Kitty Giraudel will show you how to create realistic-looking switch buttons using pseudo-elements and checkboxes (without writing a single line of JavaScript).
Designer Jonathan Snook of Shopify provides a quick introduction into scalable and modular architecture for CSS (SMACSS). If you’re still not familiar with its concepts, you should watch this video series.
If you want to style parts of a web page differently depending on whether JavaScript is available or not, it can be useful to use JavaScript to change or add a class name to the html element. Roger Johansson will show you probably most effective way to handle this.