olor`, `rgb(from rebeccapurple r g 20% / alpha)`, `rgb(102, 51, 51)`);
    test_valid_value(`color`, `rgb(from rebeccapurple r g b / 20%)`, `rgba(102, 51, 153, 0.2)`);
    test_valid_value(`color`, `rgb(from rgb(20%, 40%, 60%, 80%) 20% g b / alpha)`, `rgba(51, 102, 153, 0.8)`);
    test_valid_value(`color`, `rgb(from rgb(20%, 40%, 60%, 80%) r 20% b / alpha)`, `rgba(51, 51, 153, 0.8)`);
    test_valid_value(`color`, `rgb(from rgb(20%, 40%, 60%, 80%) r g 20% / alpha)`, `rgba(51, 102, 51, 0.8)`);
    test_vali