body {
            font-family: Arial, sans-serif;
            margin: 20px;
        }
        
        .container {
            max-width: 400px;
            margin: 0 auto;
            padding: 20px;
        }
        
        input, select, button {
            width: 100%;
            padding: 10px;
            margin: 10px 0;
            border: 1px solid #ccc;
            border-radius: 5px;
        }
        
        button {
            background-color: #4CAF50;
            color: white;
            font-size: 16px;
            cursor: pointer;
        }
        
        button:hover {
            background-color: #45a049;
        }
        
        .result {
            margin-top: 20px;
            font-weight: bold;
        }
        
        /* Responsive design */
        @media only screen and (max-width: 768px) {
            body {
                margin: 10px;
            }

            .container {
                max-width: 100%;
                padding: 15px;
            }

            input, select, button {
                font-size: 14px;
                padding: 8px;
            }

            button {
                font-size: 14px;
            }
        }
        
        @media only screen and (max-width: 480px) {
            .container {
                padding: 10px;
            }

            input, select, button {
                font-size: 12px;
                padding: 6px;
            }

            button {
                font-size: 12px;
            }
        }