.primo_on{
float:left;margin-right:1px;margin-top:5px;background:url(../../images/col_dx_tab_1_on.png) no-repeat bottom center;width:173px;height:37px}

.primo_off{
float:left;margin-right:1px;margin-top:5px;background:url(../../images/col_dx_tab_2_off.png) no-repeat bottom center;width:160px;height:37px
}

.secondo_on{
float:left;margin-right:1px;margin-top:5px;background:url(../../images/col_dx_tab_2_on.png) no-repeat bottom center;width:173px;height:37px
}

.secondo_off{
float:left;margin-right:2px;margin-top:5px;background:url(../../images/col_dx_tab_2_off.png) no-repeat bottom center;width:160px;height:37px
}

.allineato_a_sinistra{
float:left;	
}

.allineato_a_destra{
float:right;	
}