CSS | Type: CSSHorizontal AND vertical centering

CSS
.selector { position: absolute; left: 50%; top: 50%; transform: translate(-50%, -50%); }

OR, another approach:

Note it’s child element that’s centered, within the element the CSS targets.

HTML
<div class="hv-center">
  <div class="child"></div>
</div>

CSS
.hv-center {
  display: flex; /*activates flex*/
  justify-content: center;
  align-items: center; /*vertical*/
}