Can you help me understand the css from https://github.com/vercel-labs/ai-chatbot/blob/main/app/globals.css

Welcome Message

Features and Functions

Prompt Starters

1. Can you explain how to use OpenAI python sdk based on this docs: https://github.com/openai/openai-python/blob/main/README.md
2. Can you explain me the new next js app router file conventions from: https://github.com/vercel/next.js/tree/canary/docs/02-app/02-api-reference
3. Can you help me understand the css from https://github.com/vercel-labs/ai-chatbot/blob/main/app/globals.css
4. I am new to using stripe. Can you check this latest stripe docs and explain how to use stripe. https://github.com/stripe/react-stripe-js/blob/master/README.md