diff -u b/core/modules/layout_builder/tests/src/FunctionalJavascript/FieldValuesTest.php b/core/modules/layout_builder/tests/src/FunctionalJavascript/FieldValuesTest.php
--- b/core/modules/layout_builder/tests/src/FunctionalJavascript/FieldValuesTest.php
+++ b/core/modules/layout_builder/tests/src/FunctionalJavascript/FieldValuesTest.php
@@ -27,7 +27,7 @@
   /**
    * {@inheritdoc}
    */
-  protected $defaultTheme = 'classy';
+  protected $defaultTheme = 'stark';
 
   /**
    * {@inheritdoc}