1. A computer-implemented method of transforming a cascading style sheet (“CSS”) codebase for a website, including: using a processor, accessing in memory a CSS codebase that includes target tokens in customizable segments to be customized, responsive to an input invoking a module that uses the CSS codebase; selecting at least one among multiple alternative sets of customization functions that transform the target tokens within the customizable segments of the CSS codebase; scanning the CSS codebase and locating the customizable segments that include the target tokens; parsing the located customizable segments to produce segment parse trees, and transforming the target tokens from the segment parse trees according to the customization functions and outputting a customized codebase to be used with the module invoked by the input.