* Update the form focus mixin to use a manual `$enable-shadows` check so we can always ensure a focus state for accessibility and consistency
* - Add new `$input-btn-focus-width` and `$input-btn-focus-color` variables.
- Replace separate `$btn-focus-box-shadow` and `$input-focus-box-shadow`
variables with unified `$input-btn-focus-box-shadow` to match our
combined variables approach elsewhere.
* Put new focus width var to use in buttons mixins
* use new button input-box shadow var
* Add a new mixin for quickly adding linear gradient to components when $enable-gradients is set to true
* use correct var
* fix focus shadows in button mixins
* Add opt-in gradients to alerts, buttons, carousel, custom radios and checkboxes, custom file input, and dropdown items
* Generate .bg-gradient- utilities
* add headings to colors page and document bg-gradient utils
* update the button color for active status, check with yiq as it's done for basic state and hover state
* Fixed some linting issues
* Run npm tasks after scss cleanup
* Revert "Run npm tasks after scss cleanup"
This reverts commit 1103a0da68.
* Property sort order for grid
* Let's respest the property order in the mixins
* Respect property sort order in reboot file
* ::-ms-expand is a vendor-prefix, add it to the scss-lint disable
* Revert hover mixin comment
* Fixed missing mixin hover-focus
