Edit in JSFiddle

<div class="🦄">
  <h1 class="🦄-header">
    🦄 Unicorns rule!
  </h1>
</div>
.🦄 {
  height: 100%;
  display: grid;
  align-items: center;
  justify-content: center;
  background-color: cornsilk;
}

.🦄-header {
  font-size: 72px;
  color: violet;
}











/* Boilerplate styles */

html, body {
  padding: 0;
  margin: 0;
  height: 100%;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial, "Noto Sans", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol", "Noto Color Emoji";
}