JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE html>
<head>
    <meta http-equiv="Content-type" content="text/html; charset=utf-8">
    <title>Bonzai Rush</title>
    
</head>
<body>
    <h1>Don&rsquo;t get smashed!</h1>
    <div class="container">
        <div class="video">
            <iframe width="960" height="750" src="http://www.youtube.com/embed/5nmOMo4OPi4" frameborder="0" allowfullscreen></iframe>
        </div>
    </div>
</body>

CSS

body {
    padding: 20px;
    margin: 0;
}

.container {
    max-width: 300px;
    background-color: #eee;
    
}

img, object, embed, iframe, video {
    max-width: 100% !important;
    display: block;
}