mobile navigation bar doesn't show on tablets

Site URL: https://www.schreinereiml.com/

Hello dear people,
I hope you can help me out with this.

I have a problem with the mobile navigation bar. This problem only exists in the tablet view.

If you open the website on the tablet, a large area appears on the right-hand side that shouldn't be there. The opening slideshow is also displayed too large.
I think this is the cause of the problem: the slideshow is displayed too big and covers the navigation bar.
If you then click on the three bars to open the navigation bar, the view zooms in strangely and no navigation bar appears. I think it is covered by the slideshow?

I attached some screenshots of the tablet and the mobile phone version, so you can see what I'm talking about.

Here you can see the file with the custom coding I used to build the website.

https://www.dropbox.com/s/u0cyfqhyispog50/Code 2020.txt?dl=0

I really hope there is an easy fix for my problem out there and I'm just too inexperienced to find it myself.

Thank you for helping already!

Looks fine here. Do you still need help?

If yes, which tablet/browser do you use?

First: Thanks for answering.

The problem appears on my ipad with the safari browser.

I now downloaded chrome on the ipad and the webside looks fine there.

But it also looks weird using the chrome browser on my lenovo tablet.

Any ideas why this is happening?