JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <p>Im content</p>
<div>

CSS

div
{
    background: #999;
    width:200px;
    height: 20px;
    
    transition: width 1s;
    -moz-transition: width 1s; /* Firefox 4 */
    -webkit-transition: width 1s; /* Safari and Chrome */
    -o-transition: width 1s; /* Opera */
    -ms-transition: width 1s; /* IE9 (maybe) */
    
}

div:hover
{
    width:300px;
}