A framework-agnostic component library, designed to be styled. It can be done.

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A developer's post-mortem on rewriting AgnosticUI, a framework-agnostic component library, using Lit and Web Components. Covers key decisions and trade-offs including Shadow DOM encapsulation with CSS ::part for styling hooks, accessibility challenges with label/input associations inside shadow roots, the unfinished state of native form participation (formAssociated), and React 19 vs @lit/react DX comparison. Also details a CLI-first distribution model where consumers copy component source into their projects, and a playbook-based dogfooding workflow using real UI scenarios to catch integration issues unit tests miss.

Post Mortem: Rewriting AgnosticUI with Lit Web Components – Frontend Masters Blog

The DX Reality Check: React 19 vs. @lit/react