.page-about {
  background: var(--ink);
  color: var(--paper);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.85;
  -webkit-font-smoothing: antialiased;
}

.page-about h1,
.page-about h2,
.page-about h3 {
  margin: 0;
  font-family: var(--font-sans);
}

.page-about h2 {
  font-weight: 900;
  font-size: clamp(22px, 3.2vw, 34px);
  line-height: 1.25;
  letter-spacing: -0.01em;
  max-width: 20em;
}

.page-about h3 {
  font-weight: 900;
  font-size: clamp(17px, 1.8vw, 21px);
  line-height: 1.4;
}

.page-about p {
  margin: 0;
}

.page-about .inline-link {
  color: var(--cyan);
  text-decoration: underline;
  text-underline-offset: 4px;
  text-decoration-thickness: 1px;
  text-decoration-color: rgba(0, 229, 199, 0.5);
}

.page-about .inline-link:hover,
.page-about .inline-link:focus-visible {
  color: var(--cyan-soft);
  text-decoration-color: var(--cyan-soft);
}

.page-about .eyebrow {
  margin: 0;
}

/* ---------- 封面 ---------- */

.page-about .about-cover {
  position: relative;
  overflow: hidden;
  padding: calc(var(--header-h) + clamp(28px, 5vw, 56px)) 0 clamp(36px, 5vw, 60px);
  background:
    radial-gradient(90% 70% at 88% 2%, rgba(0, 229, 199, 0.16), transparent 62%),
    radial-gradient(70% 60% at 4% 98%, rgba(255, 107, 53, 0.1), transparent 58%),
    linear-gradient(180deg, var(--ink) 0%, var(--ink-deep) 100%);
}

.page-about .about-cover::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  opacity: 0.5;
  background: repeating-linear-gradient(180deg, rgba(244, 247, 250, 0.06) 0 1px, transparent 1px 4px);
}

.page-about .cover-inner {
  position: relative;
  z-index: 1;
}

.page-about .cover-grid {
  display: grid;
  gap: clamp(26px, 4vw, 44px);
  margin-top: clamp(20px, 3vw, 34px);
}

.page-about h1 {
  margin: clamp(12px, 2vw, 18px) 0 0;
  font-weight: 300;
  font-size: clamp(34px, 5.6vw, 68px);
  line-height: 1.1;
  letter-spacing: -0.02em;
  max-width: 16em;
}

.page-about .about-lead {
  margin-top: clamp(16px, 2.4vw, 26px);
  max-width: 40em;
  font-size: clamp(15px, 1.5vw, 17px);
  line-height: 1.9;
  color: rgba(244, 247, 250, 0.78);
}

.page-about .cover-mark {
  display: grid;
  gap: 6px;
  padding-top: 14px;
  border-top: 3px solid var(--cyan);
  align-content: start;
}

.page-about .mark-num {
  font-family: var(--font-mono);
  font-size: clamp(62px, 11vw, 124px);
  font-weight: 700;
  line-height: 0.88;
  letter-spacing: -0.04em;
  color: var(--cyan);
  font-variant-numeric: tabular-nums;
}

.page-about .mark-label {
  font-size: 13px;
  letter-spacing: 0.12em;
  color: rgba(244, 247, 250, 0.72);
}

.page-about .mark-stamp {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--orange);
}

.page-about .cover-stats {
  margin: clamp(28px, 4vw, 44px) 0 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: rgba(58, 85, 120, 0.65);
  border: 1px solid var(--line);
}

.page-about .cover-stat {
  margin: 0;
  padding: 16px clamp(12px, 2vw, 20px);
  background: rgba(11, 31, 58, 0.82);
}

.page-about .cover-stat dt {
  margin: 0;
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--muted);
}

.page-about .cover-stat dd {
  margin: 6px 0 0;
  display: flex;
  align-items: baseline;
  gap: 5px;
  font-family: var(--font-mono);
  font-size: clamp(22px, 3vw, 30px);
  font-weight: 700;
  line-height: 1.1;
  color: var(--cyan);
  font-variant-numeric: tabular-nums;
}

.page-about .cover-stat dd span {
  font-family: var(--font-sans);
  font-size: 12px;
  font-weight: 400;
  color: var(--muted);
}

/* ---------- 章节通用 ---------- */

.page-about .about-sec {
  padding: clamp(52px, 8vw, 96px) 0;
}

.page-about .sec-head {
  display: grid;
  gap: 14px;
}

.page-about .sec-lead {
  margin-top: clamp(16px, 2.4vw, 22px);
  max-width: 46em;
  color: rgba(244, 247, 250, 0.76);
}

.page-about figure {
  margin: 0;
}

.page-about figure img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
}

.page-about .fig-cap {
  margin-top: 10px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--muted);
}

/* ---------- 沿革 ---------- */

.page-about .about-origin {
  background: linear-gradient(180deg, var(--ink) 0%, var(--ink-deep) 100%);
}

.page-about .split-body {
  display: grid;
  gap: clamp(24px, 3vw, 36px);
  margin-top: clamp(28px, 4vw, 44px);
}

.page-about .stage-rail ol {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  gap: 6px;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  scrollbar-width: none;
}

.page-about .stage-rail ol::-webkit-scrollbar {
  display: none;
}

.page-about .stage-link {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 10px 12px;
  min-height: 44px;
  border-bottom: 3px solid transparent;
  color: var(--muted);
  text-decoration: none;
  font-size: 13px;
  white-space: nowrap;
  transition: color 0.24s var(--ease), border-color 0.24s var(--ease);
}

.page-about .stage-link:hover,
.page-about .stage-link:focus-visible {
  color: var(--paper);
  border-bottom-color: var(--cyan);
}

.page-about .stage-link.is-current {
  color: var(--cyan);
  border-bottom-color: var(--orange);
}

.page-about .stage-idx {
  font-family: var(--font-mono);
  font-weight: 700;
  font-size: 13px;
  font-variant-numeric: tabular-nums;
}

.page-about .stage-name {
  font-size: 13px;
}

.page-about .origin-copy {
  min-width: 0;
}

.page-about .phase {
  scroll-margin-top: calc(var(--header-h) + 24px);
}

.page-about .phase + .phase {
  position: relative;
  margin-top: clamp(26px, 4vw, 40px);
  padding-top: clamp(26px, 4vw, 40px);
  border-top: 1px solid var(--line);
}

.page-about .phase + .phase::before {
  content: "";
  position: absolute;
  top: -2px;
  left: 0;
  width: 64px;
  height: 3px;
  background: linear-gradient(90deg, var(--cyan), var(--orange));
}

.page-about .phase h3 {
  color: var(--cyan);
  font-family: var(--font-mono);
  font-size: clamp(15px, 1.7vw, 18px);
  letter-spacing: 0.02em;
}

.page-about .phase p {
  margin-top: 14px;
  color: rgba(244, 247, 250, 0.8);
}

.page-about .phase p:first-of-type::first-letter {
  float: left;
  margin: 4px 10px 0 0;
  font-family: var(--font-mono);
  font-size: 46px;
  line-height: 0.9;
  font-weight: 700;
  color: var(--orange-soft);
}

.page-about .origin-fig figcaption {
  padding-right: 4px;
}

/* ---------- 分工 ---------- */

.page-about .about-teams {
  background:
    radial-gradient(80% 70% at 100% 0%, rgba(31, 67, 112, 0.55), transparent 62%),
    var(--ink);
}

.page-about .team-tree {
  margin-top: clamp(28px, 4vw, 44px);
  display: grid;
  gap: 18px;
}

.page-about .tree-trunk {
  display: grid;
  gap: 4px;
  align-content: start;
  padding: 18px 20px;
  background: rgba(19, 48, 85, 0.62);
  border-left: 3px solid var(--cyan);
}

.page-about .trunk-num {
  font-family: var(--font-mono);
  font-size: clamp(30px, 4vw, 42px);
  font-weight: 700;
  line-height: 1;
  color: var(--cyan);
  font-variant-numeric: tabular-nums;
}

.page-about .trunk-label {
  font-size: 14px;
  color: var(--paper);
}

.page-about .trunk-note {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--muted);
}

.page-about .tree-branches {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: rgba(58, 85, 120, 0.5);
  border: 1px solid var(--line);
}

.page-about .tree-node {
  position: relative;
  padding: clamp(20px, 3vw, 28px);
  background: var(--ink);
  border-left: 3px solid var(--band);
  transition: border-color 0.24s var(--ease), background 0.24s var(--ease);
}

.page-about .tree-node:hover,
.page-about .tree-node:focus-within {
  border-left-color: var(--cyan);
  background: rgba(19, 48, 85, 0.55);
}

.page-about .node-head {
  color: var(--paper);
}

.page-about .node-desc {
  margin-top: 10px;
  color: rgba(244, 247, 250, 0.76);
  font-size: 15px;
}

.page-about .node-io {
  margin: 16px 0 0;
  display: grid;
  gap: 8px;
}

.page-about .node-io div {
  display: grid;
  grid-template-columns: 5.5em minmax(0, 1fr);
  gap: 10px;
  align-items: baseline;
}

.page-about .node-io dt {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.12em;
  color: var(--muted);
}

.page-about .node-io dd {
  margin: 0;
  font-size: 14px;
  color: var(--cyan-soft);
}

/* ---------- 流水线 ---------- */

.page-about .about-flow {
  background: linear-gradient(180deg, var(--ink-deep) 0%, var(--ink) 100%);
}

.page-about .pipeline {
  margin-top: clamp(28px, 4vw, 44px);
}

.page-about .pipe-path {
  display: none;
  width: 100%;
  height: 46px;
  margin-bottom: -1px;
}

.page-about .pk-line {
  stroke: var(--line);
  stroke-width: 1;
}

.page-about .pk-drop {
  stroke: var(--cyan);
  stroke-width: 1.5;
}

.page-about .pipe-nodes {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .pipe-node {
  background: linear-gradient(180deg, rgba(19, 48, 85, 0.7) 0%, rgba(7, 22, 40, 0.9) 100%);
  border: 1px solid var(--line);
  transition: border-color 0.24s var(--ease);
}

.page-about .pipe-node[open] {
  border-color: rgba(0, 229, 199, 0.55);
}

.page-about .pipe-node:hover {
  border-color: rgba(0, 229, 199, 0.4);
}

.page-about .pipe-node summary {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 4px 10px;
  padding: 16px 44px 15px 16px;
  min-height: 44px;
  cursor: pointer;
  list-style: none;
}

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

.page-about .pipe-node summary::after {
  content: "+";
  position: absolute;
  right: 16px;
  top: 14px;
  font-family: var(--font-mono);
  font-size: 18px;
  line-height: 1;
  color: var(--cyan);
}

.page-about .pipe-node[open] summary::after {
  content: "−";
}

.page-about .pipe-idx {
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 700;
  line-height: 1;
  color: var(--cyan);
  font-variant-numeric: tabular-nums;
}

.page-about .pipe-time {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--muted);
}

.page-about .pipe-name {
  flex: 1 1 100%;
  font-size: 15px;
  font-weight: 700;
  line-height: 1.5;
  color: var(--paper);
}

.page-about .pipe-body {
  padding: 0 16px 18px;
  border-top: 1px solid rgba(58, 85, 120, 0.6);
}

.page-about .pipe-body p {
  margin-top: 14px;
  font-size: 14.5px;
  line-height: 1.8;
  color: rgba(244, 247, 250, 0.76);
}

.page-about .pipe-body .pipe-out {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.06em;
  color: var(--cyan-soft);
}

.page-about .flow-fig {
  margin-top: clamp(26px, 4vw, 38px);
}

/* ---------- 覆盖 ---------- */

.page-about .about-reach {
  background:
    radial-gradient(70% 60% at 0% 100%, rgba(0, 229, 199, 0.1), transparent 60%),
    var(--ink);
}

.page-about .reach-grid {
  display: grid;
  gap: clamp(26px, 4vw, 44px);
  align-items: start;
}

.page-about .reach-copy h2 {
  margin-top: 14px;
}

.page-about .reach-copy > p {
  margin-top: 16px;
  color: rgba(244, 247, 250, 0.78);
}

.page-about .reach-stats {
  margin: clamp(24px, 3vw, 32px) 0 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: rgba(58, 85, 120, 0.55);
  border: 1px solid var(--line);
}

.page-about .reach-stat {
  margin: 0;
  padding: 14px 16px;
  background: rgba(11, 31, 58, 0.85);
}

.page-about .reach-stat dt {
  margin: 0;
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--muted);
}

.page-about .reach-stat dd {
  margin: 6px 0 0;
  display: flex;
  align-items: baseline;
  gap: 4px;
  font-family: var(--font-mono);
  font-size: clamp(18px, 2.4vw, 24px);
  font-weight: 700;
  line-height: 1.2;
  color: var(--paper);
  font-variant-numeric: tabular-nums;
}

.page-about .reach-stat dd span {
  font-family: var(--font-sans);
  font-size: 12px;
  font-weight: 400;
  color: var(--muted);
}

/* ---------- 简报（冷白实色层） ---------- */

.page-about .about-brief {
  --brief-ink: #0B1F3A;
  --brief-muted: #52637A;
  --brief-line: #D3DDE8;
  background: var(--paper);
  color: var(--brief-ink);
}

.page-about .about-brief h2 {
  color: var(--brief-ink);
}

.page-about .about-brief .eyebrow {
  color: var(--panel);
}

.page-about .about-brief .sec-lead {
  color: var(--brief-muted);
}

.page-about .brief-list {
  list-style: none;
  margin: clamp(26px, 4vw, 40px) 0 0;
  padding: 0;
}

.page-about .brief-row {
  display: grid;
  gap: 14px;
  padding: clamp(20px, 3vw, 28px) 0;
  border-top: 1px solid var(--brief-line);
  outline: none;
  transition: background 0.24s var(--ease);
}

.page-about .brief-row:last-child {
  border-bottom: 1px solid var(--brief-line);
}

.page-about .brief-row:focus-visible {
  box-shadow: 0 0 0 2px var(--cyan);
}

.page-about .brief-phase {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.18em;
  color: var(--panel);
  text-transform: uppercase;
}

.page-about .brief-title {
  margin-top: 8px;
  color: var(--brief-ink);
}

.page-about .brief-desc {
  margin-top: 10px;
  font-size: 15px;
  line-height: 1.85;
  color: var(--brief-muted);
}

.page-about .brief-side {
  display: grid;
  gap: 10px;
}

.page-about .brief-metrics {
  display: grid;
  gap: 6px;
}

.page-about .brief-metric {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: 12px;
  padding-bottom: 5px;
  border-bottom: 1px dashed var(--brief-line);
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--brief-muted);
}

.page-about .brief-metric b {
  font-weight: 700;
  color: var(--brief-ink);
  font-variant-numeric: tabular-nums;
  transition: color 0.24s var(--ease);
}

.page-about .brief-row:hover .brief-metric b,
.page-about .brief-row:focus-visible .brief-metric b {
  color: #00806F;
}

.page-about .brief-note {
  display: grid;
  grid-template-rows: 0fr;
  transition: grid-template-rows 0.32s var(--ease);
  font-size: 13px;
  line-height: 1.7;
  color: var(--brief-muted);
}

.page-about .brief-note > span {
  overflow: hidden;
}

.page-about .brief-row:hover .brief-note,
.page-about .brief-row:focus-visible .brief-note {
  grid-template-rows: 1fr;
}

.page-about .brief-note .inline-link {
  color: #00695C;
  text-decoration-color: rgba(0, 105, 92, 0.45);
}

/* ---------- 未来 ---------- */

.page-about .about-next {
  background:
    radial-gradient(70% 60% at 100% 0%, rgba(255, 107, 53, 0.12), transparent 60%),
    var(--ink-deep);
}

.page-about .next-list {
  list-style: none;
  margin: clamp(28px, 4vw, 44px) 0 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: rgba(58, 85, 120, 0.55);
  border: 1px solid var(--line);
}

.page-about .next-item {
  padding: clamp(22px, 3vw, 32px);
  background: rgba(11, 31, 58, 0.9);
}

.page-about .next-idx {
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.18em;
  color: var(--orange);
}

.page-about .next-item h3 {
  margin-top: 10px;
  color: var(--paper);
}

.page-about .next-item p {
  margin-top: 12px;
  font-size: 15px;
  line-height: 1.85;
  color: rgba(244, 247, 250, 0.74);
}

.page-about .next-cta {
  margin-top: clamp(28px, 4vw, 40px);
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- 响应式 ---------- */

@media (min-width: 720px) {
  .page-about .cover-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

@media (min-width: 860px) {
  .page-about .pipe-path {
    display: block;
  }

  .page-about .pipe-nodes {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 12px;
  }

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

@media (min-width: 900px) {
  .page-about .cover-grid {
    grid-template-columns: minmax(0, 1fr) minmax(180px, 230px);
    align-items: end;
  }

  .page-about .cover-mark {
    justify-items: end;
    text-align: right;
  }

  .page-about .team-tree {
    grid-template-columns: minmax(150px, 200px) minmax(0, 1fr);
    gap: 24px;
    align-items: start;
  }

  .page-about .reach-grid {
    grid-template-columns: minmax(0, 320px) minmax(0, 1fr);
    gap: clamp(28px, 4vw, 48px);
  }

  .page-about .brief-row {
    grid-template-columns: minmax(0, 1fr) minmax(220px, 280px);
    gap: clamp(24px, 4vw, 48px);
    align-items: start;
  }
}

@media (min-width: 1024px) {
  .page-about .split-body {
    grid-template-columns: 152px minmax(0, 1fr) minmax(240px, 300px);
    gap: clamp(24px, 3vw, 40px);
    align-items: start;
  }

  .page-about .stage-rail {
    position: sticky;
    top: calc(var(--header-h) + 28px);
  }

  .page-about .stage-rail ol {
    flex-direction: column;
    gap: 0;
    overflow: visible;
    border-left: 1px solid var(--line);
  }

  .page-about .stage-link {
    border-bottom: none;
    border-left: 3px solid transparent;
    padding: 12px 12px 12px 14px;
  }

  .page-about .stage-link:hover,
  .page-about .stage-link:focus-visible {
    border-bottom-color: transparent;
    border-left-color: var(--cyan);
  }

  .page-about .stage-link.is-current {
    border-bottom-color: transparent;
    border-left-color: var(--orange);
  }

  .page-about .stage-name {
    font-size: 12.5px;
  }
}

@media (min-width: 1200px) {
  .page-about .split-body {
    grid-template-columns: 168px minmax(0, 1fr) minmax(280px, 340px);
  }
}

@media (max-width: 520px) {
  .page-about .phase p:first-of-type::first-letter {
    font-size: 38px;
  }

  .page-about .node-io div {
    grid-template-columns: 4.5em minmax(0, 1fr);
  }

  .page-about .next-cta .btn {
    flex: 1 1 100%;
    justify-content: center;
  }
}

@media (hover: none) {
  .page-about .brief-note {
    grid-template-rows: 1fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about *,
  .page-about *::before,
  .page-about *::after {
    transition: none !important;
    animation: none !important;
  }
}