Why isn't :nth-child working in IE9?

Question

According to this page, :nth-child should work in IE9, and I have tried it before and it worked fine, but on this page, it does not appear to be working. View the page in Ch

Answer 1

My version of IE9 was locked into IE8 rendering mode, which wasn't applying the following selector:

 .parentClass > div:nth-child(n+2) .childClass

Here is where you can find the options to change it: