I agree -- it's some really elegant and powerful CSS code, which is a great example of what you can do with modern CSS, but I don't think it's meant to be about

I agree -- it's some really elegant and powerful CSS code, which is a great example of what you can do with modern CSS, but I don't think it's meant to be about the actual interaction design, or meant to say that you should do everything in CSS and not use JavaScript. As a practical matter, you need JavaScript to achieve the best usability, reusability, flexibility, etc. But it should serve as an example to JavaScript widget designers how much you can do in CSS. It's an interesting and difficult problem designing a JavaScript pie menu component that let you easily and deeply customize it in CSS.