JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container-fluid">
  <div class="center-me-fixed">
    <span>
      this should be centered
    </span>
  </div>
</div>

CSS

html, body {
    height: 100%;
}

div.container-fluid {
  border:1px solid blue;
  min-height: 100%;
}
div.container-fluid .center-me-fixed {
  position:relative;
  right:50%;
  text-align:center;
}
div.container-fluid .center-me-fixed span  {
  border:1px solid green;
  width: 500px;
  height:50px;
  display:inline-block;
  margin-right:-100%;
}