CSS Algorithms

I wouldn’t say the term “CSS algorithm” has widespread usage yet, but I think Lara Schenck might be onto something. She defines it as:

a well-defined declaration or set of declarations that produces a specific styling output

So a CSS algorithm isn’t really a component where there is some parent element and whatever it needs inside, but a CSS algorithm could involve components. A CSS algorithm isn’t just some tricky key/value pair or calculated output — but it could certainly involve those things.

The way I understand it is that they are little mini systems. In a recent post, she describes a situation involving essentially two fixed header bars and needing to deal with them in different situations. In this example, the page can be in different states (e.g. a logged-in state has a position: fixed; bar), and that affects not only the header but the content area as well. Dealing with all that together is a CSS algorithm. It’s probably the way we all work in CSS already, but now have a term to describe it. This particular example involves some CSS custom properties, a state-based class, two selectors, and a media query. Classic front-end developer stuff.

Lara is better at explaining what she means though. You should read her initial blog post, main blog post, collection of examples, and talk on the subject.

She’ll be at PPK’s CSS Day in June (hey, it’s on our conferences list!), and the idea has clearly stirred up some thoughts from him.

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