It seems sometimes when reading on desktop, Leaflet won't open any additional panels and centre them properly, but only if the browser window is a certain size. I use Firefox with vertical tabs and the sidebar minimised, and for whatever reason this makes Leaflet refuse to centre the comments or subpages when I open them. However, when I expand the sidebar, so the display becomes less wide overall, then opening a subpage or the comments will focus properly. I have only observed this on desktop, and only in this case (which is my personal default).
One other small note is that I feel it'd be nice to have another animation to slide the main leaflet page back into the centre after closing the comments/subpages, though that's not the main issue at hand here.
Hi, thanks for reporting! We just pushed a change that should make the subpage scroll behavior a bit more consistent, though possible it's still wonky at certain combos of browser + screen size (hard to test em all!)
If you're still seeing issues it might help to email us a screenshot (I don't think possible to add images yet here) and exact browser and width and behavior you're seeing so we can see if we're able to reproduce.