Sticky element gets hidden when scrolling

Hey, guys. I’m new to Webflow and having a really hard time making a sticky scroll. The phone gets hidden behind the next section. I’ve messed around with the z-index but I can’t make it work. Can anyone point me in the correct path for fixing this? Any help would be much appreciated.

Here is my public share link:
(how to access public share link)


Because those elements are siblings and the lowest has a higher z:index.


Thanks a much! I also found out that the hero_wrapper has overflow hidden.
Thanks for your help. Really appreciate it!