Shared Styles for Web Components Are Unsolved
It seems like common shared styles for web components are not completely solved yet. There is a cavalcade of sort of maybe options with a good overview on Smashing Magazine.
The two "best" options at the moment seem to be the inclusion of a
<link> element before the inline styles for the web component that points to a shared stylesheet or to actually inline all the shared styles together with the specific styles.
I have currently opted for the latter by having one function return all the common styles and calling it from each component, but I will try the former solution as well.