how to make flash blinking text using css

.waitingForConnection {
  animation: blinker 1.7s cubic-bezier(.5, 0, 1, 1) infinite alternate;  
}
@keyframes blinker { to { opacity: 0; } }

.waitingForConnection2 {
  animation: blinker2 0.6s cubic-bezier(1, 0, 0, 1) infinite alternate;  
}
@keyframes blinker2 { to { opacity: 0; } }

.waitingForConnection3 {
  animation: blinker3 1s ease-in-out infinite alternate;  
}
@keyframes blinker3 { to { opacity: 0; } }

<div class="waitingForConnection">X</div>
<div class="waitingForConnection2">Y</div>
<div class="waitingForConnection3">Z</div>