Well i'm trying it in chrome, safari and firefox on osx all with the same results.
I've fiddled with the css which seem to be centering two of the overlays but one of them is not playing ball. The "contact" overlay is not centering absolutely vertically.
For example, i'm on a 15" laptop and the contact overlay is much nearer the bottom than the top. That is the main problem. If i do something to get the contact overlay centered, it makes the other two links uncentered.