Until recently I thought I hated sites that messed with the scroll out of principle, but then I found a handful of them that do a good job of it. This is one of them.

This is a good job? It takes me a half dozen scroll actions to get each sentence of text. I'm not risking a carpal tunnel flare-up just to get through effectively one paragraph of content.

The key here is to have a foreground layer that always responds to scroll and informs the background layer based on its position