Scrolling behavior of the "Contents" sidebar is inaccurate, doesn't detect current section

[grisaitis]

Describe the bug

context
When I click on a section name under the "Contents" sidebar on the right...

expectation
I expected that section to be highlighted and any subsections expanded under the name.

bug
But instead:

• the previous section shows up as currently viewed.
• the problem is "solved" if i scroll down a little
  • (ie, only after scrolling down a smidge does the selected section become highlighted and expanded under "Contents")

problem
This is a problem for people navigating pages via the table of contents sidebar. Using the sidebar is useful for browsing large pages, but this issue makes navigation less user-friendly and sometimes very confusing.

Reproduce the bug

this can be seen on any site built with this sphinx theme. For example, in the docs for this project, it can be seen at: https://sphinx-book-theme.readthedocs.io/en/stable/customize/sidebar-primary.html#customize-the-sidebar-footer

addendum - potential causes

• when selecting a section (e.g. opening a URL like page.html#section-name), i think the page needs to be scrolled down a few pixels more. Currently, the last few pixels of the previous section are still visible.
• Maybe this is related to MAINT: Simplify toc scrolling behavior #448 and the IntersectionObserver API. Maybe a pixel offset needs to be adjusted somewhere?
  • I tried modifying sphinx-book-theme.js to have e[0].boundingClientRect.y<-20, or also -200, but noticed no change in the ui.

note
i opened an issue about this at jupyter-book/jupyter-book#1827. But I think this repo is the correct place to open this.

List your environment

No response

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[choldgraf]

Yep - thanks for noticing this. I believe this is a duplicate of the issue below, feel free to re-open if you think it's different!

• Wrong content section in the sidebar #545

[grisaitis]

thank you! yes, it is indeed a dupe.