.page-about {
  --about-year-col: 64px;
  display: block;
}

.page-about .about-hero,
.page-about .about-timeline,
.page-about .about-groups,
.page-about .about-paper,
.page-about .about-handoff,
.page-about .about-ledger-block,
.page-about .about-region {
  padding-block: clamp(30px, 5vw, 56px);
}

.page-about .about-timeline,
.page-about .about-groups,
.page-about .about-paper,
.page-about .about-handoff,
.page-about .about-ledger-block,
.page-about .about-region {
  margin-top: clamp(24px, 4vw, 44px);
}

.page-about h1,
.page-about h2,
.page-about h3 {
  text-wrap: balance;
}

.page-about .about-section-head h2 {
  margin: 10px 0 0;
  font-size: var(--step-3);
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--ice);
  max-width: 22ch;
}

.page-about .about-section-head .prose {
  margin: 16px 0 0;
  max-width: 36em;
  color: var(--silver);
  line-height: 1.78;
}

.page-about .about-section-head a {
  color: var(--cyan);
  text-decoration: none;
  border-bottom: 1px solid rgba(0, 229, 255, 0.4);
  transition: border-color 240ms var(--ease), color 240ms var(--ease);
}

.page-about .about-section-head a:hover {
  color: var(--ice);
  border-bottom-color: var(--ice);
}

/* ---------- HERO ---------- */
.page-about .about-hero {
  display: grid;
  gap: clamp(26px, 5vw, 52px);
  align-items: center;
}

.page-about .about-hero__text h1 {
  margin: 16px 0 0;
  font-size: var(--step-4);
  font-weight: 900;
  line-height: 1.04;
  letter-spacing: -0.03em;
  color: var(--ice);
}

.page-about .about-hero__text .lede {
  margin: clamp(18px, 3vw, 26px) 0 0;
  max-width: 34em;
  color: var(--silver);
  line-height: 1.8;
}

.page-about .about-stats {
  display: flex;
  flex-wrap: wrap;
  gap: clamp(18px, 3vw, 44px);
  margin: clamp(24px, 4vw, 40px) 0 0;
  padding: clamp(20px, 3vw, 28px) 0 0;
  border-top: 1px solid var(--line);
}

.page-about .about-stats > div {
  min-width: 104px;
}

.page-about .about-stats dt {
  font-size: var(--step--1);
  color: var(--silver);
  letter-spacing: 0.06em;
}

.page-about .about-stats dd {
  margin: 8px 0 0;
  font-size: var(--step-2);
  font-weight: 800;
  line-height: 1;
  color: var(--ice);
}

.page-about .about-hero__visual {
  position: relative;
  margin: 0;
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: var(--night-3);
  border: 1px solid var(--line);
  box-shadow: var(--shadow-lift);
}

.page-about .about-hero__visual img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  opacity: 0.7;
}

.page-about .about-hero__visual::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background:
    linear-gradient(152deg, rgba(0, 229, 255, 0.18), transparent 54%, rgba(255, 107, 53, 0.16)),
    linear-gradient(0deg, rgba(11, 27, 43, 0.72), transparent 60%);
}

.page-about .about-hero__visual figcaption {
  position: absolute;
  right: 14px;
  bottom: 16px;
  z-index: 1;
  writing-mode: vertical-rl;
  padding: 12px 7px;
  font-family: var(--font-mono);
  font-size: var(--step--1);
  letter-spacing: 0.2em;
  color: var(--ice);
  background: rgba(8, 19, 31, 0.74);
  border-radius: 999px;
}

/* ---------- 年份索引 ---------- */
.page-about .about-index {
  display: flex;
  margin: clamp(26px, 4vw, 44px) 0 clamp(34px, 5vw, 56px);
  padding: 0;
  list-style: none;
  overflow-x: auto;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  scrollbar-width: thin;
}

.page-about .about-index li {
  flex: 1 0 auto;
}

.page-about .about-index__item {
  display: flex;
  flex-direction: column;
  gap: 6px;
  min-width: 116px;
  padding: 15px 20px;
  text-decoration: none;
  color: var(--silver);
  border-right: 1px solid var(--line);
  transition: background-color 240ms var(--ease), color 240ms var(--ease);
}

.page-about .about-index li:last-child .about-index__item {
  border-right: 0;
}

.page-about .about-index__item .mono {
  font-size: var(--step--1);
  font-weight: 700;
  letter-spacing: 0.04em;
  color: var(--ice);
  transition: color 240ms var(--ease);
}

.page-about .about-index__tag {
  font-size: var(--step--1);
  letter-spacing: 0.14em;
}

.page-about .about-index__item:hover,
.page-about .about-index__item:focus-visible {
  background: var(--night-2);
  color: var(--cyan);
}

.page-about .about-index__item:hover .mono,
.page-about .about-index__item:focus-visible .mono {
  color: var(--cyan);
}

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

.page-about .about-track::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: linear-gradient(180deg, var(--cyan), var(--violet) 44%, var(--teal) 80%, transparent);
  opacity: 0.65;
}

.page-about .about-year {
  position: relative;
  padding: 0 0 clamp(32px, 5vw, 56px) 32px;
  scroll-margin-top: calc(var(--bar-h) + 72px);
}

.page-about .about-year::before {
  content: "";
  position: absolute;
  left: 2px;
  top: 6px;
  width: 11px;
  height: 11px;
  border-radius: 50%;
  background: radial-gradient(circle, var(--night) 0 40%, var(--cyan) 42% 100%);
  box-shadow: 0 0 0 4px rgba(0, 229, 255, 0.12);
  transition: box-shadow 240ms var(--ease);
}

.page-about .about-year__num {
  display: block;
  margin-bottom: 8px;
  font-size: var(--step--1);
  font-weight: 700;
  letter-spacing: 0.06em;
  color: var(--silver);
  transition: color 240ms var(--ease);
}

.page-about .about-year__body h3 {
  margin: 0 0 10px;
  font-size: var(--step-2);
  line-height: 1.24;
  letter-spacing: -0.012em;
  color: var(--ice);
}

.page-about .about-year__body > p {
  margin: 0 0 14px;
  max-width: 34em;
  color: var(--silver);
  line-height: 1.78;
}

.page-about .about-year__aside {
  max-width: 34em;
  padding-left: 14px;
  border-left: 2px solid var(--line-strong);
  font-size: var(--step--1);
  line-height: 1.7;
  color: var(--silver);
}

.page-about .about-year:hover::before,
.page-about .about-year:focus-within::before {
  box-shadow: 0 0 0 8px rgba(0, 229, 255, 0.16);
}

.page-about .about-year:hover .about-year__num,
.page-about .about-year:focus-within .about-year__num {
  color: var(--cyan);
}

.page-about .about-year:target::before {
  background: radial-gradient(circle, var(--night) 0 40%, var(--orange) 42% 100%);
  box-shadow: 0 0 0 8px rgba(255, 107, 53, 0.18);
}

.page-about .about-year:target .about-year__num {
  color: var(--orange);
}

/* ---------- 三组机制 ---------- */
.page-about .about-groups__grid {
  display: grid;
  gap: clamp(26px, 5vw, 52px);
  margin-top: clamp(26px, 4vw, 44px);
  align-items: start;
}

.page-about .about-groups__copy .prose {
  margin: 0 0 clamp(20px, 3vw, 30px);
  max-width: 34em;
  color: var(--silver);
  line-height: 1.78;
}

.page-about .about-roles {
  display: grid;
  gap: 16px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.page-about .about-role {
  padding: clamp(18px, 2.6vw, 26px) clamp(18px, 2.6vw, 26px) clamp(18px, 2.6vw, 26px) clamp(20px, 3vw, 28px);
  border: 1px solid var(--line);
  border-left: 3px solid var(--silver);
  border-radius: var(--radius);
  background: linear-gradient(180deg, rgba(18, 40, 61, 0.72), rgba(8, 19, 31, 0.55));
  transition: background 260ms var(--ease), box-shadow 260ms var(--ease);
}

.page-about .about-role--edit {
  border-left-color: var(--cyan);
}

.page-about .about-role--check {
  border-left-color: var(--orange);
}

.page-about .about-role--archive {
  border-left-color: var(--teal);
}

.page-about .about-role:hover {
  background: linear-gradient(180deg, rgba(18, 40, 61, 1), rgba(8, 19, 31, 0.86));
  box-shadow: var(--shadow-lift);
}

.page-about .about-role h3 {
  margin: 0 0 8px;
  font-size: var(--step-1);
  color: var(--ice);
}

.page-about .about-role p {
  margin: 0;
  max-width: 32em;
  color: var(--silver);
  line-height: 1.74;
}

.page-about .about-groups__visual {
  margin: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: var(--night-3);
}

.page-about .about-groups__visual img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 3 / 2;
  object-fit: cover;
  opacity: 0.86;
}

.page-about .about-groups__visual figcaption {
  padding: 14px 18px;
  font-size: var(--step--1);
  line-height: 1.6;
  color: var(--silver);
  background: var(--night-2);
  border-top: 1px solid var(--line);
}

/* ---------- 纸面面板 ---------- */
.page-about .about-paper__panel {
  padding: clamp(26px, 5vw, 54px);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lift);
}

.page-about .about-paper__panel .section-label {
  color: var(--teal);
}

.page-about .about-paper__panel h2 {
  margin: 10px 0 0;
  font-size: var(--step-3);
  line-height: 1.1;
  letter-spacing: -0.02em;
  color: var(--ink);
  max-width: 20ch;
}

.page-about .about-paper__lede {
  margin: 18px 0 0;
  max-width: 34em;
  color: rgba(16, 20, 24, 0.76);
  line-height: 1.78;
}

.page-about .about-paper__steps {
  counter-reset: step;
  display: grid;
  gap: 18px;
  margin: clamp(22px, 3.4vw, 34px) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-paper__steps li {
  counter-increment: step;
  position: relative;
  padding-left: 46px;
  min-height: 32px;
  max-width: 40em;
  color: rgba(16, 20, 24, 0.82);
  line-height: 1.72;
}

.page-about .about-paper__steps li::before {
  content: counter(step, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 0;
  display: grid;
  place-items: center;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  background: var(--ink);
  color: var(--paper);
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
}

/* ---------- 交付周期 ---------- */
.page-about .about-handoff__grid {
  display: grid;
  gap: 18px;
  margin-top: clamp(26px, 4vw, 42px);
}

.page-about .about-track-card {
  padding: clamp(20px, 3vw, 30px);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(165deg, rgba(18, 40, 61, 0.9), rgba(8, 19, 31, 0.82));
  transition: border-color 260ms var(--ease), box-shadow 260ms var(--ease);
}

.page-about .about-track-card:hover {
  border-color: var(--line-strong);
  box-shadow: var(--shadow-lift);
}

.page-about .about-track-card--instant {
  border-top: 3px solid var(--cyan);
}

.page-about .about-track-card--h24 {
  border-top: 3px solid var(--orange);
}

.page-about .about-track-card--std {
  border-top: 3px solid var(--silver);
}

.page-about .about-track-card .eyebrow {
  margin: 0;
}

.page-about .about-track-card h3 {
  margin: 14px 0 10px;
  font-size: var(--step-1);
  line-height: 1.3;
  color: var(--ice);
}

.page-about .about-track-card p {
  margin: 0;
  max-width: 30em;
  color: var(--silver);
  line-height: 1.74;
}

.page-about .about-track-card__link {
  margin-top: 18px;
}

.page-about .about-handoff__note {
  margin-top: clamp(30px, 5vw, 56px);
  padding: clamp(24px, 4vw, 40px);
  border: 1px solid var(--line);
  border-left: 3px solid var(--orange);
  border-radius: var(--radius);
  background: rgba(18, 40, 61, 0.55);
}

.page-about .about-handoff__note h3 {
  margin: 0 0 10px;
  font-size: var(--step-2);
  line-height: 1.22;
  color: var(--ice);
}

.page-about .about-handoff__note > p {
  margin: 0;
  max-width: 34em;
  color: var(--silver);
  line-height: 1.78;
}

.page-about .about-handoff__list {
  display: grid;
  gap: 14px;
  margin: clamp(20px, 3vw, 30px) 0 0;
  padding: 0;
  list-style: none;
}

.page-about .about-handoff__list li {
  display: grid;
  grid-template-columns: 34px 1fr;
  gap: 14px;
  align-items: start;
  max-width: 38em;
  color: var(--silver);
  line-height: 1.72;
}

.page-about .about-handoff__list .mono {
  font-size: var(--step--1);
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--orange);
  padding-top: 3px;
}

.page-about .about-handoff__cta {
  margin: clamp(22px, 3vw, 32px) 0 0;
}

/* ---------- 计数 ---------- */
.page-about .about-ledger {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(158px, 1fr));
  gap: 1px;
  margin: clamp(26px, 4vw, 44px) 0 0;
  padding: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--line);
}

.page-about .about-ledger__cell {
  padding: clamp(20px, 3vw, 30px);
  background: var(--night-2);
}

.page-about .about-ledger__cell dt {
  font-size: var(--step--1);
  letter-spacing: 0.05em;
  color: var(--silver);
}

.page-about .about-ledger__cell dd {
  margin: 12px 0 0;
  font-family: var(--font-mono);
  font-size: clamp(1.75rem, 3.4vw, 2.6rem);
  font-weight: 800;
  line-height: 1;
  color: var(--ice);
  letter-spacing: -0.02em;
}

.page-about .about-ledger__cell .unit {
  margin-left: 6px;
  font-size: var(--step--1);
  font-weight: 600;
  letter-spacing: 0.04em;
  color: var(--cyan);
}

/* ---------- 地区与备案 ---------- */
.page-about .about-region__banner {
  position: relative;
  margin: 0 0 clamp(26px, 4vw, 42px);
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  overflow: hidden;
  background: var(--night-3);
}

.page-about .about-region__banner img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 8 / 3;
  object-fit: cover;
  opacity: 0.6;
}

.page-about .about-region__banner figcaption {
  position: absolute;
  left: clamp(20px, 4vw, 44px);
  bottom: clamp(18px, 3vw, 34px);
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.page-about .about-region__banner .section-label {
  color: var(--cyan);
}

.page-about .about-region__title {
  font-size: var(--step-3);
  font-weight: 900;
  line-height: 1.08;
  letter-spacing: -0.02em;
  color: var(--ice);
}

.page-about .about-region__body {
  display: grid;
  gap: 18px;
}

.page-about .about-region__body .prose {
  margin: 0;
  max-width: 36em;
  color: var(--silver);
  line-height: 1.78;
}

.page-about .about-region__facts {
  display: grid;
  gap: 1px;
  margin: 6px 0 0;
  padding: 1px;
  list-style: none;
  border-radius: var(--radius);
  background: var(--line);
  overflow: hidden;
}

.page-about .about-region__facts li {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 20px;
  align-items: baseline;
  justify-content: space-between;
  padding: 14px 18px;
  background: var(--night-2);
}

.page-about .about-region__k {
  font-size: var(--step--1);
  letter-spacing: 0.06em;
  color: var(--silver);
}

.page-about .about-region__facts .mono {
  font-weight: 700;
  color: var(--ice);
}

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

/* ---------- 响应式 ---------- */
@media (min-width: 520px) {
  .page-about {
    --about-year-col: 78px;
  }
}

@media (min-width: 760px) {
  .page-about {
    --about-year-col: 106px;
  }

  .page-about .about-track::before {
    left: calc(var(--about-year-col) - 1px);
    top: 10px;
  }

  .page-about .about-year {
    padding-left: calc(var(--about-year-col) + 28px);
    scroll-margin-top: 140px;
  }

  .page-about .about-year::before {
    left: calc(var(--about-year-col) - 6px);
    top: 4px;
  }

  .page-about .about-year__num {
    position: absolute;
    left: 0;
    top: 0;
    width: calc(var(--about-year-col) - 24px);
    margin-bottom: 0;
    text-align: right;
    font-size: var(--step-0);
  }

  .page-about .about-year__aside {
    max-height: 0;
    opacity: 0;
    overflow: hidden;
    border-left-color: transparent;
    transition: max-height 300ms var(--ease), opacity 260ms var(--ease), border-left-color 260ms var(--ease);
  }

  .page-about .about-year:hover .about-year__aside,
  .page-about .about-year:focus-within .about-year__aside,
  .page-about .about-year:target .about-year__aside {
    max-height: 8em;
    opacity: 1;
    border-left-color: var(--cyan);
  }
}

@media (min-width: 900px) {
  .page-about .about-hero {
    grid-template-columns: minmax(0, 6fr) minmax(0, 5fr);
    gap: clamp(40px, 6vw, 84px);
    align-items: center;
  }

  .page-about .about-hero__visual {
    margin-top: 0;
  }
}

@media (min-width: 820px) {
  .page-about .about-handoff__grid {
    grid-template-columns: minmax(0, 1.24fr) minmax(0, 1fr) minmax(0, 1.06fr);
    align-items: start;
  }

  .page-about .about-track-card:nth-child(2) {
    margin-top: 26px;
  }

  .page-about .about-track-card:nth-child(3) {
    margin-top: 54px;
  }
}

@media (min-width: 960px) {
  .page-about .about-groups__grid {
    grid-template-columns: minmax(0, 6fr) minmax(0, 5fr);
    gap: clamp(36px, 5vw, 68px);
  }

  .page-about .about-groups__visual {
    position: sticky;
    top: 96px;
  }

  .page-about .about-region__body {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    align-items: start;
    column-gap: clamp(32px, 5vw, 64px);
  }

  .page-about .about-region__body .prose:first-child {
    grid-column: 1;
  }

  .page-about .about-region__facts {
    grid-column: 2;
    grid-row: 1 / span 2;
    margin-top: 0;
  }

  .page-about .about-region__cta {
    grid-column: 1;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .about-year__aside,
  .page-about .about-year::before,
  .page-about .about-year__num,
  .page-about .about-role,
  .page-about .about-track-card,
  .page-about .about-index__item {
    transition-duration: 1ms;
  }
}