On the tutorial page on a static condensation is probably a mistake in the page code which breaks the math code there.
Hi Korf,
There are a few iTutorials that have this kind of issue, but I think it’s not an error in the code, just a matter of the notebook cell not having been executed when the notebook was rendered to HTML. I’m sure the site maintainers will fix these things as time permits, but in the mean time, you may want to download the iTutorials and run them locally using jupyter. This also gives the opportunity to play with the code. 
Best,
Dow
ps. Here are instructions for downloading and running locally