XWIKI-8450: Send Message drop-down list looks different when selecting the "User" value

* Use a more specific selector.

xwiki-platform-core/xwiki-platform-web/src/main/webapp/resources/uicomponents/widgets/userpicker/userPicker.css

@@ -25,7 +25,7 @@ ul.users {
   margin: 0;
   padding: 0;
 }
-.user {
+.accepted-suggestions .user, .suggestItem .user, .users .user {
   /* Leave space for the user avatar. */
   min-height: 30px;
   padding-left: 38px;