/* CSS Custom Properties for Theme Support */
:root {
  /* Light Theme Colors */
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --text-primary: #1e293b;
  --text-secondary: #64748b;
  --text-muted: #94a3b8;
  --border-color: #e2e8f0;
  --shadow-color: rgba(0, 0, 0, 0.1);
  --accent-color: #3b82f6;
  --accent-hover: #2563eb;
  --success-color: #10b981;
  --warning-color: #f59e0b;
  --error-color: #ef4444;
  
  /* Gradients */
  --gradient-primary: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
  --gradient-secondary: linear-gradient(135deg, #f093fb 0%, #f5576c 100%);
  --gradient-accent: linear-gradient(135deg, #4facfe 0%, #00f2fe 100%);
  
  /* Typography */
  --font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  --font-size-5xl: 3rem;
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  --spacing-3xl: 4rem;
  
  /* Border Radius */
  --radius-sm: 0.375rem;
  --radius-md: 0.5rem;
  --radius-lg: 0.75rem;
  --radius-xl: 1rem;
  --radius-full: 9999px;
  
  /* Shadows */
  --shadow-sm: 0 1px 2px 0 var(--shadow-color);
  --shadow-md: 0 4px 6px -1px var(--shadow-color);
  --shadow-lg: 0 10px 15px -3px var(--shadow-color);
  --shadow-xl: 0 20px 25px -5px var(--shadow-color);
}

/* Dark Theme */
[data-theme="dark"] {
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #64748b;
  --border-color: #334155;
  --shadow-color: rgba(0, 0, 0, 0.3);
  --accent-color: #60a5fa;
  --accent-hover: #3b82f6;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--bg-primary);
  transition: background-color 0.3s ease, color 0.3s ease;
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-lg);
}

/* Header */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(var(--bg-primary), 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  z-index: 1000;
  transition: all 0.3s ease;
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-md) var(--spacing-lg);
  max-width: 1200px;
  margin: 0 auto;
}

.nav-brand {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.nav-logo {
  width: 32px;
  height: 32px;
  border-radius: var(--radius-md);
}

.nav-title {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: #ffffff;
}

.nav-menu {
  display: flex;
  align-items: center;
  gap: var(--spacing-xl);
}

.nav-link {
  text-decoration: none;
  color: #ffffff;
  font-weight: 500;
  transition: color 0.3s ease;
  position: relative;
}

.nav-link:hover {
  color: #ffffff;
  opacity: 0.8;
}

.nav-link::after {
  content: '';
  position: absolute;
  bottom: -4px;
  left: 0;
  width: 0;
  height: 2px;
  background: #ffffff;
  transition: width 0.3s ease;
}

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

/* Theme Toggle */
.theme-toggle {
  background: none;
  border: 2px solid rgba(255, 255, 255, 0.3);
  border-radius: var(--radius-full);
  padding: var(--spacing-sm);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s ease;
  color: #ffffff;
}

.theme-toggle:hover {
  border-color: #ffffff;
  color: #ffffff;
}

.theme-toggle svg {
  width: 20px;
  height: 20px;
}

.sun-icon {
  display: none;
}

[data-theme="dark"] .sun-icon {
  display: block;
}

[data-theme="dark"] .moon-icon {
  display: none;
}

/* Hero Section */
.hero {
  padding: var(--spacing-3xl) var(--spacing-lg);
  background: var(--gradient-primary);
  min-height: 100vh;
  display: flex;
  align-items: center;
  position: relative;
  overflow: hidden;
}

.hero::before {
  content: '';
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: url('data:image/svg+xml,<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100"><defs><pattern id="grain" width="100" height="100" patternUnits="userSpaceOnUse"><circle cx="25" cy="25" r="1" fill="rgba(255,255,255,0.1)"/><circle cx="75" cy="75" r="1" fill="rgba(255,255,255,0.1)"/><circle cx="50" cy="10" r="0.5" fill="rgba(255,255,255,0.05)"/><circle cx="10" cy="60" r="0.5" fill="rgba(255,255,255,0.05)"/><circle cx="90" cy="40" r="0.5" fill="rgba(255,255,255,0.05)"/></pattern></defs><rect width="100" height="100" fill="url(%23grain)"/></svg>');
  opacity: 0.3;
}

.hero-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-3xl);
  align-items: center;
  max-width: 1200px;
  margin: 0 auto;
  position: relative;
  z-index: 1;
}

.hero-text {
  color: white;
}

.hero-title {
  font-size: var(--font-size-5xl);
  font-weight: 800;
  margin-bottom: var(--spacing-md);
  line-height: 1.1;
}

.hero-subtitle {
  font-size: var(--font-size-2xl);
  font-weight: 600;
  margin-bottom: var(--spacing-lg);
  opacity: 0.9;
}

.hero-description {
  font-size: var(--font-size-lg);
  margin-bottom: var(--spacing-xl);
  opacity: 0.8;
  line-height: 1.7;
}

.hero-version {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-xl);
}

.version-label {
  font-weight: 600;
  opacity: 0.9;
}

.version-number {
  background: rgba(255, 255, 255, 0.2);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-md);
  font-weight: 700;
  backdrop-filter: blur(10px);
}

.hero-actions {
  display: flex;
  gap: var(--spacing-md);
  flex-wrap: wrap;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md) var(--spacing-xl);
  border: none;
  border-radius: var(--radius-lg);
  font-size: var(--font-size-base);
  font-weight: 600;
  text-decoration: none;
  cursor: pointer;
  transition: all 0.3s ease;
  position: relative;
  overflow: hidden;
}

.btn::before {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.2), transparent);
  transition: left 0.5s ease;
}

.btn:hover::before {
  left: 100%;
}

.btn-primary {
  background: var(--accent-color);
  color: white;
  box-shadow: var(--shadow-lg);
}

.btn-primary:hover {
  background: var(--accent-hover);
  transform: translateY(-2px);
  box-shadow: var(--shadow-xl);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.2);
  color: white;
  border: 2px solid rgba(255, 255, 255, 0.3);
  backdrop-filter: blur(10px);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.3);
  border-color: rgba(255, 255, 255, 0.5);
}

.btn-large {
  padding: var(--spacing-lg) var(--spacing-2xl);
  font-size: var(--font-size-lg);
}

.btn-outline {
  background: transparent;
  color: var(--accent-color);
  border: 2px solid var(--accent-color);
}

.btn-outline:hover {
  background: var(--accent-color);
  color: white;
}

.btn svg {
  width: 20px;
  height: 20px;
}

/* Hero Image/App Mockup */
.hero-image {
  display: flex;
  justify-content: center;
  align-items: center;
}

.app-mockup {
  width: 300px;
  height: 400px;
  background: rgba(255, 255, 255, 0.1);
  border-radius: var(--radius-xl);
  padding: var(--spacing-lg);
  backdrop-filter: blur(20px);
  border: 1px solid rgba(255, 255, 255, 0.2);
  position: relative;
  overflow: hidden;
}

.mockup-screen {
  width: 100%;
  height: 100%;
  background: var(--bg-primary);
  border-radius: var(--radius-lg);
  padding: var(--spacing-md);
  display: flex;
  flex-direction: column;
}

.mockup-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-lg);
}

.mockup-dots {
  display: flex;
  gap: var(--spacing-xs);
}

.mockup-dots span {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: var(--text-muted);
}

.mockup-content {
  flex: 1;
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.mockup-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  padding: var(--spacing-md);
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
  transition: all 0.3s ease;
  cursor: pointer;
}

.mockup-item:hover {
  background: var(--accent-color);
  color: white;
  transform: translateX(5px);
}

.mockup-item.active {
  background: var(--accent-color);
  color: white;
}

.mockup-icon {
  font-size: var(--font-size-lg);
}

/* Sections */
.section-title {
  font-size: var(--font-size-4xl);
  font-weight: 700;
  text-align: center;
  margin-bottom: var(--spacing-3xl);
  color: var(--text-primary);
}

/* Features Section */
.features {
  padding: var(--spacing-3xl) 0;
  background: var(--bg-secondary);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--spacing-xl);
}

.feature-card {
  background: var(--bg-primary);
  padding: var(--spacing-2xl);
  border-radius: var(--radius-xl);
  text-align: center;
  box-shadow: var(--shadow-md);
  transition: all 0.3s ease;
  border: 1px solid var(--border-color);
}

.feature-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-xl);
  border-color: var(--accent-color);
}

.feature-icon {
  width: 64px;
  height: 64px;
  margin: 0 auto var(--spacing-lg);
  background: var(--gradient-accent);
  border-radius: var(--radius-full);
  display: flex;
  align-items: center;
  justify-content: center;
  color: white;
}

.feature-icon svg {
  width: 32px;
  height: 32px;
}

.feature-card h3 {
  font-size: var(--font-size-xl);
  font-weight: 600;
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

.feature-card p {
  color: var(--text-secondary);
  line-height: 1.6;
}

/* Download Section */
.download {
  padding: var(--spacing-3xl) 0;
  background: var(--bg-primary);
}

.download-content {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: var(--spacing-3xl);
  align-items: center;
  max-width: 800px;
  margin: 0 auto;
}

.download-info h3 {
  font-size: var(--font-size-2xl);
  font-weight: 700;
  margin-bottom: var(--spacing-sm);
  color: var(--text-primary);
}

.download-info p {
  color: var(--text-secondary);
  margin-bottom: var(--spacing-xl);
}

.download-features {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
}

.download-feature {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  color: var(--text-secondary);
}

.download-feature svg {
  width: 20px;
  height: 20px;
  color: var(--success-color);
}

.download-actions {
  text-align: center;
}

.download-size {
  margin-top: var(--spacing-md);
  color: var(--text-muted);
  font-size: var(--font-size-sm);
}

/* About Section */
.about {
  padding: var(--spacing-3xl) 0;
  background: var(--bg-secondary);
}

.about-content {
  text-align: center;
  max-width: 600px;
  margin: 0 auto;
}

.about-content p {
  font-size: var(--font-size-lg);
  color: var(--text-secondary);
  margin-bottom: var(--spacing-xl);
  line-height: 1.7;
}

.about-links {
  display: flex;
  justify-content: center;
  gap: var(--spacing-lg);
  flex-wrap: wrap;
}

.about-link {
  color: var(--accent-color);
  text-decoration: none;
  font-weight: 500;
  padding: var(--spacing-sm) var(--spacing-md);
  border: 2px solid var(--accent-color);
  border-radius: var(--radius-md);
  transition: all 0.3s ease;
}

.about-link:hover {
  background: var(--accent-color);
  color: white;
}

/* Contact Section */
.contact {
  padding: var(--spacing-3xl) 0;
  background: var(--bg-primary);
}

.contact-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-3xl);
  max-width: 800px;
  margin: 0 auto;
}

.contact-info {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xl);
}

.contact-item h4 {
  font-size: var(--font-size-lg);
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
  color: var(--text-primary);
}

.contact-item p {
  color: var(--text-secondary);
  line-height: 1.6;
}

.contact-links {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-md);
  justify-content: center;
}

/* Footer */
.footer {
  background: var(--bg-secondary);
  padding: var(--spacing-3xl) 0 var(--spacing-xl);
  border-top: 1px solid var(--border-color);
}

.footer-content {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-xl);
  align-items: center;
  text-align: center;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
}

.footer-logo {
  width: 40px;
  height: 40px;
  border-radius: var(--radius-md);
}

.footer-title {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--text-primary);
}

.footer-links {
  display: flex;
  gap: var(--spacing-lg);
  flex-wrap: wrap;
  justify-content: center;
}

.footer-links a {
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 0.3s ease;
}

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

.footer-legal {
  color: var(--text-muted);
  font-size: var(--font-size-sm);
}

.footer-legal p {
  margin-bottom: var(--spacing-sm);
}

.footer-beian {
  display: flex;
  gap: var(--spacing-lg);
  flex-wrap: wrap;
  justify-content: center;
}

.footer-beian a {
  color: var(--text-muted);
  text-decoration: none;
  transition: color 0.3s ease;
}

.footer-beian a:hover {
  color: var(--accent-color);
}

/* Responsive Design */
@media (max-width: 768px) {
  .nav-menu {
    gap: var(--spacing-md);
  }
  
  .nav-link {
    font-size: var(--font-size-sm);
  }
  
  .hero-content {
    grid-template-columns: 1fr;
    text-align: center;
    gap: var(--spacing-xl);
  }
  
  .hero-title {
    font-size: var(--font-size-4xl);
  }
  
  .hero-actions {
    justify-content: center;
  }
  
  .app-mockup {
    width: 250px;
    height: 320px;
  }
  
  .download-content {
    grid-template-columns: 1fr;
    text-align: center;
  }
  
  .contact-content {
    grid-template-columns: 1fr;
  }
  
  .about-links {
    flex-direction: column;
    align-items: center;
  }
  
  .footer-links {
    flex-direction: column;
    gap: var(--spacing-md);
  }
  
  .footer-beian {
    flex-direction: column;
    gap: var(--spacing-sm);
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 var(--spacing-md);
  }
  
  .hero {
    padding: var(--spacing-2xl) var(--spacing-md);
  }
  
  .hero-title {
    font-size: var(--font-size-3xl);
  }
  
  .hero-subtitle {
    font-size: var(--font-size-xl);
  }
  
  .section-title {
    font-size: var(--font-size-3xl);
  }
  
  .btn {
    padding: var(--spacing-sm) var(--spacing-lg);
    font-size: var(--font-size-sm);
  }
  
  .btn-large {
    padding: var(--spacing-md) var(--spacing-xl);
    font-size: var(--font-size-base);
  }
  
  .features-grid {
    grid-template-columns: 1fr;
  }
  
  .feature-card {
    padding: var(--spacing-lg);
  }
}

/* Animations */
@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(30px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse {
  0%, 100% {
    opacity: 1;
  }
  50% {
    opacity: 0.5;
  }
}

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

/* Apply animations */
.hero-content {
  animation: fadeInUp 0.8s ease-out;
}

.feature-card {
  animation: fadeInUp 0.6s ease-out;
}

.feature-card:nth-child(2) {
  animation-delay: 0.1s;
}

.feature-card:nth-child(3) {
  animation-delay: 0.2s;
}

.feature-card:nth-child(4) {
  animation-delay: 0.3s;
}

.app-mockup {
  animation: float 3s ease-in-out infinite;
}

/* Loading Animation */
.loading {
  display: inline-block;
  width: 20px;
  height: 20px;
  border: 3px solid rgba(255, 255, 255, 0.3);
  border-radius: 50%;
  border-top-color: white;
  animation: spin 1s ease-in-out infinite;
}

@keyframes spin {
  to {
    transform: rotate(360deg);
  }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Focus styles */
button:focus,
a:focus {
  outline: 2px solid var(--accent-color);
  outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
  :root {
    --shadow-color: rgba(0, 0, 0, 0.5);
  }
  
  .btn-primary {
    border: 2px solid currentColor;
  }
}

/* Print styles */
@media print {
  .header,
  .theme-toggle,
  .btn {
    display: none;
  }
  
  body {
    background: white;
    color: black;
  }
}