Mobile in-app browser navigation glitching

Opened up an article inside the Reddit in-app browser and noticed some funky glitching in the navigation.

Issue
On open, the nav starts half-scrolled, and then on scroll you can see the bottom of the text going behind the navigation.

On mobile Chrome, Safari, and Firefox, the same thing happens- where if the user scrolls inside the nav, the content behind it scrolls- you just can't see it in these browsers due to correct screen positioning of the nav. The in-app browser seems to force the nav to have some kind of margin at the bottom.

This definitely could also be a gatsby problem, reddit mobile problem, in-app browsers as a whole problem, or this particular site problem. I also never throw out the possibility of it being a problem with my own device. I'll poke around and see what I can find.

Sidenote: I also have a CSS hack fix that prevents background content from scrolling when the user scrolls in the nav. I'll open a new issue for that if that's wanted.

Start by reproducing the navigation behavior in the Reddit in-app browser and compare it with mobile Chrome, Safari, and Firefox. Inspect the site's navigation and CSS, then verify that the navigation is positioned consistently and that scrolling within it does not expose or move the content behind it.