adopt usage of Constructable Stylesheets

[thescientist13]

I think it's just a matter of having the right NodeJS compat for Vercel, but would be cool if we could set Greenwood's Import Attributes and refactor the inline CSS in the src/components/ directory to use Constructable StyleSheets.

So instead of all the inline CSS

1. move it into its own dedicated file
2. Use Import Attributes, ex

   import sheet from './card.css' with { type: 'css' }

3. Adopt it into the Shadow Root, instead of an inline <style> tag in the template

   this.shadowRoot.adoptedStyleSheets = [ sheet ];

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I think was attempted in #22 but Vercel didn't support the Node 18.x version we wanted, but maybe it does now?