diff --git a/addons/mail/static/src/scss/discuss.scss b/addons/mail/static/src/scss/discuss.scss
index 73207ac6d62..13c28e8602f 100644
--- a/addons/mail/static/src/scss/discuss.scss
+++ b/addons/mail/static/src/scss/discuss.scss
@@ -279,6 +279,8 @@
         }
         .o_mail_mobile_tabs {
             flex: 0 0 auto;
+            z-index: 1;
+            background-color: white;
         }
     }
 }