JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
 <li id="A" class="u">1</li> 
 <li>
  <ol> 
   <li id="B" class="u">2.1</li>
   <li id="C" class="g">2.2</li> 
   <li id="D" class="u">2.3</li>
   <li id="E" class="g">2.4</li> 
  </ol>
 </li> 
 <li id="F" class="u">3</li>
</ul>

CSS

* > ul li:nth-child(4n+3) { color: red; }