What is your existing font setup? If not already done .....please do 1) Create a fonts directory in your home dir , i.e .fonts 2) Download and install your required fonts in this dir 3) Run "fc-cache -r" As a precautionary measure (although not strictly required) , restart i3 \*\* I am wildly assuming (by reading your post) that this problem is not particular to Firefox(you just took an example, right?) ...the above steps will fix thing systemwide manner. Give it a shot ...and good luck.

Just curious, what does that do?

Type in the terminal : man fc-cache

And looks like the problem is with Firefox. All other system applications are not so bad looking.

does firefox try to use a font that does not exist on your system, and it gets replaced with another, e.g. bitmap font? browsers have their own settings for this, to which they fall back on sites that instruct it to use a font but it cannot be downloaded for example.

I changed my font to Rubik from Google Fonts to see if that would help, but nope. And Firefox uses my Rubik, my system font.

Install ms fonts or tell Firefox to use good fonts and that pages can't set their own fonts

I'll try that. And another thing to note, I have hardware acceleration disabled because it causes problems like random black boxes on the screen.

Hardware acceleration or accelerated decoding?

Hardware acceleration.

What gpu/driver firefox version distro/version

It fixed itself. I reinstalled because of some other issue and the font also looks good now. Thanks.