reflex-dev/reflex ? reverse-engineered prompt

I want to build a simple web app using only Python. I'm not a frontend developer, so I'm looking for a way to create the UI and the backend logic without having to write JavaScript, HTML, or CSS. I've heard about frameworks like Reflex that let you do this, so let's use that.

As a starting project, please build me a simple web UI for an image generation API like DALL-E. It should have a text input for the user's prompt, a "Generate" button, and a space where the final image from the API is displayed. It's important that the button shows some kind of loading indicator while the image is being created. Please set up the project and provide the complete code for this in a single Python file to keep it simple.