Setting dark background leaves comments still white

I am trying to customize the Sky theme using ONLY the configuration options (which are by far the best and most extensive that I have seen). I am trying to achieve an overall "dark" look and feel - dark backgrounds and light text foregrounds. Everything looks good except the comments - they still have a white background but since the text's color is changed to lighter, it is now unreadable. See the attached screenshot.

- Is the white background of the comments hardcoded somewhere in the CSS?
- Is there a setting somewhere that affects the comment display?

Thanks!