Sidebar no longer scrolls on hover in published docs #3571
Description
Bug description
Since ~Aug 14–15, 2025, the left sidebar in published GitBook docs no longer scrolls when you hover it and use the mouse wheel / trackpad. Instead, the main page scrolls. This reproduces on GitBook’s own site (such as here: https://gitbook.com/docs/getting-started/git-sync/troubleshooting), suggesting a platform regression tied to the recent “new sidebar” changes (https://www.gitbook.com/blog/new-sidebar).
How to reproduce
- Create a page in GitBook with >20 Heading blocks (I used "Heading 2", not sure that matters)
- Under any of the headers, add 20 new lines (this makes it so the main content is scrollable)
- Publish the page
- View the published page
- Hover over the table of contents in the sidebar and try to scroll
- Observe that the sidebar does not scroll
- Scroll to the bottom of the main content
- Observe that the sidebar is cut off after the ~18th header and there is no way to see it
- Zoom out in the browser window
- Observe that the additional Headings are now shown in the sidebar
Additional context
Where a page has many more headings (>40) the user must zoom out tremendously to even see the headings at the end of the list in the sidebar so much so that the main text (and the sidebar) is completely unreadable. Restricting the ability to scroll in the sidebar as before effectively limits the number of headings that can be used on a GitBook page. This limitation is very impactful for pages that contain a lot of information, such as a technical reference page.
