:root {
  /* Google Material Design Colors */
  --primary-color: #1976d2;
  --primary-dark: #1565c0;
  --primary-light: #42a5f5;
  --secondary-color: #dc004e;
  --accent-color: #ffc107;
  --success-color: #4caf50;
  --warning-color: #ff9800;
  --error-color: #f44336;
  
  /* Neutral Colors */
  --text-primary: #212121;
  --text-secondary: #757575;
  --text-hint: #bdbdbd;
  --background: #ffffff;
  --surface: #f5f5f5;
  --border: #e0e0e0;
  
  /* Dark Mode */
  --dark-bg: #121212;
  --dark-surface: #1e1e1e;
  --dark-text: #ffffff;
  
  /* Spacing */
  --spacing-xs: 4px;
  --spacing-sm: 8px;
  --spacing-md: 16px;
  --spacing-lg: 24px;
  --spacing-xl: 32px;
  --spacing-xxl: 48px;
  
  /* Border Radius */
  --radius-sm: 4px;
  --radius-md: 8px;
  --radius-lg: 12px;
  --radius-xl: 16px;
  
  /* Shadows */
  --shadow-sm: 0 1px 3px rgba(0, 0, 0, 0.12), 0 1px 2px rgba(0, 0, 0, 0.24);
  --shadow-md: 0 3px 6px rgba(0, 0, 0, 0.16), 0 3px 6px rgba(0, 0, 0, 0.23);
  --shadow-lg: 0 10px 20px rgba(0, 0, 0, 0.19), 0 6px 6px rgba(0, 0, 0, 0.23);
}

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

body {
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--background);
}

/* Typography */
h1, h2, h3, h4, h5, h6 {
  font-weight: 600;
  line-height: 1.2;
  margin-bottom: var(--spacing-md);
}

h1 { font-size: 2.5rem; }
h2 { font-size: 2rem; }
h3 { font-size: 1.5rem; }
h4 { font-size: 1.25rem; }

p {
  margin-bottom: var(--spacing-md);
  color: var(--text-secondary);
}

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

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-sm) var(--spacing-lg);
  border-radius: var(--radius-md);
  text-decoration: none;
  font-weight: 500;
  font-size: 0.875rem;
  border: none;
  cursor: pointer;
  transition: all 0.2s ease;
  position: relative;
  overflow: hidden;
}

.btn-primary {
  background-color: var(--primary-color);
  color: white;
}

.btn-primary:hover {
  background-color: var(--primary-dark);
  transform: translateY(-1px);
  box-shadow: var(--shadow-md);
}

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

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

.btn-large {
  padding: var(--spacing-md) var(--spacing-xl);
  font-size: 1rem;
}

/* Header */
.header {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  background: rgba(255, 255, 255, 0.95);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
  z-index: 1000;
}

.nav {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-md) var(--spacing-md);
}

.nav-brand h2 {
  color: var(--primary-color);
  margin: 0;
}

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

.nav-link {
  text-decoration: none;
  color: var(--text-primary);
  font-weight: 500;
  transition: color 0.2s ease;
}

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

.nav-toggle {
  display: none;
  cursor: pointer;
}

/* Hero Section */
.hero {
  padding: calc(80px + var(--spacing-xxl)) 0 var(--spacing-xxl) 0;
  background: linear-gradient(135deg, #f5f7fa 0%, #c3cfe2 100%);
}

.hero .container {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: var(--spacing-xxl);
  align-items: center;
}

.hero-title {
  font-size: 3.5rem;
  font-weight: 700;
  color: var(--text-primary);
  margin-bottom: var(--spacing-md);
  line-height: 1.1;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--text-secondary);
  margin-bottom: var(--spacing-xl);
}

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

.hero-features {
  display: flex;
  gap: var(--spacing-xl);
}

.feature-item {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.feature-item .material-icons {
  color: var(--success-color);
  font-size: 1.25rem;
}

/* Profile Card Demo */
.profile-card-demo {
  background: white;
  border-radius: var(--radius-xl);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-lg);
  max-width: 400px;
  margin: 0 auto;
  animation: float 3s ease-in-out infinite;
}

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

.profile-header {
  display: flex;
  align-items: center;
  gap: var(--spacing-md);
  margin-bottom: var(--spacing-lg);
}

.profile-avatar {
  width: 60px;
  height: 60px;
  border-radius: 50%;
  background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
}

.profile-info h3 {
  margin: 0 0 var(--spacing-xs) 0;
  font-size: 1.25rem;
}

.profile-info p {
  margin: 0 0 var(--spacing-xs) 0;
  color: var(--text-secondary);
  font-size: 0.875rem;
}

.profile-id {
  background: var(--surface);
  padding: var(--spacing-xs) var(--spacing-sm);
  border-radius: var(--radius-sm);
  font-size: 0.75rem;
  font-family: 'Monaco', monospace;
  color: var(--primary-color);
  display: inline-block;
}

.profile-stats {
  display: flex;
  gap: var(--spacing-xl);
}

.stat {
  text-align: center;
}

.stat-number {
  display: block;
  font-size: 1.5rem;
  font-weight: 600;
  color: var(--primary-color);
}

.stat-label {
  font-size: 0.75rem;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

/* Features Section */
.features {
  padding: var(--spacing-xxl) 0;
}

.section-title {
  text-align: center;
  font-size: 2.5rem;
  margin-bottom: var(--spacing-xxl);
  color: var(--text-primary);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-xl);
}

.feature-card {
  background: white;
  padding: var(--spacing-xl);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-sm);
  transition: all 0.3s ease;
  border: 1px solid var(--border);
}

.feature-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-md);
}

.feature-icon {
  width: 60px;
  height: 60px;
  background: linear-gradient(135deg, var(--primary-color), var(--primary-light));
  border-radius: var(--radius-lg);
  display: flex;
  align-items: center;
  justify-content: center;
  margin-bottom: var(--spacing-lg);
}

.feature-icon .material-icons {
  color: white;
  font-size: 1.5rem;
}

.feature-card h3 {
  margin-bottom: var(--spacing-md);
  color: var(--text-primary);
}

/* Pricing Section */
.pricing {
  padding: var(--spacing-xxl) 0;
  background: var(--surface);
}

.pricing-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--spacing-xl);
  margin-top: var(--spacing-xxl);
}

.pricing-card {
  background: white;
  padding: var(--spacing-xl);
  border-radius: var(--radius-xl);
  box-shadow: var(--shadow-sm);
  text-align: center;
  position: relative;
  border: 2px solid transparent;
  transition: all 0.3s ease;
}

.pricing-card:hover {
  transform: translateY(-5px);
  box-shadow: var(--shadow-lg);
}

.pricing-card.featured {
  border-color: var(--primary-color);
  transform: scale(1.05);
}

.popular-badge {
  position: absolute;
  top: -10px;
  left: 50%;
  transform: translateX(-50%);
  background: var(--primary-color);
  color: white;
  padding: var(--spacing-xs) var(--spacing-md);
  border-radius: var(--radius-md);
  font-size: 0.75rem;
  font-weight: 600;
}

.price {
  display: flex;
  align-items: baseline;
  justify-content: center;
  margin: var(--spacing-lg) 0;
}

.currency {
  font-size: 1.5rem;
  color: var(--text-secondary);
}

.amount {
  font-size: 3rem;
  font-weight: 700;
  color: var(--primary-color);
}

.period {
  color: var(--text-secondary);
  margin-left: var(--spacing-xs);
}

.features-list {
  list-style: none;
  margin: var(--spacing-xl) 0;
}

.features-list li {
  display: flex;
  align-items: center;
  gap: var(--spacing-sm);
  margin-bottom: var(--spacing-md);
  text-align: left;
}

.features-list .material-icons {
  color: var(--success-color);
  font-size: 1.25rem;
}

/* Footer */
.footer {
  background: var(--text-primary);
  color: white;
  padding: var(--spacing-xxl) 0 var(--spacing-lg) 0;
}

.footer-content {
  display: grid;
  grid-template-columns: 2fr 1fr 1fr 1fr;
  gap: var(--spacing-xl);
  margin-bottom: var(--spacing-xl);
}

.footer-brand h3 {
  color: var(--primary-light);
  margin-bottom: var(--spacing-md);
}

.footer-brand p {
  color: var(--text-hint);
}

.footer-column h4 {
  color: white;
  margin-bottom: var(--spacing-md);
  font-size: 1rem;
}

.footer-column a {
  display: block;
  color: var(--text-hint);
  text-decoration: none;
  margin-bottom: var(--spacing-sm);
  transition: color 0.2s ease;
}

.footer-column a:hover {
  color: var(--primary-light);
}

.footer-bottom {
  border-top: 1px solid #333;
  padding-top: var(--spacing-lg);
  text-align: center;
}

.footer-bottom p {
  color: var(--text-hint);
  margin: 0;
}

/* Forms */
.form-group {
  margin-bottom: var(--spacing-lg);
}

.form-label {
  display: block;
  margin-bottom: var(--spacing-sm);
  font-weight: 500;
  color: var(--text-primary);
}

.form-input, .form-select, .form-textarea {
  width: 100%;
  padding: var(--spacing-md);
  border: 2px solid var(--border);
  border-radius: var(--radius-md);
  font-size: 1rem;
  transition: all 0.2s ease;
  background: white;
}

.form-input:focus, .form-select:focus, .form-textarea:focus {
  outline: none;
  border-color: var(--primary-color);
  box-shadow: 0 0 0 3px rgba(25, 118, 210, 0.1);
}

.form-textarea {
  resize: vertical;
  min-height: 100px;
}

/* Progress Bar */
.progress-bar {
  width: 100%;
  height: 8px;
  background: var(--border);
  border-radius: var(--radius-sm);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  background: linear-gradient(90deg, var(--primary-color), var(--primary-light));
  transition: width 0.3s ease;
}

/* Cards */
.card {
  background: white;
  border-radius: var(--radius-lg);
  padding: var(--spacing-xl);
  box-shadow: var(--shadow-sm);
  border: 1px solid var(--border);
}

/* Alerts */
.alert {
  padding: var(--spacing-md);
  border-radius: var(--radius-md);
  margin-bottom: var(--spacing-lg);
  border-left: 4px solid;
}

.alert-success {
  background: #e8f5e8;
  color: var(--success-color);
  border-left-color: var(--success-color);
}

.alert-error {
  background: #ffebee;
  color: var(--error-color);
  border-left-color: var(--error-color);
}

.alert-warning {
  background: #fff3e0;
  color: var(--warning-color);
  border-left-color: var(--warning-color);
}

/* Dark Mode */
.dark-mode {
  --background: var(--dark-bg);
  --surface: var(--dark-surface);
  --text-primary: var(--dark-text);
  --text-secondary: #b0b0b0;
  --border: #333;
}

.dark-mode .header {
  background: rgba(18, 18, 18, 0.95);
}

.dark-mode .form-input,
.dark-mode .form-select,
.dark-mode .form-textarea {
  background: var(--dark-surface);
  border-color: #333;
  color: var(--dark-text);
}

/* Responsive Design */
@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  
  .nav-toggle {
    display: block;
  }
  
  .hero .container {
    grid-template-columns: 1fr;
    text-align: center;
  }
  
  .hero-title {
    font-size: 2.5rem;
  }
  
  .hero-actions {
    flex-direction: column;
    align-items: center;
  }
  
  .hero-features {
    flex-direction: column;
    gap: var(--spacing-md);
  }
  
  .footer-content {
    grid-template-columns: 1fr;
    text-align: center;
  }
  
  .pricing-grid {
    grid-template-columns: 1fr;
  }
  
  .pricing-card.featured {
    transform: none;
  }
}

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

/* Animations */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.fade-in {
  animation: fadeIn 0.6s ease forwards;
}

@keyframes slideIn {
  from { transform: translateX(-100%); }
  to { transform: translateX(0); }
}

.slide-in {
  animation: slideIn 0.3s ease forwards;
}

/* Loading States */
.loading {
  position: relative;
  overflow: hidden;
}

.loading::after {
  content: '';
  position: absolute;
  top: 0;
  left: -100%;
  width: 100%;
  height: 100%;
  background: linear-gradient(90deg, transparent, rgba(255, 255, 255, 0.6), transparent);
  animation: loading 1.5s infinite;
}

@keyframes loading {
  0% { left: -100%; }
  100% { left: 100%; }
}

/* Hover Effects */
.hover-lift {
  transition: transform 0.2s ease;
}

.hover-lift:hover {
  transform: translateY(-2px);
}

/* Focus Styles */
.focus-ring:focus {
  outline: none;
  box-shadow: 0 0 0 3px rgba(25, 118, 210, 0.2);
}