:root { color-scheme: light dark; font-family: system-ui, Arial, sans-serif; }
* { box-sizing: border-box; }
body {
  min-height: 100vh; margin: 0;
  display: flex; align-items: flex-start; justify-content: center;
  background: #f2f2f2; padding: 24px;
}

.card {
  background: #fff; padding: 20px; border-radius: 12px;
  box-shadow: 0 4px 12px rgba(0,0,0,.08);
  text-align: center; width: min(95vw, 420px);
}

#game-container {
  margin: 16px auto 20px;
  display: grid; grid-template-columns: repeat(7, 50px); gap: 4px;
  justify-content: center;
}

#game-container button {
  width: 50px; height: 50px; border: none; cursor: pointer;
  background: #9aa0a6; border-radius: 6px;
  transition: filter .08s ease;
}
#game-container button.active { background: #2e7d32; }
#game-container button:active { filter: brightness(.9); }

.controls { display: flex; justify-content: center; gap: 10px; }
.controls button, #rules-button {
  padding: 8px 14px; border: none; border-radius: 8px;
  background: #1976d2; color: #fff; cursor: pointer;
}
.controls button:hover, #rules-button:hover { filter: brightness(.95); }