change font size in activity meta in BP Socila

In activity stream after every post, there comes a meta like " ABC posted an update in the group 3 months ago'

And in the comments to the updates also the meta shows the time like "2 days, 18 hours ago"

How can I reduce the font size for these texts in the content-meta and comment-meta

I have tried to change the font size in the bp-default.css but doesn't seem to work.