Unmasking a fixed element with overflow-like effect

Hi!

First post here. I am trying to unmask an element with a section that’s absolute positioned. Basically an effect very similar to this one:

Cannot figure out how to do this without custom code. Having a “fixed” element seems to make it immune to all overflow effects, etc.

This is really simple. Just use 2 different images that represent the 2 states. Make sure they are the same size. Then add them as background images to the sections on top of each other and make them fixed, center or whatever positioning you want but make sure they are identical in their styling. This will achieve that effect.