Hi there @Paul_Wilkins
There was another discussion here. The solution was given by @PaulOB, but he was also looking for alternative methods.
I was trying to build something that when 30% of the conetent height is traversed: something should happen: Bottom to top Pop appear, for example.
Key was when scroll has moved 30% of the content height, Intersection observer should do its job.
@PaulOB has designed the finbal working solution, but he was also looking for some alternative elegant way. If you can invest sometime, and have any other way to approach the same solution with more optimized code.