JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <span>
    I'm centered!
  </span>
</div>

CSS

html, body {
  min-height: 100vh;
  margin: 0;
}

.container {
  min-height: 100vh;
}

.container {
  display: flex;
  justify-content: center;
  align-items: center;
}