JSFiddle - React, Tailwind, and code Playground

HTML

<div class="t1">My divider
  <div class="t2">
  Inside the div
  </div>
</div>

CSS

body { margin:0; /* This is used to reset any browser-default margins */ }

.t1 {
    background:#f00;
    color:#fff;
}

.t2 {
  background:#212121;
  height:100vh;
}