Line-height for 'body' text is inconsistent

[jameskoster]

We utilise 13px as the default font size in the block editor. However, different areas of the UI apply different line-height values to this 13px text. Some examples:

UI area	Line-height value
	1.2
	1.4em
	1.5

It's a small detail, but these inconsistencies add up to make the UI feel less structured and cohesive.

If we wanted to pick one of the existing values I'd vote for 1.5 because it arguably has the best legibility, and gets us closest to the 4px baseline grid: 13 * 1.5 = 19.5. To be more precise, a value of 1.53846153846 * 13 = 20 🙂

Here's equivalent screenshots of the UI noted above using that value:

cc @WordPress/gutenberg-design

[jasmussen]

Definitely a fan of the line-height rounding to 20px, which fits the 4px grid. Matches very well also to the 40px buttons we are discussing in #46734.

[jasmussen]

CC: @mirka in case this affects componentry.

[mirka]

Sounds good. From the technical standpoint, the way to propagate this will be to use the Text component. It isn't used a lot in production yet, but we can push for devs to use it more once we update the font-size/line-height presets to match our current needs. It currently has a default of 13px/1.2.