JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li><a href="a">AAA</a></li>
    <li><a href="b">AAA</a></li>
    <li><a href="c">AAA</a></li>
</ul>

CSS

ul li:first-child {
  border: 1px solid #000;
}