#menu{
     padding: 0px;
     margin: auto;
     text-align: "center";
     background: #225;
}

#menu td {
text-align: center;
}

#menu td a{
    display: block;
    text-decoration: none;
    color: #fff;
    background-image: url(imagenes/boton-menu-off.png);
    background-repeat: no-repeat;
    background-position: center;
    border: solid 0px #fff;
    padding: 11px;
    position: relative;
    width: 125px;            
}

#menu td a:hover{
    display: block;
    text-decoration: none;
    color: #fff;
    background-image: url(imagenes/boton-menu-on.png);
    background-repeat: no-repeat;
    background-position: center;
    border: solid 0px #fff;
    padding: 11px;
    position: relative;
    width: 125px;
}