WordPress.org

The HTML editor has not received a lot of love. The type is too small, especially when you see it in the new distraction-free writing mode. This plugin uses the lovely M+ 2m font (the font I use for coding every day) for more beautiful writing.

M+ also has extensive international support. From its site:

All fonts were completed with Basic Latin, Latin-1 Supplement, Latin Extended-A, and IPA Extensions. And most of Greek, Cyrillic, Vietnamese, and extended glyphs and symbols were prepared too. So the fonts are in conformity with ISO-8859-1, 2, 3, 4, 5, 7, 9, 10, 13, 14, 15, 16, Windows-1252, T1, and VISCII encoding.