Once you use Sass or LESS you realize that it is much much easier to update things like colors and fonts and font sizes, since they can all become variables. Up

Once you use Sass or LESS you realize that it is much much easier to update things like colors and fonts and font sizes, since they can all become variables. Update one line of code and all of the rules will change. The number 50 you refer to is max number of lines of code the autor recommends inside of a nested rule, specifically so that you don't have to dig to far in to tweak a rule. CSS preprocessors were scary to me at first, but I once I started digging in a bit I realized I could never ever go back.