diff --git a/calendar/templates/default/app.css b/calendar/templates/default/app.css
index ad7f30ce3b..6aee363b0d 100644
--- a/calendar/templates/default/app.css
+++ b/calendar/templates/default/app.css
@@ -473,7 +473,7 @@ e.g. the div with class calendar_calTimeGrid is generated by the timeGridWidget
 	display: inline-block;
 	white-space: nowrap;
 	/* This determines how many per line */
-	flex: 1 1 20em;
+	flex: 1 1 auto;
 }
 .calendar_calDayColHeader .calendar_calEvent .calendar_calEventBody {
 	white-space: nowrap;