Issue #3497831: The Header H2 Search results title doesn't have any class for theming

Closes #3497831

core/modules/search/src/Controller/SearchController.php

@@ -99,7 +99,7 @@ public function view(Request $request, SearchPageInterface $entity) {
 
     if (count($results)) {
       $build['search_results_title'] = [
-        '#markup' => '<h2>' . $this->t('Search results') . '</h2>',
+        '#markup' => '<h2 class="results-title">' . $this->t('Search results') . '</h2>',
       ];
     }