I had to read through this twice, but I think I get it now (I’m not the sharpest knife in the drawer). Very useful if you’re doing theming in CSS.
In defence of the cascade (especially now that we’ve got CSS custom properties).
I think embracing CSS’s cascade can be a great way to encourage consistency and simplicity in UIs. Rather than every new component being a free for all, it trains both designers and developers to think in terms of aligning with and re-using what they already have.
Remember, every time you set a property in CSS you are in fact overriding something (even if it’s just the default user agent styles). In other words, CSS code is mostly expressing exceptions to a default design.
A really terrific piece by Heydon that serves as a rousing defence of the cascade in CSS. It’s set up in opposition to methodologies like BEM (and there’s plenty of back’n’forth in the comments), but the truth is that every project is different so the more approaches you have in your toolkit, the better. For many projects, something like BEM is a good idea. For others, not so much.
Funnily enough, I’ve been working something recently where I’ve been embracing the approach that Heydon describes—although, to be fair, it’s a personal project where I don’t have to think about other developers touching the HTML or CSS.
You have to be really, really geeky to find this funny. I find this funny.