.page-about {
  --about-indent: 2.75rem;
  --about-line: 1rem;
  background: var(--indigo-900);
  color: var(--paper);
  overflow-x: hidden;
}

.page-about h1,
.page-about h2,
.page-about h3 {
  font-weight: 900;
  letter-spacing: -0.02em;
  line-height: 1.2;
}

.page-about h2 {
  font-size: var(--fs-h2);
  margin: 0.75rem 0 1.5rem;
  max-width: 22em;
}

.page-about h3 {
  font-size: var(--fs-h3);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding: 1.75rem 0 3.5rem;
  isolation: isolate;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  top: -30%;
  right: -20%;
  width: 34rem;
  height: 34rem;
  background: radial-gradient(circle, rgba(192, 138, 62, 0.2), rgba(11, 21, 51, 0) 64%);
  pointer-events: none;
  z-index: -1;
}

.page-about .about-hero h1 {
  font-size: clamp(2.125rem, 7vw, 4rem);
  margin: 1rem 0 1.25rem;
  max-width: 14em;
}

.page-about .about-hero .lead {
  max-width: 32em;
}

.page-about .about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.875rem;
  margin-top: 2rem;
}

/* ---------- 时间轴章节 ---------- */
.page-about .about-flow {
  padding-top: 1rem;
}

.page-about .about-chapter__inner {
  position: relative;
  padding-left: var(--about-indent);
  padding-bottom: 3.5rem;
}

.page-about .about-chapter__inner::before {
  content: "";
  position: absolute;
  top: 0.4rem;
  bottom: 0;
  left: var(--about-line);
  width: 1px;
  background: linear-gradient(180deg, rgba(192, 138, 62, 0.55), rgba(192, 138, 62, 0.18));
}

.page-about .about-chapter__num {
  position: absolute;
  left: 0;
  top: 0;
  width: calc(var(--about-line) * 2);
  padding: 0.15rem 0;
  background: var(--indigo-900);
  color: var(--copper-500);
  font-family: var(--font-mono);
  font-size: 1.375rem;
  font-weight: 700;
  text-align: center;
  letter-spacing: 0.02em;
}

.page-about .about-intro {
  max-width: 34em;
  color: var(--gray);
  margin: 0 0 2rem;
}

/* 阶段列表 */
.page-about .stage-list {
  display: grid;
  gap: 0.875rem;
}

.page-about .stage {
  position: relative;
  border: var(--line-soft);
  background: rgba(22, 36, 79, 0.55);
  transition: border-color 0.3s ease, background-color 0.3s ease;
}

.page-about .stage::before {
  content: "";
  position: absolute;
  top: 1.5rem;
  left: calc(var(--about-line) - var(--about-indent) - 4px);
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--copper-500);
  box-shadow: 0 0 0 4px rgba(11, 21, 51, 0.9);
}

.page-about .stage[open] {
  border-color: var(--copper-500);
  background: rgba(28, 44, 92, 0.75);
}

.page-about .stage[open]::before {
  background: var(--orange);
}

.page-about .stage__summary {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0.5rem 0.875rem;
  padding: 1.125rem 1.25rem;
  cursor: pointer;
  list-style: none;
}

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

.page-about .stage__num {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  letter-spacing: 0.06em;
  color: var(--copper-200);
}

.page-about .stage__title {
  flex: 1 1 12rem;
  font-size: 1.0625rem;
  font-weight: 700;
  color: var(--white);
}

.page-about .stage__meta {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  color: var(--gray);
}

.page-about .stage__body {
  padding: 0 1.25rem 1.25rem;
}

.page-about .stage__body p {
  margin: 0;
  max-width: 34em;
  color: var(--gray);
  line-height: 1.75;
}

/* ---------- 图片 ---------- */
.page-about .about-figure {
  margin: 2rem 0 0;
}

.page-about .about-figure--wide {
  margin-top: 2.5rem;
  padding-left: var(--about-indent);
}

.page-about .about-figure figcaption {
  margin-top: 0.75rem;
  font-size: var(--fs-xs);
  color: var(--gray);
  line-height: 1.6;
}

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

/* ---------- 三条做法 ---------- */
.page-about .about-methods {
  background: var(--indigo-700);
  border-top: var(--line-soft);
  border-bottom: var(--line-soft);
  padding: 3.5rem 0;
  margin-top: 1rem;
}

.page-about .method-grid {
  display: grid;
  gap: 1rem;
}

.page-about .method {
  padding: 1.5rem 1.375rem 1.75rem;
  border: var(--line);
  background: rgba(11, 21, 51, 0.5);
  box-shadow: var(--shadow-paper);
}

.page-about .method--paper {
  background: var(--paper);
  border-color: var(--paper);
  color: var(--indigo-900);
}

.page-about .method__num {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  letter-spacing: 0.1em;
  color: var(--copper-500);
  margin: 0 0 1rem;
}

.page-about .method--paper .method__num {
  color: #8f6220;
}

.page-about .method__title {
  font-size: 1.125rem;
  margin: 0 0 0.75rem;
  color: inherit;
}

.page-about .method__text {
  margin: 0;
  font-size: var(--fs-sm);
  line-height: 1.8;
  color: var(--gray);
}

.page-about .method--paper .method__text {
  color: rgba(11, 21, 51, 0.78);
}

/* ---------- 团队 ---------- */
.page-about .about-team {
  padding: 3.5rem 0 3rem;
}

.page-about .about-team__grid {
  align-items: start;
  gap: 2rem;
}

.page-about .about-team .about-figure {
  margin-top: 0;
}

.page-about .about-team__copy .prose p {
  color: var(--gray);
}

/* 协作网络图 */
.page-about .net-map {
  margin: 2rem 0 0;
  padding: 0.75rem 0.5rem 0.25rem;
  border-top: var(--line-soft);
}

.page-about .net-map__svg {
  width: 100%;
  height: auto;
  display: block;
  overflow: visible;
}

.page-about .net-map__svg line {
  stroke: rgba(192, 138, 62, 0.38);
  stroke-width: 1;
}

.page-about .net-node {
  cursor: default;
  outline: none;
}

.page-about .net-node circle {
  fill: var(--copper-500);
  transition: fill 0.3s ease;
}

.page-about .net-node text {
  fill: var(--copper-200);
  font-family: var(--font-mono);
  font-size: 10px;
  text-anchor: middle;
  opacity: 0;
  transition: opacity 0.3s ease;
}

.page-about .net-node:hover circle,
.page-about .net-node:focus circle {
  fill: var(--orange);
}

.page-about .net-node:hover text,
.page-about .net-node:focus text {
  opacity: 1;
}

.page-about .net-hub {
  fill: var(--orange);
}

.page-about .net-hub__label {
  fill: var(--gray);
  font-family: var(--font-mono);
  font-size: 10px;
  text-anchor: middle;
}

.page-about .net-map figcaption {
  margin-top: 0.5rem;
  font-size: var(--fs-xs);
  color: var(--gray);
  line-height: 1.6;
}

/* ---------- 规模 ---------- */
.page-about .about-scale {
  background: var(--paper);
  color: var(--indigo-900);
  padding: 3.5rem 0;
}

.page-about .about-scale__grid {
  gap: 2rem;
  align-items: start;
}

.page-about .about-scale h2 {
  color: var(--indigo-900);
}

.page-about .about-scale .eyebrow {
  color: #8f6220;
}

.page-about .stat-list {
  list-style: none;
  margin: 2rem 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.75rem 1.25rem;
}

.page-about .stat__num {
  margin: 0;
  font-family: var(--font-sans);
  font-weight: 900;
  font-stretch: condensed;
  font-size: clamp(2.25rem, 7vw, 4rem);
  line-height: 1;
  letter-spacing: -0.03em;
  color: var(--indigo-900);
}

.page-about .stat__unit {
  font-size: 0.9rem;
  font-weight: 700;
  letter-spacing: 0;
  margin-left: 0.25rem;
  color: #8f6220;
}

.page-about .stat__label {
  margin: 0.5rem 0 0;
  font-size: var(--fs-xs);
  line-height: 1.6;
  color: rgba(11, 21, 51, 0.62);
}

.page-about .about-scale__note {
  margin: 2rem 0 0;
  max-width: 32em;
  font-size: var(--fs-sm);
  line-height: 1.8;
  color: rgba(11, 21, 51, 0.72);
}

.page-about .about-scale .about-figure {
  margin-top: 0;
}

@media (prefers-reduced-motion: no-preference) {
  .page-about .stat__num {
    animation: about-stat-fill 0.6s ease-out both;
  }

  .page-about .stat:nth-child(2) .stat__num {
    animation-delay: 0.08s;
  }

  .page-about .stat:nth-child(3) .stat__num {
    animation-delay: 0.16s;
  }

  .page-about .stat:nth-child(4) .stat__num {
    animation-delay: 0.24s;
  }
}

@keyframes about-stat-fill {
  from {
    opacity: 0;
    transform: translateX(-14px);
  }
  to {
    opacity: 1;
    transform: translateX(0);
  }
}

/* ---------- 合作 ---------- */
.page-about .about-coop {
  padding: 3.5rem 0 4.5rem;
}

.page-about .tier-list {
  display: grid;
  gap: 1rem;
}

.page-about .tier {
  padding: 1.375rem 1.25rem 1.5rem;
  border: var(--line-soft);
  background: rgba(22, 36, 79, 0.5);
}

.page-about .tier__name {
  margin: 0 0 0.5rem;
  font-size: 1.0625rem;
  color: var(--copper-200);
}

.page-about .tier__for {
  margin: 0 0 0.75rem;
  font-size: var(--fs-sm);
  line-height: 1.7;
  color: var(--white);
}

.page-about .tier__text {
  margin: 0;
  font-size: var(--fs-xs);
  line-height: 1.8;
  color: var(--gray);
}

.page-about .coop-detail {
  margin-top: 2.75rem;
  padding-top: 2rem;
  border-top: var(--line-soft);
}

.page-about .coop-detail__title {
  margin: 0 0 1.25rem;
  font-size: 1.125rem;
  color: var(--white);
}

.page-about .step-line {
  list-style: none;
  margin: 0 0 1.75rem;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.5rem;
  counter-reset: none;
}

.page-about .step {
  display: flex;
  align-items: baseline;
  gap: 0.5rem;
  font-size: var(--fs-sm);
  color: var(--paper);
}

.page-about .step__num {
  font-family: var(--font-mono);
  font-size: var(--fs-mono);
  color: var(--copper-500);
  letter-spacing: 0.06em;
}

.page-about .coop-detail__prose {
  max-width: 40em;
}

.page-about .coop-detail__prose p {
  color: var(--gray);
}

.page-about .about-cta {
  margin-top: 2.75rem;
  padding: 1.75rem 1.5rem;
  border: var(--line);
  background:
    linear-gradient(120deg, rgba(192, 138, 62, 0.14), rgba(11, 21, 51, 0) 62%),
    var(--indigo-700);
  display: grid;
  gap: 1.25rem;
}

.page-about .about-cta__text {
  margin: 0;
  max-width: 26em;
  font-size: 1.0625rem;
  line-height: 1.7;
  color: var(--white);
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

/* ---------- 平板及以上 ---------- */
@media (min-width: 640px) {
  .page-about .about-hero {
    padding: 2.25rem 0 4.5rem;
  }

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

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

  .page-about .about-cta {
    grid-template-columns: 1fr auto;
    align-items: center;
    padding: 2rem 1.75rem;
  }

  .page-about .stat-list {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: 1.5rem 1.25rem;
  }
}

/* ---------- 桌面 ---------- */
@media (min-width: 900px) {
  .page-about {
    --about-indent: 5.25rem;
    --about-line: 1.75rem;
  }

  .page-about .about-chapter__num {
    font-size: 1.75rem;
  }

  .page-about .about-chapter__inner {
    padding-bottom: 4.5rem;
  }

  .page-about .stage__summary {
    padding: 1.25rem 1.5rem;
  }

  .page-about .stage__body {
    padding: 0 1.5rem 1.5rem;
  }

  .page-about .method-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
    gap: 1.25rem;
  }

  .page-about .about-team,
  .page-about .about-methods,
  .page-about .about-scale {
    padding-top: 4.5rem;
    padding-bottom: 4.5rem;
  }

  .page-about .about-coop {
    padding: 4.5rem 0 5.5rem;
  }

  .page-about .about-figure--wide {
    margin-top: 1.5rem;
  }

  .page-about .net-map {
    margin-top: 2.25rem;
  }
}
<<<PAGE_CSS_END>>>