swc/crates/swc_css_parser/tests/fixture/value/custom-property/input.css

:root {
    --number: 1;
    --unit: 100vw;
    --color: #06c;

    --function: calc(1 + 1);
    --variable: var(--unit);

    --string: 'single quoted string';
    --string: "double quoted string";

    --square-block: [1, 2, 3];
    --round-block: (1, 2, 3);

    --bracket-block: {1, 2, 3};
    --JSON: [1, "2", {"three": {"a":1}}, [4]];
    --javascript: function(rule) { console.log(rule) };

    --CDO: <!--;
    --CDC: -->;
}