I was just looking at this Apple web page as I often do, just for the fun of seeing some of their web design efforts https://www.apple.com/ipad-10.2/
If you scroll down to the section where it says “Your home theatre. Home optional.” the background changes from light to dark and the header text, which is actually a graphic changes from black to white. This is then reversed when scrolling away and I am wondering if this could be done in Blocs.
Some of the video effects and mini animations are very cool as well.