body {
  background-color: #222;
}

#stage {
  background-color:black;
  display:block;
  width: 80vmin;
  height: 80vmin;
  position: absolute;
  top: calc(50vh - 40vmin);
  left: calc(50vw - 40vmin);
  padding: 0px;
}

p {
  display: flex;
  flex-flow: column;
  justify-content: center;
  width: 50%;
  height: 50%;
  border-radius:50%;
  position: absolute;
  mix-blend-mode:difference;
  transition: left 10s, top 10s, color 10s;
  left: 25%; 
  top: 25%; 
  margin: 0px;
  font-size:  30vmin;
  color: white;
  text-align: center;
}

#red { 
  background-color:#f00;
  color: #f00;
}

#green { 
  background-color: #0f0;
  color: #0f0;
}

#blue { 
  background-color: #00f;
  color: #00f;
}

#stage:hover #blue {
  left: 50%;
  top: calc(50% - 3.35%);
  color: white;
}  

#stage:hover #green {
  top: 3.35%;
  color: white;
}

#stage:hover #red {
  left: 0%;
  top: calc(50% - 3.45%);
  color: white;
}