Old habits don’t go away very easy. I removed the closing tag (there are only these three files at the moment), but no… No difference I’m afraid.
Next step for me is to make a child theme from one of the pre-installed, I think. But not today, this have taken too much of my time the last couple of days, and I don’t wish to take anymore of your time either.
Since the pre-installed themes work prefectly, the problem can’t be in CP code anyway. Thank you so much for all your engagement!