body {
    background: #121212;
    color: white;
    font-family: sans-serif;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    margin: 0;
}
.container { text-align: center; border: 1px solid #333; padding: 2rem; border-radius: 8px; }
button { padding: 10px 20px; cursor: pointer; background: #007bff; color: white; border: none; border-radius: 4px; }