@media (prefers-color-scheme: dark){
    body {color:#fff;background:#000}
    a:link {color:#cdf}
    a:hover, a:visited:hover {color:#def}
    a:visited {color:#dcf}
    pre { color: black; }
}
nav {
    display: flex;
    align-items: center;
    justify-content: space-between;
    flex-direction: row;
    text-align: center;
    font-weight: bold;
}
nav button {
    background-color: green;
    color: white;
    border-radius: 0;
    border-style: solid;
}
body{
    margin:1em auto;
    padding:0 .62em;
    font:1em/1.62 sans-serif;
}
h1,h2,h3 {
    line-height:1.2
}
pre {
    font-family: monospace;
    background-color: #eee;
    padding: 5px;
    overflow: auto;
}

@media print{
    body{
        max-width:none
    }
}