body {
  font-family: Arial, sans-serif;
  background: #f7f9fc;
  margin: 0;
  color: #333;
}

header {
  background: #2563eb;
  color: white;
  padding: 20px;
  text-align: center;
}

.container {
  max-width: 800px;
  margin: auto;
  padding: 20px;
}

.calculator {
  background: white;
  padding: 20px;
  border-radius: 8px;
  margin-bottom: 20px;
}

input, select, button {
  width: 100%;
  padding: 10px;
  margin-top: 10px;
}

button {
  background: #2563eb;
  color: white;
  border: none;
  cursor: pointer;
}

button:hover {
  opacity: 0.9;
}

footer {
  text-align: center;
  padding: 20px;
  font-size: 14px;
}