This simple theme component adds in CSS to give a cleaner experience for anon users by hiding the sidebar.
You might want to do this if (like us) you have a predominantly private site which has one or two categories set to everyone (and thus exposed to the internet). It means that casual visitors see a very simple interface that is congruent with the small amount of content they see, while logged in users get the full experience.
This was put together from the code kindly provided by @Don here:
thanks @nathank. i thought about adding your theme’s functionality to mine but i’ve left it out because it seems like a special case component for forums with private small membership, and yours works just fine. cheers!