Hi.
I tried to start from your codepen to adapt it to my needs.
However I have two problems:
For the class .box : with my modification the snap effect doesn't work anymore :
If class .red has width: 400vh the background continue. However I need the background to stay fixed only the text must change on scroll.
But if class .red has width: 100vh and overflow: auto; the snap effect doesn't work anymore..
There's my codepen :
https://codepen.io/Lo-dml/pen/GRBjGZR