Fix sticky TOC scrolling after app-pane wrapper removal

[gonogo]

Restore an independently scrollable sidebar without locking the viewport, so the full-width footer scrolls into view with the page.

Proposed changes

• Restore an independently scrollable left TOC after the .app-pane wrapper was removed in [Bug]: whitespace on long pages #513, without locking the viewport.

• Keep the full-width footer in normal document flow so it scrolls into view at the end of the content.

• Update in-page and collapsible navigation scroll handling to listen on window instead of .app-pane__content.

• Relates to [Bug]: whitespace on long pages #513

• Fixes [Enhancement]: Fix scrolling behaviour so navigation scrolls independently of content #537

[JC-DSIT]

@gonogo - thanks for the PR, a couple of issues I noticed in the screen grab below :)

Toc.Review.mp4

[JC-DSIT]

See screen recording attached to PR comments.

• border is not consistent
• screen bounces on long ToC

[gonogo]

Good spot, have now fixed footer issue. Not sure what you mean about inconsistent border though? Can you clarify? Thanks

[JC-DSIT]

Good spot, have now fixed footer issue. Not sure what you mean about inconsistent border though? Can you clarify? Thanks

Thanks @gonogo - regarding the border these screenshots may be clearer:

Either the right border of the ToC container needs to be visible for the full length at all times, or the left border of the main content. It doesn't really matter which so long as the result is the same, so whichever is easier/most sensible

[JC-DSIT]

@gonogo - is there any update on this?

[gonogo]

@JC-DSIT Have updated, moved the border - previously it was on the right of the TOC, now it's on the left of the content so it appears consistently regardless of the length of either the content or the TOC.

[JC-DSIT]

HI @gonogo - i did review the changes and the border for the table os contents is still not consistent - you can see this if you use the example documentation site and play around with expanding the ToC headings.

When we have a chance we will take a look and see if there is a better solution. In the meantime if you do make any more changes let us know

[gonogo]

@JC-DSIT Sorry I missed this before, have now reworked it using the example site to test it. Have fixed the issue by stretching the content pane so it always reaches the footer even if it's shorter than the table of contents. Have tested with the example site.