How to make banner image display full width in all views, with no scaling?

I've looked high and low and alas I found an answer to my own question that works. (It works for me in my situation. Probably won't for everyone.) - The objective is to have 100% of a Banner Image display on every page. It's a banner image with image and text and it must appear in full on every single page of a Squarespace website. It has to be a banner image as image blocks appear on only single pages.

Answer: - Size the image 1500px x 1000px. - Parallax must be disabled.

(I'm using the Brine family of templates, so I don't know if this solution will work in the other template families.)

This seems to work fine in any site design (full width, full background or constrained width).

I hope that helps someone and saves hours of banging your head against your desk...

Answer: - Size the image 1500px x 1000px. - Parallax must be disabled.