.page-about {
  --page-bg: #F5F0E8;
  --page-text: #1C1C1C;
  --page-primary: #0066CC;
  --page-primary-dark: #004499;
  --page-accent: #E63946;
  --page-highlight: #FFD166;
  --page-gray: #6B6B6B;
  --page-border: #D4C9B8;
  --page-sidebar-bg: #1C1C1C;
  --page-sidebar-text: #F5F0E8;
  --page-card-bg: #FFFFFF;
  --page-shadow: rgba(0, 0, 0, 0.06);
  --page-radius: 4px;
  --page-sidebar-width: 220px;
  --page-transition: 0.25s ease;

  display: block;
  background-color: var(--page-bg);
  color: var(--page-text);
  font-family: var(--font-primary, 'Inter', 'Noto Sans SC', sans-serif);
  line-height: 1.6;
  min-height: 100vh;
}

/* ===== 面包屑 ===== */
.page-about__breadcrumb {
  max-width: var(--content-max-width, 1200px);
  margin: 0 auto;
  padding: 16px 20px 0;
  font-size: 14px;
  color: var(--page-gray);
}
.page-about__breadcrumb .breadcrumb-link {
  color: var(--page-primary);
  text-decoration: none;
  transition: color var(--page-transition);
}
.page-about__breadcrumb .breadcrumb-link:hover,
.page-about__breadcrumb .breadcrumb-link:focus-visible {
  color: var(--page-primary-dark);
  text-decoration: underline;
}
.page-about__breadcrumb .breadcrumb-sep {
  margin: 0 6px;
  color: var(--page-border);
}
.page-about__breadcrumb [aria-current="page"] {
  color: var(--page-text);
  font-weight: 600;
}

/* ===== 时间线主容器 ===== */
.page-about__timeline {
  display: flex;
  flex-direction: column;
  max-width: var(--content-max-width, 1200px);
  margin: 0 auto;
  padding: 0 20px 40px;
}

/* ===== 侧栏 ===== */
.page-about__sidebar {
  display: none;
}

/* ===== 内容区 ===== */
.page-about__content {
  flex: 1;
  min-width: 0;
}

.page-about__main-title {
  font-family: var(--font-heading, 'Roboto Condensed', 'Noto Sans SC', sans-serif);
  font-size: 32px;
  font-weight: 700;
  line-height: 1.2;
  margin: 16px 0 32px;
  padding-bottom: 12px;
  border-bottom: 3px solid var(--page-highlight);
  position: relative;
}
.page-about__main-title::after {
  content: '';
  position: absolute;
  bottom: -3px;
  left: 0;
  width: 60px;
  height: 3px;
  background-color: var(--page-accent);
}

/* ===== 通用区块 ===== */
.page-about__section {
  margin-bottom: 48px;
  padding: 0;
}
.page-about__section-heading {
  font-family: var(--font-heading, 'Roboto Condensed', 'Noto Sans SC', sans-serif);
  font-size: 24px;
  font-weight: 700;
  line-height: 1.3;
  margin: 0 0 20px;
  color: var(--page-text);
  display: flex;
  align-items: center;
  gap: 12px;
}
.page-about__section-heading::before {
  content: '';
  display: inline-block;
  width: 6px;
  height: 24px;
  background: linear-gradient(180deg, var(--page-primary), var(--page-accent));
  border-radius: 3px;
  flex-shrink: 0;
}

/* ===== 品牌故事 ===== */
.page-about__section--story {
  display: flex;
  flex-direction: column;
  gap: 24px;
  background: var(--page-card-bg);
  border: 1px solid var(--page-border);
  border-radius: var(--page-radius);
  padding: 24px 20px;
  box-shadow: 0 2px 8px var(--page-shadow);
  position: relative;
  overflow: hidden;
}
.page-about__section--story::before {
  content: '';
  position: absolute;
  top: 0;
  right: 0;
  width: 120px;
  height: 120px;
  background: linear-gradient(135deg, transparent 50%, rgba(0,102,204,0.06) 50%);
  pointer-events: none;
}
.page-about__story-text {
  flex: 1;
}
.page-about__body-text {
  font-size: 16px;
  margin: 0 0 12px;
  max-width: 600px;
}
.page-about__emph {
  color: var(--page-primary);
  font-weight: 700;
}
.page-about__story-link {
  margin-top: 8px;
}
.page-about__story-image {
  flex-shrink: 0;
}
.page-about__img {
  display: block;
  max-width: 100%;
  height: auto;
  border-radius: var(--page-radius);
  border: 1px solid var(--page-border);
  background-color: #EDE8DD;
  object-fit: cover;
}

/* ===== 核心功能 ===== */
.page-about__section--features {
  padding: 0;
}
.page-about__features-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 20px;
}
.page-about__feature-card {
  background: var(--page-card-bg);
  border: 1px solid var(--page-border);
  border-radius: var(--page-radius);
  padding: 20px 16px;
  transition: box-shadow var(--page-transition), transform var(--page-transition);
  position: relative;
  overflow: hidden;
}
.page-about__feature-card:hover,
.page-about__feature-card:focus-within {
  box-shadow: 0 4px 16px rgba(0,102,204,0.12);
  transform: translateY(-2px);
  border-color: var(--page-primary);
}
.page-about__feature-icon {
  margin-bottom: 12px;
  width: 40px;
  height: 40px;
  transition: transform var(--page-transition);
}
.page-about__feature-card:hover .page-about__feature-icon,
.page-about__feature-card:focus-within .page-about__feature-icon {
  transform: scale(1.08);
}
.page-about__feature-icon svg rect,
.page-about__feature-icon svg circle,
.page-about__feature-icon svg path {
  transition: stroke var(--page-transition), fill var(--page-transition);
}
.page-about__feature-card:hover .page-about__feature-icon svg circle[fill] {
  fill: var(--page-accent);
}
.page-about__feature-card:hover .page-about__feature-icon svg line {
  stroke: var(--page-primary-dark);
}
.page-about__feature-title {
  font-family: var(--font-heading, 'Roboto Condensed', 'Noto Sans SC', sans-serif);
  font-size: 18px;
  font-weight: 700;
  margin: 0 0 6px;
  color: var(--page-text);
}
.page-about__feature-desc {
  font-size: 15px;
  color: var(--page-gray);
  margin: 0 0 12px;
  line-height: 1.5;
}
.page-about__feature-img-wrapper {
  margin-top: 8px;
  border-radius: var(--page-radius);
  overflow: hidden;
  background-color: #EDE8DD;
}
.page-about__img--feature {
  width: 100%;
  height: auto;
  display: block;
  border: none;
  border-radius: 0;
}
.page-about__features-cta {
  margin-top: 24px;
  text-align: center;
}

/* ===== 联系方式摘要 ===== */
.page-about__section--contact {
  padding: 0;
}
.page-about__contact-card {
  background: var(--page-card-bg);
  border: 1px solid var(--page-border);
  border-radius: var(--page-radius);
  padding: 24px 20px;
  box-shadow: 0 2px 8px var(--page-shadow);
  max-width: 520px;
}
.page-about__contact-item {
  display: flex;
  flex-direction: column;
  gap: 2px;
  margin-bottom: 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--page-border);
}
.page-about__contact-label {
  font-size: 12px;
  color: var(--page-gray);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}
.page-about__contact-value {
  font-size: 18px;
  font-weight: 600;
  color: var(--page-text);
  word-break: break-all;
}
.page-about__contact-note {
  background: rgba(0,102,204,0.04);
  border-left: 3px solid var(--page-primary);
  padding: 12px 16px;
  margin-bottom: 16px;
  border-radius: 0 var(--page-radius) var(--page-radius) 0;
}
.page-about__contact-note .mono {
  display: block;
  font-size: 12px;
  color: var(--page-primary);
  margin-bottom: 4px;
}
.page-about__contact-note p {
  font-size: 14px;
  margin: 0;
  color: var(--page-gray);
}
.page-about__contact-link {
  display: inline-block;
}

/* ===== 页内底部 ===== */
.page-about__inline-footer {
  margin-top: 32px;
  padding-top: 16px;
  border-top: 1px solid var(--page-border);
  text-align: center;
}
.page-about__inline-footer p {
  margin: 0;
  color: var(--page-gray);
}

/* ===== 工具类复用 ===== */
.page-about .mono {
  font-family: var(--font-mono, 'JetBrains Mono', monospace);
  letter-spacing: 0.02em;
}
.page-about .text-small {
  font-size: 14px;
}
.page-about .btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 10px 24px;
  font-family: var(--font-primary, 'Inter', 'Noto Sans SC', sans-serif);
  font-size: 15px;
  font-weight: 600;
  line-height: 1.4;
  border-radius: var(--page-radius);
  text-decoration: none;
  cursor: pointer;
  transition: background-color var(--page-transition), color var(--page-transition), border-color var(--page-transition), box-shadow var(--page-transition);
  border: 2px solid transparent;
  min-height: 44px;
}
.page-about .btn--outline {
  background: transparent;
  color: var(--page-primary);
  border-color: var(--page-primary);
}
.page-about .btn--outline:hover,
.page-about .btn--outline:focus-visible {
  background: var(--page-primary);
  color: #FFFFFF;
}
.page-about .btn--primary {
  background: var(--page-primary);
  color: #FFFFFF;
  border-color: var(--page-primary);
}
.page-about .btn--primary:hover,
.page-about .btn--primary:focus-visible {
  background: var(--page-primary-dark);
  border-color: var(--page-primary-dark);
  box-shadow: 0 2px 8px rgba(0,102,204,0.3);
}

/* ===== 桌面端样式（≥768px） ===== */
@media (min-width: 768px) {
  .page-about__breadcrumb {
    padding: 20px 24px 0;
  }
  .page-about__timeline {
    flex-direction: row;
    padding: 0 24px 60px;
    gap: 32px;
  }
  .page-about__sidebar {
    display: flex;
    flex-direction: column;
    width: var(--page-sidebar-width);
    min-width: var(--page-sidebar-width);
    position: sticky;
    top: 24px;
    align-self: flex-start;
    max-height: calc(100vh - 48px);
    overflow-y: auto;
    background: var(--page-sidebar-bg);
    border-radius: var(--page-radius);
    padding: 28px 16px 20px;
    color: var(--page-sidebar-text);
    box-shadow: 0 4px 20px rgba(0,0,0,0.12);
  }
  .page-about__sidebar-brand {
    display: flex;
    flex-direction: column;
    gap: 2px;
    margin-bottom: 24px;
    padding-bottom: 16px;
    border-bottom: 2px solid var(--page-highlight);
  }
  .page-about__brand-label {
    font-size: 11px;
    color: rgba(245,240,232,0.6);
    letter-spacing: 0.12em;
    text-transform: uppercase;
  }
  .page-about__brand-code {
    font-size: 20px;
    font-weight: 700;
    color: var(--page-highlight);
  }
  .page-about__sidebar-keywords {
    list-style: none;
    margin: 0 0 28px;
    padding: 0;
    display: flex;
    flex-direction: column;
    gap: 8px;
  }
  .page-about__sidebar-keywords li {
    font-size: 13px;
    color: rgba(245,240,232,0.8);
    padding: 4px 0 4px 12px;
    border-left: 2px solid transparent;
    transition: border-color var(--page-transition), color var(--page-transition);
  }
  .page-about__sidebar-keywords li:hover {
    border-left-color: var(--page-highlight);
    color: var(--page-sidebar-text);
  }
  .page-about__sidebar-dots {
    display: flex;
    flex-direction: column;
    align-items: flex-start;
    gap: 16px;
    margin-bottom: auto;
    padding: 12px 0;
  }
  .page-about__dot {
    display: block;
    width: 10px;
    height: 10px;
    border-radius: 50%;
    background: rgba(245,240,232,0.25);
    transition: background var(--page-transition), transform var(--page-transition);
  }
  .page-about__dot.is-active {
    background: var(--page-highlight);
    transform: scale(1.3);
    box-shadow: 0 0 0 4px rgba(255,209,102,0.25);
  }
  .page-about__sidebar-footer {
    margin-top: 20px;
    padding-top: 12px;
    border-top: 1px solid rgba(212,201,184,0.2);
    font-size: 12px;
    color: rgba(245,240,232,0.5);
    text-align: center;
  }
  .page-about__content {
    flex: 1;
    min-width: 0;
  }
  .page-about__main-title {
    font-size: 36px;
    margin: 8px 0 36px;
  }
  .page-about__section {
    margin-bottom: 56px;
  }
  .page-about__section--story {
    flex-direction: row;
    align-items: flex-start;
    padding: 32px 28px;
    gap: 32px;
  }
  .page-about__story-text {
    flex: 1;
  }
  .page-about__story-image {
    width: 300px;
    flex-shrink: 0;
  }
  .page-about__features-grid {
    grid-template-columns: 1fr 1fr;
    gap: 24px;
  }
  .page-about__feature-card {
    padding: 24px 20px;
  }
  .page-about__feature-card:nth-child(2) {
    margin-top: 16px;
  }
  .page-about__feature-card:nth-child(3) {
    margin-bottom: 16px;
  }
  .page-about__contact-card {
    padding: 28px 24px;
  }
  .page-about__contact-item {
    flex-direction: row;
    align-items: baseline;
    gap: 16px;
  }
  .page-about__contact-label {
    min-width: 80px;
    font-size: 13px;
  }
  .page-about__contact-value {
    font-size: 20px;
  }
}

/* ===== 大桌面端（≥1024px） ===== */
@media (min-width: 1024px) {
  .page-about__timeline {
    gap: 48px;
  }
  .page-about__sidebar {
    width: 240px;
    min-width: 240px;
    padding: 32px 20px 24px;
  }
  .page-about__main-title {
    font-size: 40px;
  }
  .page-about__section--story {
    padding: 40px 36px;
    gap: 40px;
  }
  .page-about__features-grid {
    gap: 28px;
  }
  .page-about__feature-card {
    padding: 28px 24px;
  }
  .page-about__contact-card {
    padding: 32px 28px;
  }
}

/* ===== 确保窄屏不溢出 ===== */
@media (max-width: 767px) {
  .page-about {
    overflow-x: hidden;
  }
  .page-about__timeline {
    padding: 0 12px 32px;
  }
  .page-about__main-title {
    font-size: 28px;
    word-break: break-word;
  }
  .page-about__section--story {
    padding: 20px 16px;
  }
  .page-about__feature-card {
    padding: 16px 12px;
  }
  .page-about__contact-card {
    padding: 20px 16px;
  }
  .page-about__img {
    width: 100%;
    height: auto;
  }
  .page-about__story-image {
    max-width: 100%;
  }
  .page-about__features-cta .btn {
    width: 100%;
    max-width: 320px;
  }
  .page-about__contact-link {
    width: 100%;
    text-align: center;
  }
}

/* ===== 可访问性增强 ===== */
.page-about *:focus-visible {
  outline: 2px solid var(--page-primary);
  outline-offset: 2px;
}
.page-about .btn:focus-visible {
  outline: 2px solid var(--page-primary-dark);
  outline-offset: 2px;
}