diff --git a/mail/templates/default/app.css b/mail/templates/default/app.css
index 1317e6aa50..96746a9f21 100644
--- a/mail/templates/default/app.css
+++ b/mail/templates/default/app.css
@@ -1051,4 +1051,5 @@ div#mail-index_nm.splitter-pane {min-height: 100px;}
 }
 .mailPreviewHeaders et2-select-email::part(control) {
 	border: none;
-}
\ No newline at end of file
+}
+#popupMainDiv {height: 100%}
\ No newline at end of file