diff -u b/core/lib/Drupal/Core/Asset/CssCollectionRenderer.php b/core/lib/Drupal/Core/Asset/CssCollectionRenderer.php
--- b/core/lib/Drupal/Core/Asset/CssCollectionRenderer.php
+++ b/core/lib/Drupal/Core/Asset/CssCollectionRenderer.php
@@ -72,9 +72,8 @@
           throw new \Exception('Invalid CSS asset type.');
       }
 
-      // Attributes may only be set if the stylesheet is outputted
-      // independently.
-      if (!empty($element['#attributes']['href']) && !empty($css_asset['attributes'])) {
+      // Merge any additional attributes.
+      if (!empty($css_asset['attributes'])) {
         $element['#attributes'] += $css_asset['attributes'];
       }