    <style>
            body {
            font-family: Arial, sans-serif;
            max-width: 400px;
            margin: 0 auto;
            padding: 20px;
            background-color: #f4f4f4;
        }
        form {
          font-size: 18px;
        }
        label {
            display: block;
            margin-bottom: 10px;
            font-weight: bold;
            color: #333;
        }
       #calculator {
        max-width: 88%;
        width: 450px;
        margin-left: auto;
        margin-right: auto;
        }
        input, select {
            width: 100%;
            padding: 10px;
            margin-bottom: 10px;
            border: 1px solid #ccc;
            border-radius: 4px;
            box-sizing: border-box;
            font-size: 1em;
        }
        .error-message {
            color: red;
            font-size: 0.9em;
            margin-bottom: 10px;
            display: none; /* Hidden by default */
        }
        button {
            padding: 10px;
            background-color: #28a745;
            color: white;
            border: none;
            border-radius: 4px;
            cursor: pointer;
            font-size: 1em;
            width: 100%;
        }
        button:hover {
            background-color: #218838;
        }
        #result {
            margin-top: 20px;
            font-size: 1.8em;
            padding: 15px;
            background-color: #fff;
            /*border: 1px solid #ccc;*/
            border-radius: 4px;
            /*box-shadow: 0px 0px 10px rgba(0, 0, 0, 0.1);*/
        }
        table {
            width: 100%;
            border-collapse: collapse;
            margin-top: 10px;
        }
        table, th, td {
            border: 1px solid #ddd;
        }
        th, td {
            padding: 8px;
            text-align: left;
        }
        th {
            background-color: #f2f2f2;
            font-weight: bold;
        }
    </style>