.page-about {
  --page-serif: 'Iowan Old Style', 'Palatino Linotype', 'Book Antiqua', Palatino, Georgia, 'Times New Roman', serif;
}

/* ===== Hero ===== */
.page-about__hero {
  position: relative;
  padding: calc(var(--header-h) + 3rem) 0 4.5rem;
  background:
    radial-gradient(ellipse at 75% 15%, rgba(0, 212, 255, 0.22) 0%, transparent 50%),
    radial-gradient(ellipse at 15% 85%, rgba(255, 107, 26, 0.16) 0%, transparent 45%),
    linear-gradient(135deg, #081326 0%, #0E2A55 60%, #0B1B3D 100%);
  color: var(--color-on-primary);
  overflow: hidden;
  border-bottom: 2px solid var(--color-cta);
}

.page-about__hero-bg.grid-overlay {
  position: absolute;
  inset: 0;
  background-image:
    linear-gradient(rgba(0, 212, 255, 0.08) 1px, transparent 1px),
    linear-gradient(90deg, rgba(0, 212, 255, 0.08) 1px, transparent 1px);
  background-size: 48px 48px;
  -webkit-mask-image: radial-gradient(circle at 50% 30%, black 0%, transparent 75%);
  mask-image: radial-gradient(circle at 50% 30%, black 0%, transparent 75%);
  pointer-events: none;
}

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

.page-about__hero .breadcrumb {
  margin-bottom: 2.5rem;
  font-size: 0.875rem;
}

.page-about__hero .breadcrumb a {
  color: rgba(232, 238, 249, 0.7);
  text-decoration: none;
}

.page-about__hero .breadcrumb a:hover {
  color: var(--color-accent);
}

.page-about__hero .breadcrumb [aria-current="page"] {
  color: var(--color-accent);
}

.page-about__hero .breadcrumb__sep {
  margin: 0 0.5rem;
  color: rgba(232, 238, 249, 0.4);
}

.page-about__hero-kicker {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  margin-bottom: 1.25rem;
  font-family: var(--font-body);
  font-size: 0.875rem;
  font-weight: 600;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--color-accent);
}

.page-about__hero-kicker::before {
  content: "";
  width: 2rem;
  height: 2px;
  background: var(--color-cta);
}

.page-about__hero-title {
  max-width: 58rem;
  margin-bottom: 1.5rem;
  font-family: var(--font-heading);
  font-size: clamp(2.5rem, 6vw, 4.75rem);
  line-height: 1.05;
  letter-spacing: 0.01em;
  text-transform: uppercase;
}

.page-about__hero-desc {
  max-width: 46rem;
  margin-bottom: 2.5rem;
  font-size: clamp(1rem, 1.4vw, 1.25rem);
  line-height: 1.7;
  color: rgba(232, 238, 249, 0.85);
}

.page-about__hero-track {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 1rem;
  max-width: 46rem;
  padding-top: 1.5rem;
  border-top: 1px solid rgba(0, 212, 255, 0.4);
}

.page-about__hero-track .coordinate {
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: var(--color-accent);
}

.page-about__hero-track .status-dot {
  margin-left: auto;
}

/* ===== 章节标题（编辑感） ===== */
.page-about__head .section-title {
  font-family: var(--page-serif);
  font-size: clamp(1.85rem, 3vw, 2.75rem);
  font-style: italic;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: var(--color-primary);
}

.page-about__head .section-desc {
  max-width: 44rem;
}

/* ===== 我们的开始 ===== */
.page-about__origin {
  padding: 5rem 0;
  background: var(--color-surface);
}

.page-about__origin-grid {
  display: grid;
  gap: 2.5rem;
  margin-top: 3rem;
}

.page-about__origin-copy p {
  margin-bottom: 1.5rem;
  font-size: 1.0625rem;
  line-height: 1.85;
  color: var(--color-ink);
}

.page-about__origin-copy p:first-child {
  font-size: 1.25rem;
  line-height: 1.7;
  font-weight: 500;
  color: var(--color-primary);
}

.page-about__origin-copy .entry-link {
  color: var(--color-accent);
}

.page-about__origin-note {
  align-self: start;
}

/* ===== 关键里程碑 ===== */
.page-about__milestones {
  position: relative;
  padding: 5.5rem 0 6rem;
  background:
    radial-gradient(circle at 90% 10%, rgba(155, 89, 182, 0.18), transparent 42%),
    var(--color-primary);
  color: var(--color-on-primary);
}

.page-about__milestones .section-title,
.page-about__philosophy .section-title {
  color: #fff;
}

.page-about__milestones .section-desc,
.page-about__philosophy .section-desc {
  color: rgba(232, 238, 249, 0.75);
}

.page-about__milestones .section-label,
.page-about__philosophy .section-label {
  color: var(--color-accent);
}

.page-about__legend {
  display: flex;
  flex-wrap: wrap;
  gap: 1.25rem 1.75rem;
  margin: 2.5rem 0 1.5rem;
}

.page-about__legend .legend__item {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-size: 0.875rem;
  color: rgba(232, 238, 249, 0.8);
}

.page-about__legend .legend__swatch {
  display: inline-block;
  width: 0.875rem;
  height: 0.875rem;
  border-radius: 50%;
}

.page-about__legend--start {
  background: var(--color-cta);
}

.page-about__legend--upgrade {
  background: var(--color-accent);
}

.page-about__legend--doc {
  background: var(--color-status);
}

.page-about__track {
  display: none;
}

.page-about__timeline {
  position: relative;
  margin-top: 1.5rem;
}

.page-about__timeline::before {
  content: "";
  position: absolute;
  top: 1rem;
  bottom: 1.5rem;
  left: 1.25rem;
  width: 2px;
  background: linear-gradient(180deg, var(--color-cta) 0%, var(--color-accent) 100%);
  opacity: 0.35;
}

.page-about__timeline-item {
  position: relative;
  margin-bottom: 1rem;
  padding-left: 4rem;
  border: 1px solid rgba(232, 238, 249, 0.14);
  border-radius: var(--radius);
  background: rgba(11, 27, 61, 0.55);
  color: var(--color-on-primary);
  transition: border-color 0.3s ease, background 0.3s ease, box-shadow 0.3s ease;
}

.page-about__timeline-item:hover {
  border-color: rgba(0, 212, 255, 0.4);
}

.page-about__timeline-item[open] {
  border-color: rgba(0, 212, 255, 0.45);
  background: rgba(0, 212, 255, 0.05);
  box-shadow: var(--shadow-md);
}

.page-about__timeline-summary {
  position: relative;
  display: flex;
  align-items: center;
  gap: 1rem;
  padding: 1.25rem 1.5rem 1.25rem 0;
  cursor: pointer;
  list-style: none;
}

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

.page-about__timeline-year {
  position: absolute;
  top: 1.125rem;
  left: -4rem;
  display: flex;
  align-items: center;
  justify-content: center;
  width: 2.5rem;
  height: 2.5rem;
  border: 2px solid var(--color-cta);
  border-radius: 50%;
  background: var(--color-primary);
  font-family: var(--font-heading);
  font-size: 0.8125rem;
  line-height: 1;
  color: var(--color-on-primary);
  transition: background 0.3s ease, color 0.3s ease, border-color 0.3s ease;
}

.page-about__timeline-item[open] .page-about__timeline-year {
  background: var(--color-cta);
  border-color: var(--color-cta);
  color: var(--color-primary);
}

.page-about__timeline-headline {
  flex: 1;
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
}

.page-about__timeline-headline strong {
  font-family: var(--font-heading);
  font-size: 1.125rem;
  line-height: 1.25;
  color: #fff;
}

.page-about__timeline-teaser {
  font-size: 0.9375rem;
  color: rgba(232, 238, 249, 0.7);
}

.page-about__timeline-toggle {
  margin-left: auto;
  font-family: var(--font-body);
  font-size: 1.25rem;
  font-weight: 500;
  color: var(--color-accent);
  line-height: 1;
  transition: transform 0.3s ease, color 0.3s ease;
}

.page-about__timeline-item[open] .page-about__timeline-toggle {
  transform: rotate(45deg);
  color: var(--color-cta);
}

.page-about__timeline-body {
  padding: 0 1.5rem 1.25rem 0;
}

.page-about__timeline-body p {
  margin-bottom: 1rem;
  font-size: 0.9375rem;
  line-height: 1.7;
  color: rgba(232, 238, 249, 0.82);
}

.page-about__timeline-body .entry-link {
  color: var(--color-accent);
}

.page-about__milestone-figure {
  position: relative;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  margin: 3.5rem 0 0;
  border: 1px solid rgba(232, 238, 249, 0.2);
  border-radius: var(--radius);
  background: #0E2A55;
}

.page-about__milestone-figure img,
.page-about__principles-figure img,
.page-about__closing-figure img {
  display: block;
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.page-about__figcaption {
  margin-top: 0.75rem;
  padding-left: 1rem;
  border-left: 2px solid var(--color-cta);
  font-size: 0.8125rem;
  color: rgba(232, 238, 249, 0.6);
}

.page-about__milestone-figure .page-about__figcaption {
  position: absolute;
  right: 1rem;
  bottom: 1rem;
  left: auto;
  margin: 0;
  padding: 0.4rem 0.75rem;
  border-left: none;
  background: rgba(11, 27, 61, 0.72);
  color: var(--color-on-primary);
  border-radius: 0 0.25rem 0.25rem 0;
  backdrop-filter: blur(4px);
}

/* ===== 服务原则 ===== */
.page-about__principles {
  padding: 5.5rem 0 6rem;
  background: var(--color-surface);
}

.page-about__principles-grid {
  display: grid;
  gap: 1.5rem;
  margin-top: 3rem;
}

.page-about__principle {
  padding: 1.75rem 1.75rem 2rem;
  border: 1px solid var(--color-border);
  border-top: 3px solid var(--color-cta);
  border-radius: var(--radius);
  background: #fff;
  box-shadow: var(--shadow-sm);
  transition: border-color 0.3s ease, box-shadow 0.3s ease, transform 0.3s ease;
}

.page-about__principle:hover {
  border-top-color: var(--color-accent);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.page-about__principle-title {
  margin-bottom: 0.875rem;
  font-family: var(--font-heading);
  font-size: 1.5rem;
  letter-spacing: 0.04em;
  text-transform: uppercase;
  color: var(--color-primary);
}

.page-about__principle-text {
  margin: 0;
  font-size: 1rem;
  line-height: 1.7;
  color: var(--color-muted);
}

.page-about__data-band {
  display: grid;
  gap: 2rem;
  align-items: center;
  margin-top: 3.5rem;
  padding: 2rem;
  border-radius: var(--radius);
  background: var(--color-primary);
  color: var(--color-on-primary);
}

.page-about__stats {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 2rem 1.5rem;
}

.page-about__stats .stat-item__num {
  display: block;
  font-family: var(--font-heading);
  font-size: clamp(2.25rem, 4vw, 3.5rem);
  line-height: 1;
  color: var(--color-status);
  transition: transform 0.5s ease;
}

.page-about__stats .stat-item__label {
  display: block;
  margin-top: 0.5rem;
  font-size: 0.875rem;
  color: rgba(232, 238, 249, 0.75);
}

.page-about__data-band[data-visible="true"] .page-about__stats .stat-item__num {
  transform: scale(1.05);
}

.page-about__principles-figure {
  aspect-ratio: 16 / 9;
  overflow: hidden;
  margin: 0;
  border: 1px solid rgba(232, 238, 249, 0.2);
  border-radius: var(--radius);
  background: #0E2A55;
}

/* ===== 平台理念 ===== */
.page-about__philosophy {
  position: relative;
  padding: 5.5rem 0 6rem;
  background:
    radial-gradient(circle at 10% 30%, rgba(155, 89, 182, 0.16), transparent 42%),
    var(--color-primary);
  color: var(--color-on-primary);
}

.page-about__philosophy-grid {
  display: grid;
  gap: 1.5rem;
  margin-top: 3rem;
}

.page-about__philosophy-card {
  position: relative;
  padding: 2rem 1.75rem;
  border: 1px solid rgba(232, 238, 249, 0.16);
  border-radius: var(--radius);
  background: rgba(11, 27, 61, 0.55);
  transition: border-color 0.3s ease, background 0.3s ease, transform 0.3s ease;
}

.page-about__philosophy-card:hover {
  border-color: var(--color-accent);
  background: rgba(0, 212, 255, 0.04);
  transform: translateY(-2px);
}

.page-about__philosophy-num {
  display: block;
  margin-bottom: 1.5rem;
  font-family: var(--font-heading);
  font-size: 3rem;
  line-height: 1;
  color: var(--color-cta);
  opacity: 0.9;
}

.page-about__philosophy-title {
  margin-bottom: 0.75rem;
  font-family: var(--page-serif);
  font-size: 1.5rem;
  font-style: italic;
  font-weight: 700;
  color: #fff;
}

.page-about__philosophy-card p {
  margin: 0;
  font-size: 0.9375rem;
  line-height: 1.7;
  color: rgba(232, 238, 249, 0.78);
}

.page-about__philosophy-note {
  margin-top: 3rem;
  color: rgba(232, 238, 249, 0.86);
}

/* ===== 收尾 ===== */
.page-about__closing {
  padding: 5.5rem 0 6rem;
  background: var(--color-surface);
}

.page-about__closing-grid {
  display: grid;
  gap: 2.5rem;
  align-items: center;
}

.page-about__closing-figure {
  aspect-ratio: 16 / 10;
  overflow: hidden;
  margin: 0;
  border-radius: calc(var(--radius) * 1.5);
  background: var(--color-primary);
}

.page-about__closing-body {
  max-width: 36rem;
}

.page-about__closing-body .section-label {
  color: var(--color-primary);
}

.page-about__closing-title {
  margin: 1rem 0 1.5rem;
  font-family: var(--page-serif);
  font-size: clamp(1.75rem, 3vw, 2.5rem);
  font-style: italic;
  line-height: 1.2;
  color: var(--color-primary);
}

.page-about__closing-text {
  margin-bottom: 2rem;
  font-size: 1rem;
  line-height: 1.75;
  color: var(--color-muted);
}

.page-about__closing-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 1rem;
}

/* ===== 响应式 ===== */
@media (min-width: 768px) {
  .page-about__hero {
    padding-top: calc(var(--header-h) + 4rem);
    padding-bottom: 6rem;
  }

  .page-about__origin-grid {
    gap: 3rem;
  }

  .page-about__principles-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .page-about__data-band {
    grid-template-columns: 1fr 1.3fr;
    gap: 2.5rem;
    padding: 2.5rem;
  }

  .page-about__stats {
    align-content: center;
  }

  .page-about__philosophy-grid {
    grid-template-columns: repeat(3, 1fr);
  }

  .page-about__closing-grid {
    grid-template-columns: 1fr 1fr;
    gap: 3.5rem;
  }
}

@media (min-width: 1024px) {
  .page-about__hero-container {
    padding-left: 0;
  }

  .page-about__legend {
    margin-bottom: 0.5rem;
  }

  .page-about__track {
    display: block;
    position: relative;
    height: 3rem;
    margin: 1.5rem 0 2.5rem;
  }

  .page-about__track-line {
    position: absolute;
    top: 0.5rem;
    left: 0;
    right: 0;
    height: 2px;
    background: linear-gradient(90deg, var(--color-cta), var(--color-accent));
  }

  .page-about__track-marker {
    position: absolute;
    top: 0;
    left: var(--offset);
    transform: translateX(-50%);
    font-family: var(--font-mono);
    font-size: 0.8125rem;
    color: rgba(232, 238, 249, 0.75);
    text-align: center;
  }

  .page-about__track-marker::before {
    content: "";
    display: block;
    width: 0.75rem;
    height: 0.75rem;
    margin: 0 auto 0.4rem;
    border: 2px solid var(--color-primary);
    border-radius: 50%;
    background: var(--color-cta);
    box-shadow: 0 0 0 2px var(--color-cta);
  }

  .page-about__timeline {
    margin-top: 2rem;
  }

  .page-about__timeline-toggle {
    font-size: 1.375rem;
  }

  .page-about__origin-grid {
    grid-template-columns: minmax(0, 2fr) minmax(0, 1fr);
    gap: 4rem;
  }

  .page-about__milestone-figure {
    margin-top: 4.5rem;
  }

  .page-about__closing-grid {
    gap: 5rem;
  }
}

.page-about {
  --offset: 1rem;
}