diff --git a/core/modules/field_layout/field_layout.install b/core/modules/field_layout/field_layout.install
index 6b761bc..76d0ddf 100644
--- a/core/modules/field_layout/field_layout.install
+++ b/core/modules/field_layout/field_layout.install
@@ -30,3 +30,18 @@ function field_layout_install() {
   // Invalidate the render cache since all content will now have a layout.
   Cache::invalidateTags(['rendered']);
 }
+
+/**
+ * Implements hook_uninstall().
+ */
+function field_layout_uninstall() {
+  // Remove field layout settings from all entity displays.
+  $config_factory = \Drupal::configFactory();
+  $config_names = array_merge($config_factory->listAll('core.entity_view_display.'), $config_factory->listAll('core.entity_form_display.'));
+  foreach ($config_names as $name) {
+    $config_factory->getEditable($name)->clear('third_party_settings.field_layout')->save(TRUE);
+  }
+
+  // Invalidate the render cache since all content will not have a layout.
+  Cache::invalidateTags(['rendered']);
+}
diff --git a/core/modules/field_layout/field_layout.module b/core/modules/field_layout/field_layout.module
index 14cf931..7c0d864 100644
--- a/core/modules/field_layout/field_layout.module
+++ b/core/modules/field_layout/field_layout.module
@@ -108,21 +108,17 @@ function _field_layout_apply_layout(array &$build, EntityDisplayInterface $displ
   }
 
   // Add the regions to the $build in the correct order.
-  $regions = array_keys($layout_definition['regions']);
-  foreach ($regions as $region) {
-    $build[$region]['#theme_wrappers'][] = 'field_layout_region';
-    $build[$region]['#region'] = $region;
+  foreach ($layout_definition['regions'] as $region => $region_info) {
+    $build['field_layout__' . $region]['#theme_wrappers'][] = 'field_layout_region';
+    $build['field_layout__' . $region]['#region'] = $region;
   }
 
-  $field_layout = $display->getThirdPartySetting('field_layout', 'fields', []);
-  foreach ($display->getComponents() as $name => $component) {
-    if (isset($build[$name]) && isset($field_layout[$name]['region'])) {
-      $region = $field_layout[$name]['region'];
-      if ($region !== 'hidden') {
-        $build[$region][$name] = $build[$name];
-      }
-      unset($build[$name]);
+  // Move the field from the top-level of $build into a region-specific section.
+  foreach ($display->getThirdPartySetting('field_layout', 'fields', []) as $name => $field) {
+    if (isset($build[$name]) && $field['region'] !== 'hidden') {
+      $build['field_layout__' . $field['region']][$name] = $build[$name];
     }
+    unset($build[$name]);
   }
 }
 
diff --git a/core/modules/field_layout/templates/field-layout-region.html.twig b/core/modules/field_layout/templates/field-layout-region.html.twig
index 0c0b5d3..6969b5f 100644
--- a/core/modules/field_layout/templates/field-layout-region.html.twig
+++ b/core/modules/field_layout/templates/field-layout-region.html.twig
@@ -17,7 +17,7 @@
 {%
 set classes = [
 'field-layout-region',
-'field-layout-region-' ~ region|clean_class,
+'field-layout-region--' ~ region|clean_class,
 ]
 %}
 {% if content %}
diff --git a/core/modules/field_layout/tests/src/FunctionalJavascript/FieldLayoutTest.php b/core/modules/field_layout/tests/src/FunctionalJavascript/FieldLayoutTest.php
index 705b769..09e8b3c 100644
--- a/core/modules/field_layout/tests/src/FunctionalJavascript/FieldLayoutTest.php
+++ b/core/modules/field_layout/tests/src/FunctionalJavascript/FieldLayoutTest.php
@@ -49,7 +49,7 @@ protected function setUp() {
   public function testEntityView() {
     // By default, the default layout is used.
     $this->drupalGet('node/1');
-    $this->assertSession()->elementExists('css', '.field-layout-region-content .field--name-body');
+    $this->assertSession()->elementExists('css', '.field-layout-region--content .field--name-body');
 
     // The default layout is in use.
     $this->drupalGet('admin/structure/types/manage/article/display');
@@ -91,7 +91,12 @@ public function testEntityView() {
 
     // The new layout is used.
     $this->drupalGet('node/1');
-    $this->assertSession()->elementExists('css', '.field-layout-region-left .field--name-body');
+    $this->assertSession()->elementExists('css', '.field-layout-region--left .field--name-body');
+
+    // The layout is still in use without Field UI.
+    $this->container->get('module_installer')->uninstall(['field_ui']);
+    $this->drupalGet('node/1');
+    $this->assertSession()->elementExists('css', '.field-layout-region--left .field--name-body');
   }
 
   /**