* Add dropright (right placement for our dropdown)

* Add dropleft

* moves drop left arrow to the left

Unit test for pull request #24240

Having it uppercase doesn't offer anything and the lowercase version slightly improves gzip compression.

* use a trailing slash when possible
* use https when possible
* remove a few redirected links
* consistently use `https://popper.js.org/`
* fix `iconUrl` in nuget files
* change Jekyll Windows guide to the official one

* Use `aria-selected` instead of `aria-expanded`
* Change tab.js to use `aria-selected` rather than `aria-expanded`
* Add `aria-orientation=vertical` to vertical tab list
* Remove dynamic tabs with dropdowns
* Fix non-interactive code examples
* Only set `aria-selected` on the `role="tab"` trigger - this stops `aria-selected` being incorrectly added to the `role="tabpanel"` itself (probably harmless, but nonetheless incorrect)

* fix(scrollspy): Handle nested navs when nav-link inside nav-item

* [scrolspy] Find only child .nav-link's inside .nav-item

* [scrollspyt] Add tests for nested navs with nav-link inside nav-item

* fix troy-o's in test

Use a virtual scrollbar as this is simpler than having a real one (overflow: scroll doesn't seem to work in Phantom), and disable it for the new test.

One test has also been altered to prevent erroneous fails when other inline styles are added to the body (e.g. overflow).

When the body does not overflow (achieved by hiding the QUnit container), it should not be given a margin.

* Adjust margin for sticky elements on modal

Previously white space was visible to the right of sticky elements due to right padding being added to the body. This fixes #23661.

* Add unit tests for margin of sticky elements on modal

element