diff --git a/CHANGELOG.md b/CHANGELOG.md
index cdaf985e8695c97ae540a7b2e8b1b82510a81511..7a99793a38bb8b3d58222f8d1c214b09fd3c59c9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -7,6 +7,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [1.4.3]
 - Apply fix for Owl Carousel library loading in Horizontal Boxes view display format
+- Modify display formats to keep css classes added manually in view config
 
 ## [1.4.2] - 25/05/2020
 - Removed library declaration of JS file that does not exist
diff --git a/cern_display_formats.module b/cern_display_formats.module
index cf7be33f948aed3a276e3065175e685bb4999f39..06978ea52b9083cf17577c515ed2bc72c4eedd7c 100755
--- a/cern_display_formats.module
+++ b/cern_display_formats.module
@@ -41,11 +41,14 @@ function cern_display_formats_views_pre_render(ViewExecutable $view){
 
 	$admin_form = \Drupal::config('cern_display_formats.adminsettings');	// gets the admin form
 
+	// get css classes
+	$css_classes = $view->display_handler->getOption('css_class');
+	$extra_class = '';
 	if ($view->display_handler->view->style_plugin->getPluginId() == "horizontal_boxes") {
-		$view->display_handler->setOption('css_class', 'horizontal-boxes');
 		$view->element['#attached']['library'][] = "cern_display_formats/horizontal-boxes-stylesheets";	//attaches the stylesheet
+		$extra_class = 'horizontal-boxes';
 	} elseif ($view->display_handler->view->style_plugin->getPluginId() == "collision") {
-		$view->display_handler->setOption('css_class', 'events-collision');
+		$extra_class = 'events-collision';
 	} elseif ($view->display_handler->view->style_plugin->getPluginId() == "countdown") {
 		$date_color =	$admin_form->get('countdown_date_color');
 		$link_color = $admin_form->get('countdown_link_color');
@@ -56,9 +59,9 @@ function cern_display_formats_views_pre_render(ViewExecutable $view){
 		$view->element['#attached']['drupalSettings']['displayFormats']['countdown']['linkColor'] = $link_color;
 		$view->element['#attached']['drupalSettings']['displayFormats']['countdown']['placeColor'] = $place_color;
 		$view->element['#attached']['library'][] = 'cern_display_formats/countdown-stylesheets';
-		$view->display_handler->setOption('css_class', 'events-countdown');
+		$extra_class = 'events-countdown';
 	} elseif ($view->display_handler->view->style_plugin->getPluginId() == "teaser_list") {
-		$view->display_handler->setOption('css_class', 'teaser-list');
+		$extra_class =  'teaser-list';
 	} elseif ($view->display_handler->view->style_plugin->getPluginId() == "featured_banner") {
 		$link_color = $admin_form->get('featured_banner_link_color');
 		$subtext_color = $admin_form->get('featured_banner_subtext_color');
@@ -66,19 +69,23 @@ function cern_display_formats_views_pre_render(ViewExecutable $view){
 		$view->element['#attached']['drupalSettings']['displayFormats']['featured_banner']['linkColor'] = $link_color;
 		$view->element['#attached']['drupalSettings']['displayFormats']['featured_banner']['subtextColor'] = $subtext_color;
 		$view->element['#attached']['drupalSettings']['displayFormats']['featured_banner']['backgroundColor'] = $background_color;
-		$view->display_handler->setOption('css_class', 'featured-banner');
 		$view->element['#attached']['library'][] = "cern_display_formats/featured-banner-stylesheets";	//attaches the stylesheet
+		$extra_class =  'featured-banner';
 	} elseif ($view->display_handler->view->style_plugin->getPluginId() == "vertical_boxes") {
-		$view->display_handler->setOption('css_class', 'vertical-boxes');
+		$extra_class = 'vertical-boxes';
 	} elseif ($view->display_handler->view->style_plugin->getPluginId() == "accordion") {
-		$view->display_handler->setOption('css_class', 'accordion-cern');
 		$view->element['#attached']['library'][] = 'cern_display_formats/accordion-stylesheets'; //attaches the stylesheet
 		$title_color = $admin_form->get('accordion_title_color');
 		$view->element['#attached']['drupalSettings']['displayFormats']['accordion']['titleColor'] = $title_color;
+		$extra_class = 'accordion-cern';
 	} elseif ($view->display_handler->view->style_plugin->getPluginId() == "card_grid") {
-		$view->display_handler->setOption('css_class', 'card-grid');
+		$extra_class =  'card-grid';
 	} elseif ($view->display_handler->view->style_plugin->getPluginId() == "event_grid") {
-		$view->display_handler->setOption('css_class', 'event-grid');
 		$view->element['#attached']['library'][] = "cern_display_formats/event-grid-stylesheets";	//attaches the stylesheet
+		$extra_class =  'event-grid';
 	}
+
+	// glues together the rest of the css classes with the extra class
+	$css_classes = implode( ' ', array( $css_classes, $extra_class) );
+	$view->display_handler->setOption('css_class', $css_classes);
 }