body {
    font-family: Arial, sans-serif;
    background-color: #f5f5f5;
    margin: 0;
    padding: 20px;
}

.container {
    max-width: 600px;
    margin: 0 auto;
    background: white;
    padding: 20px;
    border-radius: 8px;
    box-shadow: 0 2px 10px rgba(0,0,0,0.1);
}

button {
    padding: 10px 20px;
    margin: 5px;
    font-size: 16px;
    cursor: pointer;
}

button:disabled {
    opacity: 0.5;
    cursor: not-allowed;
}

#error {
    color: red;
}

#result h2 {
    color: #2c6fbb;
}