/* CSS Variables for Light/Dark Mode */
:root {
  /* Light mode colors */
  --bg-primary: #ffffff;
  --bg-secondary: #f8fafc;
  --bg-tertiary: #f1f5f9;
  --text-primary: #0f172a;
  --text-secondary: #475569;
  --text-muted: #64748b;
  --border: #e2e8f0;
  --shadow: rgba(0, 0, 0, 0.1);
  --accent: #3b82f6;
  --accent-hover: #2563eb;
  --gradient-start: #3b82f6;
  --gradient-end: #8b5cf6;
}

[data-theme="dark"] {
  /* Dark mode colors */
  --bg-primary: #0f172a;
  --bg-secondary: #1e293b;
  --bg-tertiary: #334155;
  --text-primary: #f8fafc;
  --text-secondary: #cbd5e1;
  --text-muted: #94a3b8;
  --border: #475569;
  --shadow: rgba(0, 0, 0, 0.3);
  --accent: #60a5fa;
  --accent-hover: #3b82f6;
  --gradient-start: #60a5fa;
  --gradient-end: #a78bfa;
}

/* Reset and Base Styles */
* {
  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(--bg-primary);
  transition: background-color 0.3s ease, color 0.3s ease;
}

.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 2rem;
}

/* Header */
.header {
  background: var(--bg-primary);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(10px);
}

.nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 0;
}

.logo-text {
  font-size: 1.5rem;
  font-weight: 700;
  color: var(--text-primary);
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 2rem;
}

.nav-links a {
  text-decoration: none;
  color: var(--text-secondary);
  font-weight: 500;
  transition: color 0.3s ease;
}

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

.theme-toggle {
  background: none;
  border: none;
  font-size: 1.5rem;
  cursor: pointer;
  padding: 0.5rem;
  border-radius: 50%;
  transition: background-color 0.3s ease;
}

.theme-toggle:hover {
  background-color: var(--bg-tertiary);
}

/* Hero Section */
.hero {
  padding: 4rem 0;
  background: linear-gradient(135deg, var(--bg-primary) 0%, var(--bg-secondary) 100%);
}

.hero-content {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 4rem;
  align-items: center;
  min-height: 70vh;
}

.hero-title {
  font-size: 3.5rem;
  font-weight: 700;
  line-height: 1.2;
  margin-bottom: 1.5rem;
}

.gradient-text {
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.hero-subtitle {
  font-size: 1.25rem;
  color: var(--text-secondary);
  margin-bottom: 2rem;
  line-height: 1.7;
}

.hero-buttons {
  display: flex;
  gap: 1rem;
  flex-wrap: wrap;
}

.btn {
  padding: 0.875rem 2rem;
  border: none;
  border-radius: 0.5rem;
  font-size: 1rem;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.3s ease;
  text-decoration: none;
  display: inline-block;
  text-align: center;
}

.btn-primary {
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  color: white;
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 10px 25px var(--shadow);
}

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

.btn-secondary:hover {
  background: var(--bg-tertiary);
  transform: translateY(-2px);
}

.btn-large {
  padding: 1.25rem 3rem;
  font-size: 1.125rem;
}

/* Book Showcase */
.book-showcase {
  perspective: 1000px;
}

.book-cover {
  width: 300px;
  height: 400px;
  background: var(--bg-secondary);
  border-radius: 1rem;
  box-shadow: 0 20px 40px var(--shadow);
  position: relative;
  transform: rotateY(-15deg) rotateX(5deg);
  transition: transform 0.3s ease;
  cursor: pointer;
}

.book-cover:hover {
  transform: rotateY(-5deg) rotateX(2deg);
}

.book-spine {
  position: absolute;
  left: -10px;
  top: 0;
  width: 20px;
  height: 100%;
  background: var(--gradient-start);
  border-radius: 10px 0 0 10px;
}

.book-content {
  padding: 2rem;
  height: 100%;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  align-items: center;
}

.book-title {
  font-family: 'Crimson Text', serif;
  font-size: 1.5rem;
  font-weight: 600;
  text-align: center;
  color: var(--text-primary);
}

.book-illustration {
  font-size: 4rem;
  text-align: center;
}

/* Features Section */
.features {
  padding: 6rem 0;
  background: var(--bg-secondary);
}

.section-title {
  font-size: 2.5rem;
  font-weight: 700;
  text-align: center;
  margin-bottom: 3rem;
  color: var(--text-primary);
}

.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: 2rem;
}

.feature-card {
  background: var(--bg-primary);
  padding: 2.5rem;
  border-radius: 1rem;
  border: 1px solid var(--border);
  text-align: center;
  transition: transform 0.3s ease, box-shadow 0.3s ease;
}

.feature-card:hover {
  transform: translateY(-5px);
  box-shadow: 0 15px 30px var(--shadow);
}

.feature-icon {
  font-size: 3rem;
  margin-bottom: 1rem;
}

.feature-card h3 {
  font-size: 1.5rem;
  font-weight: 600;
  margin-bottom: 1rem;
  color: var(--text-primary);
}

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

/* How It Works Section */
.how-it-works {
  padding: 6rem 0;
  background: var(--bg-primary);
}

.steps {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
  gap: 2rem;
  margin-top: 3rem;
}

.step {
  text-align: center;
  padding: 2rem;
}

.step-number {
  width: 60px;
  height: 60px;
  background: linear-gradient(135deg, var(--gradient-start), var(--gradient-end));
  color: white;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.5rem;
  font-weight: 700;
  margin: 0 auto 1rem;
}

.step h3 {
  font-size: 1.25rem;
  font-weight: 600;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

.step p {
  color: var(--text-secondary);
}

/* CTA Section */
.cta {
  padding: 6rem 0;
  background: linear-gradient(135deg, var(--bg-secondary) 0%, var(--bg-tertiary) 100%);
  text-align: center;
}

.cta-content h2 {
  font-size: 2.5rem;
  font-weight: 700;
  margin-bottom: 1rem;
  color: var(--text-primary);
}

.cta-content p {
  font-size: 1.25rem;
  color: var(--text-secondary);
  margin-bottom: 2rem;
}

/* Footer */
.footer {
  background: var(--bg-secondary);
  padding: 2rem 0;
  text-align: center;
  border-top: 1px solid var(--border);
}

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

/* Responsive Design */
@media (max-width: 768px) {
  .hero-content {
    grid-template-columns: 1fr;
    text-align: center;
  }
  
  .hero-title {
    font-size: 2.5rem;
  }
  
  .book-cover {
    width: 250px;
    height: 350px;
  }
  
  .nav-links {
    gap: 1rem;
  }
  
  .hero-buttons {
    justify-content: center;
  }
  
  .features-grid {
    grid-template-columns: 1fr;
  }
  
  .steps {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 480px) {
  .container {
    padding: 0 1rem;
  }
  
  .hero-title {
    font-size: 2rem;
  }
  
  .section-title {
    font-size: 2rem;
  }
}