JSFiddle - React, Tailwind, and code Playground

HTML

<div class="first">
    <div class="second">
        <span>TESTING</span>
    </div>
</div>

CSS

div.first > div.second {
  border: 1px solid red;
  height: 2em;
}

div.first > div.second > span{
  position: relative;
  top: 50%;
  transform: translateY(-50%);
}