body {

    background:#111;
    color:#eee;
    font-family:Arial, sans-serif;

}


.container {

    max-width:600px;
    margin:auto;
    padding:20px;

}


h1 {

    text-align:center;

}


.card {

    background:#222;
    padding:20px;
    margin:15px 0;
    border-radius:12px;

}


button {

    width:100%;
    padding:12px;
    margin-top:10px;

    background:#1976d2;
    color:white;

    border:0;
    border-radius:8px;

    font-size:16px;

}


button:active {

    background:#0d47a1;

}


pre {

    white-space:pre-wrap;
    font-size:12px;

}