If all you did was put the second header inside the main element and used position sticky, you'd get the _exact_ same effect without any js and only a couple of lines of CSS.

I don't understand why you'd chose an incredibly more complex solution that is objectively worse in nearly every way.

What am I supposed to see?

On Android Firefox Preview as well as Kiwi Browser (chromium) I simply see a list without anything sticky.

Same for desktop mode in both Android browsers.

This will provide 2 headers without the double sliding animation (which is potentially distracting).

1. Stack two headers on top of each other, both of them sticky. (Only topmost header is visible.)

2. At a certain scroll position, fade/scroll/hide the top header.