This Image is chrome extestion's Design so far. Please understand it will change as i update it

You want us to do all the work? Like, this can't be everything, right?

For extensions, that colors should not be too distracting. The design should be in a way that it blends in the regular flow. It should achieve the purpose (in this case showing quotes) without putting much effort.

Here there are two things to care about. The background and text. For the background, you can pick light colors using any of your favorite color pickers. For text, choose any good readable typeface. fonts.google.com/ has some good ones.