.page-about {
  --about-rule: 1px solid var(--mist);
  --about-paper-lift: 0 1px 0 var(--mist), 0 18px 30px -26px rgba(21, 23, 27, 0.55);
}

.page-about .crumbs {
  padding: 14px 0 6px;
}

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

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

/* 首屏声明带 */
.page-about .about-brief {
  display: grid;
  gap: 26px;
  padding: 10px 0 30px;
}

.page-about .about-brief__text h1 {
  margin: 10px 0 14px;
  font-family: var(--font-display);
  font-size: clamp(30px, 8vw, 58px);
  font-weight: 800;
  line-height: 1.04;
  letter-spacing: -0.02em;
  max-width: 18ch;
}

.page-about .about-brief__text .lede {
  max-width: 46ch;
  margin: 0;
  color: var(--ink-soft);
}

.page-about .about-brief__stats {
  margin: 0;
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1px;
  background: var(--mist);
  border: var(--about-rule);
}

.page-about .about-stat {
  background: var(--paper);
  padding: 14px 16px 16px;
}

.page-about .about-stat dt {
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--slate);
  margin-bottom: 8px;
}

.page-about .about-stat dd {
  margin: 0;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 20px;
  font-weight: 600;
  color: var(--ink);
}

/* 阶段索引：窄屏横向滚动，宽屏纵向列表 */
.page-about .timeline {
  padding: 4px 0 22px;
}

.page-about .timeline__list {
  list-style: none;
  margin: 0;
  padding: 0 0 8px;
  display: flex;
  gap: 10px;
  overflow-x: auto;
  scroll-snap-type: x proximity;
  -webkit-overflow-scrolling: touch;
}

.page-about .timeline__item {
  flex: 0 0 auto;
  scroll-snap-align: start;
}

.page-about .timeline__node {
  display: block;
  min-width: 232px;
  min-height: 44px;
  padding: 14px 16px;
  background: var(--paper);
  border: var(--about-rule);
  border-left: 3px solid var(--gobi);
  text-decoration: none;
  color: var(--ink);
  transition: background-color var(--t-base), border-color var(--t-base);
}

.page-about .timeline__node:hover {
  background: rgba(233, 197, 63, 0.25);
}

.page-about .timeline__node:focus-visible {
  outline: 2px solid var(--night);
  outline-offset: 2px;
}

.page-about .timeline__year {
  display: block;
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--gobi);
  margin-bottom: 6px;
}

.page-about .timeline__label {
  display: block;
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.page-about .timeline__hint {
  display: block;
  margin-top: 6px;
  font-size: 13px;
  color: var(--slate);
}

/* 阶段展板 */
.page-about .stage {
  padding: 34px 0 4px;
  border-top: var(--about-rule);
}

.page-about .stage__marker {
  display: flex;
  align-items: baseline;
  gap: 12px;
  margin-bottom: 14px;
}

.page-about .stage__year {
  font-family: var(--font-display);
  font-size: clamp(26px, 6.5vw, 32px);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1;
  color: var(--ink);
}

.page-about .stage__code {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--slate);
}

.page-about .stage__plate {
  position: relative;
  isolation: isolate;
  background: var(--paper);
  border: var(--about-rule);
  border-left: 3px solid var(--gobi);
  box-shadow: var(--about-paper-lift);
  padding: 22px 20px 24px;
}

.page-about .stage__plate::before {
  content: "";
  position: absolute;
  z-index: -1;
  inset: 8px -8px -8px 8px;
  background: var(--paper-deep);
  border: var(--about-rule);
  transition: transform var(--t-base);
}

.page-about .stage__plate:hover::before {
  transform: translate(4px, 2px);
}

.page-about .stage__text h2 {
  margin: 0 0 12px;
  font-family: var(--font-display);
  font-size: clamp(21px, 4.6vw, 30px);
  font-weight: 700;
  line-height: 1.14;
  letter-spacing: -0.01em;
}

.page-about .stage__text p {
  margin: 0 0 14px;
  font-size: 16px;
  line-height: 1.75;
  color: var(--ink-soft);
}

.page-about .stage__media {
  margin: 6px 0 16px;
}

.page-about .stage__media .frame__caption {
  font-size: 12px;
  color: var(--slate);
}

.page-about .rule-note {
  font-size: 14px;
  line-height: 1.7;
  color: var(--slate);
  margin: 0;
}

/* 团队与校核 */
.page-about .crew {
  padding: 44px 0 8px;
  border-top: var(--about-rule);
}

.page-about .crew h2 {
  margin: 10px 0 12px;
  font-family: var(--font-display);
  font-size: clamp(22px, 5vw, 32px);
  font-weight: 700;
  letter-spacing: -0.01em;
}

.page-about .crew > p {
  max-width: 62ch;
  margin: 0 0 20px;
  color: var(--ink-soft);
}

.page-about .crew__caption {
  caption-side: top;
  text-align: left;
  font-size: 12px;
  color: var(--slate);
  padding-bottom: 8px;
}

.page-about .crew-steps {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  border-top: var(--about-rule);
}

.page-about .crew-steps li {
  display: grid;
  grid-template-columns: 36px minmax(0, 1fr);
  gap: 14px;
  align-items: baseline;
  padding: 14px 0;
  border-bottom: var(--about-rule);
}

.page-about .crew-steps__num {
  font-size: 13px;
  color: var(--gobi);
  letter-spacing: 0.06em;
}

.page-about .crew-steps p {
  margin: 0;
  font-size: 15px;
  line-height: 1.7;
  color: var(--ink-soft);
}

/* 编号规则深色面板 */
.page-about .numbering {
  margin: 46px 0 0;
  background: var(--panel);
  color: var(--paper);
  border: 1px solid var(--ink);
  padding: 26px 20px 28px;
  display: grid;
  gap: 22px;
}

.page-about .numbering h2 {
  margin: 10px 0 12px;
  font-family: var(--font-display);
  font-size: clamp(22px, 5vw, 30px);
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--paper);
}

.page-about .numbering p {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: rgba(244, 241, 234, 0.78);
  max-width: 52ch;
}

.page-about .numbering .eyebrow {
  color: var(--card-yellow);
}

.page-about .numbering__code {
  margin: 0;
  padding: 16px 16px 18px;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 13px;
  line-height: 2;
  white-space: pre;
  overflow-x: auto;
  background: rgba(244, 241, 234, 0.06);
  border: 1px solid rgba(244, 241, 234, 0.18);
  color: var(--paper);
}

.page-about .numbering__k {
  color: var(--night-bright);
}

/* 常见问题 */
.page-about .qa {
  padding: 44px 0 8px;
}

.page-about .qa h2 {
  margin: 0 0 16px;
  font-family: var(--font-display);
  font-size: clamp(21px, 4.6vw, 28px);
  font-weight: 700;
  letter-spacing: -0.01em;
}

.page-about .qa__list {
  border-top: var(--about-rule);
}

.page-about .qa .disclosure {
  border-bottom: var(--about-rule);
}

.page-about .qa .disclosure__body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.75;
  color: var(--ink-soft);
}

/* 下一页入口 */
.page-about .next {
  padding: 44px 0 56px;
}

.page-about .next h2 {
  margin: 0 0 16px;
  font-family: var(--font-display);
  font-size: clamp(21px, 4.6vw, 28px);
  font-weight: 700;
  letter-spacing: -0.01em;
}

.page-about .next__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--mist);
  border: var(--about-rule);
}

.page-about .next__item {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 2px 12px;
  align-items: baseline;
  min-height: 64px;
  padding: 15px 16px;
  background: var(--paper);
  text-decoration: none;
  color: var(--ink);
  transition: background-color var(--t-base);
}

.page-about .next__item:hover {
  background: rgba(233, 197, 63, 0.25);
}

.page-about .next__item:focus-visible {
  outline: 2px solid var(--night);
  outline-offset: 2px;
}

.page-about .next__k {
  grid-row: 1 / span 2;
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--gobi);
}

.page-about .next__t {
  font-family: var(--font-display);
  font-size: 19px;
  font-weight: 700;
  letter-spacing: -0.01em;
}

.page-about .next__d {
  font-size: 13px;
  line-height: 1.6;
  color: var(--slate);
}

@media (min-width: 720px) {
  .page-about .about-brief {
    grid-template-columns: minmax(0, 1.25fr) minmax(0, 1fr);
    gap: 40px;
    align-items: start;
    padding: 18px 0 38px;
  }

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

  .page-about .numbering {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: 32px;
    align-items: start;
    padding: 32px 30px 34px;
  }

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

@media (min-width: 900px) {
  .page-about .timeline__list {
    flex-direction: column;
    gap: 0;
    overflow: visible;
    padding-bottom: 0;
    border-top: var(--about-rule);
  }

  .page-about .timeline__item {
    flex: 1 1 auto;
  }

  .page-about .timeline__node {
    min-width: 0;
    display: grid;
    grid-template-columns: 148px minmax(0, 1fr);
    gap: 4px 22px;
    align-items: baseline;
    padding: 15px 18px;
    border: 0;
    border-bottom: var(--about-rule);
    border-left: 3px solid var(--gobi);
  }

  .page-about .timeline__year {
    grid-column: 1;
    grid-row: 1 / span 2;
    margin-bottom: 0;
    padding-top: 3px;
  }

  .page-about .timeline__label {
    grid-column: 2;
    grid-row: 1;
  }

  .page-about .timeline__hint {
    grid-column: 2;
    grid-row: 2;
    margin-top: 0;
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-height var(--t-base), opacity var(--t-base);
  }

  .page-about .timeline__node:hover .timeline__hint,
  .page-about .timeline__node:focus-visible .timeline__hint {
    max-height: 3.4em;
    opacity: 1;
  }

  .page-about .stage {
    display: grid;
    grid-template-columns: 132px minmax(0, 1fr);
    gap: 0 36px;
    padding: 52px 0 10px;
  }

  .page-about .stage__marker {
    flex-direction: column;
    gap: 10px;
    margin-bottom: 0;
    align-self: start;
    position: sticky;
    top: calc(var(--header-h) + 26px);
  }

  .page-about .stage__year {
    font-size: 30px;
  }

  .page-about .stage__plate {
    padding: 28px 26px 30px;
  }

  .page-about .stage--media-right .stage__plate,
  .page-about .stage--media-left .stage__plate {
    display: grid;
    gap: 12px 30px;
    align-items: start;
  }

  .page-about .stage--media-right .stage__plate {
    grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr);
  }

  .page-about .stage--media-left .stage__plate {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1.4fr);
  }

  .page-about .stage--media-right .stage__media,
  .page-about .stage--media-left .stage__media {
    margin: 4px 0 0;
  }

  .page-about .crew {
    padding-top: 54px;
  }

  .page-about .numbering {
    margin-top: 56px;
    padding: 36px 34px 38px;
  }

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

@media (prefers-reduced-motion: reduce) {
  .page-about .stage__plate::before,
  .page-about .stage__plate:hover::before {
    transform: none;
    transition: none;
  }

  .page-about .timeline__hint,
  .page-about .timeline__node,
  .page-about .next__item {
    transition: color var(--t-base), background-color var(--t-base), border-color var(--t-base);
  }
}