Timeline z-index

I checked out the article about stacking context, and indeed after some hard reading I understand the concept.

However, none the wiser I still do not see a viable solution to my problem. Is this impossible to rectify or am I just missing something obvious.

Do I need to manipulate the DOM somehow, so due to the rearrangements I can “force” my popup to appear above the timeline.

Of course I’d rather not go that route.