UPDATE: I just wanted to say thank you to Ricky for finding the term "Clipping" for me, as well as this obscurely titled post "CSS change color on scroll / cut text - overflow z-index" which might explain why I couldn't find it with my search terms.
This is an advanced technique that modifies a basic color change on scroll position.
I can't find the sample website where I first saw this effect and it is killing me. I've gone through my history for hours!
So the trick is this: I have a website with several block sections, and one of the sections has a background that is primarily white, so the white sticky nav bar logo and text don't show properly. What I want to happen is that when this white section passes through the nav bar it slowly fills the white text with black, from the bottom up.
I don't need you to code this for me, just can somebody tell me if they have seen a website that does this so I can reference it?