.page-about {
  --about-rail-w: 260px;
  --about-amber-soft: rgba(255, 181, 71, 0.12);
  background: var(--ink-900);
  color: var(--paper);
  padding-block: var(--space-4) var(--space-7);
  overflow-x: clip;
}

.page-about .breadcrumbs {
  font-size: var(--fs-label);
  letter-spacing: 0.1em;
  color: var(--mist);
  margin-bottom: var(--space-4);
}

.page-about .breadcrumbs ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  margin: 0;
  padding: 0;
}

.page-about .breadcrumbs a {
  color: var(--mist);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 160ms ease, border-color 160ms ease;
}

.page-about .breadcrumbs a:hover,
.page-about .breadcrumbs a:focus-visible {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

.page-about .breadcrumbs li + li::before {
  content: "/";
  margin-right: 0.5rem;
  color: var(--line);
}

/* ---------- 页头 ---------- */

.page-about .about-head {
  position: relative;
  display: grid;
  gap: var(--space-3);
  padding-block: var(--space-4) var(--space-6);
  border-bottom: 1px solid var(--line-soft);
  margin-bottom: var(--space-5);
  overflow: hidden;
}

.page-about .about-head::after {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, var(--line-soft) 1px, transparent 1px),
    linear-gradient(to bottom, var(--line-soft) 1px, transparent 1px);
  background-size: 72px 72px;
  opacity: 0.2;
  pointer-events: none;
  -webkit-mask-image: linear-gradient(115deg, transparent 40%, #000 100%);
  mask-image: linear-gradient(115deg, transparent 40%, #000 100%);
}

.page-about .about-head > * {
  position: relative;
  z-index: 1;
}

.page-about .about-head .eyebrow {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--fs-label);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--cyan);
}

.page-about .about-title {
  margin: 0;
  max-width: 15em;
  font-size: var(--fs-display);
  line-height: var(--lh-tight);
  letter-spacing: -0.02em;
  font-weight: 800;
}

.page-about .about-lede {
  margin: 0;
  max-width: 40em;
  color: var(--paper-86);
  font-size: var(--fs-body);
  line-height: var(--lh-body);
}

/* ---------- 双栏骨架 ---------- */

.page-about .about-split {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-5);
  align-items: start;
}

.page-about .about-body {
  min-width: 0;
}

.page-about .about-index {
  border-top: 1px solid var(--line-soft);
  padding-top: var(--space-3);
}

.page-about .about-index-title {
  margin: 0 0 var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--fs-label);
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--mist);
}

.page-about .about-index-list {
  list-style: none;
  margin: 0;
  padding: 0 0 var(--space-1);
  display: flex;
  gap: var(--space-2);
  overflow-x: auto;
  scroll-snap-type: x proximity;
}

.page-about .about-index-list li {
  flex: 0 0 auto;
  scroll-snap-align: start;
}

.page-about .about-index-list a {
  display: flex;
  align-items: baseline;
  gap: 0.45rem;
  padding: 0.4rem 0.7rem;
  font-size: var(--fs-small);
  color: var(--mist);
  text-decoration: none;
  border: 1px solid var(--line-soft);
  white-space: nowrap;
  transition: color 160ms ease, border-color 160ms ease, background 160ms ease;
}

.page-about .about-index-list a .mono-num {
  font-size: 0.68rem;
  letter-spacing: 0.06em;
  color: var(--line);
  transition: color 160ms ease;
}

.page-about .about-index-list a:hover,
.page-about .about-index-list a:focus-visible {
  color: var(--paper);
  border-color: var(--line);
}

.page-about .about-index-list a.is-active {
  color: var(--cyan);
  border-color: var(--cyan);
  background: var(--cyan-soft);
}

.page-about .about-index-list a.is-active .mono-num {
  color: var(--cyan);
}

/* ---------- 章节通用 ---------- */

.page-about .about-section {
  padding-block: var(--space-6);
  border-top: 1px solid var(--line-soft);
}

.page-about .about-body > .about-section:first-child {
  border-top: 0;
  padding-top: 0;
}

.page-about .about-section-head {
  max-width: 58ch;
  margin-bottom: var(--space-5);
}

.page-about .about-section-head .eyebrow {
  margin: 0 0 var(--space-2);
  font-family: var(--font-mono);
  font-size: var(--fs-label);
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--amber);
}

.page-about .about-section-head .section-title {
  margin: 0 0 var(--space-3);
  font-size: var(--fs-h2);
  line-height: 1.22;
  letter-spacing: -0.01em;
  font-weight: 800;
}

.page-about .about-section-head .section-note {
  margin: 0;
  color: var(--paper-86);
  font-size: var(--fs-body);
  line-height: var(--lh-body);
}

/* ---------- 图片 ---------- */

.page-about .about-figure {
  margin: 0 0 var(--space-5);
}

.page-about .about-figure-frame {
  border: 1px solid var(--line-soft);
  background: var(--ink-800);
  overflow: hidden;
}

.page-about .about-figure-frame img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  filter: saturate(0.85) contrast(1.06);
}

.page-about .media-caption {
  margin: var(--space-2) 0 0;
  font-size: var(--fs-small);
  color: var(--mist);
  line-height: 1.7;
}

/* ---------- 产品线 ---------- */

.page-about .about-lines {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--line-soft);
}

.page-about .about-line {
  display: grid;
  grid-template-columns: 2.25rem minmax(0, 1fr);
  column-gap: var(--space-3);
  align-items: baseline;
  padding: var(--space-4) 0;
  border-bottom: 1px solid var(--line-soft);
  transition: background 160ms ease;
}

.page-about .about-line-num {
  grid-column: 1;
  grid-row: 1;
  font-size: var(--fs-label);
  color: var(--line);
  letter-spacing: 0.08em;
}

.page-about .about-line-title {
  grid-column: 2;
  grid-row: 1;
  margin: 0;
  font-size: var(--fs-h3);
  font-weight: 700;
  letter-spacing: 0.01em;
  transition: color 160ms ease;
}

.page-about .about-line-text {
  grid-column: 2;
  grid-row: 2;
  margin: var(--space-1) 0 0;
  color: var(--paper-86);
  font-size: var(--fs-body);
  line-height: var(--lh-body);
  max-width: 52ch;
}

.page-about .about-line:hover .about-line-title {
  color: var(--cyan);
}

/* ---------- 数据带 ---------- */

.page-about .about-stats {
  list-style: none;
  margin: var(--space-5) 0 0;
  padding: var(--space-4) 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: var(--space-4) var(--space-3);
  border-top: 1px solid var(--line-soft);
  border-bottom: 1px solid var(--line-soft);
  background: linear-gradient(90deg, rgba(72, 242, 200, 0.07), transparent 75%);
}

.page-about .about-stats li {
  display: grid;
  gap: 0.25rem;
  padding-left: var(--space-3);
  border-left: 1px solid var(--line);
}

.page-about .about-stat-num {
  font-family: var(--font-mono);
  font-size: clamp(1.45rem, 2.6vw, 2rem);
  font-weight: 600;
  line-height: 1.1;
  color: var(--cyan);
}

.page-about .about-stat-label {
  font-size: var(--fs-label);
  letter-spacing: 0.08em;
  color: var(--mist);
  line-height: 1.5;
}

/* ---------- 归档体系 ---------- */

.page-about .about-archive {
  display: grid;
  gap: var(--space-5);
}

.page-about .about-archive-text p {
  margin: 0 0 var(--space-3);
  color: var(--paper-86);
  font-size: var(--fs-body);
  line-height: var(--lh-body);
  max-width: 50ch;
}

.page-about .about-archive-media {
  margin: 0;
}

.page-about .about-archive-frame {
  border: 1px solid var(--line-soft);
  background: var(--ink-800);
  overflow: hidden;
}

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

.page-about .about-find {
  list-style: none;
  margin: var(--space-4) 0 0;
  padding: 0;
  display: grid;
  gap: var(--space-2);
}

.page-about .about-find li {
  display: grid;
  grid-template-columns: 4.25rem minmax(0, 1fr);
  gap: var(--space-3);
  padding: var(--space-2) 0;
  border-bottom: 1px dashed var(--line-soft);
  font-size: var(--fs-small);
  line-height: 1.8;
  color: var(--paper-86);
}

.page-about .about-find-key {
  font-family: var(--font-mono);
  font-size: var(--fs-label);
  letter-spacing: 0.08em;
  color: var(--amber);
}

.page-about .about-scale {
  margin-top: var(--space-5);
  display: grid;
  gap: var(--space-3);
}

.page-about .about-scale-row {
  display: grid;
  gap: 0.4rem;
}

.page-about .about-scale-top {
  display: flex;
  justify-content: space-between;
  align-items: baseline;
  gap: var(--space-3);
  font-size: var(--fs-small);
}

.page-about .about-scale-name {
  color: var(--paper-86);
}

.page-about .about-scale-val {
  font-family: var(--font-mono);
  color: var(--cyan);
  letter-spacing: 0.04em;
}

.page-about .about-scale-track {
  height: 8px;
  background: var(--ink-700);
  border: 1px solid var(--line-soft);
}

.page-about .about-scale-fill {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, var(--teal), var(--cyan));
}

.page-about .about-scale-fill--teams {
  width: 72%;
}

.page-about .about-scale-fill--posts {
  width: 100%;
}

.page-about .about-scale-fill--cities {
  width: 44%;
}

/* ---------- 内容流水线 ---------- */

.page-about .about-flow {
  list-style: none;
  margin: 0 0 var(--space-5);
  padding: 0;
}

.page-about .about-flow-step {
  position: relative;
  display: grid;
  grid-template-columns: 2.75rem minmax(0, 1fr);
  gap: var(--space-3);
  padding-bottom: var(--space-5);
}

.page-about .about-flow-step::before {
  content: "";
  position: absolute;
  left: 1.31rem;
  top: 2.6rem;
  bottom: 0.2rem;
  width: 1px;
  background: var(--line-soft);
}

.page-about .about-flow-step:last-child {
  padding-bottom: 0;
}

.page-about .about-flow-step:last-child::before {
  display: none;
}

.page-about .about-flow-node {
  width: 2.75rem;
  height: 2.75rem;
  display: grid;
  place-items: center;
  border: 1px solid var(--line);
  background: var(--ink-800);
  color: var(--cyan);
  font-size: var(--fs-label);
  letter-spacing: 0.06em;
  z-index: 1;
  transition: border-color 160ms ease, color 160ms ease, background 160ms ease;
}

.page-about .about-flow-step:hover .about-flow-node {
  border-color: var(--cyan);
  background: var(--cyan-soft);
}

.page-about .about-flow-body h3 {
  margin: 0.55rem 0 var(--space-1);
  font-size: var(--fs-h3);
  font-weight: 700;
}

.page-about .about-flow-body p {
  margin: 0;
  color: var(--paper-86);
  font-size: var(--fs-body);
  line-height: var(--lh-body);
  max-width: 46ch;
}

.page-about .about-figure--flow {
  margin-bottom: 0;
}

/* ---------- 团队象限 ---------- */

.page-about .about-quads {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
}

.page-about .about-quad {
  --quad-accent: var(--cyan);
  position: relative;
  background: var(--ink-800);
  padding: var(--space-4);
  display: grid;
  align-content: start;
  gap: var(--space-2);
  transition: background 180ms ease;
}

.page-about .about-quad:nth-child(even) {
  --quad-accent: var(--amber);
}

.page-about .about-quad::after {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  width: 2px;
  height: 100%;
  background: var(--quad-accent);
  transform: scaleY(0);
  transform-origin: top;
  transition: transform 200ms ease;
}

.page-about .about-quad:hover,
.page-about .about-quad:focus-within {
  background: var(--ink-700);
}

.page-about .about-quad:hover::after,
.page-about .about-quad:focus-within::after {
  transform: scaleY(1);
}

.page-about .about-quad-label {
  margin: 0;
  font-family: var(--font-mono);
  font-size: var(--fs-label);
  letter-spacing: 0.14em;
  color: var(--quad-accent);
}

.page-about .about-quad h3 {
  margin: 0;
  font-size: var(--fs-h3);
  font-weight: 700;
  line-height: 1.4;
  transition: color 180ms ease;
}

.page-about .about-quad:hover h3 {
  color: var(--quad-accent);
}

.page-about .about-quad p:last-child {
  margin: 0;
  font-size: var(--fs-small);
  color: var(--paper-86);
  line-height: 1.8;
}

.page-about .about-partner-note {
  margin: var(--space-4) 0 0;
  padding-left: var(--space-3);
  border-left: 2px solid var(--teal);
  font-size: var(--fs-small);
  line-height: 1.85;
  color: var(--mist);
  max-width: 58ch;
}

.page-about .about-partner-note a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid var(--cyan);
}

.page-about .about-partner-note a:hover,
.page-about .about-partner-note a:focus-visible {
  color: var(--paper);
  border-bottom-color: var(--paper);
}

/* ---------- 阶段时间轴 ---------- */

.page-about .about-timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: var(--space-3);
}

.page-about .about-phase details {
  position: relative;
  background: var(--ink-800);
  border: 1px solid var(--line-soft);
  padding-left: var(--space-4);
}

.page-about .about-phase details::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 3px;
  background: var(--line);
  transition: background 200ms ease;
}

.page-about .about-phase details[open] {
  background: var(--ink-700);
}

.page-about .about-phase details[open]::before {
  background: var(--amber);
}

.page-about .about-phase summary {
  cursor: pointer;
  list-style: none;
  padding: var(--space-4) var(--space-4) var(--space-4) 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 0.4rem var(--space-3);
  align-items: baseline;
}

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

.page-about .about-phase summary:focus-visible {
  outline: 1px solid var(--cyan);
  outline-offset: 2px;
}

.page-about .about-phase-num {
  font-size: var(--fs-label);
  letter-spacing: 0.14em;
  color: var(--amber);
}

.page-about .about-phase-title {
  font-size: var(--fs-h3);
  font-weight: 700;
  line-height: 1.4;
  transition: color 160ms ease;
}

.page-about .about-phase summary:hover .about-phase-title {
  color: var(--cyan);
}

.page-about .about-phase-sub {
  font-size: var(--fs-small);
  color: var(--mist);
  letter-spacing: 0.04em;
}

.page-about .about-phase-body {
  display: grid;
  gap: var(--space-2);
  padding: 0 var(--space-4) var(--space-4) 0;
}

.page-about .about-phase-body p {
  margin: 0;
  color: var(--paper-86);
  font-size: var(--fs-small);
  line-height: var(--lh-body);
  max-width: 56ch;
}

/* ---------- 适用人群 ---------- */

.page-about .about-audience {
  display: grid;
  gap: var(--space-4);
}

.page-about .about-aud {
  position: relative;
  padding: var(--space-4);
  display: grid;
  align-content: start;
  gap: var(--space-2);
  background: var(--ink-800);
  border: 1px solid var(--line-soft);
}

.page-about .about-aud::before {
  content: "";
  position: absolute;
  inset: 0 0 auto 0;
  height: 2px;
  background: var(--cyan);
}

.page-about .about-aud--partner::before {
  background: var(--amber);
}

.page-about .about-aud-label {
  margin: 0;
  font-size: var(--fs-label);
  letter-spacing: 0.16em;
  color: var(--mist);
}

.page-about .about-aud h3 {
  margin: 0;
  font-size: var(--fs-h3);
  font-weight: 700;
  line-height: 1.4;
}

.page-about .about-aud p {
  margin: 0;
  font-size: var(--fs-small);
  color: var(--paper-86);
  line-height: var(--lh-body);
}

.page-about .about-aud-actions {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-top: var(--space-2);
}

.page-about .about-links {
  margin: var(--space-5) 0 0;
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  padding-top: var(--space-4);
  border-top: 1px solid var(--line-soft);
}

/* ---------- 桌面增强 ---------- */

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

  .page-about .about-line {
    grid-template-columns: 2.25rem 12rem minmax(0, 1fr);
    column-gap: var(--space-4);
  }

  .page-about .about-line-title {
    grid-column: 2;
  }

  .page-about .about-line-text {
    grid-column: 3;
    grid-row: 1;
    margin-top: 0;
  }

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

  .page-about .about-phase summary {
    grid-template-columns: 6.5rem minmax(0, 1fr) auto;
  }

  .page-about .about-phase-sub {
    grid-column: 3;
    grid-row: 1;
  }
}

@media (min-width: 960px) {
  .page-about {
    padding-block: var(--space-5) var(--space-7);
  }

  .page-about .about-split {
    grid-template-columns: var(--about-rail-w) minmax(0, 1fr);
    gap: var(--space-6);
  }

  .page-about .about-rail {
    position: sticky;
    top: calc(var(--header-h) + var(--space-4));
    align-self: start;
  }

  .page-about .about-index {
    border-top: 0;
    border-left: 1px solid var(--line-soft);
    padding-top: 0;
    padding-left: var(--space-3);
  }

  .page-about .about-index-list {
    flex-direction: column;
    overflow: visible;
    gap: 0;
    padding-bottom: 0;
  }

  .page-about .about-index-list li {
    flex: 1 1 auto;
    width: 100%;
  }

  .page-about .about-index-list a {
    border: 0;
    border-bottom: 1px solid transparent;
    padding: 0.4rem 0;
    white-space: normal;
    width: 100%;
  }

  .page-about .about-index-list a.is-active {
    background: transparent;
    border-color: transparent;
    border-bottom-color: var(--cyan);
  }

  .page-about .about-archive {
    grid-template-columns: minmax(0, 1.1fr) minmax(0, 0.9fr);
    gap: var(--space-6);
    align-items: start;
  }

  .page-about .about-audience {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: var(--space-5);
  }

  .page-about .about-title {
    max-width: 13em;
  }
}

@media (min-width: 1280px) {
  .page-about .about-head {
    padding-block: var(--space-5) var(--space-7);
  }

  .page-about .about-archive-text p {
    max-width: 54ch;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-line,
  .page-about .about-line-title,
  .page-about .about-index-list a,
  .page-about .about-quad,
  .page-about .about-quad h3,
  .page-about .about-quad::after,
  .page-about .about-flow-node,
  .page-about .about-phase-title,
  .page-about .breadcrumbs a {
    transition: none;
  }

  .page-about .about-quad::after {
    transform: scaleY(1);
  }
}
<<<END>>>