body, html {
  padding: 0;
  margin: 0;
  height: 100%;
}
svg {
  width: 100%;
  height: 100%;
  background: white;
}

.bubble {
  fill: rgba(0,0,0,0.1);
}
.bubble:hover {
  stroke: black;
  vector-effect: non-scaling-stroke;
}

.link {
  fill: none;
  stroke: rgb(60,120,205);
  stroke-width: 0.2;
  vector-effect: non-scaling-stroke;
  pointer-events: none;
}