span.cursor {
  display: inline-block;
  background-color: #ccc;
  margin-left: 0.1rem;
  width: 3px;
  animation: blink 1s infinite;
}
span.cursor.typing {
  animation: none;
}
@keyframes blink {
  0%  { background-color: #ccc; }
  49% { background-color: #ccc; }
  50% { background-color: transparent; }
  99% { background-color: transparent; }
  100%  { background-color: #ccc; }
}