How can I constantly fade an HTML button in and out with CSS?

Question

I'm designing an HTML game and I would like to know how I can constantly fade in and out the "START" button in the game with CSS.

• If jQuery is needed, that's okay; however, whenever possible, please use pure HTML and CSS. Thanks!

Answer 1

.pulseButton {
  animation: pulse 5s infinite;
}

@keyframes pulse {
  0% {
    opacity: 1;
  }
  50% {
    opacity: 0;
  }
  100% {
    opacity: 1;
  }
}`