Use an automated browser compliance solution

[toni-sharpe]

We should find some automated solution for handling browser differences as much as possible and add that to the build pipeline.

A good example is auto-prefixer which will add any required CSS property prefixes based on a set of provided browser versions to support. We might even be able to say 'any browser over 1%' or something like that as it uses API data from Can I Use.

If the solution was capable of handling things like CSS grid conversions to IE11 then that would be great.