.button_ex {
width: 181px;
height: 43px;
}

.button_ex a {
display: block;
width: 181px;
height: 43px;
background: url(immagini/interno01.gif) no-repeat top left;
}

.button_ex a:hover {
background-position: top right;
}


.button_ex2 {
width: 181px;
height: 43px;
}

.button_ex2 a {
display: block;
width: 181px;
height: 43px;
background: url(immagini/interno02.gif) no-repeat top left;
}

.button_ex2 a:hover {
background-position: top right;
}


.button_ex3 {
width: 181px;
height: 43px;
}

.button_ex3 a {
display: block;
width: 181px;
height: 43px;
background: url(immagini/interno03.gif) no-repeat top left;
}

.button_ex3 a:hover {
background-position: top right;
}


.button_ex4 {
width: 181px;
height: 43px;
}

.button_ex4 a {
display: block;
width: 181px;
height: 43px;
background: url(immagini/interno04.gif) no-repeat top left;
}

.button_ex4 a:hover {
background-position: top right;
}