.page-about {
  background: var(--ink);
  color: var(--bone);
  padding-bottom: clamp(56px, 9vw, 112px);
  overflow-x: clip;
}

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

.page-about .breadcrumb {
  padding-top: clamp(16px, 3vw, 28px);
}

.page-about .breadcrumb a {
  color: var(--mist);
  text-decoration: none;
}

.page-about .breadcrumb a:hover {
  color: var(--cyan);
}

/* ---------- 首屏 ---------- */

.page-about .about-hero {
  position: relative;
  display: grid;
  gap: clamp(24px, 5vw, 48px);
  padding-block: clamp(28px, 6vw, 56px) clamp(36px, 6vw, 64px);
  border-bottom: 2px solid var(--moss);
}

.page-about .about-hero::before {
  content: "";
  position: absolute;
  left: 0;
  bottom: -2px;
  width: clamp(64px, 18vw, 180px);
  height: 6px;
  background: var(--cyan);
}

.page-about .about-hero h1 {
  margin: 14px 0 0;
  font-size: clamp(32px, 6.2vw, 68px);
  line-height: 1.08;
  letter-spacing: -0.02em;
  font-weight: 900;
  max-width: 17ch;
}

.page-about .lead {
  margin: 20px 0 0;
  max-width: 46ch;
  font-size: clamp(15px, 2.4vw, 17px);
  line-height: 1.75;
  color: var(--mist);
}

.page-about .hero-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--moss);
  border: 2px solid var(--moss);
  box-shadow: var(--shadow-hard);
  align-self: start;
}

.page-about .hero-stat {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 16px 14px;
  background: var(--pine);
  min-width: 0;
}

.page-about .hero-stat-num {
  font-size: clamp(26px, 5vw, 36px);
  font-weight: 900;
  line-height: 1;
  letter-spacing: -0.02em;
  color: var(--bone);
  white-space: nowrap;
}

.page-about .hero-stat-label {
  font-size: 12px;
  line-height: 1.5;
  color: var(--mist);
}

/* ---------- 章节骨架 ---------- */

.page-about .chapter {
  display: grid;
  gap: 16px;
  padding-block: clamp(44px, 8vw, 92px);
  border-top: 2px solid var(--moss);
}

.page-about .chapter:first-of-type {
  border-top: 0;
  padding-top: clamp(36px, 6vw, 72px);
}

.page-about .chapter-mark {
  display: flex;
  align-items: center;
  gap: 14px;
}

.page-about .chapter-num {
  font-size: 26px;
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--cyan);
  line-height: 1;
}

.page-about .chapter-rule {
  flex: 1;
  height: 2px;
  background: var(--moss);
}

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

.page-about .chapter h2 {
  margin: 0 0 10px;
  font-size: clamp(23px, 4.2vw, 40px);
  line-height: 1.16;
  letter-spacing: -0.02em;
  font-weight: 900;
}

.page-about .chapter-sub {
  margin: 0 0 clamp(22px, 4vw, 34px);
  max-width: 54ch;
  font-size: 15px;
  line-height: 1.78;
  color: var(--mist);
}

.page-about .chapter h3 {
  font-weight: 900;
  letter-spacing: -0.01em;
}

/* ---------- 01 分工 ---------- */

.page-about .roles-layout {
  display: grid;
  gap: 24px;
}

.page-about .duty-grid {
  display: grid;
  gap: 14px;
  min-width: 0;
}

.page-about .duty {
  background: var(--pine);
  border: 2px solid var(--moss);
  transition: border-color var(--dur) var(--ease), transform var(--dur) var(--ease);
}

.page-about .duty:hover {
  border-color: var(--cyan);
}

.page-about .duty .expander-toggle {
  position: relative;
  display: block;
  width: 100%;
  padding: 16px 16px 18px;
  background: transparent;
  border: 0;
  color: var(--bone);
  font: inherit;
  text-align: left;
  cursor: pointer;
}

.page-about .duty .expander-icon {
  position: absolute;
  top: 14px;
  right: 14px;
  font-size: 18px;
  line-height: 1;
  color: var(--cyan);
}

.page-about .duty-line {
  display: flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 8px 10px;
  padding-right: 30px;
}

.page-about .duty-name {
  font-size: 19px;
  font-weight: 900;
  letter-spacing: -0.01em;
}

.page-about .duty-count {
  font-size: 12px;
  color: var(--cyan);
  letter-spacing: 0.04em;
}

.page-about .duty-desc {
  display: block;
  margin-top: 8px;
  font-size: 14px;
  line-height: 1.72;
  color: var(--mist);
}

.page-about .duty .expander-panel ul {
  list-style: none;
  margin: 0;
  padding: 0 16px 18px;
  display: grid;
  gap: 8px;
}

.page-about .duty .expander-panel li {
  position: relative;
  padding-left: 14px;
  font-size: 14px;
  line-height: 1.72;
  color: var(--mist);
}

.page-about .duty .expander-panel li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 10px;
  width: 6px;
  height: 2px;
  background: var(--moss);
}

.page-about .roles-figure {
  margin: 0;
}

.page-about .media-caption {
  margin-top: 10px;
  font-size: 12px;
  line-height: 1.65;
  color: var(--mist);
}

/* ---------- 02 时间线 ---------- */

.page-about .timeline-frame {
  position: relative;
  margin-top: 4px;
  padding: clamp(22px, 4vw, 40px) clamp(16px, 3vw, 32px);
  border: 2px solid var(--moss);
  background: var(--pine);
  overflow: hidden;
}

.page-about .timeline-frame > img {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  object-fit: cover;
  opacity: 0.16;
  pointer-events: none;
}

.page-about .timeline {
  position: relative;
  z-index: 1;
  list-style: none;
  margin: 0;
  padding-left: 26px;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 12px;
  bottom: 12px;
  width: 2px;
  background: linear-gradient(var(--cyan), var(--moss));
}

.page-about .tl-item {
  position: relative;
  padding-bottom: 30px;
}

.page-about .tl-item:last-child {
  padding-bottom: 0;
}

.page-about .tl-item::before {
  content: "";
  position: absolute;
  left: -26px;
  top: 7px;
  width: 10px;
  height: 10px;
  border: 2px solid var(--cyan);
  border-radius: 50%;
  background: var(--ink);
}

.page-about .tl-year {
  display: block;
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--cyan);
}

.page-about .tl-title {
  margin: 6px 0 6px;
  font-size: 19px;
  line-height: 1.3;
}

.page-about .tl-text {
  margin: 0;
  max-width: 56ch;
  font-size: 15px;
  line-height: 1.75;
  color: var(--mist);
}

/* ---------- 03 机制 ---------- */

.page-about .mech-list {
  display: grid;
  border-top: 2px solid var(--moss);
}

.page-about .mech {
  display: grid;
  gap: 6px;
  padding: 20px 0;
  border-bottom: 2px solid var(--moss);
}

.page-about .mech-num {
  font-size: 13px;
  letter-spacing: 0.08em;
  color: var(--cyan);
}

.page-about .mech-title {
  margin: 0;
  font-size: 18px;
  line-height: 1.35;
}

.page-about .mech-text {
  margin: 6px 0 0;
  font-size: 15px;
  line-height: 1.78;
  color: var(--mist);
}

.page-about .about-figure {
  margin: clamp(24px, 4vw, 36px) 0 0;
}

/* ---------- 04 覆盖 ---------- */

.page-about .cov-band {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--moss);
  border: 2px solid var(--moss);
  box-shadow: var(--shadow-hard);
}

.page-about .cov-item {
  background: var(--pine);
  padding: 18px 16px;
  min-width: 0;
}

.page-about .cov-num {
  display: block;
  font-size: clamp(23px, 4vw, 32px);
  font-weight: 900;
  line-height: 1.05;
  letter-spacing: -0.02em;
  color: var(--bone);
  white-space: nowrap;
}

.page-about .cov-label {
  display: block;
  margin-top: 6px;
  font-size: 12px;
  line-height: 1.5;
  color: var(--mist);
}

.page-about .scene-grid {
  display: grid;
  gap: 18px;
  margin-top: clamp(24px, 4vw, 36px);
}

.page-about .scene {
  padding: 2px 0 2px 16px;
  border-left: 2px solid var(--moss);
  transition: border-color var(--dur) var(--ease);
}

.page-about .scene:hover {
  border-left-color: var(--orange);
}

.page-about .scene h3 {
  margin: 0 0 6px;
  font-size: 17px;
  line-height: 1.35;
}

.page-about .scene p {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--mist);
}

/* ---------- 05 做法 ---------- */

.page-about .rule-quote {
  margin: 0;
  padding: 18px 18px 18px 20px;
  border-left: 2px solid var(--orange);
  background: var(--pine);
  font-size: clamp(16px, 2.8vw, 21px);
  line-height: 1.62;
  font-weight: 900;
  letter-spacing: -0.01em;
  color: var(--bone);
}

.page-about .rule-list {
  list-style: none;
  margin: 22px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .rule-list li {
  position: relative;
  padding-left: 20px;
  font-size: 15px;
  line-height: 1.76;
  color: var(--mist);
}

.page-about .rule-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 11px;
  width: 10px;
  height: 2px;
  background: var(--mist);
}

.page-about .rule-note {
  margin: 22px 0 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--mist);
}

.page-about .rule-note a {
  color: var(--bone);
  text-decoration: none;
  border-bottom: 2px solid var(--moss);
  padding-bottom: 1px;
}

.page-about .rule-note a:hover {
  color: var(--cyan);
  border-bottom-color: var(--cyan);
}

/* ---------- 06 开始 ---------- */

.page-about .start-steps {
  display: grid;
  gap: 14px;
}

.page-about .start-step {
  padding: 18px 16px 20px;
  border: 2px solid var(--moss);
  background: var(--pine);
}

.page-about .step-num {
  display: inline-block;
  font-size: 11px;
  letter-spacing: 0.1em;
  color: var(--cyan);
  border: 1px solid var(--moss);
  padding: 3px 8px;
}

.page-about .start-step h3 {
  margin: 12px 0 8px;
  font-size: 18px;
  line-height: 1.3;
}

.page-about .start-step p {
  margin: 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--mist);
}

.page-about .cta-row {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: clamp(24px, 4vw, 34px);
}

/* ---------- 响应式 ---------- */

@media (min-width: 480px) {
  .page-about .hero-stats {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 760px) {
  .page-about .duty-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    padding-bottom: 32px;
  }

  .page-about .duty-grid > .duty:nth-child(even) {
    margin-top: 32px;
  }

  .page-about .mech {
    grid-template-columns: 132px minmax(0, 1fr);
    gap: 4px 24px;
    align-items: start;
  }

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

  .page-about .scene-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 22px 28px;
  }

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

@media (min-width: 900px) {
  .page-about .about-hero {
    grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
    align-items: end;
    gap: clamp(28px, 4vw, 56px);
  }

  .page-about .chapter {
    grid-template-columns: 84px minmax(0, 1fr);
    gap: clamp(24px, 4vw, 56px);
  }

  .page-about .chapter-mark {
    flex-direction: column;
    align-items: flex-start;
    gap: 16px;
    position: sticky;
    top: 104px;
    align-self: start;
  }

  .page-about .chapter-num {
    font-size: 34px;
  }

  .page-about .chapter-rule {
    width: 2px;
    height: 72px;
    flex: none;
  }
}

@media (min-width: 1024px) {
  .page-about .roles-layout {
    grid-template-columns: minmax(0, 1fr) minmax(0, 300px);
    gap: 28px;
    align-items: start;
  }

  .page-about .roles-figure {
    position: sticky;
    top: 104px;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .duty,
  .page-about .scene {
    transition: none;
  }
}
<<<END>>>