Test code

• szh.app/code open_in_new: forwards to CodePen where you can play with HTML, CSS, and JavaScript. A safe space for breaking the internet.

• szh.app/html open_in_new: forwards to a W3Schools app where you can similarly sandbox with just HTML. The other one is better in most ways, though this one includes breadcrumb links, at the top, to some clear instructions; it's great for beginners.