diff --git a/addons/event/static/src/css/event.css b/addons/event/static/src/css/event.css
index f5bc83b2a96..ff5bfaba19b 100644
--- a/addons/event/static/src/css/event.css
+++ b/addons/event/static/src/css/event.css
@@ -14,6 +14,7 @@
   border-bottom-left-radius:3px;
   border-bottom-right-radius:3px;
   font-size: 12px;
+  border-collapse: separate;
   text-align: center;
   font-weight: bold;
   color: #8A89BA;