.page-about {
  --about-sidebar-width: 280px;
  --about-gap: 40px;
  --timeline-dot-size: 16px;
  --about-tag-bg: rgba(30, 60, 114, 0.35);
  --about-tag-border: rgba(255, 111, 0, 0.3);
  --about-section-number-color: rgba(255, 111, 0, 0.12);
}

.page-about .container {
  max-width: var(--container-max, 1200px);
  margin: 0 auto;
  padding: 0 var(--container-padding, 16px);
}

.page-about .breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 20px 0 12px;
  font-family: var(--font-body, 'Roboto', 'PingFang SC', sans-serif);
  font-size: 13px;
  color: var(--color-text-muted, #A0AAB8);
  border-bottom: 1px solid rgba(255, 111, 0, 0.1);
  margin-bottom: 32px;
}

.page-about .breadcrumb-link {
  color: var(--color-link, #FF8C00);
  text-decoration: none;
  transition: color var(--transition-fast, 0.2s ease);
}

.page-about .breadcrumb-link:hover {
  color: var(--color-link-hover, #FFB74D);
  text-decoration: underline;
}

.page-about .breadcrumb-sep {
  color: var(--color-line, #FF6F00);
  font-weight: 700;
}

.page-about .breadcrumb-current {
  color: var(--color-text-heading, #FFFFFF);
  font-weight: 400;
}

.page-about .about-layout {
  display: flex;
  flex-direction: column;
  gap: 48px;
}

/* ── 左侧窄栏 ── */
.page-about .about-sidebar {
  order: 0;
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.page-about .brand-statement {
  padding: 24px 20px;
  background: var(--color-card-bg, #1E2D3D);
  border-radius: var(--radius-lg, 24px);
  border-left: 4px solid var(--color-accent, #FF6F00);
  box-shadow: var(--shadow-card, 0 4px 24px rgba(0,0,0,0.35));
}

.page-about .brand-title {
  font-family: var(--font-heading, 'Montserrat', 'PingFang SC', sans-serif);
  font-weight: 700;
  font-size: 28px;
  color: var(--color-text-heading, #FFFFFF);
  margin: 0 0 4px;
  letter-spacing: 0.02em;
}

.page-about .brand-subtitle {
  font-family: var(--font-body, 'Roboto', 'PingFang SC', sans-serif);
  font-weight: 400;
  font-size: 15px;
  color: var(--color-accent, #FF6F00);
  margin: 0 0 12px;
  letter-spacing: 0.04em;
}

.page-about .brand-desc {
  font-family: var(--font-body, 'Roboto', 'PingFang SC', sans-serif);
  font-weight: 300;
  font-size: 14px;
  line-height: 1.6;
  color: var(--color-text-muted, #A0AAB8);
  margin: 0;
}

.page-about .feature-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  padding: 0 4px;
}

.page-about .tag {
  display: inline-block;
  padding: 6px 16px;
  font-family: var(--font-mono, 'SFMono-Regular', 'Menlo', monospace);
  font-size: 12px;
  font-weight: 500;
  color: var(--color-accent-light, #FF8C00);
  background: var(--about-tag-bg);
  border: 1px solid var(--about-tag-border);
  border-radius: 100px;
  letter-spacing: 0.02em;
  transition: background var(--transition-fast, 0.2s ease), border-color var(--transition-fast, 0.2s ease), box-shadow var(--transition-fast, 0.2s ease);
  cursor: default;
}

.page-about .tag:hover {
  background: rgba(255, 111, 0, 0.18);
  border-color: var(--color-accent, #FF6F00);
  box-shadow: 0 0 12px rgba(255, 111, 0, 0.15);
}

.page-about .page-index {
  padding: 20px;
  background: var(--color-card-bg, #1E2D3D);
  border-radius: var(--radius-md, 14px);
  border: 1px solid rgba(255, 111, 0, 0.08);
}

.page-about .index-title {
  font-family: var(--font-heading, 'Montserrat', 'PingFang SC', sans-serif);
  font-weight: 600;
  font-size: 14px;
  color: var(--color-text-heading, #FFFFFF);
  margin: 0 0 12px;
  letter-spacing: 0.06em;
  text-transform: uppercase;
  opacity: 0.7;
}

.page-about .index-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.page-about .index-link {
  display: block;
  padding: 8px 12px;
  font-family: var(--font-body, 'Roboto', 'PingFang SC', sans-serif);
  font-weight: 400;
  font-size: 14px;
  color: var(--color-text-body, #E0E6ED);
  text-decoration: none;
  border-radius: var(--radius-sm, 8px);
  border-left: 2px solid transparent;
  transition: background var(--transition-fast, 0.2s ease), border-color var(--transition-fast, 0.2s ease), color var(--transition-fast, 0.2s ease);
}

.page-about .index-link:hover {
  background: rgba(255, 111, 0, 0.08);
  border-left-color: var(--color-accent, #FF6F00);
  color: var(--color-accent-light, #FF8C00);
}

.page-about .sidebar-contact {
  padding: 16px 20px;
  background: rgba(30, 60, 114, 0.2);
  border-radius: var(--radius-md, 14px);
  border: 1px dashed rgba(255, 111, 0, 0.15);
}

.page-about .sidebar-contact .contact-label {
  font-family: var(--font-mono, 'SFMono-Regular', 'Menlo', monospace);
  font-size: 11px;
  color: var(--color-text-muted, #A0AAB8);
  margin: 0 0 4px;
  text-transform: uppercase;
  letter-spacing: 0.08em;
}

.page-about .sidebar-contact .contact-detail {
  font-family: var(--font-body, 'Roboto', 'PingFang SC', sans-serif);
  font-weight: 400;
  font-size: 15px;
  color: var(--color-accent-light, #FF8C00);
  margin: 0;
  word-break: break-all;
}

.page-about .sidebar-contact .contact-note {
  font-family: var(--font-body, 'Roboto', 'PingFang SC', sans-serif);
  font-weight: 300;
  font-size: 12px;
  color: var(--color-text-muted, #A0AAB8);
  margin: 4px 0 0;
}

/* ── 右侧宽栏 ── */
.page-about .about-content {
  order: 1;
  display: flex;
  flex-direction: column;
  gap: 56px;
}

.page-about .content-section {
  scroll-margin-top: 80px;
}

.page-about .section-header {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  margin-bottom: 20px;
  border-bottom: 2px solid rgba(255, 111, 0, 0.15);
  padding-bottom: 12px;
}

.page-about .section-title {
  font-family: var(--font-heading, 'Montserrat', 'PingFang SC', sans-serif);
  font-weight: 700;
  font-size: 22px;
  color: var(--color-text-heading, #FFFFFF);
  margin: 0;
  letter-spacing: 0.02em;
  position: relative;
  padding-left: 16px;
}

.page-about .section-title::before {
  content: '';
  position: absolute;
  left: 0;
  top: 4px;
  bottom: 4px;
  width: 4px;
  background: var(--color-accent, #FF6F00);
  border-radius: 4px;
}

.page-about .section-number {
  font-family: var(--font-heading, 'Montserrat', 'PingFang SC', sans-serif);
  font-weight: 900;
  font-size: 48px;
  color: var(--about-section-number-color);
  line-height: 1;
  user-select: none;
  pointer-events: none;
}

.page-about .section-body {
  font-family: var(--font-body, 'Roboto', 'PingFang SC', sans-serif);
  font-weight: 300;
  font-size: 15px;
  line-height: 1.8;
  color: var(--color-text-body, #E0E6ED);
}

/* 品牌定位 */
.page-about .brand-body {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.page-about .brand-text-block p {
  margin: 0 0 16px;
}

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

.page-about .brand-image-wrapper {
  width: 100%;
  max-width: 400px;
  margin: 0 auto;
}

.page-about .brand-fig {
  display: block;
  width: 100%;
  height: auto;
  border-radius: var(--radius-md, 14px);
  box-shadow: var(--shadow-glow, 0 0 20px rgba(255,111,0,0.12));
  border: 1px solid rgba(255, 111, 0, 0.1);
}

/* 核心功能 */
.page-about .features-body {
  display: flex;
  flex-direction: column;
  gap: 28px;
}

.page-about .timeline-wrapper {
  width: 100%;
}

.page-about .timeline {
  position: relative;
  display: flex;
  flex-direction: column;
  gap: 0;
  padding-left: 28px;
}

.page-about .timeline::before {
  content: '';
  position: absolute;
  left: 7px;
  top: 10px;
  bottom: 10px;
  width: 2px;
  background: linear-gradient(to bottom, var(--color-accent, #FF6F00), var(--color-primary, #1E3C72));
  border-radius: 2px;
}

.page-about .timeline-item {
  position: relative;
  padding: 16px 16px 16px 20px;
  margin-bottom: 4px;
  background: rgba(30, 45, 61, 0.4);
  border-radius: var(--radius-sm, 8px);
  border: 1px solid transparent;
  transition: background var(--transition-base, 0.35s ease), border-color var(--transition-base, 0.35s ease), box-shadow var(--transition-base, 0.35s ease);
  cursor: default;
}

.page-about .timeline-item:last-child {
  margin-bottom: 0;
}

.page-about .timeline-item:hover {
  background: rgba(30, 45, 61, 0.8);
  border-color: rgba(255, 111, 0, 0.25);
  box-shadow: 0 0 16px rgba(255, 111, 0, 0.08);
}

.page-about .timeline-dot {
  position: absolute;
  left: -28px;
  top: 22px;
  width: var(--timeline-dot-size);
  height: var(--timeline-dot-size);
  border-radius: 50%;
  background: var(--color-accent, #FF6F00);
  border: 3px solid var(--color-bg-start, #0D1B2A);
  box-shadow: 0 0 0 2px rgba(255, 111, 0, 0.3);
  transition: box-shadow var(--transition-fast, 0.2s ease), transform var(--transition-fast, 0.2s ease);
  z-index: 1;
}

.page-about .timeline-item:hover .timeline-dot {
  box-shadow: 0 0 0 4px rgba(255, 111, 0, 0.4), 0 0 16px rgba(255, 111, 0, 0.2);
  transform: scale(1.1);
}

.page-about .timeline-content {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.page-about .timeline-title {
  font-family: var(--font-heading, 'Montserrat', 'PingFang SC', sans-serif);
  font-weight: 600;
  font-size: 16px;
  color: var(--color-text-heading, #FFFFFF);
  margin: 0;
  transition: color var(--transition-fast, 0.2s ease);
}

.page-about .timeline-item:hover .timeline-title {
  color: var(--color-accent-light, #FF8C00);
}

.page-about .timeline-preview {
  font-weight: 400;
  font-size: 14px;
  color: var(--color-text-body, #E0E6ED);
  margin: 0;
  line-height: 1.6;
}

.page-about .timeline-detail {
  font-weight: 300;
  font-size: 13px;
  color: var(--color-text-muted, #A0AAB8);
  margin: 0;
  line-height: 1.5;
  max-height: 0;
  overflow: hidden;
  opacity: 0;
  transition: max-height 0.4s ease, opacity 0.4s ease, padding 0.4s ease;
  padding-top: 0;
}

.page-about .timeline-item:hover .timeline-detail {
  max-height: 80px;
  opacity: 1;
  padding-top: 6px;
}

.page-about .features-image-wrapper {
  width: 100%;
  max-width: 500px;
  margin: 0 auto;
}

.page-about .features-fig {
  display: block;
  width: 100%;
  height: auto;
  border-radius: var(--radius-md, 14px);
  border: 1px solid rgba(255, 111, 0, 0.08);
  box-shadow: var(--shadow-card, 0 4px 24px rgba(0,0,0,0.35));
}

/* 技术优势 */
.page-about .tech-body {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.page-about .tech-image-wrapper {
  width: 100%;
  max-width: 260px;
  margin: 0 auto;
}

.page-about .tech-fig {
  display: block;
  width: 100%;
  height: auto;
  border-radius: var(--radius-lg, 24px);
  border: 1px solid rgba(255, 111, 0, 0.08);
  box-shadow: var(--shadow-card, 0 4px 24px rgba(0,0,0,0.35));
}

.page-about .tech-text-block p {
  margin: 0 0 16px;
}

.page-about .tech-text-block p:last-of-type {
  margin-bottom: 0;
}

.page-about .tech-list {
  list-style: none;
  margin: 16px 0 0;
  padding: 0;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.page-about .tech-list li {
  position: relative;
  padding-left: 20px;
  font-weight: 400;
  font-size: 14px;
  color: var(--color-text-body, #E0E6ED);
  line-height: 1.5;
}

.page-about .tech-list li::before {
  content: '◆';
  position: absolute;
  left: 0;
  color: var(--color-accent, #FF6F00);
  font-size: 10px;
  top: 2px;
}

/* 服务承诺 */
.page-about .commitment-body {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.page-about .commitment-body > p {
  margin: 0;
}

.page-about .commitment-card {
  background: var(--color-card-bg, #1E2D3D);
  border-radius: var(--radius-md, 14px);
  padding: 24px 28px;
  border-left: 4px solid var(--color-accent, #FF6F00);
  box-shadow: var(--shadow-card, 0 4px 24px rgba(0,0,0,0.35));
}

.page-about .commitment-label {
  font-family: var(--font-body, 'Roboto', 'PingFang SC', sans-serif);
  font-weight: 300;
  font-size: 15px;
  color: var(--color-text-body, #E0E6ED);
  margin: 0 0 8px;
}

.page-about .commitment-email {
  font-family: var(--font-mono, 'SFMono-Regular', 'Menlo', monospace);
  font-weight: 500;
  font-size: 18px;
  color: var(--color-accent-light, #FF8C00);
  margin: 0 0 4px;
  letter-spacing: 0.02em;
}

.page-about .commitment-note {
  font-family: var(--font-body, 'Roboto', 'PingFang SC', sans-serif);
  font-weight: 300;
  font-size: 13px;
  color: var(--color-text-muted, #A0AAB8);
  margin: 0;
}

.page-about .commitment-trust {
  font-family: var(--font-heading, 'Montserrat', 'PingFang SC', sans-serif);
  font-weight: 500;
  font-size: 16px;
  color: var(--color-text-heading, #FFFFFF);
  text-align: center;
  letter-spacing: 0.04em;
  padding-top: 8px;
  border-top: 1px solid rgba(255, 111, 0, 0.1);
}

/* ── 桌面端 ≥768px ── */
@media (min-width: 768px) {
  .page-about .about-layout {
    flex-direction: row;
    align-items: flex-start;
    gap: var(--about-gap, 40px);
  }

  .page-about .about-sidebar {
    order: 0;
    width: var(--about-sidebar-width, 280px);
    flex-shrink: 0;
    position: sticky;
    top: 80px;
    max-height: calc(100vh - 120px);
    overflow-y: auto;
  }

  .page-about .about-content {
    order: 1;
    flex: 1;
    min-width: 0;
  }

  .page-about .section-title {
    font-size: 26px;
    padding-left: 20px;
  }

  .page-about .section-number {
    font-size: 56px;
  }

  .page-about .brand-body {
    flex-direction: row;
    align-items: flex-start;
    gap: 36px;
  }

  .page-about .brand-text-block {
    flex: 1;
  }

  .page-about .brand-image-wrapper {
    flex-shrink: 0;
    width: 320px;
    max-width: 40%;
    margin: 0;
  }

  .page-about .features-body {
    flex-direction: row;
    align-items: flex-start;
    gap: 32px;
  }

  .page-about .timeline-wrapper {
    flex: 1;
  }

  .page-about .features-image-wrapper {
    flex-shrink: 0;
    width: 340px;
    max-width: 45%;
    margin: 0;
  }

  .page-about .tech-body {
    flex-direction: row;
    align-items: flex-start;
    gap: 36px;
  }

  .page-about .tech-image-wrapper {
    flex-shrink: 0;
    width: 220px;
    margin: 0;
    order: 0;
  }

  .page-about .tech-text-block {
    flex: 1;
    order: 1;
  }

  .page-about .commitment-card {
    padding: 28px 36px;
  }
}

/* ── 桌面大屏 ≥1024px ── */
@media (min-width: 1024px) {
  .page-about .about-sidebar {
    width: 300px;
  }

  .page-about .brand-title {
    font-size: 32px;
  }

  .page-about .section-title {
    font-size: 30px;
  }

  .page-about .section-number {
    font-size: 64px;
  }

  .page-about .brand-image-wrapper {
    width: 360px;
  }

  .page-about .features-image-wrapper {
    width: 380px;
  }

  .page-about .tech-image-wrapper {
    width: 240px;
  }
}