Changing styles inside shadow-root

I have this problem of changing font styling inside this shadow root. I need to change stuff inside that popup. And yeah also because this is a shopify app I can not edit its HTML so I have to use JS, CSS etc.

Screnshot of the popup + dom

scrrr.PNG

I tried waiting for the shadow root to open, searched about it a lot but no real results so far (I even tried solutions from stackoverflow). Any help would be greatly appreciated.

And yeah I also forgot to mention that most of the stuff in the shadow root appears after around 5 seconds of the page load because it is a popup.

Here is dom before and after pop loads

Before popup loads

beforepopuploads.PNG

After popup loads

after popup loads.PNG