<p class="blink">点滅します</p>

* {
  box-sizing: border-box;
}
body {
  min-height: 100vh;
  margin: 0;
  padding: 10px;
  display: flex;
  justify-content: center;
  align-items: center;
}
.blink {
  -webkit-animation: blink 1s ease infinite;
  animation: blink 1s ease infinite;
}
@-webkit-keyframes blink {
  0% {opacity: 0;}
  100% {opacity: 1;}
}
@keyframes blink {
  0% {opacity: 0;}
  100% {opacity: 1;}
}