body {background: #fff;}
    .calculator-container {
      background: #eee;
      padding: 30px;
      border: 1px solid #2c3e50;
      max-width: 400px;
      width: 100%;
margin: 0 auto;
margin-top: 40px;
margin-bottom: 20px;
    }
    .calculator-container h1 {
      text-align: center;
      margin-bottom: 20px;
      color: #333;
    }
    .form-group {
      margin-bottom: 15px;
    }
    .form-group label {
      display: block;
      margin-bottom: 5px;
      color: #555;
    }
    .form-group input, .form-group select {
      width: 100%;
      padding: 10px;
      font-size: 1rem;
      border: 1px solid #ccc;
      border-radius: 4px;
    }
    .btn {
      width: 100%;
      padding: 10px;
      background: #2c3e50;
      color: #fff;
      border: none;
      font-size: 1rem;
      border-radius: 4px;
      cursor: pointer;
    }
    .btn:hover {
      background: #218838;
    }
    .result {
      margin-top: 20px;
      text-align: center;
      font-size: 1.2rem;
      color: #333;
    }