JSFiddle - React, Tailwind, and code Playground

HTML

<div class="aerakman-box"></div>

CSS

body{
    background:#CCC;
}
.aerakman-box{
    -webkit-transition: width 2s;
    -moz-transition: width 2s;
    -o-transition: width 2s;
    transition: width 2s;
    background-color:#666;
    width:50px;
    height:50px;
    position:absolute;
    top:50px;
    left:200px;
}
.aerakman-box:hover{
    -webkit-transition: width 2s;
    -moz-transition: width 2s;
    -o-transition: width 2s;
    transition: width 2s;
    width:200px;
}