They don't fit the theme at all

Is your issue with their colour, their form, or both?
All of the above.
Having similar issue on Firefox @ Manjaro Linux.
Moreover, for some reason, the Favorites section even glitches the whole layout on hover (sidebar gets narrower on hover on Favorites) – see video preview.
@AllienWorks I think the issue you're seeing is different from this one. Please open a new issue using the "Redesign" template with the link to the video there.
@AllienWorks I think the issue you're seeing is different from this one. Please open a new issue using the "Redesign" template with the link to the video there.
Issue disappeared when I manually resized the sidebar width, so probably some leftover of my old settings from non-experimental Riot version. Not sure if another logged issue is needed then..?
I have the same issue on linux on the room list. Everywhere else they use a different (and imo nicer) scrollbar style
Some more insight:
It also sounds like the idea is to move away from the current css fake scrollbar library and towards native scrollbars.
with native CSS scrollbars we can do better, like this:

Something like:
.mx_AutoHideScrollbar {
scrollbar-color: rgba(0,0,0,.2) transparent;
scrollbar-width: thin;
}
Most helpful comment
with native CSS scrollbars we can do better, like this:
Something like: