Hello @LukaA
I had a look at your site.
Looks good by the way, I like what you did.
I did not see the issue you are referring to. I reduced the size of my browser window and tested it out. I do not have a working tablet to test it on unfortunately.
I think the issue may be the cover setting. Depending on the dimensions of your image and your background settings. Try Center, Top, Width 100% for the background settings.