Scroll-Driven Animations: You want overflow: clip, not overflow: hidden

The creation of a scroll container is what trips up the scroll(nearest) lookup mechanism. In the snippet below scroll() won't find the #scroller but the #intermediate element with the overflow: hidden applied to it instead.

At its core, creating a Scroll-Driven Animation is pretty easy. Take an existing CSS Animation or WAAPI Animation, connect it to a ScrollTimeline or ViewTimeline, and you're done.

Read at Bram.us