CSS-in-rs

[qm3ster]

I don't understand the purpose of the current behavior of the css! macro.
Why is CSS being written to an external file, regardless of if the component will ever be displayed or not?
I feel like having the component own its css makes more sense than a macro writing files during compilation. This way, critical CSS can trivially be inlined during SSR.

[chinedufn]

Some prior discussion in #1

I think you'd still want to have the option to write to a file. One advantage on the write-to-file side of things is better caching since you don't have to re-download both the app and CSS when you only change the CSS (and vice versa). Often times application code will change way more often than styling.

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But yeah - totally agree that the ability to inline would be useful. Any thoughts on how we might support both cleanly?

[qm3ster]

I think the two are at odds with each other. CSS-per-component is not something you want to extract and concat with all other CSS, because this means that a change to a single component's CSS anywhere in the app invalidates the whole CSS bundle. So, there's no immediate victory right now.
On the other hand, if you use a CSS framework, and style your components with classes from there, foregoing the css! macro, the framework can stay cached. I think the best solution for the time being would be to use a combination of the two approaches.
Otherwise, maybe multiple CSS files?
Yeah, wasm code splitting is nowhere close to solved yet, but if it is, it makes sense that components would be the unit of caching.