JSFiddle - React, Tailwind, and code Playground

HTML

<div style="height: 50%;">
<div class="block" style="height: 200%;">
    
    <div class="centered">
        <span>Some text</span>
    </div>
    
</div>
</div>

CSS

.block {
  text-align: center;
  background: #c0c0c0;
  border: #a0a0a0 solid 1px;
  margin: 20px;
}
 
.block:before {
  content: '';
  display: inline-block;
  height: 100%; 
  vertical-align: middle;
  margin-right: -0.25em; /* Adjusts for spacing */
    
  /* For visualization 
  background: #808080; width: 5px;
  */
 }
 
.centered {
  display: inline-block;
  vertical-align: middle;
  width: 300px;
  padding: 10px 15px;
  border: #a0a0a0 solid 1px;
  background: #f5f5f5;
 }