body {
    font-family: 'Helvetica Neue', Arial, sans-serif;
    background-color: #f4f4f9;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}
.container {
    background: white;
    padding: 2rem;
    border-radius: 10px;
    box-shadow: 0 4px 15px rgba(0,0,0,0.1);
    text-align: center;
    width: 300px;
}
input[type="text"] {
    width: 100%;
    padding: 10px;
    margin: 10px 0;
    box-sizing: border-box;
    border: 1px solid #ccc;
    border-radius: 4px;
}
button, .btn {
    background-color: #4CAF50;
    color: white;
    padding: 10px 20px;
    border: none;
    border-radius: 4px;
    cursor: pointer;
    text-decoration: none;
    display: inline-block;
    margin-top: 10px;
}
button:hover { background-color: #45a049; }
.qr-box img { width: 200px; height: 200px; margin: 15px 0; }
code { background: #eee; padding: 2px 5px; border-radius: 3px; }