Enhance .NET8 Presentation App

I built a C# .NET 8 desktop application that leverages the ChatGPT API to turn a prompt into a full presentation, then exports it to Word and PDF. The app also lets users switch between light and dark themes. Everything works—except the light theme only flips the text colour. The background, buttons, navigation menu, text fields and every other UI element stay in their dark-mode styling. That’s the first issue to solve.

While you are inside the codebase, I also want to extend the editing workflow. When users highlight any generated text, a right-click context menu should appear where they can choose a tone (e.g. formal, casual, persuasive, etc.) and an action—Summarise or Expand. The selected text, tone and action are then sent to ChatGPT and the response should overwrite or append to the original content in the editor, all without leaving the app.

Next, I need an Export to PowerPoint option that outputs a clean .pptx. Finally, the presentation should support a card-based layout: users can add new cards (think visual slide containers) and populate each one with fresh content via a prompt.

Acceptance criteria
• Switching to light mode must recolour every visual element consistently, matching the existing dark-mode polish.
• The context-menu flow must send only the selected text, tone and action to ChatGPT and update the document seamlessly.
• Exporting to PowerPoint should mirror the current Word/PDF fidelity.
• Card layout creation and prompt-driven content insertion must feel native to the existing UI.

If you’ve handled theme overhauls, context-aware editing or OpenAI integrations before, tell me briefly about that experience when you reply. I’ll provide the repo and a quick run-through once we agree.