Brief - feed reading extension for Firefox

In keeping with my reputation, which we shall not discuss, I have another esoteric toolbar button question: Is it possible to change the color of the "number of new items" indicator that accompanies the toolbar button that shows that there are new feed items?
I don't know the name of that indicator, so that, even if I were to delve into the Brief.xpi, I likely would never find whatever it is; I would like to change it because, in adding Glasser styles to Firefox, I have now found that the white "you have x new news items" is almost invisible.