In order to run this application you need to download the project on to your computer. Then you need to click on index.html and the web page should open correctly and the tests should run. Please be patient and don't click anything until you see 'CSS Tricks' as the top title because it is the feed loaded in the last test.
If you would like to open the webpage another way then naviagate your terminal to the downloaded folder and run the command 'python -m SimpleHTTPServer' and follow the link to http://localhost:8000 in your web browser and the tests should run.