diff --git a/css/layout-builder-lock.css b/css/layout-builder-lock.css
index a3cb608f924aac203f15bbc1b9c2b3435d252357..b7ebb78259ccf7cee27c5aa5ee5d8f9c941f8a7e 100644
--- a/css/layout-builder-lock.css
+++ b/css/layout-builder-lock.css
@@ -1,4 +1,6 @@
-.layout-builder-block-locked {
+/* Using :not(b) is slightly more specific (0 1 1) than a single class selector but less
+   specific than 2 class selectors (0 2 0). The element is not likely to be a <b>. */
+.layout-builder-block-locked:not(b) {
   padding: 1.5em;
   cursor: default;
 }
diff --git a/src/LayoutBuilderLock.php b/src/LayoutBuilderLock.php
index dde898cc46d3f57eed7c3ab44a34c5dd8a52c3a5..6ea9f84a071505efe6d31faf5d660e99757a6f3c 100644
--- a/src/LayoutBuilderLock.php
+++ b/src/LayoutBuilderLock.php
@@ -216,14 +216,12 @@ class LayoutBuilderLock implements TrustedCallbackInterface {
                 }
 
                 // If moving is not allowed, remove the default layout builder
-                // classes on this block and add our own so we can reset the
+                // js class on this block and add our own so we can reset the
                 // pointer and padding.
                 if (!$allow_moving) {
-                  foreach (['layout-builder-block', 'js-layout-builder-block'] as $class) {
-                    if (isset($element['layout_builder'][$section_number][$name][$region_key][$item_key]['#attributes']['class']) && is_array($element['layout_builder'][$section_number][$name][$region_key][$item_key]['#attributes']['class'])) {
-                      $key = array_search($class, $element['layout_builder'][$section_number][$name][$region_key][$item_key]['#attributes']['class']);
-                      unset($element['layout_builder'][$section_number][$name][$region_key][$item_key]['#attributes']['class'][$key]);
-                    }
+                  if (isset($element['layout_builder'][$section_number][$name][$region_key][$item_key]['#attributes']['class']) && is_array($element['layout_builder'][$section_number][$name][$region_key][$item_key]['#attributes']['class'])) {
+                    $key = array_search('js-layout-builder-block', $element['layout_builder'][$section_number][$name][$region_key][$item_key]['#attributes']['class']);
+                    unset($element['layout_builder'][$section_number][$name][$region_key][$item_key]['#attributes']['class'][$key]);
                   }
                   $element['layout_builder'][$section_number][$name][$region_key][$item_key]['#attributes']['class'][] = 'layout-builder-block-locked';
                 }