JSFiddle - React, Tailwind, and code Playground

HTML

<input type="checkbox" id="button">
<label class="ani" for="button"></label>

CSS

input{display:none}
.ani
    {
    width:100px;
    height:100px;
    background:red;
    transition:width 2s;
    -moz-transition:width 2s; /* Firefox 4 */
    -webkit-transition:width 2s; /* Safari and Chrome */
    -o-transition:width 2s; /* Opera */
    display:block;
    }
input:checked + .ani{width:300px;}