JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li class="class1">A</li>
    <li class="class1 class2">B</li>
    <li class="class1">C</li>
</ul>
<ul>
    <li class="">A</li>
    <li class=" class2">B</li>
    <li class="">C</li>
</ul>

CSS

li.class1:first-child
{
color:#ff0000;
}