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.

Currently, `$toast-border-radius` uses the value of `.25rem`. This is inconsistent with other variables such as `$btn-border-radius` and `$input-border-radius`, which uses the "global" `$border-radius` variable.

* 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)

We don't need the extra bloat of gtag.

This reverts commit 089e3334.

This reverts commit 5e068eed.