- font size 16px to prevent zooming on iOS Safari
- search input is scrolled into view on iOS Safari
- box-shadow is displayed correctly

Improved documentation for search configurations

Added more search configurations
Display "no results found"

Removes children from the table of contents that
belong to a different page with the same title.

When `nav_order` is omitted, the order of nodes at each menu level (and in the auto-generated TOC) is alphabetical by `title`, instead of random.
Any nodes with a specified `nav_order` precede all nodes at that level where it is omitted.
Note that `nav_order` fields must have a uniform site-ide type: integers and strings cannot be mixed, otherwise Jekyll reports errors.
The implementation filters the ordered and unordered pages from `site.html_pages`, sorts them separately, and concatenates the resulting arrays.

(cherry picked from commit 99371e971406090a2dba7b9b69f514a8f87afce3)

(cherry picked from commit 468264941d08b00252a4f6f081bc2dff5920bffe)

(cherry picked from commit db50f282bab1e98397cc7434a811b8b7da2fe6dc)

(cherry picked from commit fd3c68cd1a39e059180c35c1d56ffa33ef4dfde4)

(cherry picked from commit 2b153ed074811e735aaa58d57a3fcdf7838e17f5)

(cherry picked from commit eeb3f342b17a744d0c2b2f0360359fa3276f8abd)

Deduplicated anchor heading svg,
Anchor heading svg is now centered for heading