Switch to native font stack

[jeroen]

Preview of https://github.com/ropensci-org/roweb3-styles/pull/6

Closes #881.

[maelle]

One comment: the new font looks thicker.

[jeroen]

I think we ended up making the css bolder in many places to make proxima-nova more readable, if we switch we probably need to undo that.

[maelle]

@jeroen I looked at this again, intending to change font-weight but... it does not seem that thick to me today?! I think the PR looks fine.

[steffilazerte]

If I were to really stare at them and be picky, I think I have a slight preference for our original font, but they look pretty similar, and I like the idea of using open fonts (seems to fit our mission). But the font size looks bigger on this PR than on the regular page, and I don't like that as much.

[maelle]

make font less big?

[maelle]

I'll open a new PR.

[maelle]

The problem is that in the SCSS files, we've set the font size many times (178 occurrences in 22 files).

I think looking at the different values of font sizes (there are not 178 of them) would take a little while.

For instance with the native font stack at 17px this looks ok:

Compared to Proxima nova at 18px:

Do things really look bad when just changing the font without changing the size?