Hi,
Try to add the following custom css code:
#mod-search-searchword + .btn-primary {
text-indent: -99999px;
position: relative;
width: 76px;
}
#mod-search-searchword + .btn-primary:after {
font: normal normal normal 16px/1 FontAwesome;
content: '\f002';
position: absolute;
color: #fff;
left: 30px;
text-indent: 0;
}
Cheers
Joshua