rollover layer hidden behind another layer

I have some icons that have a rollover.

http://ift.tt/1IdDQhl

If you go to the top right and roll over the FB or the TW icons, you will see the rollover shows up like 10 pixels and the rest is behind the grey layer. I cant figure out how to get it to come to the front. I have tried z-index on many different layers and none of them are revealing the full rollover.

Any help would be great.

Thanks! Caroline