vis-util/standalone/styles/popup.css

utilitie collection for visjs

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

  font-family: verdana;
  font-size: 14px;
  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;

  z-index: 5;
}