Hi Leo,
I deactivate all and get back plugin for plugin.
Now I can say (after a few test runs):
Problem Logo size/compressed: autoptimize plugin! When I activate, the Logo in mobile view will will have described problem.
Problem no menu after push the black x in mobile view: Next Gen Gallery! When I activate, no menu is coming after pushing the x.
Hope you can help to fix these problems. Special for the Next gen Gallery, because I use it often.
best,