Why isn't my hidden content working?

[DamienIrving]

On the 2016 website Melbourne had a cool feature where you could click on the name of a class in the "about" section of the page and hidden information would appear underneath:

• Website: https://feb2016.resbaz.com/melbourne
• Code: https://github.com/resbaz/resbaz-2016-02-01/blob/gh-pages/_posts/2016-02-01-melbourne.html

I've tried to implement that on the 2017 Hobart page (see code, website) but nothing happens when I click on the class name.

I was wondering if someone who knows more about html than me could take a look at hobart.html to see what the problem might be?