How to center all contents of a div in css code example

Example 1: how to center anything inside your container

display: grid;
    place-items: center;
    height: 100vh;

Example 2: how to assign something in center inside a div

IMG.displayed {
    display: block;
    margin-left: auto;
    margin-right: auto }
...
<IMG class="displayed" src="..." alt="...">