box-shadow mixin fix (#28004)

diff --git a/scss/mixins/_box-shadow.scss b/scss/mixins/_box-shadow.scss
index 291d079728a439ad7a00fa1a9bbd9bd4ce8820bf..0726d4359a8f30eef0d0ca097a17994456343675 100644 (file)
--- a/scss/mixins/_box-shadow.scss
+++ b/scss/mixins/_box-shadow.scss
@@ -2,9 +2,15 @@
   @if $enable-shadows {
     $result: ();
 
-    @for $i from 1 through length($shadow) {
-      @if nth($shadow, $i) != "none" {
-        $result: append($result, nth($shadow, $i), "comma");
+    @if (length($shadow) == 1) {
+      // We can pass `@include box-shadow(none);`
+      $result: $shadow;
+    } @else {
+      // Filter to avoid invalid properties for example `box-shadow: none, 1px 1px black;`
+      @for $i from 1 through length($shadow) {
+        @if nth($shadow, $i) != "none" {
+          $result: append($result, nth($shadow, $i), "comma");
+        }
       }
     }
     @if (length($result) > 0) {