align a div vertically and horizontally code example

Example 1: center div horizontally and vertically

.parent {
  position: relative;
}
.child {
    position: absolute;
    left: 50%;
    top: 50%;
    transform: translate(-50%, -50%);
}

Example 2: how to center horizontally and vertically block div

#html code
<div class="parent">
	<h1 class="child">CSS is cool</h1>
</div>

#css code
.parent{
  display:grid;
  place-items:center;
  
  width:560px; 
  height: 560px;
}