.datavis-diagram.bar_chart .tooltip {
    display: none;
    position: absolute;
    padding: 8px;
    background: none repeat scroll 0 0 #ffffff;
    border: 1px solid gray;
    font-size: 14px;
    min-width: 80px;
    height: auto;
    text-align: center;
    opacity: 0.8;
    color: #000;
}