Issue #2567845 by LewisNyman, davidhernandez: [regression] Fix any visual regressions from moving the System CSS to Classy

core/modules/block/css/block.admin.css

@@ -1,8 +1,9 @@
 /* Block listing page */
-.region-title .button {
+.region-title__action {
+  display: inline-block;
   margin-left: 1em; /* LTR */
 }
-[dir="rtl"] .region-title .button {
+[dir="rtl"] .region-title__action {
   margin-left: 0;
   margin-right: 1em;
 }

core/modules/block/src/BlockListBuilder.php

@@ -214,6 +214,11 @@ class BlockListBuilder extends ConfigEntityListBuilder implements FormInterface
         ),
       );
       $form['region-' . $region]['title'] = array(
+        '#theme_wrappers' => array(
+          'container' => array(
+            '#attributes' => array('class' => 'region-title__action'),
+          )
+        ),
         '#prefix' => $region != BlockInterface::BLOCK_REGION_NONE ? $title : $block_regions_with_disabled[$region],
         '#type' => 'link',
         '#title' => $this->t('Place block <span class="visually-hidden">in the %region region</span>', ['%region' => $block_regions_with_disabled[$region]]),