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Getting Started With CSS Cascade Layers, by Stephanie Eckles

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Yesterday I read Eric Meyer discussing CSS Cascade Layers and commenting that the speed at which it had transitioned from first public working draft to shipping as a full public release in every major desktop and mobile browser had made his head spin. Amazing stuff and an indicator of the turbo-boosted pace at which modern CSS is now evolving.

It also made me want to properly read up on Cascade Layers, because I knew some of the theory but now wanted to consider using it in practice. I’m no great fan of “cascade-taming” CSS frameworks like BEM and SUIT (although I acknowledge why we have them) so I’m interested to know if Cascade Layers can replace them. Stephanie Eckles’ article is an excellent primer.

I liked the idea of a specifying a stack like this:

@layer reset, base, theme, components, utilities;

You can then write styles into any of those layers at any point in a stylesheet, safe in the knowledge that the original stack definition sets the order of priority rather than the sequence in which we wrote specific styles.

Stephanie also addresses the question of whether we should write every component as a layer, which is something I’ve been considering. She advises that you could… but it’s probably not going to achieve the scoping effect that you want.

layers are not intended to solve scoping or encapsulation of styles. For that, keep an eye on another spec also being authored by Miriam Suzanne for actual native CSS scoping.

Lastly, Stephanie tackles how ready Cascade Layers are to use right now. At the time she wrote the article – January 2022 – the feature wasn’t widely supported, so wasn’t an option. Additionally Cascade Layers can’t really be used as a progressive enhancement because its nature is so all-encompassing and because testing for feature support using @supports isn’t an option.

However like Eric Meyer mentions, a few months is a long time in CSS support! And as I write in June 2022 the browser support picture is currently looking quite healthy. However given that the first browsers to add support were only released a few months ago in February or March of this year, I think we might need to wait a bit longer – maybe til the percentage of users on non-supporting browsers is negligible – before using this on larger, higher-traffic sites.

Nothing to stop us experimenting on our smaller and intranet-based sites, though!

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