Keyboard navigation: Can't determine which link is focused

[Neui]

Click on the next on a comment. Then press TAB to focus the next link.

I expected either some kind of outline (which according to Firefox dev tools has been "removed" by some CSS) or an underline or something else to indicate which link has the focus.

Instead, nothing happens (except maybe scrolling). This make navigating by links hard since it is easy to get lost.

Using Firefox 80.0 on Windows 10.