body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  background-color: #f4f4f4;
}

.calculator {
  max-width: 400px;
  margin: 50px auto;
  padding: 20px;
  background-color: #fff;
  border-radius: 5px;
  box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
}

.input-group {
  margin-bottom: 15px;
}

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

.input-group input {
  width: 100%;
  padding: 5px;
  border: 1px solid #ccc;
  border-radius: 3px;
}

button {
  display: block;
  width: 100%;
  padding: 10px;
  background-color: #007bff;
  color: #fff;
  border: none;
  border-radius: 3px;
  cursor: pointer;
}

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

#result {
  margin-top: 20px;
  font-weight: bold;
}