolute;
  inset: 0;
  background: linear-gradient(205deg, rgba(18, 166, 160, .22), rgba(7, 34, 58, .12) 58%, transparent);
  pointer-events: none;
}

.page-about .flow-figure:hover img,
.page-about .archive-figure:hover img {
  transform: scale(1.015);
}

/* ---------- 数据条 ---------- */
.page-about .team-stats {
  list-style: none;
  margin: 4px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(132px, 1fr));
  gap: 1px;
  background: var(--about-rule);
  border: 1px solid var(--about-rule);
}

.page-about .team-stats .stat {
  display: grid;
  gap: 4px;
  padding: 18px 16px;
  background: var(--sand-white);
}

.page-about .team-stats .stat-value {
  font-size: 28px;
  line-height: 1;
  letter-spacing: .04em;
  color: var(--deep-sea);
}

.page-about .team-stats .stat-label {
  font-size: 12px;
  letter-spacing: .06em;
  color: #66737e;
}

/* ---------- 年份轴 ---------- */
.page-about .archive-body {
  display: grid;
  gap: 24px;
}

.page-about .year-axis {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px 14px;
}

.page-about .year-node {
  display: grid;
  gap: 4px;
  padding: 14px 0 14px 20px;
  border-left: 1px solid var(--about-rule);
  position: relative;
  transition: border-color 240ms var(--ease);
}

.page-about .year-node::before {
  content: "";
  position: absolute;
  left: -4px;
  top: 19px;
  width: 7px;
  height: 7px;
  background: var(--about-rule);
  transition: background 240ms var(--ease), transform 240ms var(--ease);
}

.page-about .year-node:hover,
.page-about .year-node:focus-visible {
  border-left-color: var(--tide-teal);
}

.page-about .year-node:hover::before,
.page-about .year-node:focus-visible::before {
  background: var(--signal-orange);
  transform: scale(1.35);
}

.page-about .year-code {
  font-size: 15px;
  letter-spacing: .12em;
  color: var(--deep-sea);
}

.page-about .year-range {
  font-size: 13px;
  color: #5d6a75;
}

.page-about .year-note {
  font-size: 12px;
  line-height: 1.6;
  color: #7b868f;
  transition: color 240ms var(--ease);
}

.page-about .year-node:hover .year-note,
.page-about .year-node:focus-visible .year-note {
  color: var(--tide-teal);
}

/* ---------- 内容合作（靛紫分区） ---------- */
.page-about .about-section--violet {
  background: var(--indigo-violet);
  color: var(--sand-white);
  padding: 34px 26px 38px;
}

.page-about .about-section--violet .about-section-head {
  border-top-color: rgba(245, 239, 228, .28);
}

.page-about .about-section--violet .about-section-head .section-title {
  color: var(--sand-white);
}

.page-about .about-section--violet .about-section-head .eyebrow {
  color: var(--tide-teal-soft);
}

.page-about .about-section--violet .prose {
  color: rgba(245, 239, 228, .86);
}

.page-about .about-section--violet .prose a {
  color: var(--tide-teal-soft);
}

.page-about .about-section--violet .prose a:hover,
.page-about .about-section--violet .prose a:focus-visible {
  color: var(--signal-orange);
}

/* ---------- 结尾行动区 ---------- */
.page-about .about-cta {
  background: var(--deep-sea);
  color: var(--sand-white);
  padding: 68px 0 84px;
  position: relative;
  overflow: hidden;
}

.page-about .about-cta::before {
  content: "";
  position: absolute;
  top: 0;
  left: 0;
  width: 38%;
  height: 3px;
  background: var(--signal-orange);
}

.page-about .about-cta-inner {
  display: grid;
  gap: 20px;
  justify-items: start;
}

.page-about .about-cta .eyebrow {
  margin: 0;
  color: var(--tide-teal-soft);
  letter-spacing: .26em;
}

.page-about .about-cta .section-title {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(26px, 3.6vw, 44px);
  line-height: 1.1;
  letter-spacing: .03em;
  font-weight: 800;
  color: var(--sand-white);
}

.page-about .about-cta-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 6px;
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .about-detail summary {
    grid-template-columns: 40px minmax(0, 1fr) auto;
    grid-template-areas: "idx name meta";
    gap: 20px;
    align-items: center;
  }

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

@media (min-width: 1000px) {
  .page-about .about-layout {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: 64px;
    padding-top: 68px;
  }

  .page-about .about-rail {
    border-right: 1px solid var(--about-rule);
    padding-right: 32px;
  }

  .page-about .about-rail-inner {
    position: sticky;
    top: calc(var(--header-h) + 40px);
  }

  .page-about .about-toc-list {
    flex-direction: column;
    flex-wrap: nowrap;
    gap: 2px;
  }

  .page-about .about-rail-mark {
    display: block;
  }

  .page-about .about-split {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, .9fr);
    gap: 44px;
  }

  .page-about .about-split--reverse {
    grid-template-columns: minmax(0, .78fr) minmax(0, 1.22fr);
  }

  .page-about .about-hero .lede {
    font-size: 18px;
  }

  .page-about .about-section--violet {
    padding: 40px 38px 44px;
  }

  .page-about .about-cta {
    padding: 84px 0 100px;
  }
}