:root {
  --color-bg: #0f172a;
  --color-surface: #1e293b;
  --color-text: #f1f5f9;
  --color-text-muted: #94a3b8;
  --color-primary: #3b82f6;
  --color-primary-hover: #2563eb;
  --color-secondary: #64748b;
  --color-border: #334155;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif;
  --font-mono: "SF Mono", Monaco, monospace;
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --radius: 0.5rem;
}

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

html {
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-sans);
  background: var(--color-bg);
  color: var(--color-text);
  line-height: 1.6;
}

/* Skip link */
.skip-link {
  position: absolute;
  top: -40px;
  left: 0;
  background: var(--color-primary);
  color: white;
  padding: var(--space-2) var(--space-4);
  z-index: 100;
  transition: top 0.2s;
}
.skip-link:focus {
  top: 0;
}

/* Focus visible */
:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* Reduced motion */
@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }
  *, *::before, *::after {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Light mode */
@media (prefers-color-scheme: light) {
  :root {
    --color-bg: #f8fafc;
    --color-surface: #ffffff;
    --color-text: #0f172a;
    --color-text-muted: #64748b;
    --color-primary: #2563eb;
    --color-primary-hover: #1d4ed8;
    --color-secondary: #94a3b8;
    --color-border: #e2e8f0;
  }
  .code-block {
    background: #f1f5f9;
    color: #0f172a;
  }
}

a {
  color: var(--color-primary);
  text-decoration: none;
}

a:hover {
  text-decoration: underline;
}

/* Hero */
.hero {
  text-align: center;
  padding: var(--space-16) var(--space-4);
  background: linear-gradient(180deg, var(--color-bg) 0%, var(--color-surface) 100%);
  border-bottom: 1px solid var(--color-border);
}

.hero h1 {
  font-size: 3rem;
  font-weight: 800;
  margin-bottom: var(--space-4);
}

.hero .tagline {
  font-size: 1.25rem;
  color: var(--color-text-muted);
  max-width: 600px;
  margin: 0 auto var(--space-2);
}

.hero .subtitle {
  font-size: 1rem;
  color: var(--color-text-muted);
  margin-bottom: var(--space-8);
}

.cta {
  display: flex;
  gap: var(--space-4);
  justify-content: center;
  flex-wrap: wrap;
}

.btn-primary,
.btn-secondary {
  padding: var(--space-3) var(--space-6);
  border-radius: var(--radius);
  font-weight: 600;
  transition: background 0.2s;
}

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

.btn-primary:hover {
  background: var(--color-primary-hover);
  text-decoration: none;
}

.btn-secondary {
  background: var(--color-surface);
  color: var(--color-text);
  border: 1px solid var(--color-border);
}

.btn-secondary:hover {
  background: var(--color-border);
  text-decoration: none;
}

/* Sections */
section {
  padding: var(--space-12) var(--space-4);
  max-width: 1100px;
  margin: 0 auto;
}

section h2 {
  font-size: 2rem;
  margin-bottom: var(--space-8);
  text-align: center;
}

/* Cards */
.cards {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(280px, 1fr));
  gap: var(--space-6);
}

.card {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-6);
  text-align: center;
}

.card .icon {
  font-size: 2.5rem;
  margin-bottom: var(--space-4);
}

.card h3 {
  font-size: 1.25rem;
  margin-bottom: var(--space-2);
}

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

/* Pipeline */
.phases {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: var(--space-4);
  align-items: stretch;
}

.phases .phase-arrow {
  display: none;
}

.phase {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-4) var(--space-6);
  text-align: center;
  min-width: 200px;
}

.phase-num {
  display: block;
  font-size: 0.875rem;
  color: var(--color-primary);
  font-weight: 700;
  margin-bottom: var(--space-1);
}

.phase h3 {
  font-size: 1.125rem;
  margin-bottom: var(--space-1);
}

.phase-output {
  font-size: 0.875rem;
  color: var(--color-text-muted);
}

.phase-time {
  font-size: 0.75rem;
  color: var(--color-secondary);
  margin-top: var(--space-1);
}

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

.phase-total {
  text-align: center;
  margin-top: var(--space-6);
  color: var(--color-text-muted);
  font-size: 1.125rem;
}

/* Concepts */
.concepts {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
  gap: var(--space-6);
}

.concept {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-6);
}

.concept h3 {
  font-size: 1.125rem;
  margin-bottom: var(--space-2);
  color: var(--color-primary);
}

.concept p {
  color: var(--color-text-muted);
  font-size: 0.95rem;
}

/* Quickstart */
.quickstart {
  display: flex;
  flex-direction: column;
  gap: var(--space-6);
  max-width: 700px;
  margin: 0 auto;
}

.step {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-6);
  display: flex;
  gap: var(--space-4);
  align-items: flex-start;
}

.step-num {
  background: var(--color-primary);
  color: white;
  width: 2rem;
  height: 2rem;
  border-radius: 50%;
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  flex-shrink: 0;
}

.step h3 {
  font-size: 1.125rem;
  margin-bottom: var(--space-2);
}

.code-block {
  background: #0b1220;
  border: 1px solid var(--color-border);
  border-left: 4px solid var(--color-primary);
  border-radius: var(--radius);
  padding: var(--space-4);
  overflow-x: auto;
  font-family: var(--font-mono);
  font-size: 0.875rem;
  color: #ffffff;
  white-space: pre-wrap;
  overflow-wrap: break-word;
}

.quickstart-output {
  text-align: center;
  color: var(--color-text-muted);
  margin-top: var(--space-4);
}

/* Coverage */
.coverage {
  text-align: center;
}

.badges {
  display: flex;
  gap: var(--space-4);
  justify-content: center;
  margin-bottom: var(--space-8);
  flex-wrap: wrap;
}

.badge {
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius);
  padding: var(--space-2) var(--space-4);
  font-size: 0.875rem;
  font-weight: 600;
}

.badge.pass {
  color: #22c55e;
  border-color: rgba(34, 197, 94, 0.3);
}

.badge.mit {
  color: var(--color-primary);
  border-color: rgba(59, 130, 246, 0.3);
}

.table-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
  margin: 0 calc(-1 * var(--space-4));
  padding: 0 var(--space-4);
}

.coverage-table {
  width: 100%;
  max-width: 600px;
  margin: 0 auto;
  border-collapse: collapse;
  font-size: 0.95rem;
  min-width: 400px;
}

.coverage-table th,
.coverage-table td {
  padding: var(--space-3) var(--space-4);
  border-bottom: 1px solid var(--color-border);
  text-align: left;
}

.coverage-table th {
  color: var(--color-text-muted);
  font-weight: 600;
  font-size: 0.875rem;
  text-transform: uppercase;
  letter-spacing: 0.05em;
  background: var(--color-surface);
  position: sticky;
  top: 0;
}

.coverage-table tbody tr:nth-child(odd) {
  background: rgba(255, 255, 255, 0.02);
}

.coverage-table tbody tr:hover {
  background: rgba(59, 130, 246, 0.08);
}

.coverage-table .total td {
  border-top: 2px solid var(--color-border);
  font-weight: 700;
}

/* Footer */
footer {
  text-align: center;
  padding: var(--space-12) var(--space-4);
  border-top: 1px solid var(--color-border);
  background: var(--color-surface);
}

footer .links {
  display: flex;
  gap: var(--space-6);
  justify-content: center;
  margin-bottom: var(--space-6);
  flex-wrap: wrap;
}

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

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

footer .license {
  color: var(--color-text-muted);
  font-size: 0.875rem;
  margin-bottom: var(--space-2);
}

footer .attribution {
  color: var(--color-secondary);
  font-size: 0.75rem;
}

/* Tablet */
@media (min-width: 641px) and (max-width: 1023px) {
  .phases {
    grid-template-columns: repeat(3, 1fr);
  }
}

/* Desktop */
@media (min-width: 1024px) {
  .phases {
    grid-template-columns: repeat(5, 1fr);
  }
}

/* Mobile */
@media (max-width: 640px) {
  .hero h1 {
    font-size: 2rem;
  }

  .hero .tagline {
    font-size: 1rem;
  }

  section {
    padding: var(--space-8) var(--space-4);
  }

  section h2 {
    font-size: 1.5rem;
  }

  .cards {
    grid-template-columns: 1fr;
  }

  .concepts {
    grid-template-columns: 1fr;
  }

  .phases {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: var(--space-2);
  }

  .phases .phase-arrow {
    display: block;
  }

  .step {
    flex-direction: column;
  }

  footer .links {
    flex-direction: column;
    gap: var(--space-2);
  }
}