.page-about {
  --about-hero-bg: linear-gradient(135deg, #1B5E20 0%, #2E7D32 100%);
  --about-card-bg: #FFFFFF;
  --about-card-border: rgba(27,94,32,0.12);
  --about-card-radius: 12px;
  --about-timeline-color: #FFD700;
  --about-timeline-line: rgba(255,215,0,0.25);
  --about-icon-size: 36px;
  --about-annotation-color: rgba(255,215,0,0.5);
}

/* 面包屑 */
.page-about .breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px;
  padding: 16px var(--spacing-md) 0;
  font-family: var(--font-body);
  font-size: var(--fs-small);
  color: var(--color-text-dark);
  max-width: 1200px;
  margin: 0 auto;
}

.page-about .breadcrumb a {
  color: var(--color-deep-green);
  text-decoration: none;
  transition: color var(--transition-fast);
}

.page-about .breadcrumb a:hover,
.page-about .breadcrumb a:focus-visible {
  color: var(--color-gold);
  text-decoration: underline;
}

.page-about .breadcrumb-sep {
  color: var(--color-border);
  font-size: 18px;
  line-height: 1;
}

.page-about .breadcrumb [aria-current="page"] {
  color: var(--color-text-dark);
  font-weight: 500;
}

/* 品牌 Hero */
.page-about .brand-hero {
  background: var(--about-hero-bg);
  margin: 0 var(--spacing-md);
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl) var(--spacing-md);
  position: relative;
  overflow: hidden;
  max-width: 1200px;
  margin-left: auto;
  margin-right: auto;
}

.page-about .brand-hero::before {
  content: '';
  position: absolute;
  inset: 0;
  background: radial-gradient(circle at 80% 20%, rgba(255,215,0,0.08) 0%, transparent 60%);
  pointer-events: none;
}

.page-about .brand-hero-inner {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--spacing-md);
  position: relative;
  z-index: 1;
}

.page-about .brand-logo {
  width: 120px;
  height: 120px;
  border-radius: 50%;
  border: 3px solid var(--color-gold);
  object-fit: cover;
  background: var(--color-bg-white);
  flex-shrink: 0;
}

.page-about .brand-hero-text {
  text-align: center;
  position: relative;
}

.page-about .brand-hero-text h1 {
  font-family: var(--font-headings);
  font-size: var(--fs-h1);
  color: var(--color-white);
  margin: 0 0 4px;
  letter-spacing: 0.02em;
  text-transform: uppercase;
  line-height: 1.1;
}

.page-about .brand-tagline {
  font-family: var(--font-body);
  font-size: var(--fs-body);
  color: var(--color-gold);
  margin: 0;
  font-weight: 400;
  opacity: 0.9;
}

.page-about .brand-hero-text .annotation {
  position: absolute;
  top: -8px;
  right: -56px;
  font-family: var(--font-headings);
  font-size: var(--fs-tiny);
  color: var(--about-annotation-color);
  transform: rotate(90deg);
  transform-origin: left center;
  letter-spacing: 0.3em;
  white-space: nowrap;
  pointer-events: none;
}

/* 双栏内容区 */
.page-about .content-split {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
  padding: var(--spacing-lg) var(--spacing-md);
  max-width: 1200px;
  margin: 0 auto;
}

/* 品牌理念 */
.page-about .brand-story {
  background: var(--color-bg-white);
  border-radius: var(--radius-md);
  padding: var(--spacing-lg) var(--spacing-md);
  box-shadow: var(--shadow-card);
  border-left: 4px solid var(--color-gold);
}

.page-about .brand-story h2 {
  font-family: var(--font-headings);
  font-size: var(--fs-h2);
  color: var(--color-deep-green);
  margin: 0 0 var(--spacing-sm);
  line-height: 1.2;
  position: relative;
  display: inline-block;
}

.page-about .brand-story h2::after {
  content: '';
  display: block;
  width: 60%;
  height: 3px;
  background: var(--color-gold);
  margin-top: 4px;
  border-radius: 2px;
}

.page-about .brand-story p {
  font-family: var(--font-body);
  font-size: var(--fs-body);
  line-height: var(--lh-body);
  color: var(--color-text-dark);
  margin: 0 0 var(--spacing-sm);
}

.page-about .brand-story p:last-child {
  margin-bottom: 0;
}

.page-about .brand-story a {
  color: var(--color-deep-green);
  font-weight: 500;
  text-decoration: underline;
  text-underline-offset: 2px;
  transition: color var(--transition-fast);
}

.page-about .brand-story a:hover,
.page-about .brand-story a:focus-visible {
  color: var(--color-gold);
}

/* 核心功能 */
.page-about .core-features {
  background: var(--color-surface-light);
  border-radius: var(--radius-md);
  padding: var(--spacing-lg) var(--spacing-md);
  box-shadow: var(--shadow-card);
}

.page-about .core-features h2 {
  font-family: var(--font-headings);
  font-size: var(--fs-h2);
  color: var(--color-deep-green);
  margin: 0 0 var(--spacing-md);
  line-height: 1.2;
  position: relative;
  display: inline-block;
}

.page-about .core-features h2::after {
  content: '';
  display: block;
  width: 60%;
  height: 3px;
  background: var(--color-gold);
  margin-top: 4px;
  border-radius: 2px;
}

.page-about .feature-list {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-sm);
}

/* 功能卡片（可展开） */
.page-about .feature-card {
  background: var(--about-card-bg);
  border: 1px solid var(--about-card-border);
  border-radius: var(--about-card-radius);
  overflow: hidden;
  transition: box-shadow var(--transition-med), border-color var(--transition-med);
  list-style: none;
}

.page-about .feature-card[open] {
  box-shadow: var(--shadow-hover);
  border-color: var(--color-gold);
}

.page-about .feature-card summary {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-sm) var(--spacing-md);
  cursor: pointer;
  font-family: var(--font-body);
  font-weight: 500;
  color: var(--color-text-black);
  list-style: none;
  user-select: none;
  transition: background var(--transition-fast);
}

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

.page-about .feature-card summary:hover,
.page-about .feature-card summary:focus-visible {
  background: rgba(27,94,32,0.04);
}

.page-about .feature-icon {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: var(--about-icon-size);
  height: var(--about-icon-size);
  border-radius: 50%;
  background: var(--color-deep-green);
  color: var(--color-gold);
  font-family: var(--font-headings);
  font-size: var(--fs-small);
  font-weight: 700;
  flex-shrink: 0;
  line-height: 1;
}

.page-about .feature-title {
  flex: 1;
  font-size: var(--fs-body);
  font-weight: 600;
  color: var(--color-text-black);
}

.page-about .expand-icon {
  font-size: 20px;
  font-weight: 300;
  color: var(--color-deep-green);
  transition: transform var(--transition-med);
  line-height: 1;
  flex-shrink: 0;
}

.page-about .feature-card[open] .expand-icon {
  transform: rotate(45deg);
}

.page-about .feature-detail {
  padding: 0 var(--spacing-md) var(--spacing-sm);
  padding-left: calc(var(--spacing-md) + var(--about-icon-size) + var(--spacing-sm));
  font-family: var(--font-body);
  font-size: var(--fs-small);
  line-height: var(--lh-body);
  color: var(--color-text-dark);
  border-top: 1px solid var(--color-border);
  margin-top: 0;
  padding-top: var(--spacing-sm);
}

.page-about .feature-detail p {
  margin: 0 0 8px;
}

.page-about .feature-detail p:last-child {
  margin-bottom: 0;
}

.page-about .feature-detail a {
  color: var(--color-deep-green);
  font-weight: 500;
  text-decoration: underline;
  text-underline-offset: 2px;
}

.page-about .feature-detail a:hover {
  color: var(--color-gold);
}

/* 功能示意图 */
.page-about .features-illustration {
  display: block;
  width: 100%;
  max-width: 500px;
  height: auto;
  border-radius: var(--radius-md);
  margin: var(--spacing-md) auto 0;
  object-fit: cover;
  box-shadow: var(--shadow-card);
}

/* 版本时间线 */
.page-about .version-timeline {
  padding: var(--spacing-lg) var(--spacing-md);
  max-width: 1200px;
  margin: 0 auto;
  position: relative;
}

.page-about .version-timeline h2 {
  font-family: var(--font-headings);
  font-size: var(--fs-h2);
  color: var(--color-deep-green);
  margin: 0 0 var(--spacing-lg);
  line-height: 1.2;
  position: relative;
  display: inline-block;
}

.page-about .version-timeline h2::after {
  content: '';
  display: block;
  width: 60%;
  height: 3px;
  background: var(--color-gold);
  margin-top: 4px;
  border-radius: 2px;
}

.page-about .timeline {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  padding-left: 20px;
}

.page-about .timeline::before {
  content: '';
  position: absolute;
  left: 8px;
  top: 0;
  bottom: 0;
  width: 3px;
  background: var(--about-timeline-line);
  border-radius: 2px;
}

.page-about .timeline-node {
  position: relative;
  padding-left: var(--spacing-md);
  transition: transform var(--transition-med);
}

.page-about .timeline-node:hover {
  transform: translateX(4px);
}

.page-about .timeline-marker {
  position: absolute;
  left: -20px;
  top: 6px;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background: var(--color-deep-green);
  border: 3px solid var(--about-timeline-color);
  box-shadow: 0 0 0 3px rgba(255,215,0,0.15);
  transition: box-shadow var(--transition-med), transform var(--transition-med);
  z-index: 1;
}

.page-about .timeline-node:hover .timeline-marker,
.page-about .timeline-node:focus-within .timeline-marker {
  box-shadow: 0 0 0 6px rgba(255,215,0,0.25);
  transform: scale(1.15);
}

.page-about .timeline-content {
  background: var(--color-bg-white);
  border-radius: var(--radius-md);
  padding: var(--spacing-sm) var(--spacing-md);
  box-shadow: var(--shadow-card);
  border-left: 3px solid var(--color-gold);
  transition: box-shadow var(--transition-med);
}

.page-about .timeline-node:hover .timeline-content {
  box-shadow: var(--shadow-hover);
}

.page-about .timeline-version {
  font-family: var(--font-headings);
  font-size: var(--fs-h3);
  color: var(--color-deep-green);
  display: block;
  line-height: 1.2;
  margin-bottom: 2px;
}

.page-about .timeline-desc {
  font-family: var(--font-body);
  font-size: var(--fs-small);
  color: var(--color-text-dark);
  margin: 0;
  line-height: 1.5;
}

.page-about .timeline-bg {
  display: block;
  width: 100%;
  max-width: 800px;
  height: auto;
  border-radius: var(--radius-md);
  margin: var(--spacing-lg) auto 0;
  object-fit: cover;
  opacity: 0.6;
}

/* 支持链接 */
.page-about .support-link {
  padding: var(--spacing-md) var(--spacing-md) var(--spacing-lg);
  max-width: 1200px;
  margin: 0 auto;
  text-align: center;
  font-family: var(--font-body);
  font-size: var(--fs-small);
  color: var(--color-text-dark);
}

.page-about .support-link a {
  color: var(--color-deep-green);
  font-weight: 600;
  text-decoration: underline;
  text-underline-offset: 2px;
  transition: color var(--transition-fast);
}

.page-about .support-link a:hover {
  color: var(--color-gold);
}

/* ===== 桌面端增强 ===== */
@media (min-width: 768px) {
  .page-about .breadcrumb {
    padding-left: var(--spacing-lg);
    padding-right: var(--spacing-lg);
  }

  .page-about .brand-hero {
    padding: var(--spacing-xl) var(--spacing-lg);
  }

  .page-about .brand-hero-inner {
    flex-direction: row;
    gap: var(--spacing-lg);
  }

  .page-about .brand-logo {
    width: 160px;
    height: 160px;
  }

  .page-about .brand-hero-text {
    text-align: left;
  }

  .page-about .brand-hero-text .annotation {
    top: -12px;
    right: -64px;
    font-size: var(--fs-small);
  }

  .page-about .content-split {
    flex-direction: row;
    gap: var(--spacing-lg);
    padding-left: var(--spacing-lg);
    padding-right: var(--spacing-lg);
  }

  .page-about .brand-story {
    flex: 1.1;
    padding: var(--spacing-xl) var(--spacing-lg);
  }

  .page-about .core-features {
    flex: 0.9;
    padding: var(--spacing-xl) var(--spacing-lg);
  }

  .page-about .core-features h2,
  .page-about .brand-story h2 {
    font-size: calc(var(--fs-h2) * 0.9);
  }

  .page-about .features-illustration {
    margin-top: var(--spacing-lg);
  }

  .page-about .version-timeline {
    padding-left: var(--spacing-lg);
    padding-right: var(--spacing-lg);
  }

  .page-about .timeline {
    flex-direction: row;
    padding-left: 0;
    gap: var(--spacing-md);
    justify-content: space-between;
  }

  .page-about .timeline::before {
    left: 0;
    right: 0;
    top: 12px;
    bottom: auto;
    width: auto;
    height: 3px;
  }

  .page-about .timeline-node {
    flex: 1;
    padding-left: 0;
    padding-top: var(--spacing-lg);
    text-align: center;
  }

  .page-about .timeline-marker {
    left: 50%;
    top: 0;
    transform: translateX(-50%);
  }

  .page-about .timeline-node:hover .timeline-marker {
    transform: translateX(-50%) scale(1.15);
  }

  .page-about .timeline-content {
    text-align: left;
    padding: var(--spacing-sm) var(--spacing-md);
    min-height: 80px;
    display: flex;
    flex-direction: column;
    justify-content: center;
  }

  .page-about .timeline-version {
    font-size: calc(var(--fs-h3) * 0.85);
  }

  .page-about .timeline-bg {
    margin-top: var(--spacing-xl);
  }

  .page-about .support-link {
    padding-bottom: var(--spacing-xl);
  }
}

@media (min-width: 1024px) {
  .page-about .brand-hero {
    padding: 80px var(--spacing-xl);
  }

  .page-about .brand-logo {
    width: 200px;
    height: 200px;
  }

  .page-about .brand-hero-text h1 {
    font-size: var(--fs-h1);
  }

  .page-about .brand-story {
    padding: var(--spacing-xl);
  }

  .page-about .core-features {
    padding: var(--spacing-xl);
  }

  .page-about .content-split {
    gap: var(--spacing-xl);
  }
}