/* Global Styles & Design System */
:root {
  --bg-dark: #0b0f19;
  --bg-card: rgba(22, 29, 47, 0.7);
  --bg-card-hover: rgba(30, 41, 67, 0.8);
  --border-color: rgba(255, 255, 255, 0.1);
  --border-glow: rgba(99, 102, 241, 0.4);
  
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  
  --accent-primary: #6366f1;
  --accent-secondary: #8b5cf6;
  --accent-cyan: #06b6d4;
  --accent-emerald: #10b981;
  --accent-rose: #f43f5e;
  --accent-amber: #f59e0b;
  
  --gradient-hero: linear-gradient(135deg, #6366f1 0%, #a855f7 50%, #ec4899 100%);
  --gradient-card: linear-gradient(180deg, rgba(30, 41, 59, 0.5) 0%, rgba(15, 23, 42, 0.8) 100%);
  --gradient-glow: radial-gradient(circle at 50% 0%, rgba(99, 102, 241, 0.15) 0%, transparent 70%);

  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', Consolas, monospace;
}

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

html {
  scroll-behavior: smooth;
  font-family: var(--font-sans);
  background-color: var(--bg-dark);
  color: var(--text-primary);
  line-height: 1.6;
}

body {
  min-height: 100vh;
  overflow-x: hidden;
  background-image: var(--gradient-glow);
  background-repeat: no-repeat;
  background-position: top center;
}

/* Container */
.container {
  max-width: 1120px;
  margin: 0 auto;
  padding: 0 1.5rem;
}

/* Header & Nav */
header {
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  background: rgba(11, 15, 25, 0.8);
  border-bottom: 1px solid var(--border-color);
}

.nav-container {
  display: flex;
  justify-content: space-between;
  align-items: center;
  height: 4rem;
}

.brand {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  font-size: 1.25rem;
  font-weight: 700;
  color: var(--text-primary);
  text-decoration: none;
}

.brand-icon {
  font-size: 1.5rem;
  filter: drop-shadow(0 0 8px rgba(99, 102, 241, 0.6));
}

.nav-links {
  display: flex;
  align-items: center;
  gap: 1.5rem;
  list-style: none;
}

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

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

/* Buttons */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  padding: 0.65rem 1.25rem;
  border-radius: 0.5rem;
  font-weight: 600;
  font-size: 0.95rem;
  text-decoration: none;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  cursor: pointer;
  border: 1px solid transparent;
}

.btn-primary {
  background: var(--gradient-hero);
  color: #fff;
  box-shadow: 0 4px 14px rgba(99, 102, 241, 0.35);
}

.btn-primary:hover {
  transform: translateY(-2px);
  box-shadow: 0 6px 20px rgba(99, 102, 241, 0.5);
}

.btn-secondary {
  background: rgba(255, 255, 255, 0.05);
  color: var(--text-primary);
  border-color: var(--border-color);
}

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

/* Hero Section */
.hero {
  padding: 5rem 0 3.5rem;
  text-align: center;
  position: relative;
}

.badge {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  padding: 0.35rem 0.9rem;
  border-radius: 9999px;
  background: rgba(99, 102, 241, 0.1);
  border: 1px solid rgba(99, 102, 241, 0.3);
  color: #a5b4fc;
  font-size: 0.85rem;
  font-weight: 500;
  margin-bottom: 1.5rem;
}

.badge-dot {
  width: 0.5rem;
  height: 0.5rem;
  border-radius: 50%;
  background-color: var(--accent-cyan);
  box-shadow: 0 0 8px var(--accent-cyan);
}

.hero-title {
  font-size: clamp(2.5rem, 5vw, 4rem);
  font-weight: 800;
  line-height: 1.15;
  margin-bottom: 1.5rem;
  letter-spacing: -0.02em;
}

.hero-title .gradient-text {
  background: var(--gradient-hero);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
}

.hero-subtitle {
  font-size: 1.2rem;
  color: var(--text-secondary);
  max-width: 780px;
  margin: 0 auto 2.5rem;
  line-height: 1.7;
}

.hero-cta {
  display: flex;
  justify-content: center;
  gap: 1rem;
  flex-wrap: wrap;
}

/* Section Headings */
.section {
  padding: 4rem 0;
}

.section-header {
  text-align: center;
  max-width: 680px;
  margin: 0 auto 3rem;
}

.section-title {
  font-size: 2.25rem;
  font-weight: 700;
  margin-bottom: 0.75rem;
  letter-spacing: -0.01em;
}

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

/* Cost-Gap Metrics Grid */
.metrics-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(240px, 1fr));
  gap: 1.5rem;
  margin-bottom: 2rem;
}

.metric-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 1rem;
  padding: 1.75rem;
  position: relative;
  overflow: hidden;
  transition: all 0.3s ease;
  backdrop-filter: blur(8px);
}

.metric-card:hover {
  transform: translateY(-4px);
  border-color: var(--border-glow);
  box-shadow: 0 10px 30px rgba(0, 0, 0, 0.4);
}

.metric-card.under-estimate {
  border-left: 4px solid var(--accent-rose);
}

.metric-card.over-estimate {
  border-left: 4px solid var(--accent-amber);
}

.metric-card.ground-truth {
  border-left: 4px solid var(--accent-emerald);
  background: linear-gradient(180deg, rgba(16, 185, 129, 0.08) 0%, rgba(15, 23, 42, 0.8) 100%);
}

.metric-label {
  font-size: 0.875rem;
  color: var(--text-secondary);
  font-weight: 500;
  margin-bottom: 0.5rem;
}

.metric-value {
  font-family: var(--font-mono);
  font-size: 2rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
  color: var(--text-primary);
}

.metric-delta {
  display: inline-flex;
  align-items: center;
  gap: 0.25rem;
  padding: 0.2rem 0.5rem;
  border-radius: 0.375rem;
  font-size: 0.85rem;
  font-family: var(--font-mono);
  font-weight: 600;
}

.metric-delta.danger {
  background: rgba(244, 63, 94, 0.15);
  color: #fda4af;
}

.metric-delta.warning {
  background: rgba(245, 158, 11, 0.15);
  color: #fde047;
}

.metric-delta.success {
  background: rgba(16, 185, 129, 0.15);
  color: #6ee7b7;
}

.metric-context {
  font-size: 0.8rem;
  color: var(--text-muted);
  margin-top: 0.75rem;
}

/* Callout Box */
.callout-box {
  background: rgba(245, 158, 11, 0.08);
  border: 1px solid rgba(245, 158, 11, 0.3);
  border-radius: 0.75rem;
  padding: 1.25rem 1.5rem;
  display: flex;
  gap: 1rem;
  align-items: flex-start;
  margin-top: 1.5rem;
}

.callout-icon {
  font-size: 1.5rem;
  flex-shrink: 0;
}

.callout-text {
  font-size: 0.95rem;
  color: #fef08a;
  line-height: 1.6;
}

/* Two-Tier Cards */
.tiers-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(320px, 1fr));
  gap: 2rem;
}

.tier-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 1rem;
  padding: 2.25rem;
  position: relative;
  transition: all 0.3s ease;
  display: flex;
  flex-direction: column;
}

.tier-card:hover {
  border-color: var(--border-glow);
  transform: translateY(-4px);
  box-shadow: 0 12px 36px rgba(0, 0, 0, 0.4);
}

.tier-tag {
  align-self: flex-start;
  padding: 0.25rem 0.75rem;
  border-radius: 9999px;
  font-size: 0.75rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  margin-bottom: 1.25rem;
}

.tier-tag.tier-a {
  background: rgba(99, 102, 241, 0.15);
  color: #a5b4fc;
  border: 1px solid rgba(99, 102, 241, 0.3);
}

.tier-tag.tier-b {
  background: rgba(6, 182, 212, 0.15);
  color: #67e8f9;
  border: 1px solid rgba(6, 182, 212, 0.3);
}

.tier-title {
  font-size: 1.5rem;
  font-weight: 700;
  margin-bottom: 0.5rem;
}

.tier-subtitle {
  font-size: 0.95rem;
  color: var(--accent-cyan);
  font-weight: 500;
  margin-bottom: 1rem;
}

.tier-desc {
  color: var(--text-secondary);
  font-size: 0.95rem;
  margin-bottom: 1.5rem;
  flex-grow: 1;
}

.tier-features {
  list-style: none;
  display: flex;
  flex-direction: column;
  gap: 0.75rem;
  margin-top: auto;
}

.tier-features li {
  display: flex;
  align-items: flex-start;
  gap: 0.6rem;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.tier-features li::before {
  content: "✓";
  color: var(--accent-emerald);
  font-weight: bold;
}

/* Quick Start / Code Blocks */
.quickstart-container {
  background: rgba(15, 23, 42, 0.95);
  border: 1px solid var(--border-color);
  border-radius: 1rem;
  overflow: hidden;
  box-shadow: 0 20px 40px rgba(0, 0, 0, 0.5);
  margin-bottom: 2rem;
}

.code-header {
  background: rgba(30, 41, 59, 0.6);
  padding: 0.75rem 1.25rem;
  display: flex;
  justify-content: space-between;
  align-items: center;
  border-bottom: 1px solid var(--border-color);
}

.code-title {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--text-secondary);
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.copy-btn {
  background: rgba(255, 255, 255, 0.05);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  padding: 0.35rem 0.75rem;
  border-radius: 0.375rem;
  font-size: 0.8rem;
  cursor: pointer;
  transition: all 0.2s ease;
  font-family: var(--font-sans);
}

.copy-btn:hover {
  background: rgba(255, 255, 255, 0.15);
  color: var(--text-primary);
}

pre {
  padding: 1.25rem;
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.9rem;
  line-height: 1.6;
  color: #e2e8f0;
}

code {
  font-family: var(--font-mono);
}

.token-keyword { color: #c084fc; }
.token-function { color: #60a5fa; }
.token-string { color: #4ade80; }
.token-number { color: #facc15; }
.token-comment { color: #64748b; font-style: italic; }
.token-macro { color: #f472b6; }

/* Demo Section */
.demo-box {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 1rem;
  padding: 1.5rem;
  text-align: center;
}

.demo-player-wrapper {
  position: relative;
  padding-bottom: 56.25%; /* 16:9 aspect ratio */
  height: 0;
  overflow: hidden;
  border-radius: 0.75rem;
  border: 1px solid var(--border-color);
  background: #000;
}

.demo-player-wrapper iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: 0;
}

.demo-fallback {
  margin-top: 1rem;
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.demo-fallback a {
  color: var(--accent-cyan);
  text-decoration: underline;
}

/* Links & Footer */
footer {
  border-top: 1px solid var(--border-color);
  padding: 3rem 0;
  margin-top: 4rem;
  background: rgba(11, 15, 25, 0.95);
}

.footer-container {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 1.5rem;
}

.footer-brand {
  display: flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 600;
  color: var(--text-secondary);
}

.footer-links {
  display: flex;
  gap: 1.5rem;
  list-style: none;
}

.footer-link {
  color: var(--text-muted);
  text-decoration: none;
  font-size: 0.9rem;
  transition: color 0.2s ease;
}

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

/* Responsive adjustments */
@media (max-width: 768px) {
  .hero-title {
    font-size: 2.25rem;
  }
  
  .nav-links {
    gap: 1rem;
  }
  
  .btn {
    width: 100%;
  }

  .hero-cta {
    flex-direction: column;
  }
}