body {
  font-family: Arial, sans-serif;
  text-align: center;
  background-color: #f3f3f3;
  padding: 20px;
}

h1 {
  margin-bottom: 20px;
}

.sudoku-grid {
  display: grid;
  grid-template-columns: repeat(9, 40px);
  grid-template-rows: repeat(9, 40px);
  gap: 2px;
  justify-content: center;
  margin: 0 auto 20px;
}

.sudoku-grid input {
  width: 38px;
  height: 38px;
  text-align: center;
  font-size: 18px;
  border: 1px solid #ccc;
}

.controls button {
  margin: 5px;
  padding: 10px 20px;
  font-size: 16px;
  cursor: pointer;
}