How do I change the BuddyPress Activity Stream button colors?

The buttons on BuddyPress Activity Stream are transparent on a white background. Can you please tell me what CSS I need to use to change them to #001C35? I have seriously been searching and trying online for days and I can't believe there's not a simple CSS snippet or explaination on BuddyPress' site.

Thanks in advance for any response you may have. I'm sure I'm overlooking something simple.