Reference: I uploaded a screenshot of my code, or a rough sketch of the system, for an OAuth 2.0 flow.

Task: redraw it as a tidy OAuth 2.0 flow diagram meant for technical docs.

Components (use exactly these):
- User
- Client App
- Authorization Server
- Resource Server

Color code:
- blue (#2196F3) for actions taken by the user
- green (#4CAF50) for successful responses
- orange (#FF9800) for authorization steps

Labelled arrows, in this order:
1. Authorization Request
2. Authorization Grant
3. Access Token Request
4. Access Token
5. Protected Resource Request
6. Protected Resource

Style: modern and minimalist, lots of white space. Near the key arrows, add small callouts with code snippets in a monospace font.

Output: 2000×2000, optimized to be embedded in documentation.