/* ==============================================================================
   KindleRecs Marketing & Landing Design System
   Modern Obsidian Glassmorphism + Electric Neon Gradient Palette
   ============================================================================== */

@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&family=Outfit:wght@500;600;700;800;900&display=swap');

:root {
  --bg-dark: #070a12;
  --bg-card: rgba(15, 23, 42, 0.65);
  --bg-card-hover: rgba(30, 41, 59, 0.85);
  --border-subtle: rgba(255, 255, 255, 0.08);
  --border-glow: rgba(99, 102, 241, 0.35);

  --accent-indigo: #6366f1;
  --accent-violet: #8b5cf6;
  --accent-amber: #f59e0b;
  --accent-cyan: #06b6d4;
  --accent-emerald: #10b981;

  --text-main: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;

  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  --font-display: 'Outfit', sans-serif;

  --radius-lg: 20px;
  --radius-md: 14px;
  --radius-sm: 8px;
}

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

html {
  scroll-behavior: smooth;
  color-scheme: dark;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-dark);
  color: var(--text-main);
  line-height: 1.6;
  overflow-x: hidden;
  background-image: 
    radial-gradient(circle at 15% 10%, rgba(99, 102, 241, 0.12) 0%, transparent 40%),
    radial-gradient(circle at 85% 25%, rgba(139, 92, 246, 0.10) 0%, transparent 45%),
    radial-gradient(circle at 50% 75%, rgba(6, 182, 212, 0.07) 0%, transparent 50%);
  background-attachment: fixed;
}

/* Typography */
h1, h2, h3, h4, .brand-font {
  font-family: var(--font-display);
  letter-spacing: -0.025em;
  font-weight: 700;
  color: #ffffff;
}

.gradient-text {
  background: linear-gradient(135deg, #ffffff 0%, #cbd5e1 40%, #818cf8 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.gradient-accent {
  background: linear-gradient(135deg, #f59e0b 0%, #ec4899 50%, #8b5cf6 100%);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 24px;
}

/* Header & Nav */
header {
  position: sticky;
  top: 0;
  z-index: 100;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  background: rgba(7, 10, 18, 0.75);
  border-bottom: 1px solid var(--border-subtle);
  transition: all 0.3s ease;
}

.nav-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  height: 76px;
}

.logo-group {
  display: flex;
  align-items: center;
  gap: 12px;
  text-decoration: none;
}

.logo-img {
  width: 40px;
  height: 40px;
  border-radius: 10px;
  box-shadow: 0 4px 12px rgba(99, 102, 241, 0.3);
}

.logo-text {
  font-size: 1.35rem;
  font-weight: 800;
  background: linear-gradient(135deg, #ffffff, #a5b4fc);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 32px;
  list-style: none;
}

.nav-links a {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 0.95rem;
  font-weight: 500;
  transition: color 0.2s;
}

.nav-links a:hover {
  color: #ffffff;
}

.nav-cta {
  display: flex;
  align-items: center;
  gap: 12px;
}

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 24px;
  border-radius: 12px;
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  cursor: pointer;
  transition: all 0.25s cubic-bezier(0.16, 1, 0.3, 1);
  border: 1px solid transparent;
}

.btn-primary {
  background: linear-gradient(135deg, var(--accent-indigo), var(--accent-violet));
  color: #ffffff;
  box-shadow: 0 4px 20px rgba(99, 102, 241, 0.35);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 8px 30px rgba(99, 102, 241, 0.55);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.05);
  color: #ffffff;
  border-color: var(--border-subtle);
  backdrop-filter: blur(10px);
}

.btn-secondary:hover {
  background: rgba(255, 255, 255, 0.1);
  border-color: rgba(255, 255, 255, 0.2);
  transform: translateY(-2px);
}

.btn-lg {
  padding: 16px 32px;
  font-size: 1.05rem;
  border-radius: 14px;
}

/* Hero Section */
.hero-section {
  padding: 100px 0 80px;
  text-align: center;
  position: relative;
}

.badge-pill {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  padding: 6px 16px;
  border-radius: 9999px;
  background: rgba(99, 102, 241, 0.1);
  border: 1px solid rgba(99, 102, 241, 0.25);
  font-size: 0.85rem;
  font-weight: 600;
  color: #a5b4fc;
  margin-bottom: 24px;
}

.hero-title {
  font-size: clamp(2.5rem, 6vw, 4.25rem);
  line-height: 1.1;
  margin-bottom: 24px;
  font-weight: 800;
}

.hero-subtitle {
  font-size: clamp(1.1rem, 2vw, 1.35rem);
  color: var(--text-secondary);
  max-width: 740px;
  margin: 0 auto 40px;
}

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

.hero-visual {
  position: relative;
  max-width: 1000px;
  margin: 0 auto;
  border-radius: var(--radius-lg);
  overflow: hidden;
  box-shadow: 0 20px 60px rgba(0, 0, 0, 0.8), 0 0 80px rgba(99, 102, 241, 0.25);
  border: 1px solid rgba(255, 255, 255, 0.12);
}

.hero-visual img {
  width: 100%;
  display: block;
}

/* Interactive Preview Section */
.preview-section {
  padding: 100px 0;
  position: relative;
}

.section-head {
  text-align: center;
  margin-bottom: 60px;
}

.section-head h2 {
  font-size: clamp(2rem, 4vw, 3rem);
  margin-bottom: 16px;
}

.section-head p {
  color: var(--text-secondary);
  font-size: 1.15rem;
  max-width: 600px;
  margin: 0 auto;
}

/* Interactive Card Deck Mockup */
.deck-container {
  max-width: 480px;
  margin: 0 auto;
  position: relative;
  perspective: 1000px;
}

.swipe-card {
  background: var(--bg-card);
  border: 1px solid var(--border-glow);
  border-radius: var(--radius-lg);
  padding: 24px;
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  box-shadow: 0 16px 40px rgba(0, 0, 0, 0.6);
  transition: transform 0.4s cubic-bezier(0.175, 0.885, 0.32, 1.275), opacity 0.3s ease;
}

.card-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
}

.genre-tag {
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  padding: 4px 10px;
  border-radius: 6px;
  background: rgba(139, 92, 246, 0.15);
  color: #c4b5fd;
  border: 1px solid rgba(139, 92, 246, 0.3);
}

.library-badge {
  display: inline-flex;
  align-items: center;
  gap: 6px;
  font-size: 0.8rem;
  font-weight: 600;
  padding: 4px 10px;
  border-radius: 6px;
  background: rgba(16, 185, 129, 0.15);
  color: #6ee7b7;
  border: 1px solid rgba(16, 185, 129, 0.3);
}

.card-book-info {
  margin-bottom: 18px;
}

.card-book-title {
  font-size: 1.35rem;
  font-weight: 700;
  margin-bottom: 4px;
}

.card-book-author {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-bottom: 12px;
}

.card-summary {
  font-size: 0.9rem;
  color: #cbd5e1;
  line-height: 1.5;
  margin-bottom: 18px;
}

.similarity-pill {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  background: rgba(255, 255, 255, 0.04);
  font-size: 0.82rem;
  color: #a5b4fc;
}

.card-actions {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  margin-top: 24px;
}

.action-btn {
  width: 58px;
  height: 58px;
  border-radius: 50%;
  border: 1px solid var(--border-subtle);
  background: rgba(255, 255, 255, 0.05);
  color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.4rem;
  cursor: pointer;
  transition: all 0.2s ease;
}

.action-btn.dislike:hover {
  background: rgba(239, 68, 68, 0.2);
  border-color: rgba(239, 68, 68, 0.5);
  color: #f87171;
  transform: scale(1.1);
}

.action-btn.like:hover {
  background: rgba(16, 185, 129, 0.2);
  border-color: rgba(16, 185, 129, 0.5);
  color: #34d399;
  transform: scale(1.1);
}

/* Features Grid */
.features-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 30px;
}

.feature-card {
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 36px 30px;
  transition: all 0.3s ease;
  backdrop-filter: blur(12px);
}

.feature-card:hover {
  transform: translateY(-6px);
  background: var(--bg-card-hover);
  border-color: var(--border-glow);
  box-shadow: 0 12px 30px rgba(99, 102, 241, 0.15);
}

.feature-icon {
  width: 52px;
  height: 52px;
  border-radius: 14px;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 1.6rem;
  margin-bottom: 20px;
  background: rgba(99, 102, 241, 0.15);
  color: #818cf8;
  border: 1px solid rgba(99, 102, 241, 0.3);
}

.feature-card h3 {
  font-size: 1.35rem;
  margin-bottom: 12px;
}

.feature-card p {
  color: var(--text-secondary);
  font-size: 0.95rem;
}

/* How It Works */
.steps-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: 24px;
  margin-top: 40px;
}

.step-card {
  position: relative;
  background: rgba(15, 23, 42, 0.4);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 32px 24px;
}

.step-num {
  font-size: 2.5rem;
  font-weight: 900;
  font-family: var(--font-display);
  color: rgba(99, 102, 241, 0.25);
  margin-bottom: 12px;
}

.step-card h3 {
  font-size: 1.2rem;
  margin-bottom: 8px;
}

.step-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

/* CTA Banner */
.cta-banner {
  padding: 80px 40px;
  border-radius: var(--radius-lg);
  background: linear-gradient(135deg, rgba(99, 102, 241, 0.15), rgba(139, 92, 246, 0.15));
  border: 1px solid var(--border-glow);
  text-align: center;
  margin: 100px 0;
  backdrop-filter: blur(20px);
}

.cta-banner h2 {
  font-size: clamp(2rem, 4vw, 3rem);
  margin-bottom: 16px;
}

.cta-banner p {
  color: var(--text-secondary);
  font-size: 1.15rem;
  max-width: 600px;
  margin: 0 auto 36px;
}

/* Footer */
footer {
  border-top: 1px solid var(--border-subtle);
  padding: 60px 0 40px;
  color: var(--text-muted);
  font-size: 0.9rem;
}

.footer-top {
  display: flex;
  justify-content: space-between;
  align-items: center;
  flex-wrap: wrap;
  gap: 24px;
  margin-bottom: 40px;
}

.footer-links {
  display: flex;
  gap: 24px;
  list-style: none;
}

.footer-links a {
  color: var(--text-secondary);
  text-decoration: none;
  transition: color 0.2s;
}

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

/* Legal Pages */
.legal-content {
  max-width: 800px;
  margin: 60px auto 100px;
  background: var(--bg-card);
  border: 1px solid var(--border-subtle);
  border-radius: var(--radius-lg);
  padding: 48px;
}

.legal-content h1 {
  font-size: 2.5rem;
  margin-bottom: 8px;
}

.legal-content .meta {
  color: var(--text-muted);
  font-size: 0.9rem;
  margin-bottom: 36px;
}

.legal-content h2 {
  font-size: 1.4rem;
  margin: 28px 0 12px;
  color: #e2e8f0;
}

.legal-content p, .legal-content li {
  color: var(--text-secondary);
  margin-bottom: 16px;
  font-size: 1rem;
}

.legal-content ul {
  padding-left: 24px;
  margin-bottom: 24px;
}

@media (max-width: 768px) {
  .nav-links {
    display: none;
  }
  .legal-content {
    padding: 24px;
  }
}