JSFiddle - React, Tailwind, and code Playground

HTML

<iframe width="560" height="315" src="//www.youtube.com/embed/TEH4G2Qsk2U" frameborder="0" allowfullscreen></iframe>

CSS

iframe {
    width:100%;
    background:red;
    height: 0;
    padding-bottom: 33%;    
}