ryzom-core/nel/tools/htmlcss_test/tests/01-syntax-tests.html

<!DOCTYPE html>
<html>
	<body>
		<style>
:lang(en) { --text: '(en)'; }
:lang(de-DE) { --text: '(de-DE)'; }
a { test: " (" var(--lang) ")"}

div {
	/* '--a' and '--b' are both 'initial' */
	--should-not-exist: var(--a, var(--b, ( "p() " ) ), { "b" [ "r" ] });
	/* 'before -var- after' */
	--concate-test: 'before' var(--exists) 'after';
	--exists: '-var-';
	/* fallback should be at least one char */
	--invalid-fallback: var(--exists,);
	/* using fallback */
	--fallback: var(--a, 'ok');
}
		</style>
		<div data-ruleset="--concate-test: 'before' '-var-' 'after'; --exists: '-var-'; --fallback: 'ok';"
			data-ruleunset="--should-not-exists: 1; --invalid-fallback: 1;" />

		<a lang="en" data-ruleset="--text: '(en)';">link</a>
		<a lang="de" data-ruleunset="--text: 1;">link</a>

	</body>
</html>