Yes, we were targeting mobile/tablet devices at the time too (well bolting on to existing code base). For example, the CSS to dynamically swap between a side me

Yes, we were targeting mobile/tablet devices at the time too (well bolting on to existing code base). For example, the CSS to dynamically swap between a side menu and hamburger button wasn't complex (as well as a few other layout changes we made based on screen size), but getting everything to resize properly had a significant/constant overhead during development. Mostly because any given solution took hours to work out. The alternative of feeding separate style sheets makes it easier to develop, but much harder to test even with the responsive design buttons in ff/chrome. That is probably also why I haven't seen many web apps that try to do everything with a single set of CSS pages recently.