Twenty Nineteen: Typographic scale improvements

[kjellr]

As noted during the early development of Twenty Nineteen, there are a couple improvements to the font size and typographic scale:

• The theme sets a base font size of 22px. Ideally, this should be set to 100%. ( Discussion: ​https://github.com/WordPress/twentynineteen/issues/62 )
• The em-based typographic scale built on top of that 22px size does not always resolve to exact pixels. ( Discussion: ​https://github.com/WordPress/twentynineteen/issues/164 )

It's worth noting that adjusting this scale at this point must:

1. Preserve the current appearance. Font sizes must be close enough to what's live currently that they don't appear visually different. Adjusting our math so that type sizes are rounded up/down to the nearest pixel when rendered is fine, but we don't want to implement a whole new, different type scale.
2. Use pixel or rem-based sizes in the editor styles in order to override the default pixel-based font sizes used in Gutenberg.

[sabernhardt]

As part of the ​proposal to retire default themes, Twenty Nineteen might not have any more enhancements soon.

It could be too late for this ticket.

[karmatosed]

I agree with @sabernhardt that for now looking at reviewing this doesn't fit the current work. It absolutely though might be something to consider depending on how we take the themes into their next life - be that block based or not. As a result, I would recommend closing this but having tickets like this in our mind when we work on the future of default themes.

Thank you everyone for your input and collaboration on this. We can always reopen should that be needed.