Scrolling photos at different speeds with pure CSS
Multi-Column Different-Speed Scrolling
A developer demonstrates how to make two columns of photos scroll at different rates using only CSS. The right column drifts upward faster via a scroll-driven animation, while each image also zooms and shifts as it enters the viewport. No JavaScript is needed, and the technique gracefully degrades where scroll-driven animations aren't supported. A reverse-scrolling variant and a popover lightbox round out the experiment.
I got this idea stuck in my head that if you’re scrolling through a “gallery”, it sorta doesn’t matter how the things scroll past you.