diff --git a/core/modules/media_library/css/media_library.theme.css b/core/modules/media_library/css/media_library.theme.css
index f8b127ad22..dfe8a72108 100644
--- a/core/modules/media_library/css/media_library.theme.css
+++ b/core/modules/media_library/css/media_library.theme.css
@@ -139,15 +139,11 @@
 
 /* Media add form selection styles. */
 .media-library-add-form__selected-media {
-  margin-top: 1em;
+  margin: 1em -8px 0 -8px;
   padding-top: 1em;
   border-top: 1px solid #c0c0c0;
 }
 
-.media-library-add-form__selected-media .media-library-item {
-  width: 120px;
-}
-
 .media-library-add-form__selected-media .media-library-item .field--name-thumbnail img {
   height: 100px;
 }
@@ -286,16 +282,26 @@
   border: 1px solid #dbdbdb;
 }
 
+/* The selected items in the add form should be shown a bit smaller. */
+.media-library-add-form__selected-media .media-library-item--grid {
+  width: 33.3%;
+}
+
 @media screen and (min-width: 45em) {
   .media-library-item--grid {
-    width: 33%;
+    width: 33.3%;
   }
 
-  /* Use a smaller width for the modal and widget since there is less space. */
+  /* Change the width for the modal and widget since there is less space. */
   .media-library-widget-modal .media-library-item--grid,
   .media-library-selection .media-library-item--grid {
     width: 50%;
   }
+
+  /* The selected items in the add form should be shown a bit smaller. */
+  .media-library-add-form__selected-media .media-library-item--grid {
+    width: 25%;
+  }
 }
 
 @media screen and (min-width: 60em) {
@@ -303,23 +309,33 @@
     width: 25%;
   }
 
-  /* Use a smaller width for the modal and widget since there is less space. */
+  /* Change the width for the modal and widget since there is less space. */
   .media-library-widget-modal .media-library-item--grid,
   .media-library-selection .media-library-item--grid {
-    width: 33%;
+    width: 33.3%;
+  }
+
+  /* The selected items in the add form should be shown a bit smaller. */
+  .media-library-add-form__selected-media .media-library-item--grid {
+    width: 16.6%;
   }
 }
 
 @media screen and (min-width: 77em) {
   .media-library-item--grid {
-    width: 16%;
+    width: 16.6%;
   }
 
-  /* Use a smaller width for the modal and widget since there is less space. */
+  /* Change the width for the modal and widget since there is less space. */
   .media-library-widget-modal .media-library-item--grid,
   .media-library-selection .media-library-item--grid {
     width: 25%;
   }
+
+  /* The selected items in the add form should be shown a bit smaller. */
+  .media-library-add-form__selected-media .media-library-item--grid {
+    width: 16.6%;
+  }
 }
 
 .media-library-item--grid .field--name-thumbnail {
@@ -344,7 +360,7 @@
   border-radius: 3px;
 }
 
-.media-library-item--grid.checked {
+.media-library-item--grid.checked:before {
   border-color: #0076c0;
 }
 
diff --git a/core/modules/media_library/src/Form/AddFormBase.php b/core/modules/media_library/src/Form/AddFormBase.php
index 6ea135a5ba..788b14208d 100644
--- a/core/modules/media_library/src/Form/AddFormBase.php
+++ b/core/modules/media_library/src/Form/AddFormBase.php
@@ -592,7 +592,7 @@ public function updateWidget(array &$form, FormStateInterface $form_state) {
     }
 
     // Pass the selection to the field widget based on the current widget ID.
-    $opener_id = MediaLibraryState::fromRequest($this->getRequest())->getOpenerId();
+    $opener_id = $this->getMediaLibraryState($form_state)->getOpenerId();
     if ($field_id = MediaLibraryWidget::getOpenerFieldId($opener_id)) {
       // The added media items get an ID  when they are saved in ::submitForm().
       // For that reason the added media items are keyed by delta in the form
diff --git a/core/modules/media_library/tests/src/FunctionalJavascript/MediaLibraryTest.php b/core/modules/media_library/tests/src/FunctionalJavascript/MediaLibraryTest.php
index fcc3fff4e2..f5893c33ca 100644
--- a/core/modules/media_library/tests/src/FunctionalJavascript/MediaLibraryTest.php
+++ b/core/modules/media_library/tests/src/FunctionalJavascript/MediaLibraryTest.php
@@ -729,7 +729,7 @@ public function testWidgetUpload() {
     $assert_session->pageTextNotContains($png_image->filename);
 
     // Assert we can also directly insert uploaded files in the widget.
-    $assert_session->elementExists('css', '.media-library-open-button[href*="field_twin_media"]')->click();
+    $assert_session->elementExists('css', '.media-library-open-button[name^="field_twin_media"]')->click();
     $assert_session->assertWaitOnAjaxRequest();
     $assert_session->pageTextContains('Add or select media');
     $page->clickLink('Type Three');
@@ -803,7 +803,7 @@ public function testWidgetUpload() {
     $assert_session->pageTextContains('Unlimited Cardinality Image');
 
     // Assert we can now only upload one more media item.
-    $assert_session->elementExists('css', '.media-library-open-button[href*="field_twin_media"]')->click();
+    $assert_session->elementExists('css', '.media-library-open-button[name^="field_twin_media"]')->click();
     $assert_session->assertWaitOnAjaxRequest();
     $assert_session->pageTextContains('Add or select media');
     $page->clickLink('Type Four');
@@ -845,7 +845,7 @@ public function testWidgetUpload() {
 
     // Assert we can also remove selected items from the selection area in the
     // upload form.
-    $assert_session->elementExists('css', '.media-library-open-button[href*="field_unlimited_media"]')->click();
+    $assert_session->elementExists('css', '.media-library-open-button[name^="field_unlimited_media"]')->click();
     $assert_session->assertWaitOnAjaxRequest();
     $assert_session->pageTextContains('Add or select media');
     $page->clickLink('Type Three');
@@ -1013,7 +1013,7 @@ public function testWidgetOEmbed() {
     $assert_session->pageTextContains('Custom video title');
 
     // Assert we can directly insert added oEmbed media in the widget.
-    $assert_session->elementExists('css', '.media-library-open-button[href*="field_unlimited_media"]')->click();
+    $assert_session->elementExists('css', '.media-library-open-button[name^="field_unlimited_media"]')->click();
     $assert_session->assertWaitOnAjaxRequest();
     $assert_session->pageTextContains('Add or select media');
     $page->clickLink('Type Five');
@@ -1028,7 +1028,7 @@ public function testWidgetOEmbed() {
 
     // Assert we can remove selected items from the selection area in the oEmbed
     // form.
-    $assert_session->elementExists('css', '.media-library-open-button[href*="field_unlimited_media"]')->click();
+    $assert_session->elementExists('css', '.media-library-open-button[name^="field_unlimited_media"]')->click();
     $assert_session->assertWaitOnAjaxRequest();
     $assert_session->pageTextContains('Add or select media');
     $page->clickLink('Type Five');