> think there is a clear tension between the component desire for encapsulation vs the web designer wanting to impose their styling on the nested components

This is the inherent tension. It requires good web component authoring to expose:

1. `part`s that can be accessed by application-level CSS

2. slots for the application developer to inject html

3. CSS custom properties (--variable) -- these pierce the shadow DOM

The web component authors have to be very intentional about these things. There are good examples and bad examples and I think people are still learning how to do this well.