<a class="blink" href="#">button</a>

* {
	box-sizing: border-box;
}
body {
	min-height: 100vh;
	margin: 0;
	padding: 10px;
	display: flex;
	justify-content: center;
	align-items: center;
}
a {
	font-weight: 600;
	color: #fff;
	background: #5876a3;
	padding: 10px 20px;
	border-radius: 5px;
	text-decoration: none;
	box-shadow: 0 4px 0 #3f5c88;
}


.blink {
	position: relative;
	overflow: hidden;
}
.blink::before {
  content: "";
  width: 20px;
  height: 100%;
  background: rgba(255,255,255,.8);
  position: absolute;
  top: -100px;
  left: 0;
  opacity: 0;
  -webkit-transform: rotate(45deg);
  transform: rotate(45deg);
  -webkit-animation: blink 2s ease-in-out infinite;
	animation: blink 2s ease-in-out infinite;
}
@-webkit-keyframes blink {
  0% {
    -webkit-transform: scale(0) rotate(45deg);
		transform: scale(0) rotate(45deg);
    opacity: 0;
  }
  80% {
    -webkit-transform: scale(0) rotate(45deg);
		transform: scale(0) rotate(45deg);
    opacity: .5;
  }
  81% {
    -webkit-transform: scale(4) rotate(45deg);
		transform: scale(4) rotate(45deg);
    opacity: 1;
  }
  100% {
    -webkit-transform: scale(50) rotate(45deg);
		transform: scale(50) rotate(45deg);
    opacity: 0;
  }
}
@keyframes blink {
  0% {
    -webkit-transform: scale(0) rotate(45deg);
		transform: scale(0) rotate(45deg);
    opacity: 0;
  }
  80% {
    -webkit-transform: scale(0) rotate(45deg);
		transform: scale(0) rotate(45deg);
    opacity: .5;
  }
  81% {
    -webkit-transform: scale(4) rotate(45deg);
		transform: scale(4) rotate(45deg);
    opacity: 1;
  }
  100% {
    -webkit-transform: scale(50) rotate(45deg);
		transform: scale(50) rotate(45deg);
    opacity: 0;
  }
}