jrtechs-vis/lib/network/css/network-tooltip.css

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

  font-family: verdana;
  font-size:14px;
  font-color:#000000;
  background-color: #f5f4ed;

  -moz-border-radius: 3px;
  -webkit-border-radius: 3px;
  border-radius: 3px;
  border: 1px solid #808074;

  box-shadow: 3px 3px 10px rgba(0, 0, 0, 0.2);
  pointer-events: none;
}