.page-about {
  position: relative;
  color: var(--text);
  font-family: var(--font-body);
  font-size: 16px;
  line-height: 1.75;
  background: var(--ink);
  overflow-x: clip;
}

.page-about *,
.page-about *::before,
.page-about *::after {
  box-sizing: border-box;
}

.page-about h1,
.page-about h2,
.page-about h3 {
  font-family: var(--font-display);
  font-weight: 800;
  letter-spacing: -0.02em;
  line-height: 1.22;
  margin: 0;
  color: var(--text);
}

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

.page-about .eyebrow {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.26em;
  text-transform: uppercase;
  color: var(--aurora);
  margin: 0 0 14px;
}

.page-about .breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--muted);
  margin-bottom: 28px;
}

.page-about .breadcrumb a {
  color: var(--muted);
  text-decoration: none;
  transition: color 180ms var(--ease);
}

.page-about .breadcrumb a:hover,
.page-about .breadcrumb a:focus-visible {
  color: var(--aurora);
}

/* ---------- 首屏：主题声明 + 索引 ---------- */

.page-about .about-open {
  padding: 28px 0 48px;
  background:
    radial-gradient(1100px 520px at 78% -12%, rgba(123, 92, 255, 0.18), transparent 62%),
    radial-gradient(760px 420px at 6% 0%, rgba(53, 224, 208, 0.10), transparent 60%),
    var(--ink);
}

.page-about .about-open__grid {
  display: grid;
  gap: 36px;
}

.page-about h1 {
  font-size: clamp(30px, 7.4vw, 54px);
  margin: 0 0 20px;
  max-width: 14em;
}

.page-about .about-open__lead {
  font-size: 16px;
  color: var(--muted);
  max-width: 36em;
  margin: 0 0 30px;
}

.page-about .about-open__stats {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  grid-template-columns: 1fr;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .about-open__stats li {
  display: flex;
  flex-direction: column;
  gap: 4px;
  padding: 15px 18px;
  background: var(--nebula);
}

.page-about .about-open__stat-num {
  font-family: var(--font-mono);
  font-size: 21px;
  line-height: 1.2;
  letter-spacing: 0.02em;
  color: var(--aurora);
}

.page-about .about-open__stat-label {
  font-size: 13px;
  color: var(--muted);
  line-height: 1.5;
}

.page-about .about-open__toc-col {
  align-self: start;
}

.page-about .toc-title {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--violet);
  text-transform: uppercase;
  margin: 0 0 12px;
}

.page-about .toc-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
  counter-reset: toc;
}

.page-about .toc-list li {
  counter-increment: toc;
}

.page-about .toc-link {
  display: block;
  padding: 9px 12px 9px 34px;
  position: relative;
  font-size: 14px;
  color: var(--muted);
  text-decoration: none;
  background: rgba(6, 10, 22, 0.55);
  border: 1px solid var(--line);
  border-left: 2px solid transparent;
  transition: color 180ms var(--ease), border-color 180ms var(--ease), background-color 180ms var(--ease);
}

.page-about .toc-link::before {
  content: counter(toc, decimal-leading-zero);
  position: absolute;
  left: 12px;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--font-mono);
  font-size: 11px;
  color: var(--line);
  transition: color 180ms var(--ease);
}

.page-about .toc-link:hover,
.page-about .toc-link:focus-visible {
  color: var(--text);
  border-left-color: var(--aurora);
  background: var(--aurora-wash);
}

.page-about .toc-link:hover::before,
.page-about .toc-link:focus-visible::before {
  color: var(--aurora);
}

/* ---------- 章节骨架 ---------- */

.page-about .about-sec {
  position: relative;
  padding: 52px 0;
  border-top: 1px solid var(--line);
}

.page-about .about-sec--nebula { background: var(--nebula); }
.page-about .about-sec--stone  { background: var(--stone); }
.page-about .about-sec--ink    { background: var(--ink); }

.page-about .about-sec--top-aurora {
  border-top-color: rgba(53, 224, 208, 0.38);
}

.page-about .about-sec__inner {
  position: relative;
}

.page-about .about-sec__grid {
  display: grid;
  gap: 30px;
}

.page-about .about-sec__body h2 {
  font-size: clamp(22px, 3.4vw, 30px);
  margin: 0 0 18px;
  max-width: 22em;
}

.page-about .about-sec__body > p {
  color: var(--muted);
  max-width: 38em;
}

/* ---------- 竖排注释：窄屏横向标签 ---------- */

.page-about .annot {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.24em;
  text-transform: uppercase;
  color: var(--muted);
  line-height: 1.4;
  margin: 0 0 16px;
  padding-left: 10px;
  border-left: 2px solid var(--aurora);
}

/* ---------- 侧栏通用 ---------- */

.page-about .about-sec__side {
  align-self: start;
}

.page-about .plate {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--muted);
  margin: 0 0 14px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--line);
}

.page-about .about-side-list {
  list-style: none;
  margin: 0 0 20px;
  padding: 0;
  counter-reset: side;
  display: grid;
  gap: 12px;
}

.page-about .about-side-list li {
  counter-increment: side;
  position: relative;
  padding-left: 32px;
  font-size: 14px;
  line-height: 1.65;
  color: var(--muted);
}

.page-about .about-side-list li::before {
  content: counter(side, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 3px;
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--alert);
}

.page-about .about-side-note {
  font-size: 13px;
  line-height: 1.7;
  color: var(--muted);
  margin: 0 0 16px;
  padding: 12px 14px;
  background: rgba(6, 10, 22, 0.5);
  border-left: 2px solid var(--line);
}

.page-about .about-sec--stone .about-side-note {
  background: rgba(6, 10, 22, 0.42);
}

/* ---------- 双栏分工卡片 ---------- */

.page-about .about-pair {
  display: grid;
  gap: 16px;
  margin-top: 28px;
}

.page-about .about-pair__card {
  padding: 22px 22px 24px;
}

.page-about .about-pair__card--shift {
  border-color: rgba(123, 92, 255, 0.42);
}

.page-about .plate-index {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--aurora);
  margin: 0 0 14px;
}

.page-about .about-pair__card--shift .plate-index {
  color: var(--violet);
}

.page-about .about-pair__list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 11px;
}

.page-about .about-pair__list li {
  position: relative;
  padding-left: 18px;
  font-size: 15px;
  line-height: 1.7;
  color: rgba(238, 242, 247, 0.86);
}

.page-about .about-pair__list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.72em;
  width: 6px;
  height: 6px;
  background: var(--aurora);
  transform: rotate(45deg);
  opacity: 0.85;
}

.page-about .about-pair__card--shift .about-pair__list li::before {
  background: var(--violet);
}

/* ---------- 生成流程时间轴 ---------- */

.page-about .about-flow {
  list-style: none;
  margin: 28px 0 0;
  padding: 0;
  border-left: 1px solid var(--line);
}

.page-about .about-flow li {
  position: relative;
  padding: 0 0 26px 28px;
}

.page-about .about-flow li:last-child {
  padding-bottom: 0;
}

.page-about .about-flow li::before {
  content: "";
  position: absolute;
  left: -5px;
  top: 9px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--ink);
  border: 1px solid var(--aurora);
}

.page-about .about-flow__num {
  display: block;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.22em;
  color: var(--aurora);
  margin-bottom: 5px;
}

.page-about .about-flow h3 {
  font-size: 17px;
  margin: 0 0 6px;
}

.page-about .about-flow p {
  margin: 0;
  font-size: 15px;
  line-height: 1.7;
  color: var(--muted);
}

/* ---------- 媒体框与图注 ---------- */

.page-about .about-sec__side figure {
  margin: 0 0 24px;
}

.page-about .about-sec__side figure:last-child {
  margin-bottom: 0;
}

.page-about .media-frame img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about .media-caption {
  margin-top: 12px;
  font-size: 13px;
  line-height: 1.65;
  color: var(--muted);
}

/* ---------- 派生结构图 ---------- */

.page-about .derive-figure {
  margin: 30px 0 0;
  padding: 26px 16px 10px;
  border: 1px solid var(--line);
  background-color: rgba(13, 20, 36, 0.86);
  background-image:
    linear-gradient(rgba(42, 53, 80, 0.45) 1px, transparent 1px),
    linear-gradient(90deg, rgba(42, 53, 80, 0.45) 1px, transparent 1px);
  background-size: 44px 44px, 44px 44px;
}

.page-about .derive-figure figcaption {
  margin-top: 8px;
}

.page-about .derive-tree {
  display: block;
  width: 100%;
  height: auto;
}

.page-about .derive-tree .dt-link {
  fill: none;
  stroke: rgba(53, 224, 208, 0.36);
  stroke-width: 1.2;
}

.page-about .derive-tree .dt-link--violet {
  stroke: rgba(123, 92, 255, 0.42);
}

.page-about .derive-tree .dt-node {
  fill: var(--ink);
  stroke: var(--aurora);
  stroke-width: 1.6;
}

.page-about .derive-tree .dt-node--violet {
  stroke: var(--violet);
}

.page-about .derive-tree .dt-label {
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  fill: var(--muted);
}

.page-about .derive-tree .dt-label--strong {
  fill: var(--text);
  font-size: 12px;
  letter-spacing: 0.12em;
}

.page-about .derive-tree .dt-node-group {
  transform-box: fill-box;
  transform-origin: center;
  transition: opacity 200ms var(--ease);
}

.page-about .derive-tree .dt-node-group:hover .dt-node {
  stroke-width: 3;
  filter: drop-shadow(0 0 7px rgba(53, 224, 208, 0.7));
}

.page-about .derive-tree .dt-node-group:hover .dt-label {
  fill: var(--aurora);
}

/* ---------- 链支持分层表格 ---------- */

.page-about .chain-table-wrap {
  margin-top: 28px;
  overflow-x: auto;
  border: 1px solid var(--line);
  -webkit-overflow-scrolling: touch;
}

.page-about .chain-table {
  width: 100%;
  min-width: 480px;
  border-collapse: collapse;
  font-size: 14px;
}

.page-about .chain-table caption {
  caption-side: top;
  text-align: left;
  padding: 12px 16px;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--muted);
  text-transform: uppercase;
  border-bottom: 1px solid var(--line);
  background: rgba(6, 10, 22, 0.4);
}

.page-about .chain-table th,
.page-about .chain-table td {
  padding: 13px 16px;
  text-align: left;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}

.page-about .chain-table thead th {
  font-family: var(--font-mono);
  font-size: 12px;
  font-weight: 500;
  letter-spacing: 0.1em;
  color: var(--muted);
  background: rgba(42, 53, 80, 0.4);
}

.page-about .chain-table tbody th[scope="row"] {
  position: sticky;
  left: 0;
  z-index: 1;
  font-weight: 700;
  color: var(--text);
  background: var(--stone);
  border-right: 1px solid var(--line);
  white-space: nowrap;
}

.page-about .chain-table tbody td {
  color: var(--muted);
  line-height: 1.6;
}

.page-about .chain-table__total th,
.page-about .chain-table__total td {
  border-bottom: 0;
  color: var(--aurora);
  font-weight: 700;
}

.page-about .chain-table__total th[scope="row"] {
  color: var(--aurora);
}

/* ---------- 链 ID 复制行 ---------- */

.page-about .about-chainid {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  margin: 20px 0 0;
  padding: 12px 16px;
  font-size: 13px;
  color: var(--muted);
  background: rgba(6, 10, 22, 0.6);
  border: 1px solid var(--line);
}

.page-about .about-chainid code {
  font-family: var(--font-mono);
  font-size: 14px;
  color: var(--aurora);
  padding: 2px 9px;
  background: var(--aurora-wash);
  border: 1px solid rgba(53, 224, 208, 0.3);
}

/* ---------- 适配清单统计 ---------- */

.page-about .matrix-stats {
  display: grid;
  gap: 14px;
  margin: 26px 0;
}

.page-about .matrix-stats__item {
  padding: 6px 0 6px 14px;
  border-left: 2px solid var(--violet);
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.page-about .matrix-stats__num {
  font-family: var(--font-mono);
  font-size: 25px;
  line-height: 1.15;
  color: var(--text);
}

.page-about .matrix-stats__item span:last-child {
  font-size: 13px;
  color: var(--muted);
  line-height: 1.55;
}

/* ---------- 核对清单 ---------- */

.page-about .check-list {
  display: grid;
  gap: 2px;
  margin-top: 28px;
}

.page-about .check-list__title {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
  color: var(--aurora);
  margin: 0 0 10px;
}

.page-about .check-item {
  display: flex;
  align-items: flex-start;
  gap: 12px;
  padding: 12px 14px;
  cursor: pointer;
  background: rgba(6, 10, 22, 0.55);
  border: 1px solid var(--line);
  transition: border-color 180ms var(--ease), background-color 180ms var(--ease);
}

.page-about .check-item:hover {
  border-color: rgba(53, 224, 208, 0.42);
}

.page-about .check-input {
  flex: none;
  width: 16px;
  height: 16px;
  margin: 3px 0 0;
  accent-color: var(--aurora);
}

.page-about .check-label {
  font-size: 14px;
  line-height: 1.65;
  color: var(--muted);
}

.page-about .check-item:has(.check-input:checked) {
  border-color: rgba(78, 216, 138, 0.45);
  background: var(--pass-wash);
}

.page-about .check-item:has(.check-input:checked) .check-label {
  color: var(--text);
}

/* ---------- 边界列表 ---------- */

.page-about .limit-list {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  gap: 10px;
}

.page-about .limit-list li {
  display: grid;
  gap: 4px;
  padding: 16px 18px;
  background: rgba(6, 10, 22, 0.6);
  border-left: 3px solid var(--alert);
}

.page-about .limit-list__mark {
  font-family: var(--font-display);
  font-size: 15px;
  font-weight: 800;
  letter-spacing: 0.02em;
  color: var(--alert);
}

.page-about .limit-list li p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--muted);
}

/* ---------- 出口按钮与内链 ---------- */

.page-about .about-next {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 30px;
}

.page-about .about-links {
  list-style: none;
  margin: 0 0 20px;
  padding: 0;
  display: grid;
  gap: 2px;
}

.page-about .about-links a {
  display: block;
  padding: 11px 14px;
  font-size: 14px;
  line-height: 1.6;
  color: var(--text);
  text-decoration: none;
  background: rgba(6, 10, 22, 0.55);
  border: 1px solid var(--line);
  border-left: 2px solid var(--violet);
  transition: color 180ms var(--ease), border-color 180ms var(--ease), background-color 180ms var(--ease);
}

.page-about .about-links a:hover,
.page-about .about-links a:focus-visible {
  color: var(--aurora);
  border-left-color: var(--aurora);
  background: var(--aurora-wash);
}

/* ---------- 响应式 ---------- */

@media (min-width: 480px) {
  .page-about .about-open__stats {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

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

@media (min-width: 720px) {
  .page-about .about-pair {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 22px;
  }

  .page-about .about-pair__card--shift {
    margin-top: 24px;
  }

  .page-about .about-sec {
    padding: 64px 0;
  }
}

@media (min-width: 980px) {
  .page-about .about-open {
    padding: 40px 0 64px;
  }

  .page-about .about-open__grid {
    grid-template-columns: minmax(0, 7fr) minmax(240px, 3fr);
    gap: 48px;
    align-items: start;
  }

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

  .page-about .about-sec {
    padding: 76px 0;
  }

  .page-about .about-sec__grid--split {
    grid-template-columns: minmax(0, 7fr) minmax(260px, 3fr);
    gap: 48px;
  }

  .page-about .about-sec__body h2 {
    margin-bottom: 22px;
  }

  .page-about .to-top {
    display: block;
  }
}

@media (min-width: 1400px) {
  .page-about .annot {
    position: absolute;
    left: -54px;
    top: 6px;
    writing-mode: vertical-rl;
    text-orientation: mixed;
    margin: 0;
    padding: 12px 0 0;
    border-left: 0;
    border-top: 2px solid var(--aurora);
    letter-spacing: 0.42em;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .derive-tree .dt-node-group,
  .page-about .toc-link,
  .page-about .about-links a,
  .page-about .check-item {
    transition: none;
  }

  .page-about .derive-tree .dt-node-group:hover .dt-node {
    filter: none;
  }
}