CSS

css align items vertical center

.parent {
  display: flex;
  justify-content: center;
  align-items: center;
}

css center vertically

/* 100vh = 100% Viewport Height */
body {
	display: flex;
	height: 100vh;
	flex-direction: column;
	justify-content: center;
}
/* add */ align-items: center; /*to also center horizontally.*/

vertical align center div

/* Flex */
.center {
  	display: flex;
  	justify-content: center;
  	align-items: center;
}
/* Without Flex */
.parent {
  	position: relative;
}
.child {
  	position: absolute;
  	top: 50%;
  	transform: translateY(-50%);
}

css vertical align center

.parent  {
  display: flex;
  justify-content: center;
  align-items: center;
}