The newest spoiler tag function works that way for me, too. (Chrome, Windows 7) I think it's designed to work that way.
The problem with Iago providing themes is that any board add-ons he's done may or may not work with other themes. It's a mess. I had to give up on themes on the board that I run. And I don't know anything about servers. It may be that it would bog us down even more.