:root {
  --bg: #0f1117;
  --panel: #171a23;
  --border: #2a2e3a;
  --accent: #4fd1c5;
  --accent-dark: #38a89d;
  --text: #e6e9ef;
  --text-dim: #9aa1ae;
  --cell-alive: #4fd1c5;
  --cell-dead: #1c1f29;
}

* {
  box-sizing: border-box;
}

body {
  margin: 0;
  min-height: 100vh;
  background: var(--bg);
  color: var(--text);
  font-family: "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  display: flex;
  justify-content: center;
  padding: 24px 16px 48px;
}

.app {
  width: 100%;
  max-width: 960px;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
}

header {
  text-align: center;
}

header h1 {
  margin: 0 0 4px;
  font-size: 1.8rem;
  letter-spacing: 0.5px;
}

.subtitle {
  margin: 0;
  color: var(--text-dim);
  font-size: 0.9rem;
}

.stats {
  display: flex;
  gap: 24px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 10px 20px;
  font-size: 0.9rem;
  color: var(--text-dim);
}

.stats strong {
  color: var(--accent);
}

#grid-canvas {
  background: var(--cell-dead);
  border: 1px solid var(--border);
  border-radius: 8px;
  max-width: 100%;
  cursor: pointer;
  image-rendering: pixelated;
}

.controls {
  width: 100%;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  justify-content: center;
  gap: 12px;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 14px 18px;
}

button {
  background: #23283a;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 8px 16px;
  font-size: 0.9rem;
  cursor: pointer;
  transition: background 0.15s ease, border-color 0.15s ease;
}

button:hover {
  border-color: var(--accent);
}

button.primary {
  background: var(--accent-dark);
  border-color: var(--accent-dark);
  color: #05201d;
  font-weight: 600;
}

button.primary:hover {
  background: var(--accent);
}

.speed-control,
.size-control {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--text-dim);
}

.size-control input {
  width: 64px;
  background: #23283a;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 8px;
}

#speed-slider {
  accent-color: var(--accent);
}

.hint {
  color: var(--text-dim);
  font-size: 0.8rem;
  margin: 0;
  text-align: center;
}

@media (max-width: 600px) {
  .stats {
    flex-direction: column;
    gap: 6px;
    align-items: center;
  }
}