Does it support css variables?

[tanekim88]

Does it support a case like this, with :root? I am getting an error when I do that.
:root {
--a: red;
}
.b{
color: var(--a);
}
.b{
color: var(--a);
}

[ChristianMurphy]

it does.
here is the test case that shows variables working.

postcss-combine-duplicated-selectors/test/duplicated-properties.js

Lines 115 to 133 in 38bd6f1

	test(
	'remove duplicate property with matching value, allow fallback',
	removeExactDuplicates,
	minify`
	.a {
	height: 10px;
	}
	.a {
	height: 10px;
	height: var(--linkHeight);
	}
	`,
	minify`
	.a {
	height: 10px;
	height: var(--linkHeight);
	}
	`,
	);

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