:root {
    --bg: white;
    --fg: black;
    --link: #06c;
    --link-visited: #528;
}
@media (prefers-color-scheme: dark) {
    :root {
        --bg: black;
        --fg: white;
        --link: #7af;
        --link-visited: #a8f;
    }
}
body {
    font-family: Verdana, Arial, sans-serif;
    background: var(--bg);
    color: var(--fg);
}
a {
    color: var(--link);
}
a:visited {
    color: var(--link-visited);
}
a:hover, a:focus {
    text-decoration: underline;
    filter: brightness(1.2);
}