Pass the `--no-langdetect` flag instead of ignoring the warning manually.

Toast should allow prevent default for hide and show events

https://getbootstrap.com/docs/4.3/extend/approach/#z-index-scales

I think it makes more sense to link to the Bootstrap package on Yarn here (like the package link for NPM above)

* Documentation tweaks
* Remove redundant `col-12` classes

* Use $popover-border-radius

* Move and rename the local $offset-border-width to the global variable

Instead now pointing to the most recent Wayback Machine archive copy.

Show the other navbar items on small screens too.

Also, fix the `update-deps` excludes and add karma since 4.x requires Node.js >= 8.

Extrapolates the previously used selector into a new mixin that only generates valid CSS by creating psuedo-classes for `valid` and `invalid`, and nothing else.

Fixes #28380.

* Fix buttons :focus state styles

Buttons :hover and :focus state shares styles.
Buttons :focus text color on 'a.btn' is now consistent with others '.btn'.

* `:focus` styles should be in sync with `.focus`.

So shared styles with hover were copy to focus definition. Rather then using
`hover-focus` mixin which do not contain `.focus`.

We use only `https` for a few months now.

Check prefers-reduced-motion variable before adding reduced motion media query for animated progress bars (#28530)