/* ==========================================================================
   贝贝云机场官方网站核心样式表
   版本: 2026.1.0
   设计规范: 极简纯原生CSS、无外部框架依赖、移动优先响应式、WCAG 2.1 AA无障碍
   ========================================================================== */

:root {
  --primary: #0284c7;
  --primary-hover: #0369a1;
  --primary-light: #e0f2fe;
  --accent: #0d9488;
  --accent-light: #ccfbf1;
  --text-main: #0f172a;
  --text-muted: #334155;
  --text-light: #64748b;
  --bg-body: #eaf4f9;
  --bg-card: #ffffff;
  --border-color: #c7e0f0;
  --border-subtle: #d6eaf5;
  --shadow-sm: 0 1px 3px 0 rgba(14, 116, 144, 0.06);
  --shadow-md: 0 4px 6px -1px rgba(14, 116, 144, 0.08), 0 2px 4px -2px rgba(14, 116, 144, 0.06);
  --shadow-lg: 0 10px 15px -3px rgba(14, 116, 144, 0.1), 0 4px 6px -4px rgba(14, 116, 144, 0.06);
  --radius-sm: 6px;
  --radius-md: 10px;
  --radius-lg: 16px;
  --max-width: 1200px;
  --header-height: 72px;
  --transition: 0.2s ease-in-out;
}

*, *::before, *::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
  -webkit-text-size-adjust: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  color: var(--text-main);
  background-color: var(--bg-body);
  line-height: 1.65;
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

img, svg {
  display: block;
  max-width: 100%;
  height: auto;
}

a {
  color: var(--primary);
  text-decoration: none;
  transition: color var(--transition);
}

a:hover {
  color: var(--primary-hover);
}

:focus-visible {
  outline: 2px solid var(--primary);
  outline-offset: 3px;
}

.skip-link {
  position: absolute;
  top: -60px;
  left: 16px;
  background: var(--primary);
  color: #ffffff;
  padding: 10px 18px;
  font-weight: 600;
  border-radius: var(--radius-sm);
  z-index: 9999;
  transition: top var(--transition);
}

.skip-link:focus {
  top: 16px;
}

.container {
  width: 100%;
  max-width: var(--max-width);
  margin-left: auto;
  margin-right: auto;
  padding-left: 20px;
  padding-right: 20px;
}

/* ==========================================================================
   Header & Navigation
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 1000;
  background-color: rgba(240, 248, 252, 0.94);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-subtle);
  height: var(--header-height);
  display: flex;
  align-items: center;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  width: 100%;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
}

.brand-icon {
  width: 34px;
  height: 34px;
  border-radius: 8px;
  box-shadow: 0 2px 6px rgba(37, 99, 235, 0.25);
  transition: transform var(--transition);
}

.brand-logo:hover .brand-icon {
  transform: scale(1.06);
}

.main-nav ul {
  display: flex;
  list-style: none;
  align-items: center;
  gap: 24px;
}

.main-nav a {
  color: var(--text-muted);
  font-weight: 500;
  font-size: 0.95rem;
  padding: 8px 4px;
  position: relative;
}

.main-nav a:hover,
.main-nav a[aria-current="page"] {
  color: var(--primary);
}

.nav-cta {
  display: flex;
  align-items: center;
}

/* ==========================================================================
   Buttons & CTAs (Touch target min 44x44px)
   ========================================================================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 44px;
  min-width: 44px;
  padding: 10px 22px;
  font-size: 1rem;
  font-weight: 600;
  border-radius: var(--radius-md);
  border: 1px solid transparent;
  cursor: pointer;
  text-align: center;
  white-space: nowrap;
  transition: all var(--transition);
  text-decoration: none;
}

.btn-primary {
  background-color: var(--primary);
  color: #ffffff;
  box-shadow: 0 2px 5px rgba(2, 132, 199, 0.25);
}

.btn-primary:hover {
  background-color: var(--primary-hover);
  color: #ffffff;
  box-shadow: 0 4px 10px rgba(2, 132, 199, 0.35);
  transform: translateY(-1px);
}

.btn-secondary {
  background-color: #ffffff;
  color: var(--text-main);
  border-color: var(--border-color);
}

.btn-secondary:hover {
  background-color: var(--bg-body);
  border-color: var(--primary);
  color: var(--primary);
}

.btn-lg {
  padding: 14px 32px;
  font-size: 1.1rem;
}

.btn-sm {
  min-height: 38px;
  padding: 6px 16px;
  font-size: 0.875rem;
}

/* ==========================================================================
   Hero Section
   ========================================================================== */
.hero {
  padding: 64px 0 48px;
  text-align: center;
  background: linear-gradient(180deg, #d3eaf8 0%, #e1f2fb 50%, var(--bg-body) 100%);
  border-bottom: 1px solid var(--border-subtle);
}

.hero-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 14px;
  background-color: var(--primary-light);
  color: var(--primary);
  font-size: 0.875rem;
  font-weight: 600;
  border-radius: 999px;
  margin-bottom: 20px;
}

.hero h1 {
  font-size: clamp(1.85rem, 4vw, 2.75rem);
  font-weight: 800;
  line-height: 1.25;
  color: var(--text-main);
  margin-bottom: 18px;
  letter-spacing: -0.02em;
}

.hero-subtitle {
  font-size: clamp(1.05rem, 2vw, 1.2rem);
  color: var(--text-muted);
  max-width: 760px;
  margin: 0 auto 32px;
}

.hero-cta-group {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 36px;
}

.hero-metrics {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 20px;
  max-width: 680px;
  margin: 0 auto;
  padding-top: 24px;
  border-top: 1px dashed var(--border-color);
}

.metric-item .metric-num {
  font-size: 1.6rem;
  font-weight: 700;
  color: var(--primary);
  display: block;
}

.metric-item .metric-label {
  font-size: 0.85rem;
  color: var(--text-light);
}

/* ==========================================================================
   Section Common
   ========================================================================== */
.section {
  padding: 72px 0;
  scroll-margin-top: calc(var(--header-height) + 16px);
}

.section-header {
  text-align: center;
  max-width: 700px;
  margin: 0 auto 48px;
}

.section-header h2 {
  font-size: clamp(1.6rem, 3vw, 2.2rem);
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 12px;
}

.section-header p {
  font-size: 1.05rem;
  color: var(--text-muted);
}

/* ==========================================================================
   Core Advantages (3 Cards)
   ========================================================================== */
.card-grid-3 {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.feature-card {
  background: var(--bg-card);
  padding: 32px 28px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-subtle);
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition);
}

.feature-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary-light);
}

.feature-icon-wrapper {
  width: 56px;
  height: 56px;
  border-radius: var(--radius-md);
  background-color: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
}

.feature-card h3 {
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 12px;
}

.feature-card p {
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.6;
}

/* ==========================================================================
   Streaming & AI Cards
   ========================================================================== */
.streaming-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 24px;
}

.support-card {
  background: var(--bg-card);
  padding: 32px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-subtle);
  box-shadow: var(--shadow-sm);
}

.support-card h3 {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-main);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.badge-tag {
  display: inline-block;
  padding: 4px 10px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  background-color: var(--accent-light);
  color: var(--accent);
  border-radius: 999px;
}

.support-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 20px;
}

.support-tag {
  padding: 6px 14px;
  background-color: var(--bg-body);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--text-muted);
}

/* ==========================================================================
   Pricing Table
   ========================================================================== */
.pricing-table-container {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  margin-bottom: 24px;
  background: var(--bg-card);
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-subtle);
  box-shadow: var(--shadow-sm);
}

.pricing-table {
  width: 100%;
  border-collapse: collapse;
  text-align: left;
  min-width: 640px;
}

.pricing-table caption {
  padding: 16px;
  font-size: 0.9rem;
  color: var(--text-light);
  text-align: right;
  caption-side: bottom;
}

.pricing-table th,
.pricing-table td {
  padding: 20px 24px;
  border-bottom: 1px solid var(--border-subtle);
}

.pricing-table thead th {
  background-color: var(--bg-body);
  color: var(--text-main);
  font-weight: 700;
  font-size: 1rem;
}

.pricing-table tbody tr:hover {
  background-color: #fafbfc;
}

.pricing-plan-name {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
}

.pricing-plan-badge {
  display: inline-block;
  padding: 2px 8px;
  font-size: 0.75rem;
  border-radius: 4px;
  background-color: var(--primary-light);
  color: var(--primary);
  margin-left: 6px;
}

.pricing-price {
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--primary);
}

.pricing-price span {
  font-size: 0.85rem;
  font-weight: 400;
  color: var(--text-light);
}

/* ==========================================================================
   Reviews / Testimonials
   ========================================================================== */
.reviews-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.review-card {
  background: var(--bg-card);
  padding: 28px;
  border-radius: var(--radius-md);
  border: 1px solid var(--border-subtle);
  box-shadow: var(--shadow-sm);
}

.review-rating {
  color: #f59e0b;
  font-size: 1.1rem;
  margin-bottom: 12px;
}

.review-content {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 18px;
}

.review-author {
  display: flex;
  align-items: center;
  gap: 12px;
}

.author-avatar {
  width: 42px;
  height: 42px;
  border-radius: 50%;
  background-color: var(--primary-light);
  color: var(--primary);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
}

.author-name {
  font-weight: 600;
  font-size: 0.95rem;
  color: var(--text-main);
}

.author-tag {
  font-size: 0.8rem;
  color: var(--text-light);
}

/* ==========================================================================
   FAQ Section (Default Expanded details/summary)
   ========================================================================== */
.faq-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
  max-width: 860px;
  margin: 0 auto;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-sm);
  overflow: hidden;
}

.faq-item summary {
  padding: 20px 24px;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-main);
  cursor: pointer;
  list-style: none;
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 44px;
}

.faq-item summary::-webkit-details-marker {
  display: none;
}

.faq-item summary::after {
  content: "+";
  font-size: 1.4rem;
  font-weight: 400;
  color: var(--primary);
  margin-left: 12px;
  transition: transform var(--transition);
}

.faq-item[open] summary::after {
  content: "−";
}

.faq-content {
  padding: 0 24px 22px;
  color: var(--text-muted);
  font-size: 0.98rem;
  line-height: 1.7;
  border-top: 1px solid var(--border-subtle);
  margin-top: -6px;
  padding-top: 16px;
}

.faq-content p + p {
  margin-top: 10px;
}

/* ==========================================================================
   Knowledge Base & Article Layout
   ========================================================================== */
.breadcrumbs {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--text-light);
  margin-bottom: 24px;
  padding: 12px 0;
  list-style: none;
}

.breadcrumbs a {
  color: var(--text-muted);
}

.breadcrumbs a:hover {
  color: var(--primary);
}

.article-list-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
  margin-top: 32px;
}

.article-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 24px;
  display: flex;
  flex-direction: column;
  box-shadow: var(--shadow-sm);
  transition: transform var(--transition), box-shadow var(--transition);
}

.article-card:hover {
  transform: translateY(-3px);
  box-shadow: var(--shadow-md);
  border-color: var(--primary);
}

.article-meta {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 0.8rem;
  color: var(--text-light);
  margin-bottom: 12px;
}

.article-tag {
  background-color: var(--primary-light);
  color: var(--primary);
  padding: 2px 8px;
  border-radius: 4px;
  font-weight: 600;
}

.article-card h2,
.article-card h3 {
  font-size: 1.2rem;
  font-weight: 700;
  margin-bottom: 12px;
  line-height: 1.4;
}

.article-card h2 a,
.article-card h3 a {
  color: var(--text-main);
}

.article-card h2 a:hover,
.article-card h3 a:hover {
  color: var(--primary);
}

.article-card p {
  color: var(--text-muted);
  font-size: 0.92rem;
  margin-bottom: 20px;
  flex-grow: 1;
}

.article-readmore {
  font-weight: 600;
  font-size: 0.9rem;
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

/* Article Detail Container */
.article-body-wrapper {
  max-width: 820px;
  margin: 0 auto;
  background: var(--bg-card);
  padding: 44px;
  border-radius: var(--radius-lg);
  border: 1px solid var(--border-subtle);
  box-shadow: var(--shadow-sm);
}

.article-body-wrapper h1 {
  font-size: clamp(1.6rem, 3.5vw, 2.3rem);
  font-weight: 800;
  color: var(--text-main);
  line-height: 1.3;
  margin-bottom: 16px;
}

.article-header-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  color: var(--text-light);
  font-size: 0.875rem;
  padding-bottom: 24px;
  margin-bottom: 32px;
  border-bottom: 1px solid var(--border-subtle);
}

.article-content {
  color: var(--text-muted);
  font-size: 1.05rem;
  line-height: 1.8;
}

.article-content h2 {
  font-size: 1.45rem;
  font-weight: 700;
  color: var(--text-main);
  margin: 36px 0 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-subtle);
}

.article-content h3 {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-main);
  margin: 24px 0 12px;
}

.article-content p {
  margin-bottom: 18px;
}

.article-content ul,
.article-content ol {
  margin: 0 0 20px 24px;
}

.article-content li {
  margin-bottom: 8px;
}

.article-highlight-box {
  background-color: var(--primary-light);
  border-left: 4px solid var(--primary);
  padding: 18px 22px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 24px 0;
  color: var(--text-main);
}

.article-cta-box {
  background: linear-gradient(135deg, #e0f2fe 0%, #ccfbf1 100%);
  border: 1px solid #bae6fd;
  padding: 30px;
  border-radius: var(--radius-md);
  text-align: center;
  margin: 36px 0;
}

/* ==========================================================================
   Footer (Strictly 4 Links)
   ========================================================================== */
.site-footer {
  margin-top: auto;
  background-color: #0b1f33;
  color: #cbd5e1;
  padding: 48px 0 36px;
  border-top: 1px solid #133352;
}

.footer-nav {
  display: flex;
  justify-content: center;
  align-items: center;
  gap: 32px;
  margin-bottom: 24px;
  flex-wrap: wrap;
}

.footer-nav a {
  color: #e2e8f0;
  font-size: 0.95rem;
  font-weight: 500;
  padding: 6px 4px;
}

.footer-nav a:hover {
  color: #38bdf8;
  text-decoration: underline;
}

.footer-copyright {
  text-align: center;
  font-size: 0.85rem;
  color: #94a3b8;
  border-top: 1px solid #1e293b;
  padding-top: 24px;
}

/* ==========================================================================
   Responsive Adaptations (@media)
   ========================================================================== */
@media (max-width: 992px) {
  .card-grid-3,
  .reviews-grid,
  .article-list-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  :root {
    --header-height: auto;
  }

  .site-header {
    padding: 12px 0;
  }

  .header-inner {
    flex-direction: column;
    gap: 12px;
  }

  .main-nav ul {
    flex-wrap: wrap;
    justify-content: center;
    gap: 14px;
  }

  .card-grid-3,
  .streaming-grid,
  .reviews-grid,
  .article-list-grid {
    grid-template-columns: 1fr;
  }

  .hero-metrics {
    grid-template-columns: 1fr;
    gap: 14px;
  }

  .article-body-wrapper {
    padding: 24px 18px;
  }

  .footer-nav {
    flex-direction: column;
    gap: 16px;
  }

  .hero-cta-group {
    flex-direction: column;
    width: 100%;
  }

  .hero-cta-group .btn {
    width: 100%;
  }
}

@media (max-width: 390px) {
  .hero h1 {
    font-size: 1.65rem;
  }
  
  .pricing-table th,
  .pricing-table td {
    padding: 14px 16px;
  }
}

/* ==========================================================================
   Snowfall Canvas Effect
   ========================================================================== */
.snow-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  pointer-events: none;
  z-index: 100;
  opacity: 0.9;
}

/* Reduced motion support */
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
  .snow-canvas {
    display: none !important;
  }
}