DOC: Getting started tutorials css adjustments
- [x] closes #57912 
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).

I implemented what I suggested in the issue.

/preview Website preview of this PR available at: https://pandas.pydata.org/preview/pandas-dev/pandas/57916/ Thanks @SilvestriStefano. Agreed looks a lot better