css merge causes bugs on mobile

I installed Autoptimize to improve my pagespeed and it helps a lot.

But there is one important option (css merge) which dosn’t work for the mobile view.

You can see the difference here: https://ibb.co/ZgvGpYG

If I only activate the css optimization, there is no problem, but every time I activate css merging, the style breaks.

Is there any possibility to fix it? :/

Thank you!

The page I need help with: [log in to see the link]