a.info{
    position:relative; /*this is the key*/
    z-index:24;
    color:#00f;
    text-decoration:none;
}

a.info:hover{
    z-index:25; background-color:#ff0
}

a.info span.info{
    display: none
}

a.info:hover span.info{ /*the span will display just on :hover state*/
    display:block;
    position:absolute;
    top:2em; left:2em; width:15em;
    border:1px solid #0cf;
    background-color:#cff; color:#000;
    text-align: center;
}

a.basic_link {
    color: #00f;
    text-decoration: none;
}

a.basic_link:hover {
    text-decoration: underline;
}