p.ok span.popinfo,
p.nok span.popinfo {
    visibility: hidden;
}

p.ok:hover span.popinfo,
p.nok:hover span.popinfo {
    visibility: visible;
    position: relative;
    top: -30px;
    height: 15px;
    background-color: #fff;
    border: 1px solid #ccc;
}