body {
  font-family: Arial, sans-serif;
  text-align: center;
}

#network {
  margin: auto;
  width: 80%;
  height: 600px;
}

circle {
  cursor: pointer;
  stroke: black;
  stroke-width: 1px;
}

text {
  font-size: 12px;
  pointer-events: none;
}

#tooltip {
  font-size: 12px;
  pointer-events: none;
  position: absolute;
  text-align: center;
  background: white;
  border: 1px solid #ccc;
  border-radius: 5px;
  padding: 5px;
  opacity: 0;
  transition: opacity 0.3s ease;
}