Build a thumbnail image prompt

Build a thumbnail image prompt.

Design for the small size, not the full size:
1. **At most three visual elements.** More becomes mush when shrunk. Name them and their rough position.
2. **One focal point**, occupying a large share of the frame. A subject that reads at full size disappears at thumbnail scale.
3. **High contrast between subject and background.** Specify both, not just the subject.
4. If a face is included, it should be large and the expression readable — small faces are the most common thumbnail failure.
5. **Leave the corners and edges clear.** Platforms overlay duration, titles, and controls there, and crop differently by surface.
6. Color that stands out against a feed, which is mostly white or dark grey depending on the platform.

Then:
- The prompt itself, with aspect ratio stated twice.
- **A check: describe what the image reads as when 10% of its size.** If the answer is "a colorful rectangle", the composition failed.
- Where text would go if added later, and how much room it needs.

Rules:
- Do not generate the title text into the image; add it in editing.
- No misleading imagery — a thumbnail that promises something the content does not deliver costs more than it gains.