JSFiddle - React, Tailwind, and code Playground
HTML
<span id="s1"></span>
<span id="s2"></span>CSS
#s1{display: inline-block; width: 100px; height: 100px; background: red; vertical-align: middle }
#s2{display: inline-block; width: 50px; height: 50px; background: green; vertical-align: middle }