Thanks, although I suspect they are not even aware of it :s
Regarding the top and bottom lines appearing on navigation hover, when I change the Customizer settings for the Primary Navigation from Below Header to Float Right it appears to fix this issue in my Edge Browser.
Can you confirm it also solves the issue in your Edge browser on the preview url?.
If so, any ideas what extra CSS is added by the GP theme in the Below Header setting? I tried switching to the Parent theme but it makes no difference so I dont think it can be any styles I’ve added.