How to reduce the font size in Mail's side-bar?

Hi,

I know this seems to be a re-hash of an old thread (https://discussions.apple.com/thread/1198891?answerId=5725527022#5725527022), but... as I upgraded to Lion, Mail's side-bar (the one you can show/hide) displays in a font that's too large for me, both in the classic and the iOS-inspired look. The font type/size selections in Mail's preferences seem to apply to everything but this region... what am I overlooking?