Board Thread:Support Requests - Getting Technical/@comment-31790818-20200720211209/@comment-168424-20200720212749

Well, unfortunately, it looks like the underlying code is a Lua module called Mbox which isn't well documented.

Also there is supposedly a template preview bug in UCP where it doesn't show the edited template in the preview so you may have to save and purge to see your changes.

Have you tried just 'yellow' instead of #f5e942?