Consider use of rem and em instead of px for font-sizes

[TSP]

As per the suggested procedure outlined here: https://css-tricks.com/rems-ems/

The benefit is that it'll be much easier to re-scale the size of text according to the preferences of the site owner for different resolutions, devices etc. without too much effort. Rem and em can also be used for margins and paddings btw. 

The downside is that you'll need to go through all existing places where font-sizes (and possibly some cases it could be beneficial to use for margins and paddings too) in order to change to this, but I personally think it would be worth it. 

Where I work we've already used this approach for other projects for quite a while. 

@Rikki: Do you see any problems or challenges with this idea? Have it been considered?

[TSP]

Any thoughts? Would really make things easier for me at least.