[Feature Request] Pin TOC filter at the top on scroll to page bottom

[filzrev]

Is your feature request related to a problem? Please describe.

When browsing the docfx site, and scroll to the bottom of the page. Then footer area is displayed at bottom.

At this time, the TOC/Affix area is scrolled. and it hide Textbox for TOC filter.

Describe the solution you'd like

The TOC/Affix navigation area is not scrolled whether the footer area is displayed or not.

Additional context Current behavior is the same as the Bootstrap 5.3 official documentation site

This behavior is not caused when using default template.