Make section sticky for a curtain reveal effect

Q: What feature / functionality are you looking for?
A: The option to make an element/section sticky so it achieves a curtain reveal effect.

Q: What problem are you trying to solve?
A: CSS: position sticky doesn’t work. I want an effect just like what’s on the bottom of this page:

Q: If solved, what value would this provide (ex. increased efficiency, cost savings, etc.)?
A: It would make our landing pages look so much more advanced and up to date in keeping with the rapidly changing design trends.

Q: Use Case example? (ex. As a ____ I want to be able to _____ so I can _____.)
A: As a designer I want to be able to toggle this feature on a per section basis. Similar to the way we add a parallax background.

Q: Is this being solved by another workaround or any other tool today?
A: I don’t think so, I’m struggling to create a topic as a new user here but would really love to put it to the community and wonder if there is an alternative workaround to achieve the same effect since there isn’t a tool to achieve this using native functionality.