JSFiddle - React, Tailwind, and code Playground

HTML

<img src="http://img1.wikia.nocookie.net/__cb20120923041524/kongregate/images/0/03/Awesome_face.png" />

CSS

img {
    -webkit-transition:all 0.5s;
    transition:all 0.5s;
    width:200px;
    height:200px;
}
img.small {
    height:50px;
    width:100px;
}

JavaScript

$( document ).ready(function() {
    $('img').addClass('small');
});