Build a Markdown Previewer example codepen not working

I’m starting the Front End Libraries project, “Build a Markdown Previewer”. When I try to run the example codepen project at

I get nothing displayed. No visible textarea to type in, nothing. I’m on Mac. I tried both the latest Firefox and Chrome. Also tried Safari. That displays the dialog for recommending Chrome or Firefox, but after that I still get a blank screen. The only thing visible in all three browsers is the hamburger menu icon for the FCC test script.

Does anybody know why the codepen is not working? I would like to see an example in action while I develop my own solution.


I don’t know why, but it doesn’t seem to be working in the Full Page View. If you switch the view to ‘Edit’, you’ll see the app.

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Yes, you are right. Thanks.