.page-about {
  display: block;
  background: var(--ink-950);
  color: var(--paper-white);
  font-family: var(--font-body);
  overflow-x: hidden;
}

/* ---------- 面包屑 ---------- */
.page-about .crumb {
  display: flex;
  align-items: center;
  gap: .5rem;
  padding: 1.5rem 0 0;
  font-size: .78rem;
  letter-spacing: .04em;
  color: var(--slate-300);
}
.page-about .crumb a {
  color: var(--slate-300);
  text-decoration: none;
  border-bottom: 1px solid transparent;
}
.page-about .crumb a:hover,
.page-about .crumb a:focus-visible {
  color: var(--signal-cyan);
  border-bottom-color: var(--signal-cyan);
}
.page-about .crumb .crumb-sep {
  color: rgba(169, 188, 207, .5);
}
.page-about .crumb span[aria-current="page"] {
  color: var(--paper-white);
}

/* ---------- 首屏拼贴 ---------- */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  background:
    radial-gradient(92% 72% at 88% 0%, rgba(53, 224, 240, .14), transparent 62%),
    radial-gradient(72% 64% at 2% 98%, rgba(255, 122, 47, .11), transparent 66%);
}
.page-about .about-hero::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(to right, var(--grid-line) 1px, transparent 1px),
    linear-gradient(to bottom, var(--grid-line) 1px, transparent 1px);
  background-size: 76px 76px;
  opacity: .42;
  pointer-events: none;
}
.page-about .hero-grid {
  position: relative;
  display: grid;
  gap: 2rem;
  padding: 1.75rem 0 3rem;
}
.page-about .hero-lead .eyebrow {
  color: var(--signal-cyan);
}
.page-about .hero-lead .display {
  font-family: var(--font-display);
  font-weight: 300;
  font-size: clamp(1.85rem, 4.6vw, 3.3rem);
  line-height: 1.24;
  letter-spacing: -.02em;
  color: var(--paper-white);
  margin: .85rem 0 1.15rem;
}
.page-about .hero-lead .lede {
  font-size: 1rem;
  line-height: 1.9;
  color: var(--slate-300);
  max-width: 40em;
  margin: 0 0 1.75rem;
}
.page-about .hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: .7rem;
}

.page-about .hero-panel {
  display: grid;
  background: var(--ink-800);
  border: 1px solid var(--grid-line);
  border-radius: var(--radius);
  overflow: hidden;
}
.page-about .panel-cell {
  display: flex;
  align-items: baseline;
  gap: .8rem;
  padding: 1rem 1.1rem;
}
.page-about .panel-cell + .panel-cell {
  border-top: 1px solid var(--grid-line);
}
.page-about .panel-cell .stat-num {
  font-family: var(--font-mono);
  font-size: 1.7rem;
  font-weight: 600;
  line-height: 1;
  color: var(--signal-cyan);
  font-feature-settings: "tnum";
  flex: none;
  min-width: 2.6em;
}
.page-about .panel-cell .stat-num em {
  font-style: normal;
  font-size: .95rem;
  color: var(--signal-orange);
  margin-left: .1em;
}
.page-about .panel-label {
  font-size: .8rem;
  line-height: 1.65;
  color: var(--slate-300);
}

/* ---------- 章节索引 ---------- */
.page-about .tour-index {
  position: relative;
  z-index: 30;
  background: rgba(10, 26, 47, .94);
  border-top: 1px solid var(--grid-line);
  border-bottom: 1px solid var(--grid-line);
}
.page-about .tour-inner {
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: .55rem 0;
  overflow-x: auto;
  scrollbar-width: none;
}
.page-about .tour-inner::-webkit-scrollbar {
  display: none;
}
.page-about .tour-caption {
  flex: none;
  font-family: var(--font-mono);
  font-size: .66rem;
  letter-spacing: .18em;
  text-transform: uppercase;
  color: var(--slate-300);
  white-space: nowrap;
}
.page-about .tour-list {
  display: flex;
  gap: .3rem;
  margin: 0;
  padding: 0;
  list-style: none;
}
.page-about .tour-list a {
  display: inline-flex;
  align-items: center;
  gap: .42rem;
  padding: .34rem .68rem;
  border: 1px solid transparent;
  border-radius: var(--radius);
  font-size: .82rem;
  color: var(--slate-300);
  text-decoration: none;
  white-space: nowrap;
  transition: color .18s ease, border-color .18s ease;
}
.page-about .tour-list a:hover,
.page-about .tour-list a:focus-visible {
  color: var(--paper-white);
  border-color: var(--signal-cyan);
}
.page-about .tour-num {
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .06em;
  color: var(--signal-cyan);
}

/* ---------- 章节外壳 ---------- */
.page-about .chapter-sec {
  padding: 3rem 0 .5rem;
  scroll-margin-top: 5.5rem;
}
.page-about .sec-head {
  margin-bottom: 2rem;
}
.page-about .sec-head::before {
  content: "";
  display: block;
  height: 2px;
  margin-bottom: 1.35rem;
  background: linear-gradient(90deg,
    var(--signal-cyan) 0%,
    rgba(53, 224, 240, .35) 16%,
    rgba(53, 224, 240, 0) 46%,
    rgba(255, 122, 47, 0) 66%,
    var(--signal-orange) 100%);
  opacity: .78;
}
.page-about .sec-index {
  margin: 0 0 .55rem;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .2em;
  text-transform: uppercase;
  color: var(--signal-orange);
}
.page-about .sec-title {
  font-family: var(--font-display);
  font-weight: 300;
  font-size: clamp(1.55rem, 3.4vw, 2.45rem);
  line-height: 1.26;
  letter-spacing: -.015em;
  color: var(--paper-white);
  margin: 0 0 .85rem;
}
.page-about .sec-lede {
  margin: 0;
  max-width: 40em;
  font-size: .95rem;
  line-height: 1.85;
  color: var(--slate-300);
}

/* ---------- 正文段落 ---------- */
.page-about .prose p {
  margin: 0 0 1.05rem;
  font-size: .95rem;
  line-height: 1.9;
  color: var(--slate-300);
}
.page-about .prose p:last-child {
  margin-bottom: 0;
}
.page-about .prose strong {
  color: var(--paper-white);
  font-weight: 600;
}
.page-about .origin-prose {
  max-width: 44em;
}

/* ---------- 01 沿革 ---------- */
.page-about .ver-track {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: .65rem;
  margin: 2rem 0 1.75rem;
}
.page-about .ver-node {
  display: flex;
  flex-direction: column;
  gap: .35rem;
  padding: .85rem .95rem;
  background: var(--ink-800);
  border: 1px solid var(--grid-line);
  border-top: 2px solid var(--signal-cyan);
  border-radius: var(--radius);
  text-decoration: none;
  transition: background .2s ease, border-color .2s ease;
}
.page-about .ver-node:hover,
.page-about .ver-node:focus-visible {
  background: var(--ink-700);
  border-color: var(--signal-cyan);
}
.page-about .ver-tag {
  font-family: var(--font-mono);
  font-size: .82rem;
  font-weight: 600;
  letter-spacing: .1em;
  color: var(--signal-cyan);
}
.page-about .ver-cap {
  font-size: .8rem;
  color: var(--slate-300);
}

.page-about .about-figure {
  margin: 0 0 2rem;
}

.page-about .ver-list {
  margin: 0;
  padding: 0;
  list-style: none;
  border-left: 1px solid var(--grid-line);
}
.page-about .ver-item {
  position: relative;
  padding: 0 0 1.65rem 1.4rem;
}
.page-about .ver-item:last-child {
  padding-bottom: 0;
}
.page-about .ver-item::before {
  content: "";
  position: absolute;
  left: -4px;
  top: .42rem;
  width: 7px;
  height: 7px;
  background: var(--signal-orange);
  border-radius: 50%;
}
.page-about .ver-id {
  margin: 0 0 .3rem;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .16em;
  color: var(--signal-cyan);
}
.page-about .ver-name {
  margin: 0 0 .45rem;
  font-size: 1.02rem;
  font-weight: 600;
  color: var(--paper-white);
}
.page-about .ver-text {
  margin: 0;
  max-width: 42em;
  font-size: .9rem;
  line-height: 1.85;
  color: var(--slate-300);
}

/* ---------- 02 编号 ---------- */
.page-about .code-layout {
  display: grid;
  gap: 1.75rem;
}
.page-about .code-intro .prose {
  max-width: 44em;
  margin-bottom: 1.75rem;
}
.page-about .code-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: .7rem;
}
.page-about .code-card {
  position: relative;
  padding: 1rem 1.05rem 1.1rem;
  background: var(--ink-800);
  border: 1px solid var(--grid-line);
  border-radius: var(--radius);
  transition: border-color .2s ease, transform .2s ease;
}
.page-about .code-card:hover {
  border-color: var(--signal-cyan);
  transform: translateY(-2px);
}
.page-about .code-card-head {
  display: flex;
  align-items: center;
  gap: .6rem;
  margin-bottom: .5rem;
}
.page-about .code-letter {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 1.7rem;
  height: 1.7rem;
  flex: none;
  background: var(--signal-cyan);
  color: var(--ink-950);
  font-family: var(--font-mono);
  font-size: .85rem;
  font-weight: 700;
  border-radius: var(--radius);
}
.page-about .code-name {
  margin: 0;
  font-size: .98rem;
  font-weight: 600;
  color: var(--paper-white);
}
.page-about .code-desc {
  margin: 0 0 .7rem;
  font-size: .84rem;
  line-height: 1.7;
  color: var(--slate-300);
}
.page-about .code-sublist {
  display: flex;
  flex-wrap: wrap;
  gap: .3rem;
  margin: 0;
  padding: 0;
  list-style: none;
}
.page-about .code-sublist li {
  padding: .18rem .48rem;
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .05em;
  color: var(--slate-300);
  background: rgba(53, 224, 240, .08);
  border: 1px solid rgba(53, 224, 240, .22);
  border-radius: var(--radius);
}
.page-about .code-figure {
  margin: 0;
}
.page-about .code-outro {
  margin-top: 2rem;
  max-width: 46em;
  padding-left: 1rem;
  border-left: 3px solid var(--signal-orange);
}

/* ---------- 03 值守 ---------- */
.page-about .crew-layout {
  display: grid;
  gap: 1.75rem;
}
.page-about .crew-stats {
  display: grid;
  gap: .7rem;
}
.page-about .crew-stat {
  padding: 1rem 1.05rem;
  background: linear-gradient(150deg, var(--ink-800), var(--ink-950));
  border: 1px solid var(--grid-line);
  border-radius: var(--radius);
}
.page-about .crew-num {
  margin: 0 0 .35rem;
  display: flex;
  align-items: baseline;
  gap: .25rem;
  color: var(--signal-cyan);
}
.page-about .crew-num .stat-num {
  font-family: var(--font-mono);
  font-size: 2rem;
  font-weight: 600;
  line-height: 1;
  font-feature-settings: "tnum";
}
.page-about .crew-unit {
  font-size: .78rem;
  color: var(--slate-300);
}
.page-about .crew-cap {
  margin: 0;
  font-size: .82rem;
  line-height: 1.7;
  color: var(--slate-300);
}

/* ---------- 04 资料 ---------- */
.page-about .docs-layout {
  display: grid;
  gap: 1.75rem;
}
.page-about .docs-figure {
  margin: 0;
}
.page-about .docs-body .prose {
  max-width: 46em;
  margin-bottom: 1.5rem;
}
.page-about .docs-taxonomy {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: .45rem;
  margin: 0;
  padding: 0;
  list-style: none;
}
.page-about .docs-taxonomy li {
  padding: .55rem .7rem;
  font-size: .82rem;
  color: var(--paper-white);
  background: var(--ink-800);
  border-left: 2px solid var(--signal-cyan);
  border-radius: var(--radius);
}
.page-about .docs-taxonomy li:nth-child(even) {
  border-left-color: var(--signal-orange);
}

/* ---------- 05 原则 ---------- */
.page-about .rulebook {
  display: grid;
  gap: 0;
  border-top: 1px solid var(--grid-line);
}
.page-about .rule {
  padding: 1.5rem 0;
  border-bottom: 1px solid var(--grid-line);
}
.page-about .rule-num {
  margin: 0 0 .5rem;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .2em;
  color: var(--signal-orange);
}
.page-about .rule-line {
  margin: 0 0 .7rem;
  font-family: var(--font-display);
  font-weight: 400;
  font-size: 1.2rem;
  line-height: 1.4;
  letter-spacing: -.01em;
  color: var(--paper-white);
}
.page-about .rule-note {
  margin: 0 0 .7rem;
  font-size: .9rem;
  line-height: 1.85;
  color: var(--slate-300);
}
.page-about .rule-scene {
  margin: 0;
  padding-left: .85rem;
  border-left: 3px solid var(--signal-orange);
  font-size: .86rem;
  line-height: 1.75;
  color: var(--paper-white);
}

/* ---------- 收尾 ---------- */
.page-about .about-next {
  margin-top: 3rem;
  padding: 3rem 0 3.5rem;
  background:
    radial-gradient(80% 90% at 0% 0%, rgba(53, 224, 240, .12), transparent 60%),
    var(--ink-800);
  border-top: 1px solid var(--grid-line);
}
.page-about .about-next .eyebrow {
  color: var(--signal-cyan);
  margin-bottom: .6rem;
}
.page-about .next-title {
  margin: 0 0 1.75rem;
  font-family: var(--font-display);
  font-weight: 300;
  font-size: clamp(1.35rem, 2.8vw, 2rem);
  line-height: 1.3;
  letter-spacing: -.015em;
  color: var(--paper-white);
}
.page-about .next-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: .7rem;
}
.page-about .next-item {
  display: grid;
  gap: .3rem;
  padding: 1rem 1.05rem;
  background: rgba(10, 26, 47, .6);
  border: 1px solid var(--grid-line);
  border-radius: var(--radius);
  text-decoration: none;
  transition: border-color .2s ease, background .2s ease;
}
.page-about .next-item:hover,
.page-about .next-item:focus-visible {
  background: var(--ink-950);
  border-color: var(--signal-cyan);
}
.page-about .next-num {
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .18em;
  color: var(--signal-orange);
}
.page-about .next-name {
  font-size: .98rem;
  font-weight: 600;
  color: var(--paper-white);
}
.page-about .next-desc {
  font-size: .82rem;
  line-height: 1.65;
  color: var(--slate-300);
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .code-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
  .page-about .docs-taxonomy {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .next-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 900px) {
  .page-about .crumb {
    padding-top: 2rem;
  }
  .page-about .hero-grid {
    grid-template-columns: minmax(0, 1.5fr) minmax(0, 1fr);
    gap: 2.75rem;
    align-items: start;
    padding: 2.5rem 0 4rem;
  }
  .page-about .tour-index {
    position: sticky;
    top: 0;
  }
  .page-about .chapter-sec {
    padding: 5rem 0 1rem;
    scroll-margin-top: 4.5rem;
  }
  .page-about .ver-track {
    grid-template-columns: repeat(4, minmax(0, 1fr));
    gap: .8rem;
    margin: 2.5rem 0 2rem;
  }
  .page-about .ver-list {
    columns: 2;
    column-gap: 3rem;
  }
  .page-about .ver-item {
    break-inside: avoid;
  }
  .page-about .crew-layout {
    grid-template-columns: minmax(0, .78fr) minmax(0, 1.22fr);
    gap: 3rem;
    align-items: start;
  }
  .page-about .docs-layout {
    grid-template-columns: minmax(0, .8fr) minmax(0, 1.2fr);
    gap: 3rem;
    align-items: start;
  }
  .page-about .rule {
    display: grid;
    grid-template-columns: minmax(0, .85fr) minmax(0, 1.15fr);
    column-gap: 2.5rem;
    align-items: start;
    padding: 1.85rem 0;
  }
  .page-about .rule-num {
    grid-column: 1;
    grid-row: 1;
    margin-bottom: .45rem;
  }
  .page-about .rule-line {
    grid-column: 1;
    grid-row: 2;
    margin-bottom: 0;
  }
  .page-about .rule-note {
    grid-column: 2;
    grid-row: 1 / span 2;
    margin-bottom: 1rem;
    align-self: end;
  }
  .page-about .rule-scene {
    grid-column: 2;
    grid-row: 3;
  }
  .page-about .next-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (min-width: 1080px) {
  .page-about .code-layout {
    grid-template-columns: minmax(0, 1.32fr) minmax(0, .68fr);
    gap: 3rem;
    align-items: start;
  }
  .page-about .code-figure {
    position: sticky;
    top: 5rem;
  }
  .page-about .code-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 1280px) {
  .page-about .docs-taxonomy {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .code-card,
  .page-about .ver-node,
  .page-about .next-item {
    transition: none;
    transform: none;
  }
}
</main>