.page-about {
  --pa-paper: #F2F4F0;
  --pa-ink-text: #0C1317;
  --pa-ink-muted: #5C686E;
  --pa-strong: var(--paper);
  --pa-body: var(--text);
  --pa-quiet: var(--muted);
  --pa-hair: var(--line);
  --pa-panel: var(--ink-2);
  --pa-accent: var(--blue);
  background: var(--ink);
  color: var(--text);
  padding-top: calc(var(--header-h) + .5rem);
  overflow-x: hidden;
}

.page-about .pa-section--paper {
  --pa-strong: #0C1317;
  --pa-body: #28343A;
  --pa-quiet: #5C686E;
  --pa-hair: rgba(12, 19, 23, .16);
  --pa-panel: rgba(255, 255, 255, .62);
  --pa-accent: var(--pitch);
  background: var(--paper);
  color: var(--pa-ink-text);
}

/* ---------- 面包屑 ---------- */
.page-about .pa-crumbs {
  padding: 1.1rem 0 0;
}
.page-about .breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  gap: .5rem;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .08em;
  text-transform: uppercase;
  color: var(--muted);
}
.page-about .breadcrumbs a {
  color: var(--muted);
  text-decoration: none;
}
.page-about .breadcrumbs a:hover,
.page-about .breadcrumbs a:focus-visible {
  color: var(--lime);
}

/* ---------- 首屏 ---------- */
.page-about .pa-hero {
  position: relative;
  padding: clamp(2rem, 5vw, 3.5rem) 0 clamp(3rem, 7vw, 5.5rem);
}
.page-about .pa-hero::before {
  content: "";
  position: absolute;
  inset: -8% -40%;
  background-image:
    linear-gradient(var(--grid) 1px, transparent 1px),
    linear-gradient(90deg, var(--grid) 1px, transparent 1px);
  background-size: 84px 84px;
  transform: translateY(var(--parallax-y, 0px));
  pointer-events: none;
}
.page-about .pa-hero-grid {
  position: relative;
  z-index: 1;
  display: grid;
  gap: clamp(2rem, 5vw, 3.5rem);
}
.page-about .pa-kicker {
  margin: 0 0 .9rem;
  font-family: var(--font-mono);
  font-size: .72rem;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--pa-accent);
}
.page-about .pa-title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(2.1rem, 6.4vw, 4.25rem);
  line-height: 1.04;
  letter-spacing: -.01em;
  color: var(--pa-strong);
}
.page-about .pa-lede {
  max-width: 44rem;
  margin: 1.25rem 0 0;
  font-size: clamp(1rem, 1.5vw, 1.06rem);
  line-height: 1.85;
  color: var(--pa-body);
}
.page-about .pa-hero-cta {
  display: flex;
  flex-wrap: wrap;
  gap: .55rem 1.5rem;
  margin-top: 1.75rem;
}
.page-about .pa-hero-cta a {
  font-family: var(--font-mono);
  font-size: .78rem;
  letter-spacing: .06em;
  color: var(--lime);
  text-decoration: none;
  padding-bottom: 2px;
  border-bottom: 1px solid rgba(200, 255, 61, .35);
  transition: border-color .2s var(--ease), color .2s var(--ease);
}
.page-about .pa-hero-cta a:hover,
.page-about .pa-hero-cta a:focus-visible {
  border-color: var(--lime);
}

.page-about .pa-hero-stats {
  display: grid;
  gap: 1.15rem;
  border-top: 1px solid var(--pa-hair);
  padding-top: 1.4rem;
}
.page-about .pa-stat {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: .35rem .95rem;
}
.page-about .pa-stat-bar {
  grid-row: 1 / span 2;
  width: 3px;
  min-height: 3rem;
  background: var(--lime);
}
.page-about .pa-stat:nth-child(2) .pa-stat-bar { background: var(--blue); }
.page-about .pa-stat:nth-child(3) .pa-stat-bar { background: var(--teal); }
.page-about .pa-stat-num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: clamp(2.4rem, 7vw, 3.75rem);
  line-height: .95;
  color: var(--pa-strong);
}
.page-about .pa-stat-label {
  font-size: .8rem;
  line-height: 1.7;
  color: var(--pa-quiet);
}

/* ---------- 章节索引 ---------- */
.page-about .pa-toc {
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: var(--ink-2);
}
.page-about .pa-toc-inner {
  display: flex;
  align-items: center;
  gap: .2rem;
  padding: .3rem 0;
  overflow-x: auto;
  scrollbar-width: none;
  -webkit-overflow-scrolling: touch;
}
.page-about .pa-toc-inner::-webkit-scrollbar { display: none; }
.page-about .pa-toc-label {
  flex: none;
  margin-right: .8rem;
  padding: .7rem .95rem .7rem 0;
  border-right: 1px solid var(--line);
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--muted);
  white-space: nowrap;
}
.page-about .pa-toc a {
  flex: none;
  padding: .7rem .85rem;
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .05em;
  color: var(--text);
  text-decoration: none;
  white-space: nowrap;
  border-radius: 2px;
  transition: background .18s var(--ease), color .18s var(--ease);
}
.page-about .pa-toc a:hover,
.page-about .pa-toc a:focus-visible {
  background: var(--lime);
  color: var(--ink);
}

/* ---------- 章节骨架 ---------- */
.page-about .pa-section {
  position: relative;
  padding: clamp(3rem, 8vw, 6.5rem) 0;
}
.page-about .pa-section + .pa-section {
  border-top: 1px solid var(--pa-hair);
}
.page-about .pa-section--paper::before {
  content: "";
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(12, 19, 23, .05) 1px, transparent 1px),
    linear-gradient(90deg, rgba(12, 19, 23, .05) 1px, transparent 1px);
  background-size: 96px 96px;
  pointer-events: none;
}
.page-about .pa-section > .container {
  position: relative;
  z-index: 1;
}
.page-about .pa-section-head {
  display: grid;
  gap: .3rem;
  max-width: 50rem;
  margin-bottom: clamp(1.75rem, 4vw, 2.75rem);
}
.page-about .pa-section-title {
  margin: 0;
  font-family: var(--font-display);
  font-weight: 700;
  font-size: clamp(1.55rem, 3.6vw, 2.5rem);
  line-height: 1.14;
  color: var(--pa-strong);
}
.page-about .pa-section-note {
  max-width: 42rem;
  margin: .85rem 0 0;
  font-size: .88rem;
  line-height: 1.8;
  color: var(--pa-quiet);
}

/* ---------- 图文框 ---------- */
.page-about .pa-figure {
  margin: 0 0 clamp(1.75rem, 4vw, 2.5rem);
  border: 1px solid var(--pa-hair);
  background: var(--pa-panel);
  overflow: hidden;
}
.page-about .pa-figure img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  filter: saturate(.92);
}
.page-about .pa-figure figcaption {
  padding: .7rem .85rem;
  border-top: 1px solid var(--pa-hair);
  font-family: var(--font-mono);
  font-size: .7rem;
  line-height: 1.7;
  letter-spacing: .03em;
  color: var(--pa-quiet);
}
.page-about .pa-figure--tall {
  margin-bottom: 0;
}

/* ---------- 窄栏正文 + 悬挂旁注 ---------- */
.page-about .pa-read {
  display: grid;
  gap: 1.75rem;
}
.page-about .pa-prose p {
  margin: 0 0 1.05em;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--pa-body);
}
.page-about .pa-prose p:last-child { margin-bottom: 0; }
.page-about .pa-side {
  font-size: .8rem;
  line-height: 1.75;
  color: var(--pa-quiet);
  border-top: 1px solid var(--pa-hair);
  padding-top: .9rem;
}
.page-about .pa-side-title {
  display: block;
  margin-bottom: .45rem;
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--pa-accent);
}
.page-about .pa-side p { margin: 0; }

/* ---------- 五道环节 ---------- */
.page-about .pa-steps {
  list-style: none;
  margin: 0;
  padding: 0;
}
.page-about .pa-step {
  display: grid;
  gap: .7rem;
  padding: clamp(1.2rem, 3vw, 1.8rem) 0;
  border-top: 1px solid var(--pa-hair);
}
.page-about .pa-step:first-child {
  border-top: 0;
  padding-top: 0;
}
.page-about .pa-step-num {
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 1.3rem;
  letter-spacing: .02em;
  color: var(--lime);
}
.page-about .pa-section--paper .pa-step-num { color: var(--pitch); }
.page-about .pa-step-title {
  margin: 0 0 .5rem;
  font-size: 1.02rem;
  font-weight: 700;
  color: var(--pa-strong);
}
.page-about .pa-step-body p {
  margin: 0;
  font-size: .94rem;
  line-height: 1.8;
  color: var(--pa-body);
}
.page-about .pa-step-check {
  display: inline-block;
  margin-top: .75rem;
  font-family: var(--font-mono);
  font-size: .72rem;
  line-height: 1.7;
  letter-spacing: .04em;
  color: var(--pa-quiet);
}

/* ---------- 折叠核对清单 ---------- */
.page-about .pa-checklist {
  margin-top: 1.75rem;
  border: 1px solid var(--pa-hair);
  background: var(--pa-panel);
}
.page-about .pa-checklist > summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: .95rem 1.05rem;
  cursor: pointer;
  list-style: none;
  font-family: var(--font-mono);
  font-size: .76rem;
  letter-spacing: .05em;
  color: var(--pa-strong);
}
.page-about .pa-checklist > summary::-webkit-details-marker { display: none; }
.page-about .pa-checklist > summary::after {
  content: "+";
  font-size: 1.05rem;
  color: var(--pa-accent);
}
.page-about .pa-checklist[open] > summary::after { content: "−"; }
.page-about .pa-checklist > summary:focus-visible {
  outline: 2px solid var(--pa-accent);
  outline-offset: -2px;
}
.page-about .pa-check-list {
  list-style: none;
  margin: 0;
  padding: 0 1.05rem 1.05rem;
  display: grid;
  gap: .7rem;
}
.page-about .pa-check-list li {
  padding-top: .7rem;
  border-top: 1px dashed var(--pa-hair);
  font-size: .86rem;
  line-height: 1.8;
  color: var(--pa-body);
}
.page-about .pa-check-key {
  display: block;
  margin-bottom: .2rem;
  font-family: var(--font-mono);
  font-size: .7rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--pa-accent);
}

/* ---------- 时间线 ---------- */
.page-about .pa-timeline {
  position: relative;
  list-style: none;
  margin: 0;
  padding: 0 0 0 1.9rem;
}
.page-about .pa-timeline::before {
  content: "";
  position: absolute;
  left: 6px;
  top: .7rem;
  bottom: .7rem;
  width: 1px;
  background: var(--pa-hair);
}
.page-about .pa-timeline > li {
  position: relative;
  padding-bottom: 1.2rem;
}
.page-about .pa-timeline > li:last-child { padding-bottom: 0; }
.page-about .pa-timeline > li::before {
  content: "";
  position: absolute;
  left: -1.9rem;
  top: .6rem;
  width: 13px;
  height: 13px;
  border: 1px solid var(--pa-hair);
  border-radius: 50%;
  background: var(--ink);
}
.page-about .pa-section--paper .pa-timeline > li::before {
  background: var(--paper);
}
.page-about .pa-timeline > li:has(details[open])::before {
  background: var(--lime);
  border-color: var(--lime);
}
.page-about .pa-phase > summary {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: .5rem 1rem;
  padding: .15rem 0;
  cursor: pointer;
  list-style: none;
}
.page-about .pa-phase > summary::-webkit-details-marker { display: none; }
.page-about .pa-phase > summary:focus-visible {
  outline: 2px solid var(--pa-accent);
  outline-offset: 3px;
}
.page-about .pa-chip {
  flex: none;
  padding: .18rem .5rem;
  border: 1px solid var(--pa-hair);
  font-family: var(--font-mono);
  font-size: .66rem;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--pa-quiet);
}
.page-about .pa-phase-title {
  font-size: 1.02rem;
  font-weight: 700;
  color: var(--pa-strong);
}
.page-about .pa-phase-more {
  margin-left: auto;
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .08em;
  color: var(--pa-accent);
}
.page-about .pa-phase[open] .pa-phase-more { opacity: .35; }
.page-about .pa-phase-body {
  max-width: 44rem;
  margin-top: .85rem;
}
.page-about .pa-phase-body p {
  margin: 0 0 .8em;
  font-size: .92rem;
  line-height: 1.85;
  color: var(--pa-body);
}
.page-about .pa-phase-body p:last-child { margin-bottom: 0; }

/* ---------- 团队 ---------- */
.page-about .pa-team {
  display: grid;
  gap: clamp(1.75rem, 4vw, 3rem);
}
.page-about .pa-team-lede {
  margin: 0 0 1.5rem;
  font-size: 1rem;
  line-height: 1.85;
  color: var(--pa-body);
}
.page-about .pa-roles {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1rem;
}
.page-about .pa-role {
  padding: 1.15rem 1.05rem;
  border: 1px solid var(--pa-hair);
  background: var(--pa-panel);
}
.page-about .pa-role-count {
  display: block;
  font-family: var(--font-mono);
  font-variant-numeric: tabular-nums;
  font-size: 2.2rem;
  line-height: 1;
  color: var(--pa-strong);
}
.page-about .pa-role-bar {
  display: block;
  width: 28px;
  height: 3px;
  margin-top: .85rem;
  background: var(--pitch);
}
.page-about .pa-role:nth-child(2) .pa-role-bar { background: var(--blue); }
.page-about .pa-role:nth-child(3) .pa-role-bar { background: var(--teal); }
.page-about .pa-role-name {
  margin: .8rem 0 .4rem;
  font-size: .98rem;
  font-weight: 700;
  color: var(--pa-strong);
}
.page-about .pa-role-desc {
  margin: 0;
  font-size: .85rem;
  line-height: 1.78;
  color: var(--pa-body);
}
.page-about .pa-side--inline {
  margin-top: 1.5rem;
  max-width: 44rem;
}

/* ---------- 内容边界 ---------- */
.page-about .pa-boundary {
  display: grid;
  gap: clamp(1.5rem, 4vw, 2.75rem);
}
.page-about .pa-boundary-col {
  padding-top: 1.15rem;
  border-top: 2px solid var(--pitch);
}
.page-about .pa-boundary-col--mute {
  border-top-color: var(--red);
}
.page-about .pa-boundary-title {
  margin: 0 0 1.1rem;
  font-family: var(--font-display);
  font-size: 1.1rem;
  font-weight: 700;
  letter-spacing: .01em;
  color: var(--pa-strong);
}
.page-about .pa-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: .85rem;
}
.page-about .pa-list li {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: .7rem;
  font-size: .92rem;
  line-height: 1.78;
  color: var(--pa-body);
}
.page-about .pa-list li::before {
  content: "";
  width: 7px;
  height: 7px;
  margin-top: .62em;
  border: 1px solid var(--pitch);
}
.page-about .pa-list--mute li::before {
  border-color: var(--red);
  border-radius: 50%;
}
.page-about .pa-boundary-foot {
  margin: 1.35rem 0 0;
  font-family: var(--font-mono);
  font-size: .74rem;
  line-height: 1.75;
  color: var(--pa-quiet);
}

/* ---------- 常见疑问 ---------- */
.page-about .pa-qa {
  display: grid;
  gap: .75rem;
  max-width: 52rem;
}
.page-about .pa-qa details {
  border: 1px solid var(--pa-hair);
  background: var(--pa-panel);
}
.page-about .pa-qa > details > summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding: 1.05rem 1.15rem;
  cursor: pointer;
  list-style: none;
  font-size: .98rem;
  font-weight: 700;
  line-height: 1.6;
  color: var(--pa-strong);
}
.page-about .pa-qa > details > summary::-webkit-details-marker { display: none; }
.page-about .pa-qa > details > summary::after {
  content: "+";
  flex: none;
  font-family: var(--font-mono);
  font-size: 1.1rem;
  color: var(--pa-accent);
}
.page-about .pa-qa > details[open] > summary::after { content: "−"; }
.page-about .pa-qa > details > summary:focus-visible {
  outline: 2px solid var(--pa-accent);
  outline-offset: -2px;
}
.page-about .pa-qa-body {
  padding: 0 1.15rem 1.15rem;
  font-size: .9rem;
  line-height: 1.85;
  color: var(--pa-body);
}
.page-about .pa-qa-body p { margin: 0; }

/* ---------- 延伸入口 ---------- */
.page-about .pa-links {
  display: grid;
  gap: .85rem;
}
.page-about .pa-link-card {
  display: block;
  padding: 1.1rem 1.15rem;
  border: 1px solid var(--pa-hair);
  background: var(--pa-panel);
  text-decoration: none;
  transition: border-color .2s var(--ease), transform .2s var(--ease);
}
.page-about .pa-link-card:hover,
.page-about .pa-link-card:focus-visible {
  border-color: var(--pitch);
}
.page-about .pa-link-label {
  display: block;
  font-family: var(--font-mono);
  font-size: .68rem;
  letter-spacing: .12em;
  text-transform: uppercase;
  color: var(--pa-accent);
}
.page-about .pa-link-name {
  display: block;
  margin-top: .5rem;
  font-size: 1rem;
  font-weight: 700;
  color: var(--pa-strong);
}
.page-about .pa-link-desc {
  display: block;
  margin-top: .4rem;
  font-size: .82rem;
  line-height: 1.75;
  color: var(--pa-body);
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .pa-roles {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .pa-links {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
  .page-about .pa-boundary {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

@media (min-width: 768px) {
  .page-about .pa-step {
    grid-template-columns: 4.5rem minmax(0, 1fr);
    gap: 1.5rem;
  }
  .page-about .pa-step-num {
    font-size: 1.5rem;
  }
}

@media (min-width: 900px) {
  .page-about .pa-read {
    grid-template-columns: minmax(0, 40rem) minmax(13rem, 17rem);
    justify-content: center;
    gap: clamp(2rem, 5vw, 4rem);
  }
  .page-about .pa-side {
    border-top: 0;
    border-left: 1px solid var(--pa-hair);
    padding: 0 0 0 .95rem;
  }
  .page-about .pa-team {
    grid-template-columns: minmax(0, .82fr) minmax(0, 1.18fr);
    align-items: start;
  }
  .page-about .pa-side--inline {
    border-left: 0;
    border-top: 1px solid var(--pa-hair);
    padding: .9rem 0 0;
  }
}

@media (min-width: 980px) {
  .page-about .pa-hero-grid {
    grid-template-columns: minmax(0, 1.4fr) minmax(0, 1fr);
    align-items: end;
    gap: clamp(2rem, 5vw, 4rem);
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .pa-hero::before {
    transform: none;
  }
  .page-about .pa-link-card {
    transition: none;
  }
}
</main>