As above, I’ve looked at the animations docs, and animations elements but don’t seem to find an obvious answer.
We currently have a transparent top menu panel that transitions the background color from transparent to white and the text elements (menu links) from white to black.
(I’ve just seen @George’s reply. Sounds exciting. In case it’s useful in the meantime or in general…)
You might be able to achieve what you want with dynamic classes and the browser component. Eg to apply a class called ‘shadow’ as the user begins to scroll: