BuddyPress.org

Since I can’t peer into this site’s base.css file for the theme I’m wondering how to change that attribute … ?

Ah, but you can!

For all CSS and template design issues, I highly recommend that you use the Firefox browser with the Firebug Add-on. WIth FIrebug installed in Firefox, you can see where page elements inherit their CSS–the file names, the file contents, etcetera. You can even make changes to the CSS selector parameters and see how that affects the design.

So, when you pull up any buddypress.org page, or any webpage at all, you can use Firebug within Firefox to see how the CSS selectors are styled.