Hide sender names in private conversations

stylesheets/_conversation.scss

@@ -3,6 +3,7 @@
   font-size: smaller;
 }
 
+.private .sender,
 .outgoing .sender {
   display: none;
 }

stylesheets/manifest.css

@@ -254,6 +254,7 @@ input.new-message {
 .group-update {
   font-size: smaller; }
 
+.private .sender,
 .outgoing .sender {
   display: none; }