Yes it's diffcult but not impossible.
With CSS preprocessors, for example, we can write adaptive rules by extending a class defined in choiced css library to a HTML element generated by web2py having a different css class or a specific identifier.
web2py, in my opinion, it's flexibile enough in order to obtain a soddisfacent result since it adds an identifier or class to (almost) all html components.
For example (please be aware the code - although it's working - is only for demostration!) just applying the attached file (of course compiled) to our layout.html we will obtain that shown in the following image (the grid come from estore3 by Massimo Di Pierro)