span.btnFB
{
   width: 25px;
   text-align: left;
   margin: 2px 10px 10px 0px;
   float: left;
}
span.btnFB> a > img, span.btnFB > a:hover > img + img
{
   display: block;
   border:0px;
}
span.btnFB > a > img + img, span.btnFB > a:hover > img
{
   display: none;border:0px;
}