body {
  margin: 0;
  background: black;
}
#guru {
  color: red;
  text-align: center;
  border: 7px solid red;
  font-family: monospace;
  font-size: 16px;
  font-weight: bold;

  animation: border 1.5s infinite;
}
@keyframes border {
  50% {
    border: 7px solid red;
  }
  100% {
    border: 7px solid black;
  }
}