it is due to your theme, for some reason the maker decided to have a z-index associated with #wrapper. As described many times in this support forum the fix is easy (shame the search button was removed by wordpress)
Either delete the z-index inside your themes CSS (for you on line 122) that says
z-index:20
or add to the share and follow “add your own CSS” the following details
#follow {z-index:100}
that way if the designer decided to have a funny turn and use z-index somewhere else it won’t be a problem
regards
Andy