.page-about {
  --about-index-w: 232px;
  --about-top: clamp(96px, 13vw, 148px);
  background: var(--xc-paper);
  color: var(--xc-text);
  font-family: var(--font-body);
  padding-top: var(--about-top);
}

/* ---------- 面包屑 ---------- */
.page-about .about-crumbs {
  padding-bottom: clamp(18px, 2.6vw, 30px);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
}

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

.page-about .about-hero__title {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(34px, 5.6vw, 70px);
  line-height: 1.05;
  letter-spacing: -0.025em;
  color: var(--xc-ink);
  margin: 10px 0 clamp(16px, 2.2vw, 26px);
  max-width: 18ch;
}

.page-about .about-hero__text {
  font-size: clamp(16px, 1.35vw, 17.5px);
  line-height: 1.85;
  color: var(--xc-text);
  max-width: 40ch;
  margin: 0;
}

.page-about .about-hero__plate {
  background: var(--xc-dusk);
  border: 1px solid rgba(244, 242, 238, 0.22);
  padding: clamp(18px, 2.4vw, 28px);
  color: var(--xc-paper);
}

.page-about .about-hero__plate-label {
  display: block;
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--xc-lake-mist);
  margin-bottom: 10px;
}

.page-about .about-hero__plate-text {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: rgba(244, 242, 238, 0.9);
}

.page-about .about-hero__media {
  margin: clamp(30px, 4.4vw, 56px) 0 0;
  width: 100%;
}

/* ---------- 正文骨架 ---------- */
.page-about .about-body {
  padding: clamp(48px, 7vw, 96px) 0 clamp(56px, 8vw, 110px);
}

.page-about .about-body__grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(28px, 4vw, 56px);
  align-items: start;
}

/* ---------- 章节目录 ---------- */
.page-about .about-index__label {
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--xc-muted);
  margin: 0 0 10px;
  padding-left: 12px;
}

.page-about .about-index__list {
  list-style: none;
  margin: 0;
  padding: 0 0 8px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: none;
  border-bottom: 1px solid var(--xc-line);
}

.page-about .about-index__list::-webkit-scrollbar {
  display: none;
}

.page-about .about-index__link {
  display: block;
  padding: 9px 12px;
  font-size: 13.5px;
  line-height: 1.5;
  white-space: nowrap;
  text-decoration: none;
  color: var(--xc-muted);
  border-left: 2px solid transparent;
  transition: color 0.25s var(--xc-ease), border-color 0.25s var(--xc-ease),
    background-color 0.25s var(--xc-ease);
}

.page-about .about-index__link:hover,
.page-about .about-index__link:focus-visible {
  color: var(--xc-ink);
  border-left-color: var(--xc-signal);
  background: rgba(240, 90, 40, 0.06);
  outline: none;
}

/* ---------- 章节 ---------- */
.page-about .chapter {
  margin-top: clamp(40px, 5.5vw, 72px);
  padding-top: clamp(36px, 5vw, 64px);
  border-top: 1px solid var(--xc-line);
}

.page-about .chapter:first-child {
  margin-top: 0;
  padding-top: 0;
  border-top: 0;
}

.page-about .chapter__num {
  display: block;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(34px, 4.8vw, 56px);
  line-height: 0.95;
  letter-spacing: -0.03em;
  font-variant-numeric: tabular-nums;
  color: rgba(20, 22, 26, 0.13);
  margin-bottom: 8px;
}

.page-about .chapter__title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(24px, 3.2vw, 38px);
  line-height: 1.16;
  letter-spacing: -0.015em;
  color: var(--xc-ink);
  margin: 0 0 clamp(16px, 2.4vw, 26px);
  max-width: 22ch;
}

.page-about .chapter__lead {
  font-size: 16.5px;
  line-height: 1.85;
  color: var(--xc-text);
  max-width: 38ch;
  margin: 0 0 clamp(22px, 3vw, 34px);
}

.page-about .chapter__prose p {
  font-size: 16.5px;
  line-height: 1.85;
  color: var(--xc-text);
  max-width: 38ch;
  margin: 0 0 1.15em;
}

.page-about .chapter__prose p:last-child {
  margin-bottom: 0;
}

/* ---------- 暮色说明牌 ---------- */
.page-about .about-note {
  margin-top: clamp(22px, 3vw, 32px);
  background: var(--xc-dusk);
  border: 1px solid rgba(244, 242, 238, 0.2);
  padding: clamp(16px, 2.2vw, 24px);
  max-width: 46ch;
}

.page-about .about-note__label {
  display: block;
  font-size: 12px;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--xc-lake-mist);
  margin-bottom: 9px;
}

.page-about .about-note p {
  margin: 0;
  font-size: 15px;
  line-height: 1.78;
  color: rgba(244, 242, 238, 0.9);
}

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

.page-about .timeline::before {
  content: "";
  position: absolute;
  left: 5px;
  top: 14px;
  bottom: 14px;
  width: 1px;
  background: var(--xc-line);
}

.page-about .timeline__item {
  position: relative;
  padding-left: clamp(24px, 4vw, 40px);
}

.page-about .timeline__item + .timeline__item {
  margin-top: 2px;
}

.page-about .timeline__node {
  border-bottom: 1px solid rgba(201, 198, 192, 0.6);
}

.page-about .timeline__summary {
  position: relative;
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 4px 12px;
  padding: 15px 0;
  cursor: pointer;
  list-style: none;
  outline: none;
}

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

.page-about .timeline__dot {
  position: absolute;
  left: calc(-1 * clamp(24px, 4vw, 40px) + 1px);
  top: 21px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--xc-paper);
  border: 1px solid var(--xc-lake);
  transition: background-color 0.25s var(--xc-ease),
    border-color 0.25s var(--xc-ease);
}

.page-about .timeline__stage {
  flex: 0 0 auto;
  font-size: 12px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
  color: var(--xc-lake);
}

.page-about .timeline__name {
  flex: 1 1 auto;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(17px, 2vw, 21px);
  line-height: 1.35;
  letter-spacing: -0.01em;
  color: var(--xc-ink);
  transition: color 0.25s var(--xc-ease);
}

.page-about .timeline__summary:hover .timeline__name,
.page-about .timeline__summary:focus-visible .timeline__name {
  color: var(--xc-signal-deep);
}

.page-about .timeline__node[open] .timeline__dot {
  background: var(--xc-signal);
  border-color: var(--xc-signal);
}

.page-about .timeline__body {
  padding: 0 0 18px 14px;
  border-left: 2px solid var(--xc-signal);
  margin: 0 0 4px;
}

.page-about .timeline__body p {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.82;
  color: var(--xc-text);
  max-width: 36ch;
}

/* ---------- 图文双栏 ---------- */
.page-about .about-duo {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: clamp(24px, 3.4vw, 44px);
  align-items: start;
}

.page-about .about-duo__text > p {
  font-size: 16.5px;
  line-height: 1.85;
  color: var(--xc-text);
  max-width: 38ch;
  margin: 0 0 1.15em;
}

.page-about .about-duo__media {
  margin: 0;
  width: 100%;
}

/* ---------- 分工清单 ---------- */
.page-about .roles {
  list-style: none;
  margin: clamp(22px, 3vw, 32px) 0 0;
  padding: 0;
}

.page-about .roles__item {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 14px;
  padding: 20px 0;
  border-top: 1px solid var(--xc-line);
}

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

.page-about .roles__count {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(28px, 3.4vw, 40px);
  line-height: 1;
  letter-spacing: -0.02em;
  font-variant-numeric: tabular-nums;
  color: var(--xc-signal);
  min-width: 2.2ch;
}

.page-about .roles__name {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 18px;
  line-height: 1.35;
  letter-spacing: -0.01em;
  color: var(--xc-ink);
  margin: 0 0 7px;
}

.page-about .roles__body p {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.8;
  color: var(--xc-text);
  max-width: 40ch;
}

/* ---------- 数字条 ---------- */
.page-about .figures {
  list-style: none;
  margin: 0 0 clamp(26px, 3.4vw, 38px);
  padding: 0;
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 1px;
  background: var(--xc-line);
  border: 1px solid var(--xc-line);
}

.page-about .figures__item {
  background: var(--xc-panel);
  padding: clamp(18px, 2.4vw, 26px);
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 0 6px;
}

.page-about .figures__num {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(30px, 4vw, 46px);
  line-height: 1;
  letter-spacing: -0.025em;
  font-variant-numeric: tabular-nums;
  color: var(--xc-ink);
}

.page-about .figures__unit {
  font-size: 14px;
  font-weight: 700;
  color: var(--xc-signal);
  letter-spacing: 0.04em;
}

.page-about .figures__label {
  flex: 1 1 100%;
  margin-top: 8px;
  font-size: 13.5px;
  line-height: 1.7;
  color: var(--xc-muted);
}

/* ---------- 整理方式定义表 ---------- */
.page-about .method {
  margin: clamp(22px, 3vw, 30px) 0 0;
}

.page-about .method__row {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 6px;
  padding: 16px 0;
  border-top: 1px solid var(--xc-line);
}

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

.page-about .method__key {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 16px;
  letter-spacing: -0.005em;
  color: var(--xc-lake);
}

.page-about .method__val {
  margin: 0;
  font-size: 15.5px;
  line-height: 1.8;
  color: var(--xc-text);
  max-width: 42ch;
}

/* ---------- 收尾行动区 ---------- */
.page-about .about-cta {
  background: var(--xc-stand-deep);
  color: var(--xc-paper);
  padding: clamp(48px, 7vw, 92px) 0 clamp(52px, 7vw, 96px);
}

.page-about .about-cta__inner {
  max-width: 620px;
}

.page-about .about-cta__lamp {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 38px;
  height: 38px;
  border: 1px solid rgba(244, 242, 238, 0.28);
  margin-bottom: clamp(18px, 2.4vw, 26px);
}

.page-about .about-cta__lamp-dot {
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--xc-lime);
  animation: about-lamp 2.6s var(--xc-ease) infinite;
}

@keyframes about-lamp {
  0%, 100% { opacity: 0.35; }
  50% { opacity: 1; }
}

.page-about .about-cta__title {
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(28px, 4vw, 46px);
  line-height: 1.1;
  letter-spacing: -0.02em;
  margin: 0 0 clamp(14px, 2vw, 22px);
  color: var(--xc-paper);
}

.page-about .about-cta__text {
  margin: 0 0 clamp(24px, 3.2vw, 36px);
  font-size: 16.5px;
  line-height: 1.85;
  color: rgba(244, 242, 238, 0.86);
  max-width: 44ch;
}

.page-about .about-cta__actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 16px 26px;
}

.page-about .about-cta__link {
  color: var(--xc-paper);
  font-size: 15px;
}

.page-about .about-cta__link:hover,
.page-about .about-cta__link:focus-visible {
  color: var(--xc-lime);
}

.page-about .about-cta__aside {
  margin: clamp(24px, 3.4vw, 38px) 0 0;
  padding-top: clamp(18px, 2.4vw, 26px);
  border-top: 1px solid rgba(244, 242, 238, 0.18);
  font-size: 15px;
  line-height: 1.8;
  color: rgba(244, 242, 238, 0.72);
  max-width: 44ch;
}

.page-about .about-cta__aside .link-line {
  color: var(--xc-lime);
}

/* ---------- 图片通用 ---------- */
.page-about .media-frame img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .figures {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about .method__row {
    grid-template-columns: 9.5rem minmax(0, 1fr);
    gap: 24px;
    align-items: baseline;
  }
}

@media (min-width: 900px) {
  .page-about .about-hero__grid {
    grid-template-columns: minmax(0, 7fr) minmax(0, 3fr);
    gap: clamp(32px, 4vw, 64px);
  }

  .page-about .about-duo {
    grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
    gap: clamp(32px, 4vw, 56px);
  }

  .page-about .about-duo--reverse {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.15fr);
  }
}

@media (min-width: 1000px) {
  .page-about .about-body__grid {
    grid-template-columns: var(--about-index-w) minmax(0, 1fr);
    gap: clamp(44px, 5vw, 88px);
  }

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

  .page-about .about-index__list {
    display: block;
    border-bottom: 0;
    padding-bottom: 0;
    overflow: visible;
  }

  .page-about .about-index__link {
    white-space: normal;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-cta__lamp-dot {
    animation: none;
    opacity: 1;
  }

  .page-about .about-index__link,
  .page-about .timeline__name,
  .page-about .timeline__dot {
    transition: none;
  }
}