If you uncheck the “Allow pages to choose their own fonts…” or equivalent option in your browser, web pages will display using your chosen font. However, you'd then no longer see icons from fonts like FontAwesome (https://bugzilla.mozilla.org/show_bug.cgi?id=789788). Additionally, elements that should be displayed in a monospaced font would be displayed in a proportional font instead (https://bugzilla.mozilla.org/show_bug.cgi?id=635823).


To fix these issues

1. Leave “Allow pages to choose their own fonts…” enabled.
2. Install this style.
3. Select your preferred sans-serif and monospace fonts in the browser's options. For Firefox, that's Options/Preferences → Content → Advanced. Most English sites are affected by Fonts for: Latin, but some are affected by Fonts for: Other Writing Systems.

Change log

• 2015-04-26: updated for Yahoo! Mail.
• 2015-04-10: initial release.

Downloadable fonts specified

• FontAwesome — used on a wide variety of sites
• mail, uh, date3 — Yahoo! Mail
• octicons — GitHub
• ddg-serp-icons — DuckDuckGo