.page-about {
  --about-glow-cyan: rgba(47, 227, 208, 0.14);
  --about-glow-magenta: rgba(226, 79, 168, 0.12);
  background: var(--ink-900);
  color: var(--text);
  overflow-x: hidden;
}

.page-about .breadcrumbs {
  padding-top: 18px;
  font-size: 13px;
  color: var(--text-mute);
}

.page-about .breadcrumbs ol {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  margin: 0;
  padding: 0;
}

.page-about .breadcrumbs li {
  display: flex;
  align-items: center;
  gap: 8px;
}

.page-about .breadcrumbs li + li::before {
  content: "/";
  color: var(--line);
}

.page-about .breadcrumbs a {
  color: var(--text-dim);
  text-decoration: none;
  transition: color 160ms var(--ease);
}

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

/* 首屏 */
.page-about .about-hero {
  position: relative;
  padding: 34px 0 52px;
  overflow: hidden;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  inset: auto -14% -70% 34%;
  height: 480px;
  background:
    radial-gradient(circle at 62% 42%, var(--about-glow-cyan), transparent 62%),
    radial-gradient(circle at 28% 72%, var(--about-glow-magenta), transparent 60%);
  pointer-events: none;
}

.page-about .about-hero .container {
  position: relative;
  z-index: 1;
}

.page-about .about-hero h1 {
  margin: 12px 0 0;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(32px, 7vw, 62px);
  line-height: 1.08;
  letter-spacing: -0.02em;
  max-width: 18em;
}

.page-about .about-lede {
  margin: 20px 0 0;
  max-width: 60ch;
  font-size: clamp(15px, 1.6vw, 17px);
  line-height: 1.85;
  color: var(--text-dim);
}

.page-about .scale-track {
  display: flex;
  justify-content: space-between;
  gap: 10px;
  margin-top: 40px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 11px;
  letter-spacing: 0.06em;
  color: var(--text-mute);
}

.page-about .scale-track span {
  position: relative;
  flex: 0 0 auto;
}

.page-about .scale-track span::before {
  content: "";
  position: absolute;
  top: -13px;
  left: 0;
  width: 1px;
  height: 9px;
  background: var(--line);
}

/* 通用章节 */
.page-about .section {
  padding: 52px 0;
}

.page-about .section-head {
  max-width: 720px;
}

.page-about .section-head p {
  margin: 0;
  font-size: 15px;
  line-height: 1.8;
  color: var(--text-dim);
}

.page-about h2 {
  margin: 0 0 14px;
  font-family: var(--font-display);
  font-weight: 800;
  font-size: clamp(23px, 3.2vw, 34px);
  line-height: 1.22;
  letter-spacing: -0.01em;
}

.page-about .media-frame {
  margin: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--ink-800);
}

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

/* 起点 */
.page-about .origin-grid {
  row-gap: 26px;
  align-items: start;
}

.page-about .origin-copy p {
  margin: 0 0 14px;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-dim);
}

.page-about .origin-facts {
  margin: 24px 0 0;
  display: grid;
  gap: 12px;
}

.page-about .origin-facts > div {
  display: grid;
  grid-template-columns: 58px minmax(0, 1fr);
  gap: 12px;
  padding-top: 10px;
  border-top: 1px solid var(--line-soft);
}

.page-about .origin-facts dt {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--cyan);
}

.page-about .origin-facts dd {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--text-dim);
}

/* 时间轴 */
.page-about .timeline {
  list-style: none;
  position: relative;
  margin: 30px 0 0;
  padding: 0;
}

.page-about .timeline::before {
  content: "";
  position: absolute;
  top: 12px;
  bottom: 12px;
  left: 31px;
  width: 1px;
  background: linear-gradient(180deg, var(--cyan), var(--line) 34%, var(--line));
}

.page-about .tl-item {
  position: relative;
  display: grid;
  grid-template-columns: 64px minmax(0, 1fr);
  gap: 14px;
  padding-bottom: 20px;
}

.page-about .tl-item::before {
  content: "";
  position: absolute;
  left: 27px;
  top: 12px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--ink-900);
  border: 1px solid var(--cyan);
  box-shadow: 0 0 0 4px rgba(47, 227, 208, 0.08);
}

.page-about .tl-item.is-current::before {
  background: var(--gold);
  border-color: var(--gold);
  box-shadow: 0 0 0 5px rgba(246, 185, 59, 0.16);
}

.page-about .tl-year {
  padding-top: 4px;
  font-family: var(--font-mono);
  font-size: 22px;
  font-weight: 700;
  line-height: 1;
  color: var(--text-mute);
}

.page-about .tl-item.is-current .tl-year .mono-num {
  color: var(--gold);
}

.page-about .tl-card {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--ink-800);
  box-shadow: var(--shadow-panel);
  transition: border-color 160ms var(--ease), transform 160ms var(--ease);
}

.page-about .tl-card:hover {
  border-color: rgba(47, 227, 208, 0.45);
}

.page-about .tl-card[open] {
  border-color: rgba(47, 227, 208, 0.5);
}

.page-about .tl-card > summary {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 10px;
  padding: 15px 16px;
  cursor: pointer;
  list-style: none;
}

.page-about .tl-card > summary::-webkit-details-marker {
  display: none;
}

.page-about .tl-card > summary::after {
  content: "+";
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: 18px;
  line-height: 1;
  color: var(--cyan);
}

.page-about .tl-card[open] > summary::after {
  content: "−";
}

.page-about .tl-title {
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 16px;
  color: var(--text);
}

.page-about .tl-body {
  padding: 0 16px 16px;
  font-size: 14px;
  line-height: 1.85;
  color: var(--text-dim);
}

.page-about .tl-body p {
  margin: 0;
}

/* 今天的版图 */
.page-about .about-board {
  background: linear-gradient(180deg, rgba(15, 46, 51, 0.55), rgba(7, 11, 28, 0) 92%);
  border-top: 1px solid var(--line-soft);
  border-bottom: 1px solid var(--line-soft);
}

.page-about .board-grid {
  margin-top: 26px;
  row-gap: 30px;
  align-items: start;
}

.page-about .fact-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.page-about .fact-list li {
  display: grid;
  gap: 4px;
  padding: 16px 0;
  border-top: 1px solid var(--line-soft);
}

.page-about .fact-list li:first-child {
  border-top: none;
  padding-top: 0;
}

.page-about .fact-list .mono-num {
  font-family: var(--font-mono);
  font-size: 28px;
  font-weight: 700;
  line-height: 1;
  color: var(--gold);
}

.page-about .fact-text {
  font-size: 14px;
  line-height: 1.8;
  color: var(--text-dim);
}

.page-about .version-card {
  margin-top: 16px;
  padding: 18px;
  border: 1px solid var(--line);
  border-left: 3px solid var(--gold);
  border-radius: var(--radius);
  background: var(--ink-800);
}

.page-about .version-label {
  margin: 0 0 8px;
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--text-mute);
}

.page-about .version-num {
  margin: 0 0 10px;
  font-family: var(--font-mono);
  font-size: 32px;
  font-weight: 700;
  line-height: 1;
  color: var(--gold);
}

.page-about .version-note {
  margin: 0;
  font-size: 13px;
  line-height: 1.75;
  color: var(--text-dim);
}

/* 团队 */
.page-about .team-grid {
  row-gap: 28px;
  align-items: start;
}

.page-about .team-copy p {
  margin: 0 0 14px;
  font-size: 15px;
  line-height: 1.85;
  color: var(--text-dim);
}

.page-about .team-compose {
  list-style: none;
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin: 18px 0 22px;
  padding: 0;
}

.page-about .team-compose li {
  display: flex;
  align-items: baseline;
  gap: 8px;
  padding: 9px 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(16, 23, 54, 0.7);
  font-size: 13px;
  color: var(--text-dim);
}

.page-about .team-compose .mono-num {
  font-family: var(--font-mono);
  font-size: 20px;
  font-weight: 700;
  color: var(--cyan);
}

.page-about .steps {
  list-style: none;
  counter-reset: st;
  margin: 16px 0 20px;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .steps li {
  position: relative;
  padding-left: 46px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--text-dim);
}

.page-about .steps li::before {
  counter-increment: st;
  content: counter(st, decimal-leading-zero);
  position: absolute;
  left: 0;
  top: 0;
  width: 30px;
  height: 30px;
  display: grid;
  place-items: center;
  border-radius: 2px;
  background: var(--cyan);
  color: var(--ink-900);
  font-family: var(--font-mono);
  font-size: 13px;
  font-weight: 700;
}

.page-about .team-note {
  margin: 0;
  padding: 14px 16px;
  border-left: 2px solid var(--magenta);
  background: var(--teal-deep);
  border-radius: 0 var(--radius) var(--radius) 0;
  font-size: 14px;
  line-height: 1.8;
  color: var(--text-dim);
}

/* 准则 */
.page-about .principles {
  list-style: none;
  margin: 26px 0 0;
  padding: 0;
  display: grid;
  gap: 14px;
}

.page-about .principle {
  --acc: var(--cyan);
  padding: 18px 18px 16px;
  border: 1px solid var(--line);
  border-left: 3px solid var(--acc);
  border-radius: var(--radius);
  background: var(--ink-800);
  transition: background 180ms var(--ease), border-color 180ms var(--ease);
}

.page-about .principle:nth-child(2) {
  --acc: var(--gold);
}

.page-about .principle:nth-child(3) {
  --acc: var(--magenta);
}

.page-about .principle:nth-child(4) {
  --acc: var(--green);
}

.page-about .principle:focus-visible {
  outline: 2px solid var(--cyan);
  outline-offset: 3px;
}

.page-about .principle h3 {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: 17px;
  color: var(--text);
}

.page-about .principle p {
  margin: 8px 0 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--text-dim);
}

.page-about .principle-example {
  color: var(--text-mute);
}

/* 行动区 */
.page-about .about-cta {
  padding-bottom: 64px;
}

.page-about .cta-panel {
  padding: 26px 20px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: linear-gradient(135deg, rgba(16, 23, 54, 0.96), rgba(15, 46, 51, 0.8));
}

.page-about .cta-panel h2 {
  margin-bottom: 12px;
}

.page-about .cta-panel > p {
  margin: 0;
  max-width: 58ch;
  font-size: 15px;
  line-height: 1.8;
  color: var(--text-dim);
}

.page-about .cta-links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 22px 0 18px;
}

.page-about .cta-meta {
  margin: 0;
  font-size: 13px;
  line-height: 1.7;
  color: var(--text-mute);
}

@media (min-width: 600px) {
  .page-about .fact-list li {
    grid-template-columns: 132px minmax(0, 1fr);
    gap: 18px;
    align-items: baseline;
  }

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

@media (min-width: 900px) {
  .page-about .section {
    padding: 84px 0;
  }

  .page-about .about-hero {
    padding: 56px 0 76px;
  }

  .page-about .scale-track {
    margin-top: 56px;
    font-size: 12px;
  }

  .page-about .timeline::before {
    left: 139px;
  }

  .page-about .tl-item {
    grid-template-columns: 140px minmax(0, 1fr);
    gap: 28px;
    padding-bottom: 26px;
  }

  .page-about .tl-item::before {
    left: 135px;
    top: 16px;
  }

  .page-about .tl-year {
    font-size: clamp(38px, 4.2vw, 58px);
    padding-top: 0;
  }

  .page-about .tl-item:nth-child(odd) .tl-card {
    max-width: 100%;
  }

  .page-about .tl-item:nth-child(even) .tl-card {
    max-width: 78%;
  }

  .page-about .tl-card > summary {
    padding: 18px 22px;
  }

  .page-about .tl-body {
    padding: 0 22px 20px;
    font-size: 15px;
  }

  .page-about .board-grid,
  .page-about .team-grid,
  .page-about .origin-grid {
    row-gap: 0;
  }

  .page-about .board-media {
    padding-left: 24px;
  }

  .page-about .team-media {
    padding-right: 24px;
  }

  .page-about .cta-panel {
    padding: 44px 42px;
  }
}

@media (hover: hover) and (min-width: 900px) {
  .page-about .principle .principle-example {
    max-height: 0;
    margin-top: 0;
    opacity: 0;
    overflow: hidden;
    transition: max-height 220ms var(--ease), opacity 180ms var(--ease), margin-top 180ms var(--ease);
  }

  .page-about .principle:hover,
  .page-about .principle:focus-within {
    background: var(--ink-700);
    border-color: rgba(47, 227, 208, 0.35);
  }

  .page-about .principle:hover .principle-example,
  .page-about .principle:focus-within .principle-example {
    max-height: 160px;
    margin-top: 10px;
    opacity: 1;
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .tl-card,
  .page-about .principle,
  .page-about .principle-example,
  .page-about .breadcrumbs a {
    transition: none;
  }
}