question: RichProgressBar is hard to read in light theme
context: As shown in the screenshot,RichProgressBar is hard to read in light theme.  I don't have much time to report a bug, so I open a discussion temporary.
answer: Thanks @tshu-w fr reporting the issue! I will look into if it's possible to detect theme in interactive environments.
  Till then you could customize the description color by customizing RichProgressTheme
  trainer = Trainer(..., callbacks=RichProgressBar(theme=RichProgressBarTheme(description="black")))
  Do check RichProgressTheme out to customize styles for various components.