There are different approaches to that currently. Since we are using lit to write our custom elements we would probably use their packages that allow ssr: https://lit.dev/docs/ssr/overview/ But currently we are not doing any ssr.

One optimisation we did in the meantime was to pull unsafeCSS out into a baseComponent so it is only ran once. In the solution above unsafeCSS will parse the CSS for every component, which is unnecessary.

Thank you! Yeah that makes sense since they pierce through the ShadowDOM. We use them too in our component library for that use case.