Overriding font defaults (notably unit... rem vs px)

[twrichards]

Sharing here for posterity a discussion @tjsilver and I had with @SiAdcock and @sndrs about overriding font defaults (notably unit, i.e. rem vs px)...

Useful Links:

• final implementation of the font scale unit overriding in pinboard - https://github.com/guardian/editorial-tools-pinboard/pull/42/files#r598940079
• eslint rule to prevent use of originals - https://github.com/guardian/editorial-tools-pinboard/pull/42/files#r598938357