.page-about {
  --about-measure: 40rem;
  --about-rail: 7rem;
  display: block;
}

/* ---------- 面包屑 ---------- */
.page-about .breadcrumbs {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.5rem;
  padding-block: 1.1rem;
  font-size: 0.82rem;
  letter-spacing: 0.04em;
  color: var(--mist);
}

.page-about .breadcrumbs a {
  color: var(--mist);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 180ms ease, border-color 180ms ease;
}

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

.page-about .breadcrumbs [aria-current="page"] {
  color: var(--silver);
}

/* ---------- 首屏 ---------- */
.page-about .about-hero {
  position: relative;
  padding-block: clamp(1.75rem, 5vw, 3.5rem) clamp(2.25rem, 6vw, 4.5rem);
  background:
    linear-gradient(180deg, var(--deep) 0%, var(--ink) 78%),
    var(--ink);
  border-bottom: 1px solid var(--line);
  overflow: hidden;
}

.page-about .about-hero::after {
  content: "";
  position: absolute;
  inset-block: -30% -30%;
  inset-inline-end: -12%;
  width: 46%;
  background: linear-gradient(135deg, rgba(53, 240, 208, 0.11), rgba(142, 123, 255, 0.06) 55%, transparent 80%);
  clip-path: polygon(38% 0, 100% 0, 100% 100%, 0 100%);
  pointer-events: none;
}

.page-about .about-hero-inner {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: 1fr;
  gap: clamp(1.75rem, 5vw, 3.5rem);
}

.page-about .eyebrow {
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.2em;
  color: var(--accent);
  margin: 0 0 0.7rem;
}

.page-about .about-hero h1 {
  margin: 0 0 1.1rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(2rem, 6vw, 3.5rem);
  line-height: 1.14;
  letter-spacing: -0.012em;
  color: var(--white);
}

.page-about .about-hero .lede {
  margin: 0 0 1.6rem;
  max-width: 36rem;
  font-size: clamp(1rem, 1.5vw, 1.09rem);
  line-height: 1.85;
  color: var(--mist);
}

.page-about .about-hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin: 0;
}

.page-about .btn {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.72rem 1.35rem;
  font-size: 0.88rem;
  letter-spacing: 0.03em;
  text-decoration: none;
  border: 1px solid var(--line-strong);
  transition: background 180ms ease, color 180ms ease, border-color 180ms ease, transform 180ms ease;
}

.page-about .btn:hover,
.page-about .btn:focus-visible {
  transform: translateY(-2px);
}

.page-about .btn--accent {
  background: var(--cyan);
  border-color: var(--cyan);
  color: var(--ink);
  font-weight: 600;
}

.page-about .btn--accent:hover,
.page-about .btn--accent:focus-visible {
  background: var(--yellow);
  border-color: var(--yellow);
}

.page-about .btn--ghost {
  color: var(--white);
  background: transparent;
}

.page-about .btn--ghost:hover,
.page-about .btn--ghost:focus-visible {
  border-color: var(--cyan);
  color: var(--cyan);
}

/* ---------- 首屏侧栏 ---------- */
.page-about .about-hero-panel {
  border: 1px solid var(--line);
  background: var(--card);
  box-shadow: var(--shadow-card);
  padding: 1.35rem 1.35rem 0.9rem;
}

.page-about .panel-title {
  margin: 0 0 0.6rem;
  font-family: var(--font-mono);
  font-size: 0.72rem;
  letter-spacing: 0.2em;
  color: var(--yellow);
}

.page-about .panel-list {
  margin: 0;
}

.page-about .panel-row {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: baseline;
  gap: 0.5rem 1rem;
  padding-block: 0.8rem;
  border-top: 1px solid var(--line);
}

.page-about .panel-row dt {
  font-size: 0.82rem;
  color: var(--mist);
}

.page-about .panel-row dd {
  margin: 0;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  color: var(--white);
}

/* ---------- 规模数据带 ---------- */
.page-about .stat-band {
  background: var(--steel);
  border-bottom: 1px solid var(--line);
}

.page-about .stat-band-inner {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border-inline: 1px solid var(--line);
}

.page-about .stat-cell {
  background: var(--steel);
  padding: clamp(1.1rem, 3vw, 1.7rem) clamp(0.9rem, 2.4vw, 1.4rem);
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.page-about .stat-cell:nth-child(4n + 1) { --accent: var(--cyan); }
.page-about .stat-cell:nth-child(4n + 2) { --accent: var(--yellow); }
.page-about .stat-cell:nth-child(4n + 3) { --accent: var(--orange); }
.page-about .stat-cell:nth-child(4n + 4) { --accent: var(--violet); }

.page-about .stat-cell .num {
  display: block;
  font-family: var(--font-mono);
  font-size: clamp(1.55rem, 4.4vw, 2.35rem);
  line-height: 1;
  color: var(--accent);
  letter-spacing: -0.02em;
}

.page-about .stat-label {
  font-size: 0.8rem;
  line-height: 1.6;
  color: var(--mist);
}

/* ---------- 章节骨架 ---------- */
.page-about .about-flow {
  padding-block: clamp(1.5rem, 4vw, 3rem) clamp(2.5rem, 6vw, 5rem);
}

.page-about .chapter {
  display: grid;
  grid-template-columns: 1fr;
  gap: 0.6rem;
  padding-block: clamp(2.25rem, 6vw, 4.25rem);
  border-top: 1px solid var(--line);
}

.page-about .chapter--cyan { --accent: var(--cyan); }
.page-about .chapter--yellow { --accent: var(--yellow); }
.page-about .chapter--orange { --accent: var(--orange); }
.page-about .chapter--violet { --accent: var(--violet); }

.page-about .chapter-rail {
  position: relative;
}

.page-about .chapter-num {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.95rem;
  letter-spacing: 0.16em;
  color: var(--accent);
}

.page-about .chapter-num::after {
  content: "";
  display: block;
  width: 2.4rem;
  height: 2px;
  margin-top: 0.55rem;
  background: var(--accent);
  opacity: 0.7;
}

.page-about .chapter-body > * {
  max-width: var(--about-measure);
}

.page-about .chapter-body > .wide,
.page-about .chapter-body > .flow-scroll {
  max-width: none;
}

.page-about .chapter-body h2 {
  margin: 0 0 1.05rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(1.45rem, 3.4vw, 2.15rem);
  line-height: 1.28;
  color: var(--white);
}

.page-about .chapter-body > p:not(.eyebrow) {
  margin: 0 0 1.1rem;
  font-size: 1.0125rem;
  line-height: 1.9;
  color: var(--mist);
}

.page-about .chapter-body strong {
  color: var(--white);
  font-weight: 600;
}

.page-about .chapter-body a {
  color: var(--white);
  text-decoration: none;
  border-bottom: 1px solid var(--accent);
  transition: color 180ms ease, border-color 180ms ease;
}

.page-about .chapter-body a:hover,
.page-about .chapter-body a:focus-visible {
  color: var(--accent);
}

/* ---------- 四道环节 SVG ---------- */
.page-about .flow-scroll {
  overflow-x: auto;
  margin-block: 1.5rem 1.9rem;
  padding-bottom: 0.5rem;
}

.page-about .flow-track {
  display: block;
  width: 100%;
  min-width: 560px;
  height: auto;
}

.page-about .flow-line {
  stroke: var(--line-strong);
  stroke-width: 1;
}

.page-about .flow-node-label {
  font-family: var(--font-body);
  font-size: 15px;
  font-weight: 500;
  fill: var(--white);
}

.page-about .flow-node-sub {
  font-family: var(--font-body);
  font-size: 12px;
  fill: var(--mist);
}

/* ---------- 图 ---------- */
.page-about .about-figure {
  margin: 1.7rem 0 1.9rem;
}

.page-about .about-figure img {
  display: block;
  width: 100%;
  max-width: 100%;
  height: auto;
  object-fit: cover;
  border: 1px solid var(--line);
  background: var(--card);
}

.page-about .figure-caption {
  margin-top: 0.7rem;
  font-size: 0.78rem;
  line-height: 1.7;
  color: var(--mist);
  border-left: 2px solid var(--accent);
  padding-left: 0.75rem;
}

/* ---------- 折叠说明 ---------- */
.page-about .about-details {
  margin-top: 1.4rem;
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
}

.page-about .about-details summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 1rem;
  padding-block: 0.95rem;
  cursor: pointer;
  list-style: none;
  font-size: 0.9rem;
  color: var(--white);
  transition: color 180ms ease;
}

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

.page-about .about-details summary::after {
  content: "+";
  font-family: var(--font-mono);
  font-size: 1.1rem;
  line-height: 1;
  color: var(--accent);
}

.page-about .about-details[open] summary::after {
  content: "–";
}

.page-about .about-details summary:hover,
.page-about .about-details summary:focus-visible {
  color: var(--accent);
}

.page-about .about-details p {
  margin: 0 0 1.05rem;
  max-width: 36rem;
  font-size: 0.92rem;
  line-height: 1.85;
  color: var(--mist);
}

/* ---------- 引文条 ---------- */
.page-about .pull-note {
  border-top: 1px solid var(--line);
  border-bottom: 1px solid var(--line);
  background: linear-gradient(90deg, rgba(255, 106, 43, 0.07), transparent 62%);
}

.page-about .pull-note-inner {
  padding-block: clamp(1.6rem, 4.5vw, 2.9rem);
  border-left: 3px solid var(--orange);
  padding-left: clamp(1rem, 3vw, 1.6rem);
}

.page-about .pull-note p {
  margin: 0;
  max-width: 34rem;
  font-family: var(--font-display);
  font-size: clamp(1.08rem, 2.4vw, 1.42rem);
  line-height: 1.6;
  color: var(--white);
}

/* ---------- 后续入口 ---------- */
.page-about .about-next {
  border-top: 1px solid var(--line);
  background: var(--deep);
  padding-block: clamp(2.25rem, 6vw, 4rem);
}

.page-about .about-next h2 {
  margin: 0 0 0.7rem;
  font-family: var(--font-display);
  font-weight: 600;
  font-size: clamp(1.35rem, 3vw, 1.95rem);
  color: var(--white);
}

.page-about .about-next-lede {
  margin: 0 0 1.75rem;
  max-width: 34rem;
  font-size: 0.95rem;
  line-height: 1.85;
  color: var(--mist);
}

.page-about .next-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1px;
  background: var(--line);
  border: 1px solid var(--line);
}

.page-about .next-item {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  padding: 1.35rem 1.25rem;
  background: var(--deep);
  text-decoration: none;
  border-top: 2px solid transparent;
  transition: background 180ms ease, border-color 180ms ease, transform 180ms ease;
}

.page-about .next-item:hover,
.page-about .next-item:focus-visible {
  background: var(--card);
  transform: translateY(-2px);
}

.page-about .next-item:nth-child(4n + 1) { border-top-color: var(--cyan); }
.page-about .next-item:nth-child(4n + 2) { border-top-color: var(--yellow); }
.page-about .next-item:nth-child(4n + 3) { border-top-color: var(--orange); }
.page-about .next-item:nth-child(4n + 4) { border-top-color: var(--violet); }

.page-about .next-tag {
  font-family: var(--font-mono);
  font-size: 0.68rem;
  letter-spacing: 0.2em;
  color: var(--mist);
}

.page-about .next-title {
  font-family: var(--font-display);
  font-size: 1.06rem;
  font-weight: 600;
  line-height: 1.4;
  color: var(--white);
}

.page-about .next-desc {
  font-size: 0.84rem;
  line-height: 1.7;
  color: var(--mist);
}

/* ---------- 响应式 ---------- */
@media (min-width: 640px) {
  .page-about .stat-band-inner {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }

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

@media (min-width: 900px) {
  .page-about .about-hero-inner {
    grid-template-columns: minmax(0, 1.4fr) minmax(280px, 0.7fr);
    align-items: end;
  }

  .page-about .about-hero-panel {
    padding: 1.6rem 1.6rem 1.1rem;
  }

  .page-about .chapter {
    grid-template-columns: var(--about-rail) minmax(0, 1fr);
    gap: clamp(2rem, 4vw, 3.25rem);
  }

  .page-about .chapter-rail {
    position: sticky;
    top: 7.5rem;
    align-self: start;
  }

  .page-about .chapter-num {
    font-size: 1.05rem;
  }

  .page-about .chapter-body > p:not(.eyebrow) {
    font-size: 1.04rem;
  }
}

@media (min-width: 1040px) {
  .page-about .next-grid {
    grid-template-columns: repeat(4, minmax(0, 1fr));
  }
}

@media (prefers-reduced-motion: reduce) {
  .page-about .btn,
  .page-about .next-item,
  .page-about .breadcrumbs a,
  .page-about .chapter-body a {
    transition: none;
  }

  .page-about .btn:hover,
  .page-about .btn:focus-visible,
  .page-about .next-item:hover,
  .page-about .next-item:focus-visible {
    transform: none;
  }
}