.page-about {
  --about-rail: 224px;
  --about-gap: 48px;
  --about-fold: 22px;
  background: var(--ink-900);
  color: var(--paper-100);
  font-family: var(--font-body);
  font-size: 17px;
  line-height: 1.85;
  padding-bottom: 0;
}

.page-about .section-title {
  font-family: var(--font-display);
  font-size: clamp(26px, 3.6vw, 40px);
  font-weight: 600;
  line-height: 1.14;
  letter-spacing: -0.005em;
  margin: 0;
  color: var(--paper-100);
}

.page-about .lede {
  font-size: 17px;
  line-height: 1.9;
  color: var(--slate-400);
  max-width: 54ch;
  margin: 0 0 28px;
}

.page-about .mono {
  font-family: var(--font-mono);
  letter-spacing: 0.02em;
}

.page-about .about-v {
  color: var(--gold-400);
  font-weight: 500;
}

/* ---------- 首屏分屏 ---------- */
.about-hero {
  position: relative;
  padding: 32px 0 68px;
  border-bottom: 1px solid var(--line-soft);
  background:
    radial-gradient(120% 96% at 100% 0%, rgba(51, 80, 122, 0.38) 0%, rgba(11, 18, 32, 0) 62%),
    var(--ink-900);
}

.about-hero__inner {
  display: grid;
  gap: 40px;
  align-items: center;
}

.about-hero__copy h1 {
  font-family: var(--font-display);
  font-size: clamp(38px, 8vw, 66px);
  font-weight: 600;
  line-height: 1.04;
  letter-spacing: -0.012em;
  margin: 14px 0 22px;
  color: var(--paper-100);
}

.about-hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.about-hero__facts {
  display: flex;
  flex-wrap: wrap;
  gap: 18px 36px;
  margin: 34px 0 0;
  padding-top: 22px;
  border-top: 1px solid var(--line-soft);
}

.about-hero__facts > div {
  display: flex;
  flex-direction: column;
  gap: 3px;
}

.about-hero__facts dt {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--slate-400);
}

.about-hero__facts dd {
  margin: 0;
  font-size: 15px;
  color: var(--paper-100);
}

.about-hero__visual {
  position: relative;
  padding: 18px;
  border: 1px solid var(--line-soft);
  background: linear-gradient(180deg, rgba(18, 28, 46, 0.92), rgba(11, 18, 32, 0.96));
  box-shadow: 8px 8px 0 rgba(11, 18, 32, 0.62);
}

.about-hero__visual::before {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image: repeating-linear-gradient(0deg, rgba(244, 237, 224, 0.045) 0 1px, rgba(244, 237, 224, 0) 1px 4px);
}

.about-hero__visual::after {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  border-width: 0 var(--about-fold) var(--about-fold) 0;
  border-style: solid;
  border-color: transparent var(--ink-900) transparent transparent;
}

.about-hero__visual svg {
  display: block;
  width: 100%;
  height: auto;
}

.hero-svg .s-frame { fill: none; stroke: var(--line-600); stroke-width: 1; }
.hero-svg .s-bar { fill: rgba(27, 41, 64, 0.92); stroke: var(--line-600); stroke-width: 1; }
.hero-svg .s-grid { stroke: var(--line-soft); stroke-width: 1; }
.hero-svg .s-slot { fill: var(--line-600); opacity: 0.6; }
.hero-svg .s-panel { fill: rgba(27, 41, 64, 0.88); stroke: var(--line-600); stroke-width: 1; }
.hero-svg .s-path { fill: none; stroke: var(--gold-400); stroke-width: 2; stroke-linecap: round; stroke-linejoin: round; }
.hero-svg .s-node { fill: var(--ink-900); stroke: var(--celadon-400); stroke-width: 2; }
.hero-svg .s-node-gold { fill: var(--gold-400); stroke: var(--gold-200); stroke-width: 2; }
.hero-svg .s-axis { stroke: var(--line-soft); stroke-width: 1; }
.hero-svg .s-tick { stroke: var(--slate-400); stroke-width: 1; opacity: 0.6; }
.hero-svg .s-tick-gold { stroke: var(--gold-400); stroke-width: 2; }

/* ---------- 档案网格 ---------- */
.about-archive {
  display: grid;
  gap: 40px;
  padding-top: 56px;
  padding-bottom: 72px;
}

.about-rail {
  border-left: 3px solid var(--gold-400);
  padding-left: 14px;
}

.about-rail__title {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--slate-400);
  text-transform: uppercase;
}

.year-rail {
  list-style: none;
  margin: 0;
  padding: 0 0 6px;
  display: flex;
  gap: 8px;
  overflow-x: auto;
  scrollbar-width: thin;
}

.year-rail__item {
  flex: none;
}

.year-rail__link {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 8px 12px;
  text-decoration: none;
  color: var(--slate-400);
  border: 1px solid var(--line-soft);
  background: rgba(18, 28, 46, 0.6);
  white-space: nowrap;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease), background var(--dur) var(--ease);
}

.year-rail__link:hover,
.year-rail__link:focus-visible {
  color: var(--paper-100);
  border-color: var(--gold-200);
  background: rgba(215, 164, 69, 0.08);
}

.year-rail__year {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.04em;
  color: var(--gold-400);
}

.year-rail__label {
  font-size: 14px;
}

.about-block {
  min-width: 0;
}

.about-head {
  display: flex;
  align-items: baseline;
  gap: 14px;
  margin-bottom: 22px;
}

.about-head__index {
  flex: none;
  font-size: 12px;
  color: var(--gold-400);
  border: 1px solid rgba(215, 164, 69, 0.42);
  padding: 2px 8px;
  line-height: 1.6;
}

/* ---------- 纸面卡片 ---------- */
.page-about .paper-card {
  position: relative;
  background: var(--paper-100);
  color: var(--paper-ink);
  border: 1px solid var(--line-hard);
  padding: 28px 24px;
  box-shadow: 6px 6px 0 rgba(11, 18, 32, 0.58);
}

.page-about .paper-card p {
  margin: 0 0 16px;
  font-size: 16px;
  line-height: 1.9;
}

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

.about-card::after {
  content: "";
  position: absolute;
  top: 0;
  right: 0;
  border-width: 0 var(--about-fold) var(--about-fold) 0;
  border-style: solid;
  border-color: transparent var(--ink-900) transparent transparent;
}

.page-about .paper-card .annotation {
  margin-top: 20px;
  font-size: 13px;
  line-height: 1.7;
  color: rgba(20, 26, 38, 0.78);
  border-left: 3px solid var(--gold-400);
  padding: 8px 0 8px 12px;
  background: var(--paper-200);
}

/* ---------- 横向演进带 ---------- */
.about-block--band {
  background: var(--ink-800);
  border: 1px solid var(--line-soft);
  padding: 30px 22px 34px;
}

.about-head--band {
  margin-bottom: 18px;
}

.about-band__figure {
  margin: 0 0 28px;
}

.page-about .media-frame {
  margin: 0;
  border: 1px solid var(--line-600);
  overflow: hidden;
  background: var(--ink-700);
}

.page-about .media-frame img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  filter: brightness(0.62) saturate(0.85);
}

.page-about .media-frame__caption {
  display: block;
  padding: 8px 12px;
  font-size: 12px;
  line-height: 1.6;
  color: var(--slate-400);
  background: var(--ink-700);
  border-top: 1px solid var(--line-soft);
}

.about-timeline {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 18px;
}

.page-about .timeline__step {
  position: relative;
  padding-left: 18px;
  border-left: 2px solid var(--line-600);
}

.page-about .timeline__step--legacy {
  border-left-color: var(--clay-500);
}

.page-about .timeline__step--current {
  border-left-color: var(--gold-400);
}

.page-about .timeline__label {
  display: block;
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--gold-400);
}

.page-about .timeline__value {
  margin: 4px 0 0;
  font-family: var(--font-display);
  font-size: 21px;
  font-weight: 600;
  line-height: 1.25;
  color: var(--paper-100);
}

.about-timeline__note {
  margin: 8px 0 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--slate-400);
}

/* ---------- 三层分工 ---------- */
.about-stack {
  display: grid;
  gap: 14px;
}

.about-stack__layer {
  background: var(--ink-700);
  border: 1px solid var(--line-soft);
  border-left: 4px solid var(--celadon-400);
  padding: 22px 22px 20px;
}

.about-stack__layer--support {
  border-left-color: var(--gold-400);
}

.about-stack__layer--review {
  border-left-color: var(--clay-500);
}

.about-stack__layer h3 {
  margin: 0 0 8px;
  font-family: var(--font-display);
  font-size: 22px;
  font-weight: 600;
  letter-spacing: 0.01em;
  color: var(--paper-100);
}

.about-stack__layer p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: rgba(244, 237, 224, 0.82);
}

/* ---------- 工序 ---------- */
.about-workflow {
  display: grid;
  gap: 24px;
  margin-bottom: 26px;
}

.about-workflow__body p {
  margin: 0 0 14px;
  font-size: 16px;
  line-height: 1.9;
  color: rgba(244, 237, 224, 0.86);
}

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

.about-workflow__body .annotation {
  font-size: 13px;
  line-height: 1.75;
  color: var(--slate-400);
  border-left: 3px solid var(--gold-400);
  background: var(--ink-800);
  padding: 10px 0 10px 12px;
}

.about-workflow__figure {
  margin: 0;
}

.about-steps {
  display: grid;
  gap: 0;
  border-top: 1px solid var(--line-soft);
}

.page-about .about-step {
  border-bottom: 1px solid var(--line-soft);
}

.page-about .about-step__summary {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 16px 4px;
  cursor: pointer;
  list-style: none;
  color: var(--paper-100);
  transition: color var(--dur) var(--ease), background var(--dur) var(--ease);
}

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

.page-about .about-step__summary:hover,
.page-about .about-step__summary:focus-visible {
  color: var(--gold-200);
  background: rgba(215, 164, 69, 0.06);
}

.about-step__num {
  flex: none;
  font-size: 13px;
  color: var(--gold-400);
}

.about-step__name {
  font-family: var(--font-display);
  font-size: 20px;
  font-weight: 600;
  letter-spacing: 0.01em;
}

.page-about .about-step .disclosure__body {
  padding: 0 4px 18px 44px;
}

.page-about .about-step .disclosure__body p {
  margin: 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--slate-400);
}

/* ---------- 覆盖范围 ---------- */
.about-stats {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line-soft);
  border: 1px solid var(--line-soft);
}

.about-stats__cell {
  background: var(--ink-800);
  padding: 20px 18px;
}

.about-stats__num {
  display: block;
  font-family: var(--font-mono);
  font-size: 30px;
  font-weight: 500;
  line-height: 1.1;
  color: var(--gold-400);
}

.about-stats__label {
  display: block;
  margin-top: 8px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--slate-400);
}

.about-strata {
  margin: 26px 0 0;
}

.about-strata img {
  max-height: 220px;
}

/* ---------- 收束 ---------- */
.about-close {
  max-width: 62ch;
  border-top: 2px solid var(--gold-400);
  padding-top: 26px;
}

.about-close p {
  margin: 16px 0 24px;
  font-size: 16px;
  line-height: 1.9;
  color: rgba(244, 237, 224, 0.84);
}

.about-close__links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

/* ---------- 响应式 ---------- */
@media (min-width: 768px) {
  .about-stats {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .about-hero {
    padding: 48px 0 84px;
  }

  .page-about .paper-card {
    padding: 34px 32px;
  }

  .about-block--band {
    padding: 38px 32px 42px;
  }

  .about-timeline {
    grid-auto-flow: column;
    grid-auto-columns: minmax(0, 1fr);
    gap: 0;
    padding-top: 4px;
    border-top: 2px solid var(--line-600);
  }

  .page-about .timeline__step {
    padding: 18px 16px 0 0;
    border-left: 0;
    border-top: 0;
  }

  .page-about .timeline__step::after {
    content: "";
    position: absolute;
    top: -6px;
    left: 0;
    width: 9px;
    height: 9px;
    border-radius: 50%;
    background: var(--clay-500);
    box-shadow: 0 0 0 3px var(--ink-800);
  }

  .page-about .timeline__step--current::after {
    background: var(--gold-400);
    box-shadow: 0 0 0 3px var(--ink-800), 0 0 0 5px rgba(215, 164, 69, 0.28);
  }

  .page-about .timeline__step + .timeline__step {
    padding-left: 18px;
    border-left: 1px solid var(--line-soft);
  }

  .about-workflow {
    grid-template-columns: minmax(0, 1fr) minmax(0, 0.72fr);
    align-items: start;
    gap: 32px;
  }

  .about-close {
    padding-top: 32px;
  }
}

@media (min-width: 1024px) {
  .about-hero__inner {
    grid-template-columns: 5fr 7fr;
    gap: 56px;
    align-items: center;
  }

  .about-hero__visual {
    margin-top: -18px;
  }

  .about-archive {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    column-gap: var(--about-gap);
    row-gap: 66px;
    padding-top: 72px;
    padding-bottom: 96px;
  }

  .about-rail {
    grid-row: 1 / -1;
    position: sticky;
    top: calc(var(--header-h) + 24px);
    align-self: start;
    padding-left: 16px;
  }

  .year-rail {
    flex-direction: column;
    gap: 2px;
    overflow: visible;
    padding-bottom: 0;
  }

  .year-rail__link {
    flex-direction: column;
    align-items: flex-start;
    gap: 1px;
    padding: 9px 12px;
    border-color: transparent;
    background: transparent;
  }

  .year-rail__link:hover,
  .year-rail__link:focus-visible {
    border-color: var(--gold-200);
    background: rgba(215, 164, 69, 0.07);
  }

  .about-block--band {
    grid-column: 1 / -1;
  }

  .about-stack {
    gap: 0;
  }

  .about-stack__layer {
    box-shadow: 6px 6px 0 rgba(11, 18, 32, 0.5);
  }

  .about-stack__layer + .about-stack__layer {
    margin-top: 16px;
  }

  .about-stack__layer--support {
    margin-left: 26px;
  }

  .about-stack__layer--review {
    margin-left: 52px;
  }
}

@media (hover: hover) and (min-width: 768px) {
  .about-timeline__note {
    max-height: 0;
    margin-top: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-height 220ms var(--ease), opacity 200ms var(--ease), margin-top 200ms var(--ease);
  }

  .page-about .timeline__step:hover .about-timeline__note,
  .page-about .timeline__step:focus-within .about-timeline__note {
    max-height: 150px;
    margin-top: 8px;
    opacity: 1;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about * {
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
  }
}