diff --git a/addons/mail/static/src/components/discuss/discuss.scss b/addons/mail/static/src/components/discuss/discuss.scss
index 54395708940..720c406a025 100644
--- a/addons/mail/static/src/components/discuss/discuss.scss
+++ b/addons/mail/static/src/components/discuss/discuss.scss
@@ -13,11 +13,6 @@
     }
 }
 
-.o_Discuss_chatWindowHeader {
-    width: map-get($sizes, 100);
-    flex: 0 0 auto;
-}
-
 .o_Discuss_content {
     height: map-get($sizes, 100);
     overflow: auto;