Issue on mobile with 2 section (left and right) #22

Hello, I'm working on a site with 2 offside section as header element. I have a bug on something weird.
Let's say I have 2 sections (Projects & About) layout like this:

PROJECT MY SITE ABOUT

if I click on Project, project is active (open), and If i want to click on about to make about active, my layout is getting broken !

My problem only happen on mobile

Here is my site
https://albinmetthey.fr/

Can you help me out ?

Thanks a lot