CSS Variables

index.html

					<!doctype html>
<html>
	<head>
		<title>CSS Variables</title>
		<link href="/assets/reset.css" rel="stylesheet">
		<link href="setup.css" rel="stylesheet">
		<link href="style.css" rel="stylesheet">
	</head>
	<body>
		<section>
			<p>This is some text in the first element.</p>
			<p>There can be multiple elements within it, maybe even that wrap to multiple lines.</p>
		</section>
		<section>
			<p>And some more in the second element.</p>
		</section>
		<section>
			<p>Then a third one, too.</p>
		</section>
	</body>
</html>

setup.css

					/* Special “entire document” selector, akin to `html`. */
:root {
	--spacing: 1rem; /* So we can reuse, below. */
	--border: solid black calc(var(--spacing) / 5); /* Any value, including `calc()`. */
}

/* Same as before, but now using the `var()`. */
body {
	font-family: sans-serif;
	padding: var(--spacing);
}

section {
	/* Second value here is a “fallback,” used if a variable hasn’t been declared. */
	background-color: var(--background, deepskyblue);
	border-block-start: var(--border);
	padding: var(--spacing);

	&:nth-child(2) { --background: gold; }
	&:nth-child(3) { --background: tomato; }

	&:not(:first-child) { margin-block-start: var(--spacing); }
}

style.css

					section:nth-child(2) {
	/* Overries our `:root` one, within this selector. */
	--spacing: 3rem;
}