gistfile1.css

.tabbrowser-tab::before {
    display: inline-block;
    padding-top: 8px;
    content: attr(pos);
    font-weight: bold;
    color: #eee;
    font-size: 0.8em;
    margin-right: -1em;
    z-index:65535;
    position:relative;
    text-shadow: rgba(0,0,0,.2) 1px 0,
                 rgba(0,0,0,.2) 0 1px,
                 rgba(0,0,0,.2) -1px 0,
                 rgba(0,0,0,.2) 0 -1px,
                 blue 0 0 0.4em;
}