diff --git a/templates/base/components/collapsible-section/layout.html.twig b/templates/base/components/collapsible-section/layout.html.twig
index 9dacd7caf..db8b6264c 100644
--- a/templates/base/components/collapsible-section/layout.html.twig
+++ b/templates/base/components/collapsible-section/layout.html.twig
@@ -1,5 +1,5 @@
 <div id="{{ oUIBlock.GetId() }}"
-	 class="ibo-collapsible-section {{ oUIBlock.GetAdditionalCSSClass() }}{% if oUIBlock.IsOpenedByDefault() %} ibo-is-opened{% endif %}{% if oUIBlock.IsHidden() %} ibo-is-hidden{% endif %}">
+	 class="ibo-collapsible-section {{ oUIBlock.GetAdditionalCSSClasses() }}{% if oUIBlock.IsOpenedByDefault() %} ibo-is-opened{% endif %}{% if oUIBlock.IsHidden() %} ibo-is-hidden{% endif %}">
 	<div class="ibo-collapsible-section--header" data-role="ibo-collapsible-section--collapse-toggler">
 		<div class="ibo-collapsible-section--action-button ibo-collapsible-section--maximize-button"><i
 					class="fas fa-caret-down"></i></div>
diff --git a/templates/base/components/panel/layout.html.twig b/templates/base/components/panel/layout.html.twig
index 15b52b01c..1d539d76a 100644
--- a/templates/base/components/panel/layout.html.twig
+++ b/templates/base/components/panel/layout.html.twig
@@ -1,7 +1,7 @@
 {# @copyright   Copyright (C) 2010-2020 Combodo SARL #}
 {# @license     http://opensource.org/licenses/AGPL-3.0 #}
 {% apply spaceless %}
-    <div id="{{ oUIBlock.GetId() }}" class="ibo-panel ibo-is-{{ oUIBlock.GetColor() }} {{ oUIBlock.GetAdditionalCSSClass() }}{% if oUIBlock.IsHidden() %} ibo-is-hidden{% endif %}" {% block iboPanelMetaData %}{% endblock %}>
+    <div id="{{ oUIBlock.GetId() }}" class="ibo-panel ibo-is-{{ oUIBlock.GetColor() }} {{ oUIBlock.GetAdditionalCSSClasses() }}{% if oUIBlock.IsHidden() %} ibo-is-hidden{% endif %}" {% block iboPanelMetaData %}{% endblock %}>
         <div class="ibo-panel--header">
             {% block iboPanelHeader %}
                 <div class="ibo-panel--header-left">
diff --git a/templates/base/layouts/content-block/layout.html.twig b/templates/base/layouts/content-block/layout.html.twig
index e64a0ae7b..2e585ff8f 100644
--- a/templates/base/layouts/content-block/layout.html.twig
+++ b/templates/base/layouts/content-block/layout.html.twig
@@ -3,12 +3,12 @@
 {# Content Block #}
 {% apply spaceless %}
 
-    {% set bHasDiv = (oUIBlock.GetAdditionalCSSClass() or oUIBlock.GetDataAttributes()) %}
+    {% set bHasDiv = (oUIBlock.GetAdditionalCSSClasses() or oUIBlock.GetDataAttributes()) %}
 
     {% block iboContentBlockContainer %}
         {% if bHasDiv %}
             <div id="{{ oUIBlock.GetId() }}"
-            class="{% if oUIBlock.GetAdditionalCSSClass() %}{{ oUIBlock.GetCSSClasses() }}{% endif %}{% if oUIBlock.IsHidden() %} ibo-is-hidden{% endif %}"
+            class="{% if oUIBlock.GetAdditionalCSSClasses() %}{{ oUIBlock.GetAdditionalCSSClasses() }}{% endif %}{% if oUIBlock.IsHidden() %} ibo-is-hidden{% endif %}"
             {% if oUIBlock.GetDataAttributes() %}
                 {% for sName, sValue in oUIBlock.GetDataAttributes() %}
                     data-{{ sName }}="{{ sValue }}"