Browser / Version: Firefox 56.0
Operating System: Windows 10
Tested Another Browser: Yes
Problem type: Design is broken
Description: Fonts from fonts.googleapis.com aren't being "served" for Firefox
Steps to Reproduce:
I noticed that, on Firefox, WhatsApp Web doesn't use the same fonts as Chrome.
Upon further investigation, I discovered that it's because WhatsApp Web on Chrome requests some fonts from fonts.googleapis.com (like Open Sans and Roboto), where Firefox doesn't.
It's possible to check this by watching the network requests on both browsers, be it via the dev tools or with the built-in logger of uBlock Origin.
The dynamic filtering panel of uBlock Origin also shows that requests are made to fonts.googleapis.com on Chrome, but not on Firefox.
It's like WhatsApp Web isn't "serving" the respective fonts (from fonts.googleapis.com) on Firefox for some reason. As a result, WhatsApp Web fonts on Firefox looks way off.
From webcompat.com with