body {
    margin: 0px;
    padding: 0px;
    background-image:url(../images/logo_a.gif);
}

#menu {
    margin: 0px;
    margin-right: 2%px;    
    border: 0px navy;
    width: 11%;
    min-width: 202px;
    max-width: 300px;
    height:100%;
    min-height: 300px;
    max-height: 900px;
    display:flexbox;
    position: fixed; 
    z-index: 100;  
    /* ajusta el contenido al centro */
    justify-content:center ;
    text-align:center;   
}

.tit_contenido {
    margin-top: 50px ;
    font-size:x-large; 
    font-family: "Lucida Handwriting";   
    text-shadow: 
    2px 2px 2px grey;     
}

.contenido {
    margin: 10px;
    width: 81%;
    float: right;
    /* ajusta el contenido al centro */
    justify-content:center;
    text-align:center;
    font-size: small;
    color: white;
}