<!doctype html>
<html>
	<head>
		<meta name="viewport" content="width=device-width, initial-scale=1">
		<link href="/assets/reset.css" rel="stylesheet">
		<link href="setup.css" rel="stylesheet">
		<link href="style.css" rel="stylesheet">
	</head>
	<body>
		<section>
			<p>This element is responsive.</p>
			<p>I’ll add some text more here so we have something to look at and so that it wraps, but the text itself isn’t important, at the moment.</p>
			<p>Some more text in it. Again the text doesn’t really matter, I just want a bit of stuff in here. A few lines, is all.</p>
		</section>
	</body>
</html>
index.html
			body {
	font-family: sans-serif;
	padding: 1rem;
}

section { padding: 1rem; }

p:not(:first-child) { margin-block-start: 1rem; }
setup.css
			:root { --background: aquamarine; }

section { background-color: var(--background); }

a { text-decoration: underline; }

/* We usually can leave `screen` off, as the default. */
@media screen and (width > 550px) {
	:root { --background: coral; }
}

@media print {
	:root {
		--background: initial; /* Resets this. */

		font-size: 18pt; /* Absolute units! */
	}

	section {
		border: 4pt solid black;
		font-family: serif;
		padding: 0.5in;
	}
}
style.css