.page-about {
  --about-content-max: 820px;
  --about-timeline-color: var(--primary-green);
  --about-accent: var(--accent-orange);
  --about-gap: 2rem;
  --about-section-spacing: 5rem;
  display: block;
  width: 100%;
  max-width: 100%;
  background-color: var(--surface-dark);
  color: var(--text-primary);
  font-family: var(--font-body);
  line-height: 1.7;
  padding: 0 1rem 3rem;
  box-sizing: border-box;
}
.page-about *,
.page-about *::before,
.page-about *::after {
  box-sizing: border-box;
}

/* ── 面包屑 ── */
.about-breadcrumb {
  max-width: var(--container-max);
  margin: 0 auto 1.5rem;
  padding: 1.25rem 0 0;
  font-size: 0.85rem;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}
.about-breadcrumb a {
  color: var(--primary-green);
  text-decoration: none;
  transition: color 0.25s;
}
.about-breadcrumb a:hover {
  color: var(--accent-orange);
}
.about-breadcrumb-sep {
  color: var(--text-secondary);
  font-size: 0.75rem;
}
.about-breadcrumb [aria-current="page"] {
  color: var(--text-primary);
  font-weight: 500;
}

/* ── Hero 框景 ── */
.about-hero {
  max-width: var(--container-max);
  margin: 0 auto var(--about-section-spacing);
  position: relative;
  padding: 2.5rem 1.5rem;
  border: 1px solid var(--border-light);
  border-left: 4px solid var(--primary-green);
  background: linear-gradient(135deg, rgba(11,26,46,0.9) 0%, rgba(18,18,18,0.95) 100%);
  overflow: hidden;
}
.about-hero-inner {
  position: relative;
  z-index: 2;
  max-width: var(--about-content-max);
}
.about-hero-title {
  font-family: var(--font-heading);
  font-weight: 900;
  font-size: clamp(2rem, 5vw, 3.2rem);
  line-height: 1.15;
  color: var(--text-primary);
  margin: 0 0 0.75rem;
  letter-spacing: -0.01em;
}
.about-hero-desc {
  font-size: clamp(1rem, 2vw, 1.2rem);
  color: var(--text-secondary);
  max-width: 640px;
  margin: 0;
  line-height: 1.6;
}
.about-hero-scale {
  position: absolute;
  bottom: 0;
  right: 0;
  display: flex;
  gap: 6px;
  padding: 0.75rem 1rem;
  opacity: 0.25;
}
.about-hero-scale span {
  display: block;
  width: 2px;
  height: 12px;
  background: var(--primary-green);
  border-radius: 1px;
}
.about-hero-scale span:nth-child(odd) {
  height: 20px;
}
.about-hero-scale span:nth-child(3) {
  height: 28px;
}

/* ── 平台定位与理念 ── */
.about-mission {
  max-width: var(--container-max);
  margin: 0 auto var(--about-section-spacing);
  display: flex;
  flex-wrap: wrap;
  gap: 2rem;
  position: relative;
}
.about-mission-body {
  flex: 1 1 100%;
  max-width: var(--about-content-max);
}
.about-mission .section-title {
  margin-bottom: 1.5rem;
}
.about-mission-text p {
  font-size: 1rem;
  color: var(--text-secondary);
  margin: 0 0 1.25rem;
  max-width: 720px;
}
.about-mission-text p:last-child {
  margin-bottom: 0;
}
.about-mission-decoration {
  display: none;
  flex: 0 0 1px;
  background: linear-gradient(180deg, var(--primary-green) 0%, transparent 80%);
  min-height: 200px;
  align-self: stretch;
}

/* ── 核心特点 ── */
.about-features {
  max-width: var(--container-max);
  margin: 0 auto var(--about-section-spacing);
}
.about-features .section-title {
  margin-bottom: 2rem;
}
.about-features-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 1.5rem;
}
.about-feature-card {
  background: var(--surface-card);
  border: 1px solid var(--border-light);
  border-radius: 0;
  padding: 1.5rem;
  position: relative;
  transition: border-color 0.3s, transform 0.3s;
}
.about-feature-card:hover {
  border-color: var(--primary-green);
  transform: translateY(-4px);
}
.about-feature-icon {
  color: var(--primary-green);
  margin-bottom: 0.75rem;
  width: 40px;
  height: 40px;
}
.about-feature-title {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.2rem;
  color: var(--text-primary);
  margin: 0 0 0.5rem;
}
.about-feature-desc {
  font-size: 0.92rem;
  color: var(--text-secondary);
  margin: 0 0 1rem;
  line-height: 1.6;
}
.about-feature-visual {
  margin-top: 0.75rem;
}
.about-feature-visual img {
  max-width: 100%;
  height: auto;
  display: block;
  border: 1px solid var(--border-light);
}
.about-feature-main-img {
  width: 100%;
  max-width: 400px;
  height: auto;
  object-fit: cover;
}
.about-feature-visual img[src*="h:200w:200"] {
  width: 200px;
  height: auto;
  max-width: 100%;
  object-fit: contain;
}

/* ── 技术升级历程 ── */
.about-timeline-section {
  max-width: var(--container-max);
  margin: 0 auto var(--about-section-spacing);
  position: relative;
}
.about-timeline-section .section-title {
  margin-bottom: 2.5rem;
}
.about-timeline {
  position: relative;
  padding-left: 2rem;
  max-width: var(--about-content-max);
}
.about-timeline::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0;
  bottom: 0;
  width: 2px;
  background: linear-gradient(180deg, var(--primary-green) 0%, var(--accent-orange) 100%);
  opacity: 0.5;
}
.about-timeline-item {
  position: relative;
  padding: 0 0 2.5rem 1.5rem;
}
.about-timeline-item:last-child {
  padding-bottom: 0;
}
.about-timeline-marker {
  position: absolute;
  left: -2rem;
  top: 0.35rem;
  width: 14px;
  height: 14px;
  border-radius: 50%;
  background: var(--surface-dark);
  border: 2px solid var(--primary-green);
  z-index: 2;
  transition: background 0.3s, transform 0.3s;
}
.about-timeline-item:hover .about-timeline-marker {
  background: var(--accent-orange);
  border-color: var(--accent-orange);
  transform: scale(1.3);
}
.about-timeline-title {
  font-family: var(--font-heading);
  font-weight: 700;
  font-size: 1.1rem;
  color: var(--text-primary);
  margin: 0 0 0.25rem;
}
.about-timeline-summary {
  font-size: 0.92rem;
  color: var(--text-secondary);
  margin: 0 0 0.35rem;
  line-height: 1.5;
}
.about-timeline-detail {
  font-size: 0.85rem;
  color: var(--text-secondary);
  line-height: 1.6;
  opacity: 0;
  max-height: 0;
  overflow: hidden;
  transition: opacity 0.4s ease, max-height 0.5s ease;
  border-left: 2px solid var(--border-light);
  padding-left: 0.75rem;
}
.about-timeline-item:hover .about-timeline-detail {
  opacity: 1;
  max-height: 200px;
}
.about-timeline-image {
  margin-top: 2.5rem;
  max-width: var(--about-content-max);
}
.about-timeline-image img {
  max-width: 100%;
  height: auto;
  display: block;
  border: 1px solid var(--border-light);
  object-fit: cover;
}

/* ── 底部引导 ── */
.about-cta {
  max-width: var(--container-max);
  margin: 0 auto;
  padding: 2rem 0 0;
  border-top: 1px solid var(--border-light);
}
.about-cta-text {
  font-size: 1rem;
  color: var(--text-secondary);
  margin: 0;
  line-height: 1.8;
}
.about-cta-text a {
  color: var(--primary-green);
  text-decoration: underline;
  text-underline-offset: 3px;
  transition: color 0.25s;
}
.about-cta-text a:hover {
  color: var(--accent-orange);
}

/* ── data-reveal 动画 ── */
.page-about [data-reveal] {
  opacity: 0;
  transform: translateY(24px);
  transition: opacity 0.6s ease-out, transform 0.6s ease-out;
}
.page-about [data-reveal].visible {
  opacity: 1;
  transform: translateY(0);
}
.page-about [data-reveal="fade-in"] {
  transform: translateY(0);
  opacity: 0;
}
.page-about [data-reveal="fade-in"].visible {
  opacity: 1;
}

/* ── 响应式：桌面端 ── */
@media (min-width: 768px) {
  .page-about {
    padding: 0 2rem 4rem;
  }
  .about-hero {
    padding: 4rem 3rem;
  }
  .about-hero-title {
    font-size: 3.2rem;
  }
  .about-mission {
    flex-wrap: nowrap;
    gap: 3rem;
  }
  .about-mission-body {
    flex: 1 1 60%;
  }
  .about-mission-decoration {
    display: block;
    flex: 0 0 2px;
    min-height: 280px;
  }
  .about-features-grid {
    grid-template-columns: repeat(3, 1fr);
    gap: 1.5rem;
  }
  .about-feature-card {
    padding: 1.75rem;
  }
  .about-timeline {
    padding-left: 3rem;
  }
  .about-timeline-item {
    padding: 0 0 2.5rem 2rem;
  }
  .about-timeline-marker {
    left: -3rem;
    width: 16px;
    height: 16px;
  }
  .about-timeline-detail {
    opacity: 0;
    max-height: 0;
  }
  .about-timeline-item:hover .about-timeline-detail {
    opacity: 1;
    max-height: 160px;
  }
  .about-timeline-image {
    margin-top: 3rem;
  }
  .about-cta {
    padding: 2.5rem 0 0;
  }
}

@media (min-width: 1024px) {
  .about-hero {
    padding: 5rem 4rem;
  }
  .about-features-grid {
    gap: 2rem;
  }
  .about-timeline-section {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 3rem;
    align-items: start;
  }
  .about-timeline-section .section-title {
    grid-column: 1 / -1;
  }
  .about-timeline {
    max-width: 100%;
  }
  .about-timeline-image {
    margin-top: 0;
    position: sticky;
    top: calc(var(--header-height) + 2rem);
  }
}

/* ── reduced-motion 兼容 ── */
@media (prefers-reduced-motion: reduce) {
  .page-about [data-reveal] {
    opacity: 1 !important;
    transform: none !important;
    transition: none !important;
  }
  .about-feature-card,
  .about-timeline-marker,
  .about-timeline-detail {
    transition: none !important;
  }
  .about-timeline-detail {
    opacity: 1;
    max-height: none;
  }
}

/* ── 窄屏保障 ── */
@media (max-width: 480px) {
  .about-hero {
    padding: 1.75rem 1rem;
  }
  .about-feature-card {
    padding: 1.25rem;
  }
  .about-timeline-item {
    padding-left: 1rem;
  }
  .about-timeline {
    padding-left: 1.5rem;
  }
  .about-timeline-marker {
    left: -1.5rem;
    width: 12px;
    height: 12px;
  }
}