diff --git a/core/modules/block/css/block.admin.css b/core/modules/block/css/block.admin.css
index edee308..64cd6b9 100644
--- a/core/modules/block/css/block.admin.css
+++ b/core/modules/block/css/block.admin.css
@@ -43,13 +43,10 @@ a.block-demo-backlink:hover {
 .block-list-secondary .form-type-search {
   padding: 0 1em;
 }
-#block-placed {
-  background-color: #ffd;
-}
-#edit-settings-admin-label label {
+.block-form .form-item-settings-admin-label label {
   display: inline;
 }
-#edit-settings-admin-label label:after {
+.block-form .form-item-settings-admin-label label:after {
   content: ':';
 }
 
@@ -60,8 +57,7 @@ screen and (min-width: 780px),
 
   .block-list-primary {
     float: left; /* LTR */
-    width: 75%;
-    padding-right: 2em;
+    width: 73%; /* Reducing 2% for whitespace to 100% container */
   }
   [dir="rtl"] .block-list-primary {
     float: right;
diff --git a/core/modules/block/js/block.admin.js b/core/modules/block/js/block.admin.js
index 422a83a..573f486 100644
--- a/core/modules/block/js/block.admin.js
+++ b/core/modules/block/js/block.admin.js
@@ -79,7 +79,7 @@
           // Just scrolling the document.body will not work in Firefox. The html
           // element is needed as well.
           $('html, body').animate({
-            scrollTop: $('#block-placed').offset().top - $container.offset().top + $container.scrollTop()
+            scrollTop: $('.js-block-placed').offset().top - $container.offset().top + $container.scrollTop()
           }, 500);
         });
       }
diff --git a/core/modules/block/src/BlockListBuilder.php b/core/modules/block/src/BlockListBuilder.php
index 293f088..b5e7120 100644
--- a/core/modules/block/src/BlockListBuilder.php
+++ b/core/modules/block/src/BlockListBuilder.php
@@ -247,9 +247,12 @@ public function buildForm(array $form, FormStateInterface $form_state) {
             ),
           );
           if ($placement && $placement == Html::getClass($entity_id)) {
-            $form['blocks'][$entity_id]['#attributes']['id'] = 'block-placed';
+            $form['blocks'][$entity_id] = array(
+              '#attributes' => array (
+              'class' => array('color-warning', 'js-block-placed')
+              )
+            );
           }
-
           $form['blocks'][$entity_id]['info'] = array(
             '#markup' => String::checkPlain($info['label']),
             '#wrapper_attributes' => array(