JSFiddle - React, Tailwind, and code Playground

HTML

<div class="div"></div>
<div class="div"></div>
<div class="div"></div>
<div class="div"></div>

CSS

div {
    margin: 10px;
    display: inline-block;
    height: 300px;
    border: 1px solid gray;
    width: 200px;
    transition: background-color 0.3s ease;
    background-color: transparent;
}
div:hover {
   background: #000;
}