Oh yeah, that page doesn't work on any of my setups, Macbook or Windows, though I haven't checked linux yet.
Could you do it similarly to how https://distantskies.neocities.org/ does it with their nav icons on the left and right columns?
custom scrollbars should actually be supported natively on chromium-based browsers as of last year, if that's helpful to know. safari and other webkit-based browsers you can still customize scrollbars on, but you'll have to duplicate all your code and add -webkit- before everything. https://caniuse.com/css-scrollbar this site's really helpful for checking what browsers support what features, at least i use it a lot
For other browsers, use the pseudo elements: ::-webkit-scrollbar, ::-webkit-scrollbar-button, ::-webkit-scrollbar-thumb, ::-webkit-scrollbar-track, ::-webkit-scrollbar-track-piece, ::-webkit-scrollbar-corner, ::-webkit-resizer (info automatically gotten from W3Schools)
KRUGSTON MENTIONED !!
HELL YEAG KRUGSTON IS MENTIONED