Firefox docs funky font size

[hkershaw-brown]

From pull #689

For the text problem, I can't reproduce the TOO LARGE TEXT issue on firefox, chrome, or safari. So I'm going to move this to its own issue, might be browser version, might be local build of docs vs readthedocs, might be something else.

I see this in Firefox, but not Chrome, so it looks even less fixable and I still approve the PR.

Here's firefox with the pull request for me:

Originally posted by @hkershaw-brown in #689 (comment)

[hkershaw-brown]

closing this since can't reproduce this. Will reopen if funkiness reoccurs