Hi!
I see what you mean now 🙂
It is actually intentional, there is a delay between the windows scroll and the result follow method, to prevent unneccessary client browser script usage.
You can actually change the z-index of the results here: https://i.imgur.com/7mlYyBE.png
I tested z-index value 1 on your site via the browser debugger, it moves the results behind the menu, so changing it to 1 should do the trick.
