JSFiddle - React, Tailwind, and code Playground

HTML

<p>All “rem” nodes should have font-size:50px (100px &times; 0.2em), equal to the first “em” node</p>
<div class="em">
    em
    <div class="em">
        em
        <div class="em">
            em
        </div>
    </div>
</div>
<div class="rem">
    rem
    <div class="rem">
        rem
        <div class="rem">
            rem
        </div>
    </div>
</div>

CSS

HTML {
    font:100px Arial, sans-serif;
    }
.body {
    float:left;
    padding-bottom:1em;
    padding:20px;
    background:#CCC;
    }
P {
    font-size:12px;
    }
.em {
    font-size:0.5em;
    }
.rem {
    font-size:0.5rem;
    }