body {
  font-family: Arial, sans-serif;
  margin: 0;
  padding: 0;
  color: #333;
  background-color: #f8f9fa;
}

.header {
  text-align: center;
  padding: 1em;
  background-color:#008000;
  color: white;
}

.calculator {
  max-width: 500px;
  margin: 2em auto;
  background-color: white;
  padding: 2em;
  border-radius: 8px;
  box-shadow: 0 4px 8px rgba(0, 0, 0, 0.1);
}

.form-group {
  margin-bottom: 1em;
}

label {
  display: block;
  margin-bottom: 0.5em;
  font-weight: bold;
}

input, select {
  width: 100%;
  padding: 0.5em;
  font-size: 1em;
  border: 1px solid #ddd;
  border-radius: 4px;
}

button {
  display: block;
  width: 100%;
  padding: 0.7em;
  background-color: #007bff;
  color: white;
  font-size: 1em;
  border: none;
  border-radius: 4px;
  cursor: pointer;
}

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

.result {
  margin-top: 1em;
  font-size: 1.2em;
  text-align: center;
  color: #007bff;
}