strange issue on bottom bar

hi there, I'm experiencing a strange issue w/ this theme while switching between tabs. I have embedded a short screencast clip of the behavior in this post. is this something you could give me some guidance on fixing? 

thanks a lot! I really love this theme.

[!(clip)](https://user-images.githubusercontent.com/81469920/113498276-aeaee680-94c8-11eb-8f3b-861c6af50612.mp4)


