It does not work that way. This color is not used as color value directly. It is base value. Actual colors for classes and element id-s are created according to this base value way before the page is created. it will be too late to change the base value if all calculations are already done.
Look at the example here and try to play with it. Change values and see how it will affect the elements on page. There is no other way to learn it but doing it