Component Style Overrides Missing in React Renderer

I am currently using A2UI v9, and I’m finding it quite difficult to override styles of the built-in components provided by the React renderer.

At the moment, there doesn’t seem to be a straightforward way to directly target or customize these components to match our design system (e.g., applying consistent styling across buttons, tabs, text, etc.).

It would be really helpful to have a built-in mechanism which allows easier style overrides—either through theming, component-level overrides.

Feature Request:
Provide a way to override or customize styles of default components in the React renderer, such as:
• Global theming support
• Component-level style overrides

This would make it much easier to integrate A2UI with existing design systems.

Look at the React renderer's source code to understand how components are currently styled. Identify the component files (like Button, Tab, Text) and see if there is an existing theming system. Research how to add a theming API or component-level style props. Check for existing examples of style overrides in the codebase or documentation. A successful change would allow users to pass custom styles via props or a theme provider.

索引モデルが issue の本文から書いたものです。