body {
	margin: 1em auto;
	padding: 1em;
	max-width: 40em;
	font: 1.1em/1.3 sans-serif;
}
nav {
	text-align: right;
}
h1, h2, h3 {
	line-height: 1.2;
}
pre {
	overflow-x: auto;
}
img {
	max-width: 40em;
	width: 100%;
}
@media (prefers-color-scheme: dark) {
	body {
		color: white;
		background: black;
	}
	a:link {
		color: skyblue;
	}
	a:visited {
		color: violet;
	}
}