a component in the middle of the page html code example

Example 1: align in the middle of page html

.centered {
  position: fixed;
  top: 50%;
  left: 50%;
  /* bring your own prefixes */
  transform: translate(-50%, -50%);
}

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="...">