.page-about {
  --about-num: 20px;
  scroll-behavior: smooth;
}

.page-about a[href^="#"] {
  scroll-margin-top: calc(var(--header-h) + 28px);
}

.page-about__wrap {
  padding-top: var(--space-sm);
  padding-bottom: var(--space-xl);
}

.page-about .breadcrumb {
  margin-bottom: var(--space-md);
}

.page-about__layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-md);
  align-items: start;
}

.page-about__body {
  min-width: 0;
}

/* 目录侧栏 */
.page-about__rail {
  min-width: 0;
}

.page-about__rail-inner {
  display: flex;
  align-items: center;
  gap: var(--space-sm);
  overflow-x: auto;
  padding: 12px 0;
  border-top: 1px solid rgba(201, 160, 99, 0.28);
  border-bottom: 1px solid rgba(201, 160, 99, 0.28);
  scrollbar-width: thin;
  scrollbar-color: var(--color-gold-dark) transparent;
  max-width: 100%;
}

.page-about__rail-label {
  flex: 0 0 auto;
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.2em;
  color: var(--color-gold-deep);
  white-space: nowrap;
}

.page-about__toc {
  display: flex;
  align-items: center;
  gap: var(--space-xs);
  list-style: none;
  margin: 0;
  padding: 0;
  width: max-content;
}

.page-about__toc-item {
  margin: 0;
}

.page-about__toc-link {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 6px 12px;
  border: 1px solid rgba(201, 160, 99, 0.28);
  background: rgba(201, 160, 99, 0.04);
  color: var(--color-ivory);
  font-family: var(--font-body);
  font-size: 14px;
  line-height: 1.4;
  white-space: nowrap;
  text-decoration: none;
  transition: all 0.2s var(--ease-out);
}

.page-about__toc-link:hover,
.page-about__toc-link:focus {
  border-color: var(--color-gold-light);
  color: var(--color-gold-light);
  background: rgba(201, 160, 99, 0.12);
}

.page-about__toc-num {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--color-gold-deep);
}

.page-about__rail-note {
  display: none;
  font-family: var(--font-body);
  font-size: 13px;
  color: var(--color-silver);
  white-space: nowrap;
  margin-left: auto;
}

/* 引言区 */
.page-about__hero {
  position: relative;
  padding: var(--space-md) 0 var(--space-lg);
  margin-bottom: var(--space-md);
  border-bottom: 2px solid var(--color-gold-deep);
}

.page-about__hero::before {
  content: "";
  position: absolute;
  right: 0;
  top: 0;
  width: 120px;
  height: 120px;
  background: linear-gradient(135deg, transparent 48%, rgba(201, 160, 99, 0.28) 49%, rgba(201, 160, 99, 0.28) 51%, transparent 52%);
  pointer-events: none;
}

.page-about__hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-md);
}

.page-about__hero-text h1 {
  margin: 10px 0 16px;
  font-family: var(--font-heading);
  font-size: 32px;
  font-weight: 800;
  line-height: 1.2;
  color: var(--color-ivory);
  max-width: 13em;
}

.page-about__hero-lead {
  margin: 0;
  max-width: 56em;
  font-size: 16px;
  line-height: 1.8;
  color: var(--color-silver);
}

.page-about__hero-image {
  margin: 0;
  align-self: center;
}

.page-about__img-crown {
  background: linear-gradient(135deg, rgba(201, 160, 99, 0.18), rgba(10, 10, 10, 0.6)), var(--color-gold-dark);
}

.page-about__img-crown img {
  display: block;
  width: 100%;
  height: auto;
  object-fit: cover;
  opacity: 0.88;
}

/* 章节 */
.page-about__section {
  padding: var(--space-lg) 0 var(--space-md);
  border-bottom: 1px solid rgba(201, 160, 99, 0.18);
}

.page-about__section:last-of-type {
  border-bottom: none;
}

.page-about__sec-head {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  margin-bottom: var(--space-md);
}

.page-about__sec-num {
  font-family: var(--font-mono);
  font-size: var(--about-num);
  font-weight: 700;
  line-height: 1;
  color: var(--color-gold-deep);
  padding-top: 2px;
}

.page-about__sec-head h2 {
  margin: 4px 0 4px;
  font-family: var(--font-heading);
  font-size: 26px;
  font-weight: 700;
  line-height: 1.25;
  color: var(--color-ivory);
}

.page-about__prose {
  max-width: 72ch;
}

.page-about__prose p {
  margin: 0 0 18px;
  font-size: 16px;
  line-height: 1.85;
  color: var(--color-silver);
}

.page-about__prose strong {
  color: var(--color-gold-light);
  font-weight: 600;
}

.page-about__prose a {
  color: var(--color-gold-deep);
  text-decoration: underline;
  text-underline-offset: 4px;
}

.page-about__prose a:hover,
.page-about__prose a:focus {
  color: var(--color-gold-light);
}

.page-about__quote {
  margin: var(--space-md) 0;
  padding: var(--space-md) var(--space-md) var(--space-md) 20px;
  border-left: 3px solid var(--color-gold-deep);
  background: linear-gradient(135deg, rgba(201, 160, 99, 0.12), rgba(201, 160, 99, 0.02));
  font-family: var(--font-heading);
  font-size: 18px;
  line-height: 1.6;
  color: var(--color-ivory);
}

/* 设计原则 */
.page-about__principles {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-sm);
  margin: var(--space-md) 0 0;
}

.page-about__prin {
  padding: var(--space-md) 20px;
  background: rgba(201, 160, 99, 0.04);
  border-top: 2px solid var(--color-gold-deep);
  border-right: 1px solid rgba(201, 160, 99, 0.25);
  border-bottom: 1px solid rgba(201, 160, 99, 0.25);
  transition: background 0.2s var(--ease-out);
}

.page-about__prin:hover {
  background: rgba(201, 160, 99, 0.08);
}

.page-about__prin-num {
  display: block;
  font-family: var(--font-mono);
  font-size: 28px;
  font-weight: 700;
  color: var(--color-gold-deep);
  margin-bottom: 10px;
}

.page-about__prin h3 {
  margin: 0 0 8px;
  font-family: var(--font-heading);
  font-size: 18px;
  color: var(--color-ivory);
}

.page-about__prin p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-silver);
}

/* 服务能力 */
.page-about__service-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-md);
  align-items: start;
}

.page-about__stats {
  padding: var(--space-md) 24px;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px 20px;
}

.page-about__stat-cell {
  text-align: left;
}

.page-about__stat-cell .stat-number {
  display: block;
  font-size: 34px;
  line-height: 1;
  margin-bottom: 6px;
}

.page-about__stat-cell .stat-label {
  font-size: 13px;
}

.page-about__capability-image {
  margin: 0;
}

.page-about__cap-img {
  background: rgba(140, 108, 30, 0.4);
}

.page-about__cap-img img {
  width: 100%;
  height: auto;
  object-fit: cover;
}

.page-about__prose-more {
  margin-top: var(--space-md);
}

/* 里程碑时间轴 */
.page-about__timeline {
  position: relative;
  margin: var(--space-md) 0 0;
  padding-left: 24px;
}

.page-about__timeline::before {
  content: "";
  position: absolute;
  left: 7px;
  top: 8px;
  bottom: 8px;
  width: 1px;
  background: linear-gradient(to bottom, var(--color-gold-light), var(--color-gold-deep) 60%, var(--color-gold-dark));
}

.page-about__milestone {
  position: relative;
  padding: 2px 0 26px 22px;
  margin-left: 0;
}

.page-about__milestone::before {
  content: "";
  position: absolute;
  left: -6px;
  top: 10px;
  width: 13px;
  height: 13px;
  transform: rotate(45deg);
  background: var(--color-bg);
  border: 2px solid var(--color-gold-deep);
  transition: background 0.2s var(--ease-out), border-color 0.2s var(--ease-out);
}

.page-about__milestone:hover::before,
.page-about__milestone:focus-within::before {
  background: var(--color-gold-light);
  border-color: var(--color-gold-light);
}

.page-about__milestone-ver {
  display: block;
  font-family: var(--font-mono);
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.08em;
  color: var(--color-gold-deep);
  margin-bottom: 6px;
}

.page-about__milestone h3 {
  margin: 0 0 6px;
  font-family: var(--font-heading);
  font-size: 18px;
  color: var(--color-ivory);
}

.page-about__milestone p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-silver);
  max-width: 68ch;
  transition: color 0.2s var(--ease-out);
}

.page-about__milestone:hover p {
  color: var(--color-ivory);
}

.page-about__timeline-figure {
  margin: var(--space-md) 0 0;
}

.page-about__timeline-img {
  background: rgba(140, 108, 30, 0.3);
}

.page-about__timeline-img img {
  width: 100%;
  height: auto;
  object-fit: cover;
}

/* 资质与合作 */
.page-about__qual-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: var(--space-sm);
  margin-top: var(--space-md);
}

.page-about__qual-card {
  padding: var(--space-md) 20px;
  background: rgba(10, 10, 10, 0.3);
  border: 1px solid rgba(201, 160, 99, 0.22);
  border-top: 2px solid var(--color-green);
  transition: border-color 0.2s var(--ease-out), background 0.2s var(--ease-out);
}

.page-about__qual-card:hover {
  border-color: var(--color-gold-deep);
  background: rgba(201, 160, 99, 0.06);
}

.page-about__qual-card h3 {
  margin: 12px 0 8px;
  font-family: var(--font-heading);
  font-size: 18px;
  color: var(--color-ivory);
}

.page-about__qual-card p {
  margin: 0;
  font-size: 14px;
  line-height: 1.7;
  color: var(--color-silver);
}

/* 延伸阅读 */
.page-about__more {
  margin-top: var(--space-lg);
  padding: var(--space-md);
  background: linear-gradient(135deg, rgba(201, 160, 99, 0.1), rgba(10, 10, 10, 0));
  border-top: 3px solid var(--color-gold-deep);
}

.page-about__more-heading {
  margin: 0 0 16px;
  font-family: var(--font-heading);
  font-size: 20px;
  font-weight: 700;
  color: var(--color-ivory);
}

.page-about__more-list {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
}

@media (min-width: 768px) {
  .page-about__hero h1 {
    font-size: 40px;
  }

  .page-about__hero-grid {
    grid-template-columns: minmax(0, 1.05fr) minmax(300px, 0.95fr);
  }

  .page-about__principles {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }

  .page-about__service-grid {
    grid-template-columns: minmax(0, 1fr) minmax(240px, 0.8fr);
  }

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

@media (min-width: 1024px) {
  .page-about__layout {
    grid-template-columns: 200px minmax(0, 800px);
    gap: var(--space-xl);
    justify-content: center;
  }

  .page-about__rail-inner {
    position: sticky;
    top: calc(var(--header-h) + 24px);
    flex-direction: column;
    align-items: flex-start;
    gap: 20px;
    padding: 20px 0 20px 18px;
    overflow: visible;
    border-top: none;
    border-bottom: none;
    border-left: 2px solid var(--color-gold-deep);
    background: transparent;
  }

  .page-about__toc {
    display: block;
    width: auto;
  }

  .page-about__toc-item + .page-about__toc-item {
    margin-top: 10px;
  }

  .page-about__toc-link {
    border: none;
    background: transparent;
    padding: 4px 8px;
  }

  .page-about__toc-link:hover,
  .page-about__toc-link:focus {
    border: none;
    background: rgba(201, 160, 99, 0.08);
  }

  .page-about__rail-note {
    display: block;
    margin-left: 0;
    font-size: 13px;
  }

  .page-about__section {
    padding: var(--space-xl) 0 var(--space-lg);
  }

  .page-about__more-list {
    gap: 16px;
  }
}