valid_value(`color`, `oklab(from oklab(-2 -3 -4 / -500%) l a b / alpha)`, `oklab(0 -3 -4 / 0)`);

    // Test nesting relative colors.
    test_valid_value(`color`, `oklab(from oklab(from oklab(0.25 0.2 0.5) l a b) l a b)`, `oklab(0.25 0.2 0.5)`);

    // Testing non-oklab origin to see conversion.
    test_valid_value(`color`, `oklab(from color(display-p3 0 0 0) l a b / alpha)`, `oklab(0 0 0)`);

    // Testing replacement with 0.
    test_valid_value(`color`, `oklab(from oklab(0.25 0.2 0.5) 0 0 0)`, `okla