Let's start with a demo: https://ooo.lamplightdev.workers.dev:This is a simple page that renders a list of 10 items. Try it with and without JavaScript enabled in your browser. There's a few things to notice:The 'app shell' renders first - you see the header and the footer, but there's a loading placeholder where the list of items will be rendered.After a second the loading placeholder is replaced with the list of items - but with each item itself having a loading placeholder.The content of the ...