Dear Itamar, thank you for your instruction, I found it now. It is in: moodle/theme/bootstrapbase/style/moodle.css
I also removed the c0,c1, c2, c3 in the BUZZ, make no diffrecnece, don't know why the style sheet has the c0, c1,c2 etc difined.
Thanks to you and Helen, you have answered all of my questions.
I can apply what I learned from you to my database templates now.
Love Database, love Moodle.