/* ==========================================================================
   网际快车机场 (Wangji Kuaiche Airport) - 磁悬浮真空管道客运 Design System
   Hyperloop Vacuum Tube & Maglev White Aesthetic Theme (Enhanced Dynamic FX)
   ========================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700;800&family=JetBrains+Mono:wght@400;500;700&display=swap');

:root {
  /* Hyperloop Glacier White Palette */
  --bg-main: #f8fafc;
  --bg-secondary: #f1f5f9;
  --bg-card: rgba(255, 255, 255, 0.88);
  --bg-tube: rgba(241, 245, 249, 0.75);
  
  --text-dark: #0f172a;
  --text-main: #334155;
  --text-muted: #64748b;
  --text-light: #94a3b8;
  
  /* Vacuum Tube Energy Accents */
  --accent-cyan: #0ea5e9;
  --accent-cyan-light: #38bdf8;
  --accent-blue: #0284c7;
  --accent-indigo: #6366f1;
  --accent-glow: rgba(56, 189, 248, 0.25);
  --accent-glow-strong: rgba(14, 165, 233, 0.4);
  
  /* Glassmorphism & Airlock Borders */
  --glass-bg: rgba(255, 255, 255, 0.85);
  --glass-border: rgba(226, 232, 240, 0.9);
  --tube-border: rgba(56, 189, 248, 0.35);
  --card-shadow: 0 10px 30px -5px rgba(15, 23, 42, 0.05), 0 0 18px 0 rgba(56, 189, 248, 0.09);
  --card-shadow-hover: 0 22px 45px -10px rgba(14, 165, 233, 0.18), 0 0 30px 0 rgba(14, 165, 233, 0.25);

  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 24px;
  --radius-full: 9999px;
  
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --font-mono: 'JetBrains Mono', monospace;
}

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

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

body {
  font-family: var(--font-sans);
  background-color: var(--bg-main);
  color: var(--text-main);
  line-height: 1.75;
  overflow-x: hidden;
  position: relative;
  background-image: 
    radial-gradient(circle at 10% 10%, rgba(56, 189, 248, 0.09) 0%, transparent 40%),
    radial-gradient(circle at 90% 50%, rgba(99, 102, 241, 0.07) 0%, transparent 45%),
    radial-gradient(circle at 50% 90%, rgba(14, 165, 233, 0.06) 0%, transparent 50%);
}

a {
  color: var(--accent-blue);
  text-decoration: none;
  transition: all 0.25s ease;
}

a:hover {
  color: var(--accent-cyan);
}

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

/* SVG Icon Base */
.svg-icon {
  width: 1.25em;
  height: 1.25em;
  fill: currentColor;
  vertical-align: -0.2em;
  display: inline-block;
}

.svg-icon-lg {
  width: 1.75em;
  height: 1.75em;
}

/* Hyperloop Grid Canvas Layer */
#particle-canvas {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  pointer-events: none;
  z-index: 0;
}

.hyperloop-bg-grid {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  pointer-events: none;
  z-index: 0;
  background-size: 60px 60px;
  background-image: 
    linear-gradient(to right, rgba(226, 232, 240, 0.4) 1px, transparent 1px),
    linear-gradient(to bottom, rgba(226, 232, 240, 0.4) 1px, transparent 1px);
  mask-image: radial-gradient(ellipse at center, rgba(0, 0, 0, 0.65) 0%, transparent 85%);
}

.container {
  width: 100%;
  max-width: 1240px;
  margin: 0 auto;
  padding: 0 24px;
  position: relative;
  z-index: 1;
}

/* ==========================================================================
   Header & Navigation
   ========================================================================== */
.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  background: rgba(248, 250, 252, 0.88);
  border-bottom: 1px solid rgba(226, 232, 240, 0.85);
  transition: all 0.3s ease;
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 80px;
}

.logo-brand {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 1.35rem;
  font-weight: 800;
  color: var(--text-dark);
  letter-spacing: -0.5px;
}

.logo-badge {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 42px;
  height: 42px;
  background: linear-gradient(135deg, #0284c7, #0ea5e9);
  color: #fff;
  border-radius: var(--radius-md);
  box-shadow: 0 4px 14px rgba(14, 165, 233, 0.35);
  position: relative;
}

.logo-badge svg {
  width: 22px;
  height: 22px;
  fill: #ffffff;
}

.logo-badge::after {
  content: '';
  position: absolute;
  inset: -3px;
  border-radius: calc(var(--radius-md) + 3px);
  border: 1px dashed rgba(56, 189, 248, 0.6);
  animation: rotateBorder 12s linear infinite;
}

@keyframes rotateBorder {
  100% { transform: rotate(360deg); }
}

.logo-text span {
  background: linear-gradient(135deg, #0284c7, #06b6d4);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: 28px;
  list-style: none;
}

.nav-link {
  font-size: 0.95rem;
  font-weight: 600;
  color: var(--text-main);
  position: relative;
  padding: 6px 0;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: 0;
  left: 0;
  width: 0;
  height: 2px;
  background: linear-gradient(90deg, var(--accent-blue), var(--accent-cyan));
  transition: width 0.3s ease;
  border-radius: 2px;
}

.nav-link:hover {
  color: var(--accent-blue);
}

.nav-link:hover::after {
  width: 100%;
}

.header-cta-btn {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 10px 22px;
  background: linear-gradient(135deg, #0284c7 0%, #0ea5e9 100%);
  color: #ffffff !important;
  font-weight: 700;
  font-size: 0.95rem;
  border-radius: var(--radius-full);
  box-shadow: 0 4px 16px rgba(14, 165, 233, 0.3);
  transition: all 0.3s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  position: relative;
  overflow: hidden;
}

.header-cta-btn::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255,255,255,0.35), transparent);
  transition: left 0.6s ease;
}

.header-cta-btn:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 25px rgba(14, 165, 233, 0.45);
}

.header-cta-btn:hover::before {
  left: 100%;
}

.mobile-toggle {
  display: none;
  background: none;
  border: none;
  font-size: 1.5rem;
  color: var(--text-dark);
  cursor: pointer;
}

/* ==========================================================================
   Hero Section & Dynamic Vacuum Tube Frame
   ========================================================================== */
.hero-section {
  padding: 60px 0 80px;
  position: relative;
  overflow: hidden;
}

.hyperloop-tube-wrapper {
  position: relative;
  background: linear-gradient(135deg, rgba(255,255,255,0.92), rgba(241,245,249,0.78));
  border: 1px solid var(--tube-border);
  border-radius: var(--radius-lg);
  padding: 48px;
  box-shadow: var(--card-shadow);
  backdrop-filter: blur(14px);
  overflow: hidden;
}

/* Vacuum Tube Decorative Bar with Animated Stream Pulse */
.vacuum-tube-bar {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 4px;
  background: linear-gradient(90deg, transparent, rgba(56, 189, 248, 0.3), var(--accent-cyan-light), var(--accent-blue), transparent);
  box-shadow: 0 0 15px var(--accent-cyan-light);
  border-radius: var(--radius-full);
}

.vacuum-tube-bar::after {
  content: '';
  position: absolute;
  top: -2px;
  left: -20%;
  width: 30%;
  height: 8px;
  background: linear-gradient(90deg, transparent, #ffffff, var(--accent-cyan-light), transparent);
  box-shadow: 0 0 20px #38bdf8;
  animation: tubeStream 3.5s infinite linear;
}

@keyframes tubeStream {
  0% { left: -30%; }
  100% { left: 110%; }
}

.telemetry-ribbon {
  display: inline-flex;
  align-items: center;
  gap: 12px;
  padding: 8px 20px;
  background: rgba(224, 242, 254, 0.85);
  border: 1px solid rgba(56, 189, 248, 0.45);
  border-radius: var(--radius-full);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--accent-blue);
  margin-bottom: 24px;
  box-shadow: 0 2px 10px rgba(56, 189, 248, 0.15);
}

.telemetry-pulse {
  width: 8px;
  height: 8px;
  background-color: #10b981;
  border-radius: 50%;
  box-shadow: 0 0 10px #10b981;
  animation: pulseDot 1.8s infinite;
}

@keyframes pulseDot {
  0% { transform: scale(0.95); box-shadow: 0 0 0 0 rgba(16, 185, 129, 0.7); }
  70% { transform: scale(1.15); box-shadow: 0 0 0 8px rgba(16, 185, 129, 0); }
  100% { transform: scale(0.95); box-shadow: 0 0 0 0 rgba(16, 185, 129, 0); }
}

.hero-grid {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 40px;
  align-items: center;
}

.hero-content h1 {
  font-size: 2.85rem;
  font-weight: 800;
  color: var(--text-dark);
  line-height: 1.25;
  margin-bottom: 20px;
  letter-spacing: -1px;
}

.hero-content h1 .gradient-text {
  background: linear-gradient(135deg, #0284c7, #0ea5e9, #6366f1);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-description {
  font-size: 1.125rem;
  color: var(--text-main);
  margin-bottom: 32px;
  line-height: 1.8;
}

.hero-action-group {
  display: flex;
  flex-wrap: wrap;
  gap: 16px;
  align-items: center;
  margin-bottom: 32px;
}

.btn-primary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 14px 32px;
  background: linear-gradient(135deg, #0284c7 0%, #0ea5e9 100%);
  color: #ffffff !important;
  font-size: 1.05rem;
  font-weight: 700;
  border-radius: var(--radius-md);
  box-shadow: 0 6px 20px rgba(14, 165, 233, 0.35);
  transition: all 0.3s ease;
  border: none;
  cursor: pointer;
}

.btn-primary:hover {
  transform: translateY(-3px);
  box-shadow: 0 12px 32px rgba(14, 165, 233, 0.5);
}

.btn-secondary {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 14px 28px;
  background: #ffffff;
  color: var(--text-dark) !important;
  font-size: 1rem;
  font-weight: 700;
  border-radius: var(--radius-md);
  border: 1px solid rgba(203, 213, 225, 0.9);
  box-shadow: 0 4px 12px rgba(15, 23, 42, 0.03);
  transition: all 0.3s ease;
}

.btn-secondary:hover {
  border-color: var(--accent-cyan);
  color: var(--accent-blue) !important;
  transform: translateY(-2px);
}

.telemetry-metrics-bar {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 16px;
  padding-top: 24px;
  border-top: 1px dashed rgba(203, 213, 225, 0.85);
}

.metric-item {
  position: relative;
}

.metric-value {
  font-family: var(--font-mono);
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--accent-blue);
  line-height: 1.2;
}

.metric-label {
  font-size: 0.825rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* Hyperloop Visual Capsule Container */
.hero-visual {
  position: relative;
}

.hyperloop-capsule-card {
  position: relative;
  background: rgba(255, 255, 255, 0.96);
  border-radius: var(--radius-lg);
  padding: 16px;
  border: 1px solid rgba(186, 230, 253, 0.85);
  box-shadow: 0 18px 40px rgba(14, 165, 233, 0.15);
  overflow: hidden;
  animation: maglevFloat 6s ease-in-out infinite;
}

@keyframes maglevFloat {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

.hyperloop-capsule-card img {
  border-radius: var(--radius-md);
  width: 100%;
  object-fit: cover;
}

.corner-tick {
  position: absolute;
  width: 12px;
  height: 12px;
  border-color: var(--accent-cyan);
  border-style: solid;
  pointer-events: none;
}
.tick-tl { top: 12px; left: 12px; border-width: 2px 0 0 2px; }
.tick-tr { top: 12px; right: 12px; border-width: 2px 2px 0 0; }
.tick-bl { bottom: 12px; left: 12px; border-width: 0 0 2px 2px; }
.tick-br { bottom: 12px; right: 12px; border-width: 0 2px 2px 0; }

.card-valve-tag {
  position: absolute;
  bottom: 24px;
  right: 24px;
  background: rgba(15, 23, 42, 0.88);
  color: #38bdf8;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  padding: 4px 12px;
  border-radius: 4px;
  backdrop-filter: blur(4px);
  border: 1px solid rgba(56, 189, 248, 0.3);
}

/* ==========================================================================
   Section Headers
   ========================================================================== */
.section-header {
  text-align: center;
  max-width: 760px;
  margin: 0 auto 56px;
}

.section-tag {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.825rem;
  font-weight: 700;
  color: var(--accent-blue);
  text-transform: uppercase;
  letter-spacing: 1px;
  padding: 4px 14px;
  background: rgba(224, 242, 254, 0.85);
  border-radius: var(--radius-full);
  margin-bottom: 12px;
  border: 1px solid rgba(56, 189, 248, 0.3);
}

.section-title {
  font-size: 2.25rem;
  font-weight: 800;
  color: var(--text-dark);
  line-height: 1.3;
  margin-bottom: 16px;
  letter-spacing: -0.5px;
}

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

/* ==========================================================================
   Core Advantages (Features)
   ========================================================================== */
.advantages-section {
  padding: 80px 0;
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 32px 24px;
  position: relative;
  transition: all 0.35s cubic-bezier(0.165, 0.84, 0.44, 1);
  box-shadow: var(--card-shadow);
  display: flex;
  flex-direction: column;
  overflow: hidden;
}

.feature-card::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: linear-gradient(90deg, transparent, var(--accent-cyan), transparent);
  opacity: 0;
  transition: opacity 0.3s ease;
}

.feature-card:hover {
  transform: translateY(-6px);
  border-color: var(--tube-border);
  box-shadow: var(--card-shadow-hover);
}

.feature-card:hover::before {
  opacity: 1;
}

.feature-icon-wrapper {
  width: 56px;
  height: 56px;
  background: linear-gradient(135deg, #e0f2fe, #bae6fd);
  color: var(--accent-blue);
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 20px;
  position: relative;
}

.feature-icon-wrapper svg {
  width: 28px;
  height: 28px;
  fill: var(--accent-blue);
}

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

.feature-card p {
  font-size: 0.95rem;
  color: var(--text-muted);
  line-height: 1.7;
  flex-grow: 1;
}

.feature-telemetry-code {
  margin-top: 16px;
  font-family: var(--font-mono);
  font-size: 0.75rem;
  color: var(--accent-blue);
  background: rgba(241, 245, 249, 0.9);
  padding: 4px 10px;
  border-radius: 4px;
  display: inline-block;
  width: fit-content;
  border: 1px solid rgba(226, 232, 240, 0.8);
}

/* ==========================================================================
   Pricing Section
   ========================================================================== */
.pricing-section {
  padding: 80px 0;
  background: linear-gradient(180deg, transparent, rgba(224, 242, 254, 0.35), transparent);
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 24px;
  align-items: stretch;
}

.pricing-card {
  background: #ffffff;
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: 36px 28px;
  position: relative;
  display: flex;
  flex-direction: column;
  transition: all 0.35s ease;
  box-shadow: var(--card-shadow);
}

.pricing-card.popular {
  border: 2px solid var(--accent-blue);
  box-shadow: 0 18px 40px rgba(14, 165, 233, 0.22);
  transform: scale(1.03);
}

.popular-badge {
  position: absolute;
  top: -14px;
  left: 50%;
  transform: translateX(-50%);
  background: linear-gradient(135deg, #0284c7, #0ea5e9);
  color: #ffffff;
  font-size: 0.75rem;
  font-weight: 800;
  text-transform: uppercase;
  letter-spacing: 1px;
  padding: 4px 18px;
  border-radius: var(--radius-full);
  box-shadow: 0 4px 12px rgba(14, 165, 233, 0.3);
}

.plan-name {
  font-size: 1.3rem;
  font-weight: 800;
  color: var(--text-dark);
  margin-bottom: 8px;
}

.plan-subtitle {
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-bottom: 24px;
  min-height: 40px;
}

.plan-price-box {
  margin-bottom: 24px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--bg-secondary);
}

.plan-price {
  font-size: 2.5rem;
  font-weight: 800;
  color: var(--text-dark);
  line-height: 1;
  font-family: var(--font-mono);
}

.plan-price span {
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-muted);
  font-family: var(--font-sans);
}

.plan-features {
  list-style: none;
  margin-bottom: 32px;
  flex-grow: 1;
}

.plan-features li {
  font-size: 0.925rem;
  color: var(--text-main);
  margin-bottom: 12px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.plan-features li svg {
  width: 16px;
  height: 16px;
  fill: var(--accent-cyan);
  flex-shrink: 0;
}

.pricing-card .btn-primary, .pricing-card .btn-secondary {
  width: 100%;
  text-align: center;
}

/* ==========================================================================
   Target Audience Section
   ========================================================================== */
.audience-section {
  padding: 80px 0;
}

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

.audience-card {
  background: var(--bg-card);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 32px;
  box-shadow: var(--card-shadow);
  transition: all 0.3s ease;
}

.audience-card:hover {
  transform: translateY(-4px);
  border-color: var(--accent-cyan-light);
  box-shadow: var(--card-shadow-hover);
}

.audience-header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin-bottom: 16px;
}

.audience-avatar {
  width: 48px;
  height: 48px;
  background: linear-gradient(135deg, #0ea5e9, #6366f1);
  color: #fff;
  border-radius: var(--radius-md);
  display: flex;
  align-items: center;
  justify-content: center;
}

.audience-avatar svg {
  width: 24px;
  height: 24px;
  fill: #ffffff;
}

.audience-card h3 {
  font-size: 1.2rem;
  font-weight: 700;
  color: var(--text-dark);
}

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

/* ==========================================================================
   Tutorial Section
   ========================================================================== */
.tutorial-section {
  padding: 80px 0;
  background: linear-gradient(180deg, rgba(241, 245, 249, 0.6), transparent);
}

.tutorial-tabs-wrapper {
  background: #ffffff;
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: 40px;
  box-shadow: var(--card-shadow);
}

.tutorial-nav {
  display: flex;
  gap: 12px;
  border-bottom: 2px solid var(--bg-secondary);
  margin-bottom: 32px;
  padding-bottom: 12px;
  overflow-x: auto;
}

.tab-btn {
  padding: 10px 24px;
  background: transparent;
  border: none;
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-muted);
  cursor: pointer;
  border-radius: var(--radius-sm);
  transition: all 0.25s ease;
  white-space: nowrap;
}

.tab-btn.active {
  background: rgba(224, 242, 254, 0.85);
  color: var(--accent-blue);
}

.tab-pane {
  display: none;
}

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

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

.step-card {
  background: var(--bg-main);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 24px;
  position: relative;
}

.step-num {
  font-family: var(--font-mono);
  font-size: 1.8rem;
  font-weight: 800;
  color: var(--accent-cyan);
  margin-bottom: 8px;
}

.step-card h4 {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-dark);
  margin-bottom: 8px;
}

.step-card p {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.6;
}

/* ==========================================================================
   Reviews Section
   ========================================================================== */
.reviews-section {
  padding: 80px 0;
}

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

.review-card {
  background: #ffffff;
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 28px;
  box-shadow: var(--card-shadow);
  display: flex;
  flex-direction: column;
  justify-content: space-between;
}

.review-stars {
  color: #f59e0b;
  font-size: 0.9rem;
  letter-spacing: 2px;
  margin-bottom: 12px;
}

.review-text {
  font-size: 0.95rem;
  color: var(--text-main);
  line-height: 1.7;
  margin-bottom: 20px;
  font-style: italic;
}

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

.user-avatar-text {
  width: 40px;
  height: 40px;
  background: var(--bg-secondary);
  color: var(--accent-blue);
  font-weight: 700;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
}

.user-info h5 {
  font-size: 0.95rem;
  font-weight: 700;
  color: var(--text-dark);
}

.user-info p {
  font-size: 0.8rem;
  color: var(--text-muted);
}

/* ==========================================================================
   FAQ Section
   ========================================================================== */
.faq-section {
  padding: 80px 0;
  background: linear-gradient(180deg, transparent, rgba(241, 245, 249, 0.5));
}

.faq-container {
  max-width: 860px;
  margin: 0 auto;
}

.faq-item {
  background: #ffffff;
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  margin-bottom: 16px;
  overflow: hidden;
  box-shadow: var(--card-shadow);
  transition: all 0.25s ease;
}

.faq-item:hover {
  border-color: var(--tube-border);
}

.faq-question {
  width: 100%;
  padding: 22px 28px;
  background: transparent;
  border: none;
  text-align: left;
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-dark);
  display: flex;
  align-items: center;
  justify-content: space-between;
  cursor: pointer;
}

.faq-icon {
  font-size: 1.4rem;
  color: var(--accent-blue);
  transition: transform 0.3s ease;
  line-height: 1;
}

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

.faq-answer {
  max-height: 0;
  overflow: hidden;
  transition: max-height 0.35s cubic-bezier(0, 1, 0, 1);
  padding: 0 28px;
}

.faq-item.active .faq-answer {
  max-height: 500px;
  padding: 0 28px 24px;
}

.faq-answer p {
  font-size: 0.975rem;
  color: var(--text-main);
  line-height: 1.75;
}

/* ==========================================================================
   Articles Catalog Grid (文章目录)
   ========================================================================== */
.articles-section {
  padding: 80px 0;
}

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

.article-card {
  background: #ffffff;
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  overflow: hidden;
  box-shadow: var(--card-shadow);
  transition: all 0.35s ease;
  display: flex;
  flex-direction: column;
}

.article-card:hover {
  transform: translateY(-6px);
  box-shadow: var(--card-shadow-hover);
  border-color: var(--accent-cyan-light);
}

.article-body {
  padding: 28px;
  display: flex;
  flex-direction: column;
  flex-grow: 1;
}

.article-tag {
  font-family: var(--font-mono);
  font-size: 0.75rem;
  font-weight: 700;
  color: var(--accent-blue);
  background: rgba(224, 242, 254, 0.8);
  padding: 3px 10px;
  border-radius: var(--radius-full);
  width: fit-content;
  margin-bottom: 12px;
}

.article-card h3 {
  font-size: 1.15rem;
  font-weight: 700;
  color: var(--text-dark);
  line-height: 1.45;
  margin-bottom: 12px;
}

.article-card p {
  font-size: 0.9rem;
  color: var(--text-muted);
  line-height: 1.6;
  margin-bottom: 20px;
  flex-grow: 1;
}

.article-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.8rem;
  color: var(--text-light);
  padding-top: 16px;
  border-top: 1px solid var(--bg-secondary);
}

/* ==========================================================================
   Article Inner Reading Layout
   ========================================================================== */
.article-page-header {
  padding: 60px 0 40px;
  background: linear-gradient(180deg, rgba(224, 242, 254, 0.5), transparent);
}

.breadcrumb-nav {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.875rem;
  color: var(--text-muted);
  margin-bottom: 20px;
}

.breadcrumb-nav a {
  color: var(--text-muted);
}
.breadcrumb-nav a:hover {
  color: var(--accent-blue);
}

.article-main-title {
  font-size: 2.4rem;
  font-weight: 800;
  color: var(--text-dark);
  line-height: 1.3;
  margin-bottom: 20px;
}

.article-header-meta {
  display: flex;
  align-items: center;
  gap: 20px;
  font-size: 0.875rem;
  color: var(--text-muted);
  padding-bottom: 20px;
  border-bottom: 1px solid var(--glass-border);
}

.article-content-wrapper {
  display: grid;
  grid-template-columns: 1fr 300px;
  gap: 40px;
  padding: 40px 0 80px;
}

.article-body-content {
  background: #ffffff;
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-lg);
  padding: 48px;
  box-shadow: var(--card-shadow);
  font-size: 1.05rem;
  line-height: 1.9;
  color: var(--text-main);
}

.article-body-content h2 {
  font-size: 1.6rem;
  font-weight: 800;
  color: var(--text-dark);
  margin: 40px 0 18px;
  padding-bottom: 10px;
  border-bottom: 2px solid var(--bg-secondary);
}

.article-body-content h3 {
  font-size: 1.3rem;
  font-weight: 700;
  color: var(--text-dark);
  margin: 30px 0 14px;
}

.article-body-content p {
  margin-bottom: 22px;
}

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

.article-body-content li {
  margin-bottom: 10px;
}

.article-cta-box {
  background: linear-gradient(135deg, #0ea5e9, #0284c7);
  color: #ffffff;
  border-radius: var(--radius-md);
  padding: 36px;
  margin: 40px 0;
  text-align: center;
  box-shadow: 0 10px 30px rgba(14, 165, 233, 0.3);
}

.article-cta-box h3 {
  color: #ffffff !important;
  font-size: 1.5rem;
  margin-bottom: 12px !important;
  border: none !important;
}

.article-cta-box p {
  color: rgba(255, 255, 255, 0.92);
  margin-bottom: 24px;
}

.article-cta-box .btn-secondary {
  background: #ffffff;
  color: var(--accent-blue) !important;
  font-weight: 800;
}

/* Article Custom FAQ Box */
.article-faq-box {
  margin-top: 48px;
  background: var(--bg-main);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 32px;
}

.article-faq-box h3 {
  font-size: 1.4rem;
  margin-top: 0 !important;
  margin-bottom: 20px !important;
  border-bottom: 1px solid var(--glass-border) !important;
}

/* Sidebar Widgets */
.sidebar-widget {
  background: #ffffff;
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-md);
  padding: 24px;
  margin-bottom: 28px;
  box-shadow: var(--card-shadow);
}

.sidebar-title {
  font-size: 1.1rem;
  font-weight: 700;
  color: var(--text-dark);
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 2px solid var(--accent-cyan-light);
}

.sidebar-links {
  list-style: none;
}

.sidebar-links li {
  margin-bottom: 12px;
}

.sidebar-links a {
  font-size: 0.925rem;
  color: var(--text-main);
  line-height: 1.5;
  display: block;
}

.sidebar-links a:hover {
  color: var(--accent-blue);
}

/* ==========================================================================
   Footer Section
   ========================================================================== */
.site-footer {
  background: #0f172a;
  color: #94a3b8;
  padding: 80px 0 30px;
  border-top: 1px solid rgba(56, 189, 248, 0.2);
  position: relative;
}

.footer-grid {
  display: grid;
  grid-template-columns: 2fr repeat(3, 1fr);
  gap: 40px;
  margin-bottom: 60px;
}

.footer-brand h3 {
  color: #ffffff;
  font-size: 1.4rem;
  font-weight: 800;
  margin-bottom: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
}

.footer-brand p {
  font-size: 0.925rem;
  line-height: 1.7;
  color: #94a3b8;
  margin-bottom: 24px;
}

.footer-title {
  color: #ffffff;
  font-size: 1.05rem;
  font-weight: 700;
  margin-bottom: 20px;
}

.footer-links {
  list-style: none;
}

.footer-links li {
  margin-bottom: 12px;
}

.footer-links a {
  color: #94a3b8;
  font-size: 0.9rem;
}

.footer-links a:hover {
  color: #38bdf8;
}

.footer-bottom {
  padding-top: 30px;
  border-top: 1px solid rgba(255, 255, 255, 0.1);
  display: flex;
  align-items: center;
  justify-content: space-between;
  font-size: 0.875rem;
}

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

.footer-legal-links a {
  color: #94a3b8;
}

.footer-legal-links a:hover {
  color: #38bdf8;
}

/* Responsive Adaptations */
@media (max-width: 1024px) {
  .features-grid, .pricing-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .pricing-card.popular {
    transform: scale(1);
  }
  .hero-grid {
    grid-template-columns: 1fr;
  }
  .article-content-wrapper {
    grid-template-columns: 1fr;
  }
  .audience-grid, .reviews-grid, .articles-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  .footer-grid {
    grid-template-columns: 1fr 1fr;
  }
}

@media (max-width: 768px) {
  .nav-menu {
    display: none;
    position: absolute;
    top: 80px;
    left: 0;
    width: 100%;
    background: #ffffff;
    flex-direction: column;
    padding: 24px;
    box-shadow: 0 10px 30px rgba(0,0,0,0.1);
    border-bottom: 1px solid var(--glass-border);
  }
  .nav-menu.show {
    display: flex;
  }
  .mobile-toggle {
    display: block;
  }
  .hero-content h1 {
    font-size: 2.1rem;
  }
  .features-grid, .pricing-grid, .audience-grid, .reviews-grid, .articles-grid, .steps-list {
    grid-template-columns: 1fr;
  }
  .hyperloop-tube-wrapper {
    padding: 24px;
  }
  .footer-grid {
    grid-template-columns: 1fr;
  }
  .footer-bottom {
    flex-direction: column;
    gap: 16px;
    text-align: center;
  }
}