.calculator {
  max-width: 400px;
  margin: 0 auto;
  padding: 20px;
  background-color: #f9f9f9;
  border-radius: 10px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

h2 {
  text-align: center;
  margin-bottom: 20px;
}

form {
  margin-bottom: 20px;
}

label {
  display: block;
  margin-bottom: 5px;
}

input[type="number"] {
  width: 100%;
  padding: 8px;
  margin-bottom: 10px;
  border: 1px solid #ccc;
  border-radius: 5px;
}

select {
  width: 100%;
  padding: 8px;
  margin-bottom: 10px;
  border: 1px solid #ccc;
  border-radius: 5px;
}

button {
  width: 49%;
  padding: 10px;
  background-color: #007bff;
  color: #fff;
  border: none;
  border-radius: 5px;
  cursor: pointer;
  transition: background-color 0.3s ease;
}

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

#result {
  text-align: center;
  font-weight: bold;
}