I’m afraid to say that it has not worked either.
I have tried removing the logo in Customizer/Header/Logo + removing ALL the CSS code I have typed before (even not this topic-related code).
Saved the changes.
Then I have added a brand new logo (saved changes) + copy/paste the latest code you kindly gave me (saved changes):
The logo places perfectly right above the nav bar but in the mobile view it moves to the center of the header.
I have played with Element Spacing/Header to let the background image to show in its entirely with the same result.