Thanks for your swift response!
I decided to right click on my header and select inspect (Q). That opened the image exactly as it looks in my header and below that it showed the image console with the Inspector tab selected.
Looking down into the HTML <body> tag, I saw that the image I had uploaded was cropped to 666x375px. I'll create a new header in those dimensions and see if it looks better.
Have a nice day! 🌻
