Custom Ui

Use create-react-app for a custom UI.
If it works use markdown with darkmode for code display and a dropdown for choosing the language.

The project uses create-react-app. Look for existing UI components and setup. The task is to build a custom UI with markdown display supporting dark mode and a language selection dropdown. Check for any existing markdown or theme libraries in package.json. Start by creating the component, integrating a markdown renderer like react-markdown, and implementing a dark mode toggle and dropdown. Verify the UI works within the existing app structure.

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