Parallax Website Design

[yellowbird]

Nancy, my misreading of your prior. My approach will work with Scale to Fit Width or not.

With Main and a Variant and Scale to Fit Width, I find there is no need to design a small mobile page.
I therefore choose 720px Mobile and 1440px Main.
If you scale the Variant objects to 50% then on a sliding browser width, the jump at 1080px is not as obvious.
If you set maximum width to 2160px, the scaling up or down at either width limit is the same, a bit like Goldilocks.
My dynamic range is therefore 1.5 both ways.
Your midpoint is only 640px so 1280px is an upscaling of 2 and 2400px makes this 3.75. With 480px you have no downscaling.

Acorn

Thanks for the detailed info and explanation Acorn.