Gradients and shadows (#24429)

* 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

1 files changed, 3 insertions, 3 deletions

diff --git a/scss/_custom-forms.scss b/scss/_custom-forms.scss
index 41dae4d76..a521dbdc9 100644
--- a/scss/_custom-forms.scss
+++ b/scss/_custom-forms.scss
@@ -22,7 +22,7 @@
 
   &:checked ~ .custom-control-indicator {
     color: $custom-control-indicator-checked-color;
-    background-color: $custom-control-indicator-checked-bg;
+    @include gradient-bg($custom-control-indicator-checked-bg);
     @include box-shadow($custom-control-indicator-checked-box-shadow);
   }
 
@@ -33,7 +33,7 @@
 
   &:active ~ .custom-control-indicator {
     color: $custom-control-indicator-active-color;
-    background-color: $custom-control-indicator-active-bg;
+    @include gradient-bg($custom-control-indicator-active-bg);
     @include box-shadow($custom-control-indicator-active-box-shadow);
   }
 
@@ -244,7 +244,7 @@
     padding: $custom-file-padding-y $custom-file-padding-x;
     line-height: $custom-file-line-height;
     color: $custom-file-button-color;
-    background-color: $custom-file-button-bg;
+    @include gradient-bg($custom-file-button-bg);
     border: $custom-file-border-width solid $custom-file-border-color;
     @include border-radius(0 $custom-file-border-radius $custom-file-border-radius 0);
   }