1 files changed, 16 insertions, 1 deletions
diff --git a/vendor/twbs/bootstrap/scss/mixins/_box-shadow.scss b/vendor/twbs/bootstrap/scss/mixins/_box-shadow.scss
index b2410e53a..0726d4359 100644
--- a/vendor/twbs/bootstrap/scss/mixins/_box-shadow.scss
+++ b/vendor/twbs/bootstrap/scss/mixins/_box-shadow.scss
@@ -1,5 +1,20 @@
 @mixin box-shadow($shadow...) {
   @if $enable-shadows {
-    box-shadow: $shadow;
+    $result: ();
+
+    @if (length($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) {
+      box-shadow: $result;
+    }
   }
 }