how to make div center of page 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 put container in center of page

#container
{
    width: 400px;
    margin-left: auto;
    margin-right: auto;
}

Example 3: how to put container in center of page

div.InSkinAlignCenter {
margin: 0 auto;
}

Example 4: div center

#inner {
  display: table;
  margin: 0 auto;
  border: 1px solid black;
}

#outer {
  border: 1px solid red;
  width:100%
}