Not solve the problem with it, I’ve done this
1. Save the title / logo as a different image file With no background (transparent PNG).
2. Save the background image as a different image (without the title).
3. Upload the background image in “Customize> Background Images”.
4. Upload the title / logo in “Customize> Site Identity.”
I went to https://jigsaw.w3.org/css-validator/#validate_by_input, I copied the child theme css valid and have stuck in the child theme css file
the result is appalling clubtheriver.com
can not be so hard to put the header image as http://achievingsustainability.com/ on this page, if you zoom up or down always remains proportions.
I have two days stuck with this problem, my morale is at rock bottom, we can do?