.galleria {
position:relative;
width:700px;
text-align:center;
}

.galleria  img  {
position:relative;
margin-bottom:15px;
}

.galleria a.btnIndietro {
position:absolute;
bottom:-10px;
left:0px;
text-indent:-3000px;
width:30px;
height:30px;
background:#222 url(../imgs/icoLeft.png) no-repeat 50% 50%;
display:block;
}

.galleria a.btnAvanti {
position:absolute;
bottom:-10px;
right:0px;
text-indent:-3000px;
width:30px;
height:30px;
background:#222 url(../imgs/icoRight.png) no-repeat 50% 50%;
display:block;
}

.galleria a.btnIndietro:hover,
.galleria a.btnAvanti:hover {
background-color:#111;
}