Placeholder for transitions reset to prevent code duplication… (#29870)

Co-authored-by: Martijn Cuppens <martijn.cuppens@gmail.com>
Co-authored-by: XhmikosR <xhmikosr@gmail.com>

scss/_reboot.scss

@@ -583,3 +583,14 @@ main {
 [hidden] {
   display: none !important;
 }
+
+// Placeholder used to reset transitions, when user prefers reduced motion
+
+@if $enable-prefers-reduced-motion-media-query {
+  @media (prefers-reduced-motion: reduce) {
+    %no-transition {
+      // stylelint-disable-next-line property-blacklist
+      transition: none !important;
+    }
+  }
+}

scss/_variables.scss

@@ -212,6 +212,14 @@ $escaped-characters: (
   (")","%29"),
 ) !default;
 
+// Selectors which are isolated in the transition mixin to prevent invalid selector stack
+$pseudo-vendor-prefixes: (
+  "::-webkit-",
+  "::-moz-",
+  "::-ms-"
+) !default;
+
+
 // Options
 //
 // Quickly modify global styling by enabling or disabling optional features.

scss/mixins/_transition.scss

@@ -9,8 +9,19 @@
   }
 
   @if $enable-prefers-reduced-motion-media-query {
-    @media (prefers-reduced-motion: reduce) {
-      transition: none;
+    $isolate: false;
+    @each $selector in $pseudo-vendor-prefixes {
+      @if str-index(quote(#{&}), $selector) {
+        $isolate: true;
+      }
+    }
+
+    @if $isolate {
+      @media (prefers-reduced-motion: reduce) {
+        transition: none;
+      }
+    } @else {
+      @extend %no-transition;
     }
   }
 }