eccapurple h w 20% / alpha)`, `rgb(128, 51, 204)`);
    test_valid_value(`color`, `hwb(from rebeccapurple h w b / .2)`, `rgba(102, 51, 153, 0.2)`);
    test_valid_value(`color`, `hwb(from rgb(20%, 40%, 60%, 80%) 25 w b / alpha)`, `rgba(153, 94, 51, 0.8)`);
    test_valid_value(`color`, `hwb(from rgb(20%, 40%, 60%, 80%) 25deg w b / alpha)`, `rgba(153, 94, 51, 0.8)`);
    test_valid_value(`color`, `hwb(from rgb(20%, 40%, 60%, 80%) h 20% b / alpha)`, `rgba(51, 102, 153, 0.8)`);
    test_valid_value(`color`, `h