diff --git a/UI/WebServerResources/UIxAttendeesEditor.css b/UI/WebServerResources/UIxAttendeesEditor.css
index f3681c61a..4130a548a 100644
--- a/UI/WebServerResources/UIxAttendeesEditor.css
+++ b/UI/WebServerResources/UIxAttendeesEditor.css
@@ -133,6 +133,9 @@ SPAN.freeBusyZoneElement
 TABLE#freeBusyHeader TR.freeBusyHeader3 SPAN.freeBusyZoneElement
 { height: .25em; }
 
+TABLE#freeBusyHeader TR.freeBusyHeader3 SPAN.freeBusyZoneElement.busy
+{ background-color: #f03 !important; }
+
 TABLE#freeBusyData TD SPAN.freeBusyZoneElement
 { height: 98%; /* not nice under Safari */ }