Which is nuts for a simple article page like this (and almost any other use case really). Just leave the native components as they are, especially scrolling.
Firefox on macOS is also completely borked. At least with my freescrolling Logitech Master MX 2. I'll scroll and it will jump the expected amount, I'll scroll some more and it will jump about 4-5x what I expect, and then I'll scroll some more and it will go backward in the page. The site is pretty much unusable for me.
I would just kill the scrollbar styling if it’s breaking the site in common browsers. Styling the scrollbar is absolutely a nice-to-have—more important to have people able to read the content. Otherwise, what’s the point?
Which is nuts for a simple article page like this (and almost any other use case really). Just leave the native components as they are, especially scrolling.