--- a/browser/themes/shared/customizableui/panelUI.inc.css
+++ b/browser/themes/shared/customizableui/panelUI.inc.css
@@ -1691,23 +1691,29 @@ toolbarpaletteitem[haswideitem][place="p
   margin: 0;
 }
 
 #widget-overflow > .panel-arrowcontainer > .panel-arrowcontent {
   padding: 0;
 }
 
 .cui-widget-panelview,
+%ifndef MOZ_PHOTON_THEME
 #widget-overflow-scroller {
+%else
+#widget-overflow-mainView {
+%endif
   overflow-y: auto;
   overflow-x: hidden;
 }
 
 #widget-overflow-scroller {
+%ifndef MOZ_PHOTON_THEME
   max-height: 30em;
+%endif
   margin-top: 10px;
   margin-bottom: 10px;
 }
 
 .widget-overflow-list {
   width: @menuPanelWidth@;
   padding-left: 10px;
   padding-right: 10px;