JSFiddle - React, Tailwind, and code Playground

HTML

<div id="layer">
<a href="xxx" id="thelink">yyy</a>
</div>

CSS

BODY { font-size:18px; }
A { color: red; }
#layer A { color: green; }

JavaScript

window.alert(
    getComputedStyle(
        document.getElementById('thelink')
    ).fontSize
);
// it alerts 18px, which is inherited from BODY in css