div.vis-network-tooltip {
  position: absolute;
  visibility: hidden;
  padding: 5px;
  white-space: nowrap;

  -moz-border-radius: 3px;
  -webkit-border-radius: 3px;
  border-radius: 3px;
  border: 1px solid;

  box-shadow: 3px 3px 10px rgba(128, 128, 128, 0.5);
}