how to put an element in the center html code example

Example 1: position absolute center

position: absolute;
margin-left: auto;
margin-right: auto;
left: 0;
right: 0;
text-align: center;

Example 2: css center text in div

/* For horizontal align: */
parent-element {text-align:center;}
/* For horizontal and vertical align: */
parent-element {position: relative;}
element-to-be-centered {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
}

/* See https://www.w3schools.com/css/css_align.asp for more info */

Example 3: center text in div container

text-align: center

Example 4: how to assign something in center inside a div

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