css align div center of page horizontal code example

Example 1: css align center

//HTML
<div class="parent">
	<span>Hello World</span>
</div>

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

Example 2: how to center a div element

/*ADD MARGIN auto to left and right*/
.box1{
    width:80%;
    margin:0 auto;
}