#key_display {
  font-size: 30px;
  opacity: 0.5;
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  z-index: -1;
  color: white;
  text-align: center;
}

body {
  background-color: black;
}

.circle {
  width: 100px;
  height: 100px;
  border-radius: 50%;
  position: absolute;
}