Is it feasible to find superfluous statements? Ex: A line of CSS that sets text color of li tags to something, but every li tag already would be that color bec

Is it feasible to find superfluous statements? Ex: A line of CSS that sets text color of li tags to something, but every li tag already would be that color because of a CSS statement for body. I'm guessing it'd be hard to build something useful and correct, but I think it'd be an interesting extension of this idea.