body {
    font-family: Arial, sans-serif;
    background: #f4f6f8;
}

.container {
    width: 800px;
    margin: 40px auto;
    background: #fff;
    padding: 25px;
    border-radius: 8px;
}

button {
    padding: 8px 20px;
    margin-top: 10px;
}

pre {
    background: #222;
    color: #0f0;
    padding: 15px;
    overflow-x: auto;
}

.error {
    color: red;
    margin-top: 10px;
}