[BUG] "cocoindex setup" title colors don't show well under bright background

Under Colab:

![Image](https://github.com/user-attachments/assets/c1620453-e479-4b3c-a9c3-dcf8f5acb6d1)

Under terminal with bright background:

<img width="953" alt="Image" src="https://github.com/user-attachments/assets/18a1d312-3657-4e59-a12c-65cd4ce19bb6" />