.page-about {
  --about-rail-w: 232px;
  --about-gap: clamp(28px, 4vw, 60px);
  position: relative;
}

/* ---------- 右侧阅读进度条 ---------- */
.page-about .about-progress {
  position: fixed;
  top: var(--header-h);
  right: 0;
  bottom: 0;
  width: 3px;
  background: var(--c-line);
  opacity: .45;
  z-index: 30;
  pointer-events: none;
}
.page-about .about-progress-bar {
  display: block;
  width: 100%;
  height: 100%;
  background: var(--c-accent);
  transform: scaleY(0);
  transform-origin: top center;
}
@supports (animation-timeline: scroll()) {
  .page-about .about-progress-bar {
    animation: about-scroll-progress linear both;
    animation-timeline: scroll(root block);
  }
}
@keyframes about-scroll-progress {
  from { transform: scaleY(0); }
  to { transform: scaleY(1); }
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  padding: clamp(26px, 4.5vw, 52px) 0 clamp(30px, 4.5vw, 56px);
  border-bottom: var(--line);
}
.page-about .about-hero-title {
  margin: 14px 0 0;
  max-width: 22ch;
  font-family: var(--ff-serif);
  font-size: clamp(1.6rem, 5.2vw, 2.75rem);
  font-weight: 600;
  line-height: 1.28;
  letter-spacing: .01em;
  color: var(--c-ink);
}
.page-about .about-hero-lede {
  margin: clamp(16px, 2vw, 24px) 0 0;
  max-width: 64ch;
  font-size: var(--fs-16);
  line-height: 1.9;
  color: var(--c-muted);
}

.page-about .about-band {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin-top: clamp(26px, 4vw, 44px);
  background: var(--c-line);
  border: var(--line);
}
.page-about .about-band .data-cell {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 16px 18px;
  background: var(--c-panel-deep);
}
.page-about .about-band .data-key {
  font-size: var(--fs-12);
  letter-spacing: .1em;
  color: var(--c-muted);
}
.page-about .about-band .data-value {
  font-family: var(--ff-mono);
  font-size: var(--fs-28);
  font-weight: 700;
  letter-spacing: .02em;
  line-height: 1;
  color: var(--c-ink);
  font-variant-numeric: tabular-nums;
}
.page-about .about-band .data-value--accent { color: var(--c-accent); }
.page-about .about-band .data-unit {
  margin-left: .3em;
  font-size: var(--fs-14);
  font-weight: 400;
  color: var(--c-muted);
}

/* ---------- 主体分栏 ---------- */
.page-about .about-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--about-gap);
  padding: clamp(30px, 4.5vw, 60px) 0 clamp(48px, 7vw, 96px);
}
.page-about .about-body { min-width: 0; }

/* ---------- 左侧目录 ---------- */
.page-about .about-rail {
  border: var(--line);
  background: var(--c-panel);
  padding: 16px 14px 18px;
}
.page-about .about-rail-title {
  margin: 0 0 12px;
  padding-bottom: 10px;
  border-bottom: var(--line);
  font-family: var(--ff-serif);
  font-size: var(--fs-14);
  letter-spacing: .14em;
  color: var(--c-muted);
}
.page-about .about-toc {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 2px;
}
.page-about .about-toc a {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 8px 8px;
  border-left: 2px solid transparent;
  font-size: var(--fs-14);
  line-height: 1.55;
  color: var(--c-muted);
  text-decoration: none;
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease), background-color var(--dur) var(--ease);
}
.page-about .about-toc a:hover,
.page-about .about-toc a:focus-visible {
  color: var(--c-accent-soft);
  border-left-color: var(--c-accent);
  background: rgba(63, 227, 176, .07);
}
.page-about .about-toc .mono {
  font-family: var(--ff-mono);
  font-size: var(--fs-12);
  color: var(--c-dim);
  letter-spacing: .06em;
}
.page-about .about-toc a:hover .mono { color: var(--c-accent); }

.page-about .about-rail-cta {
  display: grid;
  gap: 8px;
  margin-top: 16px;
  padding-top: 14px;
  border-top: var(--line);
}

/* ---------- 章节头 ---------- */
.page-about .about-section {
  padding-bottom: clamp(44px, 6vw, 88px);
}
.page-about .about-section--last { padding-bottom: 0; }

.page-about .about-section .chapter {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 10px 14px;
  margin-bottom: clamp(20px, 3vw, 32px);
  padding-bottom: 14px;
  border-bottom: var(--line);
}
.page-about .chapter-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 2.6em;
  padding: 4px 9px;
  background: var(--c-paper);
  color: #10241C;
  font-family: var(--ff-mono);
  font-size: var(--fs-12);
  font-weight: 700;
  letter-spacing: .1em;
  border-radius: var(--r-sm);
}
.page-about .chapter-title {
  flex: 1 1 auto;
  margin: 0;
  font-family: var(--ff-serif);
  font-size: clamp(1.2rem, 3.4vw, 1.75rem);
  font-weight: 600;
  line-height: 1.35;
  color: var(--c-ink);
}
.page-about .chapter-note {
  flex-basis: 100%;
  margin: 0;
  font-size: var(--fs-14);
  line-height: 1.7;
  color: var(--c-muted);
}

/* ---------- 图片 ---------- */
.page-about .about-media {
  position: relative;
  margin: 0 0 clamp(22px, 3vw, 34px);
  border: var(--line);
  background: var(--c-panel-deep);
  overflow: hidden;
}
.page-about .about-media img {
  display: block;
  width: 100%;
  height: 100%;
  max-width: 100%;
  object-fit: cover;
}
.page-about .about-media::after {
  content: "";
  position: absolute;
  inset: 0;
  pointer-events: none;
  background-image: repeating-linear-gradient(0deg, rgba(63, 227, 176, .07) 0 1px, transparent 1px 4px);
  opacity: .55;
}
.page-about .about-media--close { margin-bottom: clamp(24px, 3.4vw, 40px); }

/* ---------- 时间轴 ---------- */
.page-about .about-timeline {
  list-style: none;
  margin: 0 0 0 6px;
  padding: 0 0 0 24px;
  border-left: 1px solid var(--c-line);
}
.page-about .tl-item { position: relative; }
.page-about .tl-item::before {
  content: "";
  position: absolute;
  left: -29px;
  top: 26px;
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--c-accent);
  box-shadow: 0 0 0 4px rgba(63, 227, 176, .13);
}
.page-about .tl-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  gap: 8px 14px;
  width: 100%;
  padding: 16px 0 10px;
  border: 0;
  border-bottom: 1px solid var(--c-line);
  background: none;
  color: inherit;
  font: inherit;
  text-align: left;
  cursor: pointer;
}
.page-about .tl-year {
  font-family: var(--ff-mono);
  font-size: var(--fs-20);
  font-weight: 700;
  letter-spacing: .02em;
  color: var(--c-accent);
  font-variant-numeric: tabular-nums;
}
.page-about .tl-name {
  flex: 1 1 auto;
  min-width: 0;
  font-family: var(--ff-serif);
  font-size: var(--fs-20);
  font-weight: 600;
  color: var(--c-ink);
}
.page-about .tl-toggle {
  position: relative;
  flex: 0 0 14px;
  width: 14px;
  height: 14px;
  align-self: center;
}
.page-about .tl-toggle::before,
.page-about .tl-toggle::after {
  content: "";
  position: absolute;
  left: 50%;
  top: 50%;
  background: var(--c-muted);
  transform: translate(-50%, -50%);
  transition: transform var(--dur) var(--ease), background-color var(--dur) var(--ease);
}
.page-about .tl-toggle::before { width: 14px; height: 1px; }
.page-about .tl-toggle::after { width: 1px; height: 14px; }
.page-about .tl-head:hover .tl-toggle::before,
.page-about .tl-head:hover .tl-toggle::after { background: var(--c-accent); }
.page-about .tl-head[aria-expanded="false"] .tl-toggle::after { transform: translate(-50%, -50%) scaleY(0); }

.page-about .tl-body {
  display: grid;
  grid-template-rows: 1fr;
  transition: grid-template-rows var(--dur) var(--ease);
}
.page-about .tl-head[aria-expanded="false"] + .tl-body { grid-template-rows: 0fr; }
.page-about .tl-body-inner { overflow: hidden; }
.page-about .tl-body-inner p {
  margin: 0;
  padding: 12px 0 18px;
  max-width: 62ch;
  font-size: var(--fs-14);
  line-height: 1.9;
  color: var(--c-muted);
}

/* ---------- 流程步骤 ---------- */
.page-about .about-steps {
  list-style: none;
  margin: 0;
  padding: 0;
}
.page-about .step {
  position: relative;
  display: grid;
  grid-template-columns: 46px minmax(0, 1fr);
  gap: 16px;
  padding-bottom: 26px;
}
.page-about .step:last-child { padding-bottom: 0; }
.page-about .step::before {
  content: "";
  position: absolute;
  left: 22px;
  top: 38px;
  bottom: 0;
  width: 1px;
  background: var(--c-line);
}
.page-about .step:last-child::before { display: none; }
.page-about .step-num {
  position: relative;
  z-index: 1;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 46px;
  height: 32px;
  border: 1px solid var(--c-line);
  border-radius: var(--r-sm);
  background: var(--c-panel);
  font-family: var(--ff-mono);
  font-size: var(--fs-14);
  font-weight: 700;
  letter-spacing: .06em;
  color: var(--c-accent);
}
.page-about .step-body { min-width: 0; }
.page-about .step-title {
  margin: 4px 0 8px;
  font-family: var(--ff-serif);
  font-size: var(--fs-20);
  font-weight: 600;
  color: var(--c-ink);
}
.page-about .step-body p {
  margin: 0;
  max-width: 60ch;
  font-size: var(--fs-14);
  line-height: 1.9;
  color: var(--c-muted);
}

/* ---------- 团队 ---------- */
.page-about .about-team {
  display: grid;
  gap: 14px;
}
.page-about .team-card {
  position: relative;
  padding: 20px 18px 22px 22px;
  border: var(--line);
  background: var(--c-panel);
}
.page-about .team-card::before {
  content: "";
  position: absolute;
  inset: 0 auto 0 0;
  width: 2px;
  background: var(--c-accent);
  opacity: .55;
}
.page-about .team-card .tag { margin-bottom: 12px; }
.page-about .team-title {
  margin: 0 0 10px;
  font-family: var(--ff-serif);
  font-size: var(--fs-20);
  font-weight: 600;
  color: var(--c-ink);
}
.page-about .team-card p {
  margin: 0;
  font-size: var(--fs-14);
  line-height: 1.9;
  color: var(--c-muted);
}
.page-about .about-team-note {
  margin: clamp(18px, 2.4vw, 26px) 0 0;
  padding: 16px 18px;
  border: var(--line);
  border-left: 2px solid var(--c-dim);
  background: var(--c-panel-deep);
  font-size: var(--fs-14);
  line-height: 1.9;
  color: var(--c-muted);
}

/* ---------- 覆盖范围 ---------- */
.page-about .about-coverage-band {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--c-line);
  border: var(--line);
}
.page-about .cov-cell {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 18px 16px;
  background: var(--c-panel);
}
.page-about .cov-key {
  font-size: var(--fs-12);
  letter-spacing: .1em;
  color: var(--c-muted);
}
.page-about .cov-val {
  font-family: var(--ff-mono);
  font-size: var(--fs-28);
  font-weight: 700;
  line-height: 1;
  letter-spacing: .02em;
  color: var(--c-accent);
  font-variant-numeric: tabular-nums;
}
.page-about .cov-unit {
  margin-left: .25em;
  font-size: var(--fs-14);
  font-weight: 400;
  color: var(--c-muted);
}
.page-about .cov-desc {
  font-size: var(--fs-12);
  line-height: 1.75;
  color: var(--c-muted);
}
.page-about .about-coverage-copy {
  margin-top: clamp(20px, 2.6vw, 30px);
  display: grid;
  gap: 14px;
}
.page-about .about-coverage-copy p {
  margin: 0;
  max-width: 66ch;
  font-size: var(--fs-16);
  line-height: 1.95;
  color: var(--c-muted);
}
.page-about .about-coverage-copy a {
  color: var(--c-accent-soft);
  text-decoration: none;
  border-bottom: 1px solid rgba(63, 227, 176, .45);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.page-about .about-coverage-copy a:hover,
.page-about .about-coverage-copy a:focus-visible {
  color: var(--c-accent);
  border-color: var(--c-accent);
}

/* ---------- 支持 ---------- */
.page-about .about-support {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 1px;
  background: var(--c-line);
  border: var(--line);
}
.page-about .sup-item {
  display: grid;
  gap: 8px;
  padding: 18px 18px 20px;
  background: var(--c-panel-deep);
}
.page-about .sup-key {
  font-family: var(--ff-serif);
  font-size: var(--fs-16);
  font-weight: 600;
  color: var(--c-accent-soft);
}
.page-about .sup-val p {
  margin: 0;
  max-width: 62ch;
  font-size: var(--fs-14);
  line-height: 1.9;
  color: var(--c-muted);
}
.page-about .about-support-cta {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: clamp(20px, 2.6vw, 30px) 0 0;
}

/* ---------- 更新方向 ---------- */
.page-about .about-next {
  display: grid;
  gap: 0;
}
.page-about .next-item {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 6px 16px;
  padding: 20px 0;
  border-bottom: 1px solid var(--c-line);
}
.page-about .next-item:first-child { border-top: 1px solid var(--c-line); }
.page-about .next-idx {
  grid-row: 1 / span 2;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 40px;
  height: 28px;
  border: 1px solid var(--c-line);
  border-radius: var(--r-sm);
  background: var(--c-panel);
  font-family: var(--ff-mono);
  font-size: var(--fs-12);
  font-weight: 700;
  letter-spacing: .1em;
  color: var(--c-accent);
}
.page-about .next-title {
  margin: 0;
  font-family: var(--ff-serif);
  font-size: var(--fs-20);
  font-weight: 600;
  color: var(--c-ink);
}
.page-about .next-item p {
  grid-column: 2;
  margin: 0;
  max-width: 62ch;
  font-size: var(--fs-14);
  line-height: 1.9;
  color: var(--c-muted);
}
.page-about .about-next-note {
  margin: clamp(20px, 2.6vw, 30px) 0 0;
  font-size: var(--fs-14);
  line-height: 1.9;
  color: var(--c-muted);
}
.page-about .about-next-note a {
  color: var(--c-accent-soft);
  text-decoration: none;
  border-bottom: 1px solid rgba(63, 227, 176, .45);
  transition: color var(--dur) var(--ease), border-color var(--dur) var(--ease);
}
.page-about .about-next-note a:hover,
.page-about .about-next-note a:focus-visible {
  color: var(--c-accent);
  border-color: var(--c-accent);
}

/* ---------- 焦点样式 ---------- */
.page-about a:focus-visible,
.page-about button:focus-visible {
  outline: 2px solid var(--c-accent);
  outline-offset: 2px;
}

/* ---------- 入场显现 ---------- */
.page-about [data-reveal] {
  opacity: 1;
}
.page-about [data-reveal][data-revealed="true"] {
  animation: about-reveal var(--dur) var(--ease) both;
}
@keyframes about-reveal {
  from { opacity: 0; transform: translateY(10px); }
  to { opacity: 1; transform: none; }
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .about-team { grid-template-columns: repeat(3, minmax(0, 1fr)); }
  .page-about .about-support { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .page-about .about-coverage-band { grid-template-columns: repeat(3, minmax(0, 1fr)); }
}

@media (min-width: 720px) {
  .page-about .about-band { grid-template-columns: repeat(4, minmax(0, 1fr)); }
}

@media (min-width: 1024px) {
  .page-about .about-layout {
    grid-template-columns: minmax(180px, var(--about-rail-w)) minmax(0, 1fr);
    gap: clamp(36px, 4vw, 72px);
    align-items: start;
  }
  .page-about .about-rail {
    position: sticky;
    top: calc(var(--header-h) + 20px);
    max-height: calc(100vh - var(--header-h) - 40px);
    overflow-y: auto;
  }
  .page-about .about-coverage-band { grid-template-columns: repeat(5, minmax(0, 1fr)); }
  .page-about .about-hero-title { max-width: 24ch; }
}

@media (min-width: 1280px) {
  .page-about .about-body { padding-right: clamp(0px, 3vw, 48px); }
}

/* ---------- 动效降级 ---------- */
@media (prefers-reduced-motion: reduce) {
  .page-about .about-progress-bar { animation: none; transform: scaleY(0); }
  .page-about * {
    transition-duration: 1ms !important;
    animation-duration: 1ms !important;
  }
}
</main>