How to fix ugly font issue in 2018.1.2 with JDK 8?

I've just reinstalled my Linux Mint OS and done a fresh install of Pycharm (by decompressing the tar file, the snap installer failed). In 2017 I dealt with an issue where the font was ugly for menus and code, and it's popped up again. I tried following some guides, this one in particular:

https://gist.github.com/CrazyCoder/0d9e54f450000d3fb6edcbda6d9788be

But they seem to be referring to the 2017 version and JDK 7. I have 2018 and JDK 8. I've tried following this procedure carefully with no success. What are the current instructions for fixing this issue?

Here's what my screen looks like: