Choose plain text font

It’d just be nice to be able to choose the font + size used for the plain text messages. It looked better in 1.7.2 I think? In the appearance settings (or wherever appropriate), add an option for plain-text font family and size.

(Originally posted by sampotts on GitHub.)

I have tried MailSpring on both Windows 10 and Linux (Manjaro). The plain text emails look different for both systems.
The emails are displayed in San Serif, but on Windows 10 the text looks bold, although it isn’t. On linux it looks normal, i.e. font is skinnier.

On Windows 10
In the composer, the text does not look bold.

After the email is received, the text look bold.

(Originally posted by GNHua on GitHub.)