.page-about {
  --about-gap: clamp(22px, 3.4vw, 46px);
  --about-line-soft: rgba(83, 242, 210, 0.28);
}

.page-about .about-shell {
  padding-block: clamp(18px, 3vw, 36px) clamp(48px, 7vw, 96px);
  display: flex;
  flex-direction: column;
  gap: clamp(18px, 2.6vw, 30px);
}

.page-about .breadcrumbs {
  font-size: 13px;
  color: var(--muted);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  letter-spacing: 0.02em;
}

.page-about .breadcrumbs a {
  color: var(--muted);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 180ms var(--ease), border-color 180ms var(--ease);
}

.page-about .breadcrumbs a:hover {
  color: var(--cyan);
  border-bottom-color: var(--about-line-soft);
}

.page-about .breadcrumbs__sep {
  color: var(--edge);
}

.page-about .about-layout {
  display: grid;
  gap: clamp(24px, 4vw, 52px);
  align-items: start;
}

/* 左栏：使命宣言 */
.page-about .about-manifesto {
  display: flex;
  flex-direction: column;
  gap: 14px;
  position: relative;
}

.page-about .eyebrow {
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--amber);
  text-transform: uppercase;
  margin: 0;
}

.page-about .about-title {
  margin: 0;
  font-size: clamp(33px, 6vw, 60px);
  line-height: 1.08;
  letter-spacing: -0.02em;
  font-weight: 900;
  color: var(--mist);
}

.page-about .about-title__mark {
  color: var(--cyan);
  text-shadow: 0 0 26px rgba(83, 242, 210, 0.28);
}

.page-about .about-lead {
  margin: 0;
  color: var(--muted);
  font-size: clamp(15px, 1.5vw, 17px);
  line-height: 1.85;
}

.page-about .about-threads {
  list-style: none;
  margin: 4px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .about-thread {
  border-left: 2px solid var(--edge);
  padding: 2px 0 4px 14px;
  transition: border-color 200ms var(--ease);
}

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

.page-about .about-thread__label {
  display: block;
  font-size: 11.5px;
  letter-spacing: 0.14em;
  color: var(--cyan);
  margin-bottom: 6px;
}

.page-about .about-thread strong {
  display: block;
  font-size: 16px;
  color: var(--mist);
  font-weight: 800;
  margin-bottom: 4px;
}

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

/* 图片容器 */
.page-about .about-figure {
  position: relative;
  display: block;
  margin: 18px 0 0;
  border-radius: var(--r-lg);
  overflow: hidden;
  border: 1px solid var(--edge);
  background: var(--board);
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  height: auto;
  max-width: 100%;
  object-fit: cover;
  filter: saturate(0.92) contrast(1.06);
}

.page-about .about-figure::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image:
    linear-gradient(rgba(83, 242, 210, 0.07) 1px, transparent 1px),
    linear-gradient(90deg, rgba(83, 242, 210, 0.07) 1px, transparent 1px);
  background-size: 36px 36px;
  mix-blend-mode: screen;
}

.page-about .about-figure--wide {
  margin-top: 22px;
}

/* 右栏：手册章节 */
.page-about .about-flow {
  display: grid;
  gap: clamp(34px, 5vw, 62px);
  min-width: 0;
}

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

.page-about .chapter__head {
  display: flex;
  align-items: flex-start;
  gap: clamp(10px, 1.8vw, 20px);
  border-top: 1px solid var(--edge);
  padding-top: 16px;
}

.page-about .chapter__num {
  font-family: var(--font-num);
  font-size: clamp(44px, 7vw, 70px);
  line-height: 0.78;
  font-weight: 700;
  letter-spacing: -0.02em;
  color: rgba(83, 242, 210, 0.16);
  -webkit-text-stroke: 1.3px var(--edge);
  flex: none;
}

.page-about .chapter__title {
  margin: 0;
  padding-top: 4px;
  font-size: clamp(21px, 2.8vw, 30px);
  line-height: 1.3;
  font-weight: 800;
  letter-spacing: -0.01em;
  color: var(--mist);
}

.page-about .chapter__lead {
  margin: 16px 0 0;
  color: var(--muted);
  font-size: clamp(14.5px, 1.4vw, 16px);
  line-height: 1.85;
  max-width: 64ch;
}

.page-about .about-link {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid var(--about-line-soft);
  transition: border-color 180ms var(--ease), color 180ms var(--ease);
}

.page-about .about-link:hover {
  border-bottom-color: var(--cyan);
  color: var(--glow);
}

/* 三个阶段 */
.page-about .stages {
  list-style: none;
  margin: 20px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .stage {
  background: var(--board);
  border: 1px solid var(--edge);
  border-radius: var(--r-md);
  padding: 18px 18px 20px;
  transition: border-color 220ms var(--ease), transform 220ms var(--ease);
}

.page-about .stage:hover {
  border-color: var(--about-line-soft);
  transform: translateY(-2px);
}

.page-about .stage__tag {
  display: inline-block;
  font-family: var(--font-num);
  font-size: 13px;
  letter-spacing: 0.14em;
  color: var(--ink);
  background: var(--cyan);
  border-radius: var(--r-pill);
  padding: 4px 12px;
  margin-bottom: 10px;
}

.page-about .stage__body h3 {
  margin: 0 0 8px;
  font-size: clamp(16px, 1.7vw, 18px);
  color: var(--mist);
  font-weight: 800;
  line-height: 1.45;
}

.page-about .stage__body p {
  margin: 0;
  color: var(--muted);
  font-size: 14.5px;
  line-height: 1.8;
}

/* 筛选胶囊 */
.page-about .filter-bar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 20px;
}

.page-about .pill {
  font-family: inherit;
  font-size: 13px;
  line-height: 1;
  padding: 10px 16px;
  border-radius: var(--r-pill);
  border: 1px solid var(--edge);
  background: transparent;
  color: var(--muted);
  cursor: pointer;
  transition: background 180ms var(--ease), color 180ms var(--ease), border-color 180ms var(--ease);
}

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

.page-about .pill[aria-pressed="true"] {
  background: var(--cyan);
  border-color: var(--cyan);
  color: var(--ink);
  font-weight: 700;
}

.page-about .filter-empty {
  display: none;
  margin: 16px 0 0;
  font-size: 14px;
  color: var(--amber);
  border-left: 2px solid var(--amber);
  padding-left: 12px;
}

.page-about .filter-empty.is-visible {
  display: block;
}

/* 时间线 */
.page-about .timeline {
  position: relative;
  list-style: none;
  margin: 24px 0 0;
  padding: 0 0 0 26px;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 2px;
  background: linear-gradient(180deg, var(--cyan) 0%, var(--press) 42%, var(--edge) 100%);
  border-radius: 2px;
}

.page-about .milestone {
  position: relative;
  padding: 0 0 clamp(20px, 3vw, 30px);
}

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

.page-about .milestone::before {
  content: "";
  position: absolute;
  left: -26px;
  top: 8px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--ink);
  border: 2px solid var(--cyan);
  box-shadow: 0 0 0 4px rgba(83, 242, 210, 0.12);
}

.page-about .milestone__year {
  display: block;
  font-family: var(--font-num);
  font-size: clamp(26px, 3.4vw, 34px);
  line-height: 1;
  letter-spacing: 0.02em;
  color: var(--cyan);
  margin-bottom: 8px;
}

.page-about .milestone h3 {
  margin: 0 0 8px;
  font-size: clamp(16px, 1.7vw, 18px);
  color: var(--mist);
  font-weight: 800;
  line-height: 1.45;
}

.page-about .milestone p {
  margin: 0;
  color: var(--muted);
  font-size: 14.5px;
  line-height: 1.8;
  max-width: 62ch;
}

/* 团队分工 */
.page-about .roles {
  display: grid;
  gap: 12px;
  margin-top: 22px;
}

.page-about .role-card {
  background: var(--charcoal);
  border: 1px solid var(--edge);
  border-radius: var(--r-md);
  padding: 18px 18px 20px;
  transition: border-color 220ms var(--ease), transform 220ms var(--ease), background 220ms var(--ease);
  outline: none;
}

.page-about .role-card:hover,
.page-about .role-card:focus {
  border-color: var(--cyan);
  transform: translateY(-2px);
}

.page-about .role-card--lead {
  background: linear-gradient(150deg, var(--board), var(--charcoal));
  border-color: var(--about-line-soft);
}

.page-about .role-card__tag {
  display: inline-block;
  font-size: 11.5px;
  letter-spacing: 0.16em;
  color: var(--amber);
  border: 1px solid rgba(255, 179, 94, 0.4);
  border-radius: var(--r-pill);
  padding: 4px 11px;
  margin-bottom: 12px;
}

.page-about .role-card h3 {
  margin: 0 0 8px;
  font-size: clamp(16px, 1.7vw, 18px);
  color: var(--mist);
  font-weight: 800;
  line-height: 1.45;
}

.page-about .role-card p {
  margin: 0;
  color: var(--muted);
  font-size: 14.5px;
  line-height: 1.78;
}

.page-about .role-card__note {
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  margin-top: 0;
  font-size: 13.5px;
  color: var(--glow);
  transition: max-height 260ms var(--ease), opacity 200ms var(--ease), margin-top 200ms var(--ease);
}

.page-about .role-card:hover .role-card__note,
.page-about .role-card:focus .role-card__note,
.page-about .role-card:focus-within .role-card__note {
  max-height: 160px;
  opacity: 1;
  margin-top: 10px;
}

/* 覆盖范围 */
.page-about .coverage-grid {
  list-style: none;
  margin: 18px 0 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.page-about .coverage-card {
  background: var(--board);
  border: 1px solid var(--edge);
  border-radius: var(--r-md);
  padding: 16px 16px 18px;
  display: flex;
  flex-direction: column;
  gap: 6px;
  transition: border-color 220ms var(--ease);
}

.page-about .coverage-card:hover {
  border-color: var(--about-line-soft);
}

.page-about .coverage-card__meta {
  font-family: var(--font-num);
  font-size: 12.5px;
  letter-spacing: 0.14em;
  color: var(--muted);
}

.page-about .coverage-card__name {
  margin: 0;
  font-size: 17px;
  font-weight: 800;
  color: var(--mist);
}

.page-about .coverage-card p {
  margin: 0;
  font-size: 14px;
  line-height: 1.72;
  color: var(--muted);
}

.page-about .about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  margin-top: 22px;
}

.page-about .about-stats .stat {
  background: var(--charcoal);
  border: 1px solid var(--edge);
  border-radius: var(--r-sm);
  padding: 14px 15px;
}

.page-about .stat__value {
  display: block;
  font-family: var(--font-num);
  font-size: clamp(25px, 3.4vw, 34px);
  line-height: 1;
  color: var(--cyan);
  letter-spacing: 0.01em;
}

.page-about .stat__label {
  display: block;
  margin-top: 7px;
  font-size: 12.5px;
  line-height: 1.5;
  color: var(--muted);
}

.page-about .about-note {
  margin: 22px 0 0;
  padding: 16px 18px;
  border-radius: var(--r-md);
  border: 1px solid var(--edge);
  border-left: 3px solid var(--amber);
  background: rgba(20, 27, 25, 0.72);
  color: var(--muted);
  font-size: 14px;
  line-height: 1.78;
}

/* 服务准则 */
.page-about .rules {
  list-style: none;
  margin: 20px 0 0;
  padding: 0;
}

.page-about .rule {
  display: grid;
  gap: 6px;
  padding: 18px 0 20px;
  border-top: 1px solid var(--edge);
}

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

.page-about .rule__name {
  font-size: 16px;
  font-weight: 800;
  color: var(--mist);
  letter-spacing: 0.01em;
}

.page-about .rule__name::before {
  content: "";
  display: inline-block;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--amber);
  margin-right: 10px;
  vertical-align: middle;
}

.page-about .rule p {
  margin: 0;
  color: var(--muted);
  font-size: 14.5px;
  line-height: 1.8;
}

/* 结尾行动条 */
.page-about .about-cta {
  position: relative;
  overflow: hidden;
  border-radius: var(--r-lg);
  border: 1px solid var(--edge);
  padding: clamp(24px, 4vw, 42px);
  background: linear-gradient(118deg, var(--board) 0%, var(--charcoal) 100%);
}

.page-about .about-cta::after {
  content: "";
  position: absolute;
  top: -40%;
  right: -8%;
  width: 48%;
  height: 180%;
  background: linear-gradient(180deg, rgba(83, 242, 210, 0.16), transparent 72%);
  transform: rotate(-7deg);
  pointer-events: none;
}

.page-about .about-cta__title {
  position: relative;
  margin: 0;
  font-size: clamp(21px, 2.8vw, 29px);
  line-height: 1.32;
  font-weight: 800;
  color: var(--mist);
  letter-spacing: -0.01em;
}

.page-about .about-cta__text {
  position: relative;
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 14.5px;
  line-height: 1.8;
  max-width: 56ch;
}

.page-about .about-cta__actions {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 22px;
}

.page-about .about-cta__actions .btn {
  text-decoration: none;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 22px;
  border-radius: var(--r-pill);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.02em;
  transition: transform 180ms var(--ease), background 180ms var(--ease), color 180ms var(--ease);
}

.page-about .about-cta__actions .btn:hover {
  transform: translateY(-1px);
}

/* 平板及以上 */
@media (min-width: 700px) {
  .page-about .roles {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .page-about .role-card--lead {
    grid-row: span 2;
    display: flex;
    flex-direction: column;
    justify-content: center;
  }

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

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

  .page-about .stage {
    display: grid;
    grid-template-columns: 108px minmax(0, 1fr);
    gap: 18px;
    align-items: start;
  }

  .page-about .stage__tag {
    margin-bottom: 0;
    text-align: center;
    white-space: nowrap;
  }
}

/* 桌面：非对称双栏手册版式 */
@media (min-width: 1000px) {
  .page-about .about-layout {
    grid-template-columns: minmax(300px, 0.86fr) minmax(0, 1.14fr);
    gap: clamp(36px, 4.6vw, 68px);
  }

  .page-about .about-manifesto {
    position: sticky;
    top: calc(var(--status-h) + 22px);
  }

  .page-about .about-figure {
    clip-path: polygon(0 0, 100% 0, 100% 96%, 0 100%);
  }

  .page-about .about-figure::after {
    background-size: 42px 42px;
  }

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

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

  .page-about .role-card__note {
    max-height: 0;
  }
}

/* 窄屏兜底：移动端职责摘要直接展示，避免悬停不可用 */
@media (max-width: 699px) {
  .page-about .role-card__note {
    max-height: none;
    opacity: 1;
    margin-top: 10px;
  }

  .page-about .about-title {
    font-size: clamp(30px, 8.6vw, 44px);
  }

  .page-about .chapter__num {
    font-size: clamp(38px, 11vw, 52px);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .stage,
  .page-about .role-card,
  .page-about .pill,
  .page-about .about-cta__actions .btn,
  .page-about .role-card__note {
    transition: none;
  }

  .page-about .stage:hover,
  .page-about .role-card:hover,
  .page-about .role-card:focus,
  .page-about .about-cta__actions .btn:hover {
    transform: none;
  }
}