Thank you very mutch!!!
I've added the code to my css styles and now work fine!!!
This is my custom css code:

/* Colore sfondo barra menu */
body .yui-skin-sam .yuimenubar
{
}
/* Colore sfondo 1 sottomenu */
.yui-skin-sam .yuimenu DIV.bd
{
background: #83C1D8 !important;
}
/* Colore sfondo 2 sottomenu */
.yui-skin-sam .yuimenu DIV.bd .yuimenu DIV.bd
{
background: #83C1D8 !important;
}
/* Colore sfondo selezione */
.yui-skin-sam A.yuimenubaritemlabel-selected,
.yui-skin-sam A.yuimenuitemlabel-selected
{
background-color: #FF017E !important;
}
/* Colore font barra menu */
.yuimenubaritemlabel,
{
color: #000000 !important;
}
/* Colore font altri menu */
body .yui-skin-sam .yuimenubar .yuimenuitemlabel
{
color: #000000 !important;
}
/* Colore font selezione menu */
body .yui-skin-sam .yuimenubar .yuimenubaritemlabel:hover,
body .yui-skin-sam .yuimenubar .yuimenuitemlabel:hover
{
color: #FFFFFF !important;
cursor: pointer !important;
}
/* Ombra dei menu */
body .yui-skin-sam .yuimenubar .yui-menu-shadow
{
display: none !important;
}
/* bordo barra menu */
.yui-skin-sam .yuimenubar
{
border-color: #FF017E !important;
border-width: 2px !important;
}
/* riquadro voci menu */
.yuimenubaritemlabel
{
border-color: #5388B4 !important;
border-width: 1px !important;
background: #83C1D8 !important;
}
/* bordo sotto menu */
.yui-skin-sam .yuimenu DIV.bd
{
border-color: #FF017E !important;
border-width: 1px !important;
}
/* centratura dei menu */
.yui-skin-sam .yuimenubar
{
text-align: center !important;
}

.yui-skin-sam .yuimenubar .bd
{
display: -moz-inline-stack !important;
display: inline-block !important;
zoom: 1 !important;
}

.yui-skin-sam .yuimenubar .yuimenu .bd
{
display: block !important;
}
/* separatori */
body #{$id}.yui-skin-sam .yuimenubarnav .yuimenubaritem
{
border-right-style: none;
}
/* Margini riquadri menu */
.yuimenubaritemlabel
{
margin-left: 7px !important;
margin-right: 7px !important;
margin-top: 7px !important;
margin-bottom: 7px !important;
}
/* Rimuove bordo selezione */
#ariyui106 LI.yuimenubaritem-selected
{
background-image: none !important;
}