Here is a Thesis page showing the problem that I found (.previous is the problematic CSS class)
http://seattle.findwell.com/million-things-to-do-seattle/viaduct-demolition-walk/
Scroll to the Previous/Next links at the bottom and use Firebug to exame the CSS. You’ll see that your CSS is affecting these default Thesis links. I could add my own CSS, but certainly my strong preference is that plugin CSS does not conflict with theme CSS so that I don’t have to worry about it. I think you could make your own CSS more specific so that it doesn’t affect other areas.