A couple errors I noticed (prob has nothing to do with this problem) is the call to Google Fonts is coming up with a 404 error and your logo.png is also coming up with a 404 error.
As far as your problem is concerned, looking at the source code of that page nothing really jumps out at me. I haven't heard before of any content formatting changing when my plugin is active. In the WordPress Editor, can you look at the "text" view and see if there's anything funny going on? I do notice a bunch of span tags, which usually means something gets goofed up somewhere.