Flexbox as a base layout is convenient but tricky due to CLS or “jank”. If the dimensions of the base flex container(s) are ambiguous, then the browser constantly recomputes the dimensions as HTML streams in.

My favorite trick is to give the browser dimension hints and avoid computational properties like flex. Set as many dimensions (width/height) as possible unambiguously. My Internet speed is sufficiently slow enough that I can see layout shifts in many sites, including my own (this micro blog).

The “CSS router” has always been quite the clever trick for navigating sufficiently small sites. This site uses it to scroll switch pages, and portable.fyi gets clever with visibility :target switching. Do it just right and no one notices unless they “inspect the elements”.

It’s always humbling when I get around to reading a web related spec. HTML and CSS have a lot of functionality. JavaScript’s not bad (it’s the easiest part of web development) but gives you just enough rope to do super silly things like reinventing all built in browser functions.

White spaces in HTML trick many into writing complex CSS — web development is trollish that way. Firefox’s developer tools show generated white spaces! Hopefully your abstraction is munging HTML faithfully. It’s easy to fight white spaces without realising it. That generally leads to using unsuitable display types and other shenanigans.