JSFiddle - React, Tailwind, and code Playground

HTML

<p>Hello world! <img src="http://images.wikia.com/dragonvale/images/e/e8/Space_invader.jpg"</p>

CSS

body {
    font-size: 62.5%; /*sets 1em to 10px for convinience*/
}

p {
    font-size: 3em;
}

p img {
    height: 1em;
    width: auto;
}