JSFiddle - React, Tailwind, and code Playground
HTML
<script src="http://code.jquery.com/jquery-1.11.2.min.js"></script>
<script src="https://code.jquery.com/jquery-1.11.2.min.js"></script>
<div id="container">
<div class="red">Lorem ipsum dolor sit amet, consectetur adipisicing elit. In quod nihil .</div>
<div class="green">necessitatibus quam doloribus eos harum delectus, aspernatur accusantium, </div>
</div>
<button id="small">small</button>
CSS
#container { width:500px; height:500px;border:2px dotted maroon; }
.red, .blue, .green { display:inline-block;width: 250px; height:50px; margin:0 auto;}
.red {background:red; opacity:0.9; float:left; }
.green { background:green; opacity:0.9; float:right; }
JavaScript
$('#small').click(function() {
$('#container').animate({
'width': '200px'
}, 1000, function() {})
});