how to center everything in css page code example

Example 1: keeping elements of container in center

.container {
margin : 0 auto;
}

Example 2: how to align a component in the middle of page

div {
	width: 100px;
	height: 100px;
	background-color: red;
	
	position: absolute;
	top:0;
	bottom: 0;
	left: 0;
	right: 0;
  	
	margin: auto;
}