diff --git a/calendar/base/themes/pinstripe/calendar-views.css b/calendar/base/themes/pinstripe/calendar-views.css
index ba87138cade..82399e97348 100644
--- a/calendar/base/themes/pinstripe/calendar-views.css
+++ b/calendar/base/themes/pinstripe/calendar-views.css
@@ -527,6 +527,7 @@ calendar-navigation-buttons {
 }
 
 .title-label-box button {
+    background-color: transparent;
     /* Override button min-width so views can be narrow on narrow screen */
     min-width: 1px;
     /* Allow overflow, so long localized month names don't prevent narrow view */
diff --git a/calendar/base/themes/winstripe/calendar-views.css b/calendar/base/themes/winstripe/calendar-views.css
index 2fc30be8fc5..3cef10762a0 100644
--- a/calendar/base/themes/winstripe/calendar-views.css
+++ b/calendar/base/themes/winstripe/calendar-views.css
@@ -527,6 +527,7 @@ calendar-navigation-buttons {
 }
 
 .title-label-box button {
+    background-color: transparent;
     /* Override button min-width so views can be narrow on narrow screen */
     min-width: 1px;
     /* Allow overflow, so long localized month names don't prevent narrow view */