This seems needlessly nitpicky. You need JavaScript to view the embedded CodeSandbox, which is an interactive application within an iFrame. Good luck making what's effectively an IDE without JavaScript.
I suppose the author could show the CSS snippets inline and make you click to a demo, but that's not very fun is it?
I suppose the author could show the CSS snippets inline and make you click to a demo, but that's not very fun is it?