1. Theme: Happy Birthday. 2. Color: Use bright and lively colors such as pink, yellow, sky blue, etc. 3. Elements: including birthday cake, balloons, ribbons, candles, and other elements. 4. Font: Use interesting and easy to read fonts 5. Images: Cartoon characters or animal images can be used to add fun. 6. Layout: Elements and text should be distributed reasonably to maintain visual balance. 7. Size: The poster size is A3 (297mm x 420mm). 8. Resolution: At least 300dpi to ensure print quality. 9. File format: Save in JPEG or PNG format.-- --ar 9:16 --s 50 --niji 6