:root {
  --bg: #0f172a;
  --panel: #1e293b;
  --panel-light: #27324a;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --accent: #60a5fa;
  --ok: #10b981;
  --touch: #f59e0b;
  --bad: #ef4444;
}

* {
  box-sizing: border-box;
}

html, body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
}

header {
  padding: 1.25rem 1.5rem 0.5rem;
  text-align: center;
}

header h1 {
  margin: 0 0 0.25rem;
  font-size: 1.6rem;
}

.tagline {
  margin: 0 auto;
  max-width: 42rem;
  color: var(--muted);
  font-size: 0.9rem;
}

.tagline a {
  color: var(--accent);
}

main {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 1rem;
  padding: 1rem 1rem 2rem;
}

#setup {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem 1.25rem;
  align-items: end;
  justify-content: center;
  background: var(--panel);
  border-radius: 0.75rem;
  padding: 0.9rem 1.25rem;
  width: min(100%, 640px);
}

#setup label {
  display: flex;
  flex-direction: column;
  gap: 0.25rem;
  font-size: 0.8rem;
  color: var(--muted);
}

select, input[type="number"] {
  background: var(--panel-light);
  color: var(--text);
  border: 1px solid #334155;
  border-radius: 0.4rem;
  padding: 0.35rem 0.5rem;
  font-size: 0.95rem;
}

input[type="number"] {
  width: 4.5rem;
}

button {
  background: var(--accent);
  color: #0f172a;
  border: none;
  border-radius: 0.4rem;
  padding: 0.5rem 0.9rem;
  font-size: 0.9rem;
  font-weight: 600;
  cursor: pointer;
}

button:hover {
  filter: brightness(1.08);
}

button:active {
  filter: brightness(0.95);
}

button:disabled {
  background: var(--panel-light);
  color: var(--muted);
  cursor: not-allowed;
  filter: none;
}

#board {
  width: min(100%, 640px);
  display: flex;
  justify-content: center;
}

canvas {
  background: var(--panel);
  border-radius: 0.75rem;
  touch-action: none;
  cursor: grab;
}

#controls {
  width: min(100%, 640px);
  background: var(--panel);
  border-radius: 0.75rem;
  padding: 0.9rem 1.25rem;
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
}

.slider-label {
  font-size: 0.8rem;
  color: var(--muted);
}

input[type="range"] {
  width: 100%;
}

#readouts {
  display: flex;
  flex-wrap: wrap;
  gap: 0.4rem 1rem;
  font-size: 0.9rem;
}

#readouts span {
  font-variant-numeric: tabular-nums;
}

#marginReadout.ok { color: var(--ok); font-weight: 600; }
#marginReadout.touch { color: var(--touch); font-weight: 600; }
#marginReadout.bad { color: var(--bad); font-weight: 600; }

#status {
  min-height: 1.1rem;
  color: var(--ok);
  font-size: 0.85rem;
  font-weight: 600;
}

footer {
  text-align: center;
  color: var(--muted);
  font-size: 0.8rem;
  padding: 0 1.5rem 2rem;
}

footer p {
  max-width: 42rem;
  margin: 0 auto;
}