How do I change the look of the New Tab shortcuts on Waterfox?

So, you know how on mainstream Firefox, the shortcut icons are a bit padded to give them a uniform look?

Yeah, I wanna do that, but with Waterfox, a fork of Firefox. I know, this is not exactly the sub for that browser, but this is the closest I could find here on lemmy.

Currently on Waterfox, the padding on shortcut icons seems erratic.