:root {
  --bg: #0a0a0a;
  --surface: #111;
  --card: #161616;
  --border: #1e1e1e;
  --text: #c8c8c8;
  --dim: #555;
  --accent: #00d4aa;
  --red: #e84057;
  --font: 'JetBrains Mono', monospace;
}

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

body {
  background: var(--bg);
  color: var(--text);
  font-family: var(--font);
  font-size: 14px;
  line-height: 1.6;
}

/* ── nav ── */

nav {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem 2rem;
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  background: var(--bg);
  z-index: 100;
}

.nav-logo {
  color: var(--accent);
  text-decoration: none;
  font-weight: 700;
  font-size: 1rem;
  letter-spacing: 3px;
  flex-shrink: 0;
}

.nav-links {
  display: flex;
  gap: 1.5rem;
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.nav-links a {
  color: var(--dim);
  text-decoration: none;
  font-size: 0.8rem;
  letter-spacing: 1px;
  transition: color 0.15s;
  white-space: nowrap;
}

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

/* ── hero ── */

.hero {
  text-align: center;
  padding: 6rem 2rem 2rem;
}

.hero h1 {
  font-size: 2.2rem;
  font-weight: 300;
  letter-spacing: 5px;
  text-transform: lowercase;
}

.tagline {
  color: var(--dim);
  font-size: 0.8rem;
  letter-spacing: 2px;
  margin-top: 0.75rem;
}

/* ── intro ── */

.intro {
  max-width: 640px;
  margin: 0 auto;
  padding: 1.5rem 2rem 3rem;
  text-align: center;
}

.intro p {
  color: var(--dim);
  font-size: 0.78rem;
  line-height: 1.8;
}

/* ── category ── */

.category {
  max-width: 1100px;
  margin: 0 auto;
  padding: 0 2rem 3rem;
}

.category-header {
  display: flex;
  align-items: baseline;
  gap: 1rem;
  margin-bottom: 1rem;
  padding-bottom: 0.5rem;
  border-bottom: 1px solid var(--border);
}

.category-header h2 {
  font-size: 0.85rem;
  font-weight: 500;
  letter-spacing: 2px;
  color: var(--accent);
  text-transform: lowercase;
}

.category-header p {
  font-size: 0.7rem;
  color: var(--dim);
}

/* ── grid ── */

.grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(260px, 1fr));
  gap: 1px;
}

.card {
  background: var(--card);
  border: 1px solid var(--border);
  padding: 1.75rem;
  text-decoration: none;
  color: var(--text);
  transition: border-color 0.3s, background 0.3s;
}

.card:hover {
  border-color: var(--accent);
  background: #1a1a1a;
}

.card h3 {
  font-weight: 500;
  font-size: 0.95rem;
  margin-bottom: 0.5rem;
  color: var(--accent);
  letter-spacing: 1px;
}

.card p {
  font-size: 0.78rem;
  color: var(--dim);
  line-height: 1.5;
}

/* ── viz page ── */

.viz-page {
  max-width: 960px;
  margin: 0 auto;
  padding: 1.75rem;
}

.viz-page header { margin-bottom: 2rem; }

.viz-page h1 {
  font-size: 1.3rem;
  font-weight: 400;
  letter-spacing: 2px;
}

.subtitle {
  color: var(--dim);
  font-size: 0.8rem;
  margin-top: 0.25rem;
}

/* ── explanation ── */

.explanation {
  color: var(--dim);
  font-size: 0.75rem;
  line-height: 1.7;
  margin-bottom: 2rem;
  max-width: 640px;
}

.explanation p { margin-bottom: 0.5rem; }

.explanation code {
  color: var(--text);
  font-size: 0.72rem;
  background: var(--surface);
  padding: 0.15rem 0.35rem;
  border-radius: 2px;
}

.explanation .formula {
  color: var(--accent);
  font-size: 0.78rem;
  margin: 0.5rem 0;
  padding-left: 0.75rem;
  border-left: 1px solid var(--border);
}

/* ── data indicator ── */

.data-indicator {
  display: inline-flex;
  align-items: center;
  gap: 0.35rem;
  font-size: 0.65rem;
  color: var(--dim);
  letter-spacing: 0.5px;
  margin-bottom: 1rem;
}

.data-indicator .dot {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: var(--dim);
}

.data-indicator.live .dot { background: var(--accent); }
.data-indicator.precomputed .dot { background: #f0c040; }

/* ── canvas ── */

canvas {
  background: var(--surface);
  border: 1px solid var(--border);
  display: block;
}

.canvas-wrap {
  width: 100%;
  max-width: 600px;
}

.canvas-wrap canvas { width: 100%; height: auto; }

.canvas-row {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 1.5rem;
  margin-bottom: 1.5rem;
}

.canvas-row h3 {
  font-size: 0.75rem;
  font-weight: 400;
  color: var(--dim);
  margin-bottom: 0.5rem;
  letter-spacing: 1px;
}

.canvas-row canvas { width: 100%; height: auto; }

/* ── stats ── */

.stats {
  display: flex;
  gap: 2.5rem;
  margin: 1.5rem 0;
  flex-wrap: wrap;
}

.stat { display: flex; flex-direction: column; gap: 0.2rem; }

.stat .label {
  font-size: 0.7rem;
  color: var(--dim);
  letter-spacing: 1px;
}

.stat .value {
  font-size: 1.15rem;
  color: var(--accent);
  font-weight: 500;
  font-variant-numeric: tabular-nums;
}

/* ── controls ── */

.controls {
  display: flex;
  gap: 1rem;
  align-items: center;
  flex-wrap: wrap;
  margin-top: 1.5rem;
}

button {
  background: transparent;
  border: 1px solid var(--border);
  color: var(--text);
  font-family: var(--font);
  font-size: 0.78rem;
  padding: 0.45rem 1.1rem;
  cursor: pointer;
  transition: border-color 0.2s, color 0.2s;
  letter-spacing: 1px;
}

button:hover { border-color: var(--accent); color: var(--accent); }
button:disabled { opacity: 0.3; cursor: not-allowed; }
button.active { border-color: var(--accent); color: var(--accent); }

input[type="range"] {
  -webkit-appearance: none;
  background: var(--border);
  height: 2px;
  outline: none;
  width: 100px;
}

input[type="range"]::-webkit-slider-thumb {
  -webkit-appearance: none;
  width: 10px;
  height: 10px;
  background: var(--accent);
  border-radius: 50%;
  cursor: pointer;
}

input[type="number"], select {
  background: var(--surface);
  border: 1px solid var(--border);
  color: var(--text);
  font-family: var(--font);
  font-size: 0.78rem;
  padding: 0.4rem 0.5rem;
  width: 4.5rem;
  outline: none;
}

input[type="number"]:focus, select:focus { border-color: var(--accent); }
select { width: auto; }

label {
  font-size: 0.75rem;
  color: var(--dim);
  display: flex;
  align-items: center;
  gap: 0.4rem;
}

/* ── blackjack ── */

.table {
  display: flex;
  flex-direction: column;
  gap: 2.5rem;
  align-items: center;
  padding: 1.5rem 0;
  min-height: 300px;
}

.dealer-area, .player-area { text-align: center; }

.dealer-area h3, .player-area h3 {
  font-size: 0.75rem;
  font-weight: 400;
  color: var(--dim);
  margin-bottom: 0.75rem;
  letter-spacing: 1px;
}

.hand {
  display: flex;
  gap: 0.5rem;
  justify-content: center;
  min-height: 110px;
  align-items: center;
}

.playing-card {
  width: 72px;
  height: 100px;
  background: #f5f5f0;
  border-radius: 5px;
  display: flex;
  flex-direction: column;
  justify-content: space-between;
  padding: 5px 7px;
  font-size: 0.85rem;
  font-weight: 700;
  color: #111;
  box-shadow: 0 1px 4px rgba(0,0,0,0.4);
  user-select: none;
}

.playing-card.red { color: var(--red); }

.playing-card.face-down {
  background: linear-gradient(145deg, #1a1a2e 25%, #16213e 50%, #1a1a2e 75%);
  border: 1px solid var(--border);
}

.playing-card .rank-suit { font-size: 0.8rem; line-height: 1; }
.playing-card .center-suit {
  font-size: 1.4rem;
  text-align: center;
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
}
.playing-card .rank-suit-flip {
  font-size: 0.8rem;
  text-align: right;
  transform: rotate(180deg);
  line-height: 1;
}

.total {
  margin-top: 0.5rem;
  font-size: 1rem;
  color: var(--accent);
  min-height: 1.5rem;
}

.game-info {
  display: flex;
  justify-content: center;
  gap: 3rem;
  margin: 0.5rem 0;
}

#bet-controls, #action-controls {
  display: flex;
  gap: 0.5rem;
  justify-content: center;
}

#message {
  text-align: center;
  margin-top: 1rem;
  font-size: 0.9rem;
  min-height: 1.5rem;
  color: var(--accent);
  letter-spacing: 1px;
}

#message.loss { color: var(--red); }

/* ── responsive ── */

@media (max-width: 640px) {
  .canvas-row { grid-template-columns: 1fr; }
  .hero h1 { font-size: 1.4rem; letter-spacing: 3px; }
  .hero { padding: 4rem 1.5rem 1.5rem; }
  nav { padding: 0.75rem 1rem; }
  .nav-links { gap: 0.75rem; }
  .nav-links a { font-size: 0.7rem; }
  .stats { gap: 1.25rem; }
  .stat .value { font-size: 1rem; }
  .game-info { gap: 1.5rem; }
  .playing-card { width: 54px; height: 76px; font-size: 0.7rem; }
  .playing-card .center-suit { font-size: 1.1rem; }
  .grid { grid-template-columns: 1fr; }
  .viz-page { padding: 1rem; }
  .category { padding: 0 1rem 2rem; }
  .intro { padding: 1rem 1.5rem 2rem; }
  .controls { gap: 0.5rem; }
  .controls label { font-size: 0.7rem; }
  input[type="range"] { width: 70px; }
  .explanation { font-size: 0.7rem; }
  .category-header { flex-direction: column; gap: 0.25rem; }
}