/* ==========================================================================
   青云梯机场 (Qingyunti Airport) Official Style Sheet
   Design System: Modern Dark Theme, Cyan-Indigo Gradients, Premium Glassmorphism
   ========================================================================== */

:root {
  --bg-dark: #090d16;
  --bg-card: rgba(30, 41, 59, 0.7);
  --bg-card-hover: rgba(30, 41, 59, 0.9);
  --bg-card-solid: #1e293b;
  --bg-header: rgba(9, 13, 22, 0.85);
  
  --color-primary: #6366f1;
  --color-primary-light: #818cf8;
  --color-accent: #06b6d4;
  --color-accent-light: #38bdf8;
  --gradient-primary: linear-gradient(135deg, #6366f1 0%, #06b6d4 100%);
  --gradient-btn: linear-gradient(90deg, #818cf8 0%, #38bdf8 100%);
  --gradient-card-popular: linear-gradient(180deg, rgba(99, 102, 241, 0.15) 0%, rgba(6, 182, 212, 0.05) 100%);
  
  --text-main: #f8fafc;
  --text-muted: #94a3b8;
  --text-dim: #64748b;
  --border-color: rgba(255, 255, 255, 0.08);
  --border-hover: rgba(99, 102, 241, 0.4);
  
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --shadow-main: 0 10px 30px -10px rgba(0, 0, 0, 0.5);
  --shadow-glow: 0 0 25px rgba(99, 102, 241, 0.25);
  
  --max-width: 1200px;
  --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
}

/* Base Styles */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  font-size: 16px;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  background-color: var(--bg-dark);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
  -webkit-font-smoothing: antialiased;
}

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

a:hover {
  color: var(--text-main);
}

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

/* Layout Utilities */
.container {
  width: 100%;
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 0 24px;
}

section {
  padding: 80px 0;
  position: relative;
}

.section-header {
  text-align: center;
  max-width: 760px;
  margin: 0 auto 50px auto;
}

.section-header h2 {
  font-size: 2.25rem;
  font-weight: 700;
  letter-spacing: -0.02em;
  margin-top: 12px;
  margin-bottom: 16px;
  background: linear-gradient(135deg, #ffffff 30%, #cbd5e1 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

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

/* Badges & Tags */
.badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  padding: 6px 16px;
  border-radius: 9999px;
  background: rgba(99, 102, 241, 0.12);
  border: 1px solid rgba(99, 102, 241, 0.3);
  color: var(--color-primary-light);
  font-size: 0.875rem;
  font-weight: 500;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 28px;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  transition: var(--transition);
  border: none;
  text-decoration: none;
}

.btn-primary {
  background: var(--gradient-btn);
  color: #0f172a;
  box-shadow: 0 4px 15px rgba(56, 189, 248, 0.3);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(56, 189, 248, 0.5);
  color: #0f172a;
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-color);
  color: var(--text-main);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: var(--color-primary-light);
  color: #fff;
  transform: translateY(-2px);
}

.btn-outline-card {
  width: 100%;
  padding: 12px;
  background: transparent;
  border: 1px solid rgba(255, 255, 255, 0.2);
  color: #fff;
  border-radius: var(--radius-sm);
  font-weight: 500;
  text-align: center;
  transition: var(--transition);
}

.btn-outline-card:hover {
  border-color: var(--color-accent-light);
  background: rgba(255, 255, 255, 0.08);
}

.btn-lg {
  padding: 16px 36px;
  font-size: 1.05rem;
  border-radius: var(--radius-md);
}

/* Header & Navigation */
.site-header {
  position: sticky;
  top: 0;
  left: 0;
  width: 100%;
  z-index: 1000;
  background: var(--bg-header);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--border-color);
}

.site-header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 76px;
}

.brand-logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.3rem;
  font-weight: 800;
  color: #fff;
  text-decoration: none;
}

.brand-logo .logo-icon {
  width: 40px;
  height: 40px;
  background: var(--gradient-primary);
  border-radius: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 900;
  font-size: 1.2rem;
  box-shadow: var(--shadow-glow);
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 28px;
}

.nav-link {
  color: var(--text-muted);
  font-weight: 500;
  font-size: 0.95rem;
}

.nav-link:hover, .nav-link.active {
  color: #fff;
}

.mobile-toggle {
  display: none;
  background: none;
  border: none;
  color: #fff;
  font-size: 1.5rem;
  cursor: pointer;
}

/* Hero Section */
.hero-section {
  padding: 100px 0 80px 0;
  background: radial-gradient(circle at 50% 20%, rgba(99, 102, 241, 0.15) 0%, transparent 60%);
  text-align: center;
}

.hero-content {
  max-width: 860px;
  margin: 0 auto;
}

.hero-title {
  font-size: 3.25rem;
  font-weight: 800;
  line-height: 1.2;
  margin: 20px 0;
  letter-spacing: -0.03em;
}

.hero-title .highlight {
  background: linear-gradient(135deg, #818cf8 0%, #38bdf8 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: 1.2rem;
  color: var(--text-muted);
  margin-bottom: 36px;
  line-height: 1.7;
}

.hero-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 16px;
  flex-wrap: wrap;
  margin-bottom: 50px;
}

.hero-stats {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 24px;
  backdrop-filter: blur(10px);
}

.stat-item {
  text-align: center;
}

.stat-num {
  font-size: 1.85rem;
  font-weight: 800;
  color: var(--color-accent-light);
}

.stat-desc {
  font-size: 0.85rem;
  color: var(--text-muted);
  margin-top: 4px;
}

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

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 32px;
  transition: var(--transition);
}

.feature-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-hover);
  background: var(--bg-card-hover);
  box-shadow: var(--shadow-glow);
}

.feature-icon {
  width: 52px;
  height: 52px;
  border-radius: 12px;
  background: rgba(99, 102, 241, 0.15);
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  margin-bottom: 20px;
  color: var(--color-primary-light);
}

.feature-card h3 {
  font-size: 1.25rem;
  font-weight: 700;
  margin-bottom: 12px;
  color: #fff;
}

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

/* Pricing Section - Exact Match to Screenshot */
.pricing-section {
  background: radial-gradient(circle at 50% 50%, rgba(6, 182, 212, 0.08) 0%, transparent 70%);
}

.pricing-sub-banner {
  text-align: center;
  color: var(--text-muted);
  font-size: 0.95rem;
  margin-top: -30px;
  margin-bottom: 40px;
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 28px;
  align-items: stretch;
}

.price-card {
  background: #141c2e;
  border: 1px solid rgba(255, 255, 255, 0.1);
  border-radius: var(--radius-lg);
  padding: 36px 28px;
  display: flex;
  flex-direction: column;
  position: relative;
  transition: var(--transition);
}

.price-card.popular {
  background: linear-gradient(180deg, #1b253e 0%, #121929 100%);
  border: 1px solid var(--color-primary);
  box-shadow: 0 0 30px rgba(99, 102, 241, 0.25);
  transform: scale(1.03);
}

.card-tag {
  position: absolute;
  top: 24px;
  right: 24px;
  padding: 2px 10px;
  border-radius: 12px;
  font-size: 0.75rem;
  font-weight: 600;
}

.card-tag.tag-rumen {
  background: rgba(255, 255, 255, 0.2);
  color: #e2e8f0;
}

.card-tag.tag-tuijian {
  background: #eab308;
  color: #0f172a;
}

.card-tag.tag-jinjie {
  background: rgba(255, 255, 255, 0.2);
  color: #e2e8f0;
}

.price-card h3 {
  font-size: 1.35rem;
  font-weight: 700;
  color: #fff;
  margin-bottom: 16px;
}

.price-amount {
  font-size: 2.4rem;
  font-weight: 800;
  color: #fff;
  margin-bottom: 16px;
  display: flex;
  align-items: baseline;
  gap: 4px;
}

.price-amount span {
  font-size: 0.9rem;
  color: var(--text-muted);
  font-weight: 400;
}

.price-desc {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 28px;
  min-height: 42px;
}

.price-features {
  list-style: none;
  margin-bottom: 36px;
  flex-grow: 1;
}

.price-features li {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 0.92rem;
  color: #cbd5e1;
  margin-bottom: 14px;
}

.price-features li svg {
  color: var(--color-accent-light);
  flex-shrink: 0;
}

/* Audience Section */
.audience-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 20px;
}

.audience-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  text-align: center;
  transition: var(--transition);
}

.audience-card:hover {
  border-color: var(--color-primary-light);
  transform: translateY(-3px);
}

.audience-icon {
  font-size: 2.2rem;
  margin-bottom: 12px;
}

.audience-card h4 {
  font-size: 1.1rem;
  color: #fff;
  margin-bottom: 8px;
}

.audience-card p {
  font-size: 0.88rem;
  color: var(--text-muted);
}

/* Tutorials Section & Tabs */
.tabs-wrapper {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 32px;
}

.tabs-nav {
  display: flex;
  gap: 12px;
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 16px;
  margin-bottom: 28px;
  overflow-x: auto;
}

.tab-btn {
  padding: 10px 20px;
  border-radius: var(--radius-sm);
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-muted);
  font-size: 0.95rem;
  font-weight: 600;
  cursor: pointer;
  white-space: nowrap;
  transition: var(--transition);
}

.tab-btn.active, .tab-btn:hover {
  background: rgba(99, 102, 241, 0.15);
  border-color: rgba(99, 102, 241, 0.3);
  color: #fff;
}

.tab-content {
  display: none;
}

.tab-content.active {
  display: block;
}

.step-list {
  display: flex;
  flex-direction: column;
  gap: 20px;
}

.step-item {
  display: flex;
  gap: 20px;
  background: rgba(15, 23, 42, 0.6);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 20px;
}

.step-num {
  width: 40px;
  height: 40px;
  background: var(--gradient-primary);
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 800;
  color: #fff;
  flex-shrink: 0;
}

.step-body h4 {
  font-size: 1.1rem;
  color: #fff;
  margin-bottom: 6px;
}

.step-body p {
  color: var(--text-muted);
  font-size: 0.92rem;
}

.step-code {
  margin-top: 12px;
  background: #090d16;
  border: 1px solid var(--border-color);
  padding: 10px 16px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.85rem;
  color: var(--color-accent-light);
}

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

.testimonial-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 28px;
}

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

.testimonial-text {
  font-size: 0.95rem;
  color: var(--text-muted);
  margin-bottom: 20px;
  font-style: italic;
}

.user-info {
  display: flex;
  align-items: center;
  gap: 12px;
}

.user-avatar {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  background: var(--gradient-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #fff;
  font-weight: 700;
}

.user-details h5 {
  color: #fff;
  font-size: 0.95rem;
}

.user-details span {
  font-size: 0.8rem;
  color: var(--text-dim);
}

/* FAQ Section */
.faq-accordion {
  max-width: 860px;
  margin: 0 auto;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

.faq-item {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  overflow: hidden;
  transition: var(--transition);
}

.faq-header {
  padding: 20px 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
  font-weight: 600;
  font-size: 1.05rem;
  color: #fff;
  user-select: none;
}

.faq-icon {
  font-size: 1.4rem;
  color: var(--color-primary-light);
  transition: transform 0.3s ease;
}

.faq-item.active .faq-icon {
  transform: rotate(45deg);
}

.faq-body {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.3s ease, padding 0.3s ease;
  padding: 0 24px;
}

.faq-item.active .faq-body {
  max-height: 500px;
  padding: 0 24px 20px 24px;
}

.faq-body p {
  color: var(--text-muted);
  font-size: 0.95rem;
  line-height: 1.7;
}

/* Articles Section */
.articles-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 24px;
}

.article-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 28px;
  display: flex;
  flex-direction: column;
  transition: var(--transition);
}

.article-card:hover {
  transform: translateY(-4px);
  border-color: var(--color-primary-light);
}

.article-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.8rem;
  color: var(--text-dim);
  margin-bottom: 14px;
}

.article-tag {
  background: rgba(6, 182, 212, 0.15);
  color: var(--color-accent-light);
  padding: 2px 10px;
  border-radius: 4px;
  font-weight: 500;
}

.article-title {
  font-size: 1.15rem;
  font-weight: 700;
  color: #fff;
  margin-bottom: 12px;
  line-height: 1.4;
}

.article-excerpt {
  font-size: 0.9rem;
  color: var(--text-muted);
  margin-bottom: 20px;
  flex-grow: 1;
}

.article-link {
  font-size: 0.9rem;
  font-weight: 600;
  color: var(--color-primary-light);
  display: inline-flex;
  align-items: center;
  gap: 4px;
}

/* Article Detail Page Layout */
.article-page {
  padding: 60px 0 100px 0;
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.88rem;
  color: var(--text-dim);
  margin-bottom: 30px;
}

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

.breadcrumb a:hover {
  color: #fff;
}

.article-wrapper {
  max-width: 840px;
  margin: 0 auto;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-lg);
  padding: 40px;
}

.article-header {
  border-bottom: 1px solid var(--border-color);
  padding-bottom: 24px;
  margin-bottom: 32px;
}

.article-header h1 {
  font-size: 2.2rem;
  font-weight: 800;
  color: #fff;
  line-height: 1.3;
  margin-bottom: 16px;
}

.article-post-meta {
  display: flex;
  gap: 20px;
  font-size: 0.88rem;
  color: var(--text-muted);
}

.article-body {
  color: #cbd5e1;
  font-size: 1.05rem;
  line-height: 1.8;
}

.article-body h2 {
  font-size: 1.6rem;
  color: #fff;
  margin: 36px 0 18px 0;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--border-color);
}

.article-body h3 {
  font-size: 1.3rem;
  color: var(--color-accent-light);
  margin: 28px 0 14px 0;
}

.article-body p {
  margin-bottom: 20px;
}

.article-body ul, .article-body ol {
  margin-bottom: 24px;
  padding-left: 24px;
}

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

.callout-box {
  background: rgba(99, 102, 241, 0.1);
  border-left: 4px solid var(--color-primary-light);
  padding: 20px;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  margin: 28px 0;
}

.callout-box p {
  margin: 0;
  color: var(--text-main);
}

.related-articles {
  margin-top: 50px;
  border-top: 1px solid var(--border-color);
  padding-top: 32px;
}

.related-articles h3 {
  font-size: 1.3rem;
  color: #fff;
  margin-bottom: 20px;
}

/* Footer */
.site-footer {
  background: #060911;
  border-top: 1px solid var(--border-color);
  padding: 70px 0 30px 0;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1.5fr;
  gap: 40px;
  margin-bottom: 50px;
}

.footer-col h4 {
  font-size: 1.1rem;
  color: #fff;
  margin-bottom: 20px;
}

.footer-links {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.footer-links a {
  color: var(--text-muted);
  font-size: 0.9rem;
}

.footer-links a:hover {
  color: #fff;
}

.footer-bottom {
  border-top: 1px solid var(--border-color);
  padding-top: 30px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.85rem;
  color: var(--text-dim);
  flex-wrap: wrap;
  gap: 16px;
}

.footer-legal {
  display: flex;
  gap: 20px;
}

.footer-legal a {
  color: var(--text-dim);
}

.footer-legal a:hover {
  color: var(--text-muted);
}

/* Responsive Media Queries */
@media (max-width: 1024px) {
  .hero-title {
    font-size: 2.5rem;
  }
  .features-grid, .pricing-grid, .articles-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .price-card.popular {
    transform: none;
  }
  .audience-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-grid {
    grid-template-columns: repeat(2, 1fr);
  }
}

@media (max-width: 768px) {
  .mobile-toggle {
    display: block;
  }
  .nav-menu {
    position: fixed;
    top: 76px;
    left: -100%;
    width: 100%;
    height: calc(100vh - 76px);
    background: #090d16;
    flex-direction: column;
    padding: 40px 24px;
    align-items: flex-start;
    transition: left 0.3s ease;
  }
  .nav-menu.open {
    left: 0;
  }
  .hero-title {
    font-size: 2rem;
  }
  .hero-stats {
    grid-template-columns: repeat(2, 1fr);
  }
  .features-grid, .pricing-grid, .testimonials-grid, .articles-grid, .audience-grid {
    grid-template-columns: 1fr;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .footer-bottom {
    flex-direction: column;
    text-align: center;
  }
  .article-wrapper {
    padding: 24px;
  }
}