body {
    color: #222;
    background: #fff;
    font: 100% system-ui;
    margin: 5%;
}
a {
    color: #0033cc;
}

.center {
    display: block;
    margin-left: auto;
    margin-right: auto;
    width: 30%;
  }

@media (prefers-color-scheme: dark) {
    body {
        color: #eee;
        background: #121212;
    }

    body a {
        color: #809fff;
    }
}