.circle {
  width: 15vmax;
  height: 15vmax;
  background-color: red;
  color: white;
  font-size: 5vmax;
  
  display: flex;
  align-items: center; 
  justify-content: center;
  text-align: center; 

  border-radius: 50%;
  position: absolute;
}
body {
  background-color: black;
}