.page-about {
  --about-bg: var(--c-dark);
  --about-surface: var(--c-light);
  --about-accent: var(--c-primary);
  --about-accent-soft: #E63946;
  --about-mono: var(--font-mono);
  --about-body: var(--font-body);
  --about-head: var(--font-head);
  --about-max-width: 1200px;
  --about-gap: 1.5rem;
  --about-line-color: rgba(192,192,192,0.3);
}

/* 首屏区 */
.page-about .about-hero {
  position: relative;
  overflow: hidden;
  min-height: 40vh;
  display: flex;
  align-items: flex-end;
  padding: 2rem 1rem;
  background: var(--gradient-dark);
  color: var(--c-light);
}

.page-about .about-hero-bg {
  position: absolute;
  inset: 0;
  z-index: 0;
  opacity: 0.12;
}

.page-about .bg-grid {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.page-about .about-hero-content {
  position: relative;
  z-index: 1;
  max-width: var(--about-max-width);
  width: 100%;
  margin: 0 auto;
}

.page-about .about-breadcrumb {
  font-family: var(--about-body);
  font-size: var(--scale-small);
  margin-bottom: 0.5rem;
}

.page-about .about-breadcrumb a {
  color: var(--c-secondary);
  text-decoration: none;
  transition: color 0.2s;
}

.page-about .about-breadcrumb a:hover,
.page-about .about-breadcrumb a:focus {
  color: var(--c-accent);
}

.page-about .about-hero-heading {
  font-family: var(--about-head);
  font-size: clamp(1.8rem, 5vw, 2.5rem);
  font-weight: 700;
  line-height: 1.15;
  margin: 0 0 0.5rem;
  color: var(--c-light);
}

.page-about .about-hero-sub {
  font-family: var(--about-body);
  font-size: var(--scale-body);
  max-width: 640px;
  color: var(--c-secondary);
  line-height: 1.6;
}

/* 时间轴 */
.page-about .about-timeline {
  padding: 3rem 1rem 4rem;
  background: var(--c-light);
}

.page-about .timeline-container {
  max-width: var(--about-max-width);
  margin: 0 auto;
}

.page-about .timeline-title {
  font-family: var(--about-head);
  font-size: var(--scale-h2);
  color: var(--c-dark);
  margin: 0 0 2rem;
  padding-left: 0;
  border-left: 4px solid var(--c-primary);
  padding-left: 1rem;
}

.page-about .timeline-wrapper {
  position: relative;
  padding-left: 1rem;
}

.page-about .timeline-line {
  position: absolute;
  left: 0.5rem;
  top: 0;
  bottom: 0;
  width: 2px;
  background: var(--about-line-color);
}

.page-about .timeline-entry {
  position: relative;
  padding: 0 0 2rem 2.5rem;
}

.page-about .timeline-entry:last-child {
  padding-bottom: 0;
}

.page-about .timeline-marker {
  position: absolute;
  left: -0.75rem;
  top: 0;
  width: 2.2rem;
  height: 2.2rem;
  border-radius: 0;
  background: var(--c-primary);
  color: var(--c-light);
  font-family: var(--about-mono);
  font-size: 0.75rem;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 600;
  z-index: 1;
}

.page-about .timeline-card {
  background: var(--c-light);
  border-left: 3px solid var(--c-secondary);
  padding: 1rem 1.25rem;
  box-shadow: 0 1px 4px rgba(0,0,0,0.06);
}

.page-about .timeline-card-heading {
  font-family: var(--about-head);
  font-size: var(--scale-h3);
  margin: 0 0 0.5rem;
  color: var(--c-dark);
}

.page-about .timeline-card p {
  font-family: var(--about-body);
  font-size: var(--scale-body);
  color: #333;
  line-height: 1.6;
  margin: 0;
}

/* 版本对比区 */
.page-about .about-compare {
  padding: 3rem 1rem 4rem;
  background: var(--c-dark);
  color: var(--c-light);
}

.page-about .compare-container {
  max-width: var(--about-max-width);
  margin: 0 auto;
}

.page-about .compare-title {
  font-family: var(--about-head);
  font-size: var(--scale-h2);
  margin: 0 0 2rem;
  border-left: 4px solid var(--c-primary);
  padding-left: 1rem;
}

.page-about .compare-visual {
  position: relative;
  width: 100%;
  max-width: 800px;
  margin: 0 auto 2rem;
  cursor: pointer;
  overflow: hidden;
}

.page-about .compare-img {
  width: 100%;
  height: auto;
  display: block;
  object-fit: cover;
}

.page-about .compare-overlay {
  position: absolute;
  bottom: 0;
  left: 0;
  right: 0;
  display: flex;
  justify-content: space-between;
  padding: 0.5rem 1rem;
  background: rgba(43,45,66,0.7);
  font-family: var(--about-mono);
  font-size: 0.75rem;
  pointer-events: none;
}

.page-about .compare-label {
  padding: 0.25rem 0.5rem;
  background: var(--c-primary);
  color: var(--c-light);
}

.page-about .compare-label.old {
  background: #666;
}

.page-about .compare-table-wrapper {
  overflow-x: auto;
  margin: 0 auto;
  max-width: 800px;
}

.page-about .compare-table {
  width: 100%;
  border-collapse: collapse;
  font-family: var(--about-body);
  font-size: var(--scale-small);
  background: var(--c-dark);
}

.page-about .compare-table caption {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
}

.page-about .compare-table th,
.page-about .compare-table td {
  padding: 0.75rem 1rem;
  text-align: left;
  border-bottom: 1px solid rgba(192,192,192,0.2);
}

.page-about .compare-table th {
  font-family: var(--about-head);
  background: var(--gradient-red);
  color: var(--c-light);
  font-weight: 600;
}

.page-about .compare-table td {
  color: var(--c-light);
}

.page-about .compare-table tbody tr:hover {
  background: rgba(57,255,20,0.08);
}

/* 技术亮点区 */
.page-about .about-tech {
  padding: 3rem 1rem 4rem;
  background: var(--c-light);
}

.page-about .tech-container {
  max-width: var(--about-max-width);
  margin: 0 auto;
}

.page-about .tech-title {
  font-family: var(--about-head);
  font-size: var(--scale-h2);
  color: var(--c-dark);
  margin: 0 0 2rem;
  border-left: 4px solid var(--c-primary);
  padding-left: 1rem;
}

.page-about .tech-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: var(--about-gap);
  margin-bottom: 2.5rem;
}

.page-about .tech-card {
  background: var(--c-light);
  border: 1px solid var(--c-secondary);
  padding: 1.5rem;
  transition: box-shadow 0.2s, transform 0.2s;
}

.page-about .tech-card:hover,
.page-about .tech-card:focus-within {
  box-shadow: 0 4px 12px rgba(0,0,0,0.1);
  transform: translateY(-2px);
}

.page-about .tech-card-icon {
  color: var(--c-primary);
  margin-bottom: 0.75rem;
}

.page-about .tech-card-heading {
  font-family: var(--about-head);
  font-size: var(--scale-h3);
  margin: 0 0 0.5rem;
  color: var(--c-dark);
}

.page-about .tech-card p {
  font-family: var(--about-body);
  font-size: var(--scale-body);
  color: #444;
  line-height: 1.5;
  margin: 0;
}

.page-about .tech-image {
  max-width: 600px;
  margin: 0 auto;
}

.page-about .tech-image img {
  width: 100%;
  height: auto;
  display: block;
  object-fit: cover;
  border: 1px solid var(--c-secondary);
}

/* 承诺区 */
.page-about .about-commit {
  padding: 3rem 1rem 4rem;
  background: var(--c-dark);
  color: var(--c-light);
}

.page-about .commit-container {
  max-width: var(--about-max-width);
  margin: 0 auto;
}

.page-about .commit-title {
  font-family: var(--about-head);
  font-size: var(--scale-h2);
  margin: 0 0 1.5rem;
  border-left: 4px solid var(--c-primary);
  padding-left: 1rem;
}

.page-about .commit-text {
  font-family: var(--about-body);
  font-size: var(--scale-body);
  line-height: 1.7;
  max-width: 720px;
  margin-bottom: 1.5rem;
}

.page-about .commit-list {
  list-style: none;
  padding: 0;
  font-family: var(--about-mono);
  font-size: var(--scale-small);
}

.page-about .commit-list li {
  margin-bottom: 0.5rem;
}

.page-about .commit-list a {
  color: var(--c-accent);
  text-decoration: underline;
}

.page-about .commit-list a:hover,
.page-about .commit-list a:focus {
  color: var(--c-primary);
}

/* 工具类 */
.page-about .sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  overflow: hidden;
  clip: rect(0,0,0,0);
  white-space: nowrap;
}

/* 桌面端 */
@media (min-width: 768px) {
  .page-about .about-hero {
    padding: 3rem 2rem;
    min-height: 50vh;
  }

  .page-about .timeline-wrapper {
    padding-left: 2rem;
  }

  .page-about .timeline-line {
    left: 1.5rem;
  }

  .page-about .timeline-marker {
    left: -0.25rem;
    width: 2.8rem;
    height: 2.8rem;
    font-size: 0.875rem;
  }

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

  .page-about .compare-visual,
  .page-about .compare-table-wrapper {
    max-width: 800px;
  }
}