JSFiddle - React, Tailwind, and code Playground
HTML
<div class="shadow"></div>
<div class="noshadow"></div>CSS
div { width: 20px; height: 20px; margin: 20px; background: #f0f0f0; }
.shadow { box-shadow: 0 0 5px black; }
div:hover { outline: red solid 1px; }