[xwiki-users] Login page for Unregistered users

Hi, We are setting a 5.1 corporate Xwiki (closed wiki) so only registered users are able to access pages. For this, we have set the "prevent unregistered users from viewing pages, regardless of the page or space rights" option in xwiki admin. As a result, any unregistered user is redirected to the login page but the skin theme is broken. We have seen old posts telling to set the ColorThemes space to be viewable by guests in order to solve this issue, but it no longer works. Also, the new "Menu Application" is affected (see screenshot): http://postimg.org/image/5u3sdalyr/ Anyone knows how to solve this issue? Thanks in advance, Jaume