body {
  font-family: Arial, sans-serif;
  background: #f9f9f9;
  padding: 20px;
}
.calculator {
  background: #ffffff;
  padding: 20px;
  border-radius: 8px;
  max-width: 600px;
  margin: auto;
  box-shadow: 0 0 10px rgba(0,0,0,0.1);
}
.calculator h1 {
  margin-bottom: 20px;
  font-size: 1.8rem;
  color: #004080;
  text-align: center;
}
label {
  display: block;
  margin: 10px 0 5px;
  color: #003366;
}
input, select {
  width: 100%;
  padding: 8px;
  margin-bottom: 15px;
  border: 1px solid #c6d4e1;
  border-radius: 4px;
}

button {
  display: inline-block;
  padding: 10px 20px;
  background: #0071b3;
  color: #fff;
  border: none;
  border-radius: 4px;
  cursor: pointer;
  margin: 20px auto 0;
  text-align: center;
}

button:hover {
  background: #005999;
}
.result {
  margin-top: 20px;
  background: #e4edf7;
  padding: 15px;
  border-radius: 5px;
  color: #003366;
}