CSS footer issue

url: presslock.org

footer looks fine in chrome/safari
In firefox, .social div is pushed down and the footer doesn't extend to bottom of page.
This is a recent problem, it looked fine a couple days ago.
I've changed a couple divs around, but used the same CSS, etc.
No idea why chrome+firefox are suddenly so incongruent.
I am using position:relative to position the footer divs. Could that be the issue?