body {
  font-family: Arial, sans-serif;
  text-align: center;
  background-color: #f5f5f5;
}

h1 {
  color: darkblue;
}

#puzzle {
  margin: auto;
  padding: 20px;
  width: fit-content;
  background: #fff;
  border-radius: 10px;
  box-shadow: 0 0 10px #ccc;
}

table {
  border-collapse: collapse;
  margin: 10px auto;
}

td {
  padding: 5px;
}

input.cell {
  width: 40px;
  height: 30px;
  text-align: center;
  font-size: 18px;
  border: 1px solid #333;
  border-radius: 5px;
}

input.cell:disabled {
  background-color: #ddd;
}

#controls {
  margin-top: 20px;
}

.num-btn {
  width: 40px;
  height: 40px;
  margin: 5px;
  font-size: 18px;
}

button {
  padding: 8px 15px;
  margin: 10px;
  font-size: 16px;
  cursor: pointer;
  border-radius: 5px;
  border: none;
  background-color: #007bff;
  color: white;
}

button:hover {
  background-color: #0056b3;
}

#result {
  margin-top: 15px;
  font-weight: bold;
  font-size: 18px;
}

#timer-container {
  margin: 10px;
  font-size: 20px;
  color: #333;
}