Remove now-unneeded focus-visible backwards compat

client/scss/components/_dropdown-button.scss

@@ -26,16 +26,6 @@ $radius: theme('borderRadius.sm');
     width: 100%;
   }
 
-  @supports not selector(:has(*)) {
-    // Use no corner radius and always-on borders if `:has` is not supported.
-    --primary-button-radius-top: 0;
-    --primary-button-radius-bottom: 0;
-    --toggle-button-radius-top: 0;
-    --toggle-button-radius-bottom: 0;
-    --first-item-border-top: #{$separator};
-    --last-item-border-top: #{$separator};
-  }
-
   &:has(:not([hidden]) > [data-placement^='bottom']) {
     --primary-button-radius-top: #{$radius};
     --primary-button-radius-bottom: 0;

client/scss/components/_form-side.scss

@@ -85,13 +85,6 @@
     &:focus-within:has(:focus-visible) {
       @include focus-outline;
     }
-
-    @supports not selector(:focus-visible) {
-      &:focus-within {
-        /* Fallback for browsers without :focus-visible support */
-        @include focus-outline;
-      }
-    }
   }
 
   &__resize-grip-icon {

client/scss/components/forms/_switch.scss

@@ -93,12 +93,6 @@ $switch-border-radius: math.div(($switch-height + $switch-border * 2), 2);
     outline: theme('colors.focus') solid $switch-outline;
   }
 
-  @supports not selector(:focus-visible) {
-    [type='checkbox']:focus + &__toggle {
-      outline: theme('colors.focus') solid $switch-outline;
-    }
-  }
-
   [type='checkbox'] {
     position: absolute;
     opacity: 0;

client/scss/overrides/_utilities.focus.scss

@@ -2,15 +2,6 @@
 // Set global focus outline styles so they are consistent across the UI,
 // without individual components having to explicitly define focus styles.
 // Using !important because we want to enforce only one style is used across the UI.
-// Remove :focus selectors once we stop supporting Safari 15.4.
-*:focus {
-  outline: $focus-outline-width solid theme('colors.focus') !important;
-}
-
-*:focus:not(:focus-visible) {
-  outline: none !important;
-}
-
 *:focus-visible {
   outline: $focus-outline-width solid theme('colors.focus') !important;
 }