body {
  font-family: sans-serif;
  padding: 1rem;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.controls {
  display: flex;
  gap: 0.5rem;
  margin-top: 0.5rem;
}

.controls button {
  padding: 0.4rem 0.8rem;
  font-size: 0.95rem;
  border-radius: 4px;
  border: 1px solid #888;
  background: #fff;
  cursor: pointer;
}

.controls button:disabled {
  opacity: 0.6;
  cursor: not-allowed;
}

.bingo-grid {
  border-collapse: collapse;
  margin-top: 1rem;
}

.bingo-grid td {
  border: 1px solid #444;
  width: 120px;
  height: 120px;
  text-align: center;
  vertical-align: middle;
  padding: 0.5rem;
}

.free {
  background-color: #f0f0f0;
  font-weight: bold;
}

/* clickable state */
.bingo-grid td.selected {
  background-color: lightgreen;
}

.error {
  color: #b00;
  background: #ffecec;
  border: 1px solid #f5c6cb;
  padding: 1rem;
  margin-top: 1rem;
  border-radius: 4px;
  text-align: center;
  max-width: 600px;
}