div#nav-tree ul.children_ul ul.children_ul ul.children_ul a[class^="namespace"]::before {
    content: "N ";
    /* from .icon */
    font-family: Arial, Helvetica;
    font-weight: bold;
    font-size: 12px;
    height: 14px;
    width: 16px;
    display: inline-block;
    background-color: #0081FA;
    color: white;
    text-align: center;
    border-radius: 4px;
    margin-left: 2px;
    margin-right: 6px;
}