JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li class="common">   <p>First A</p>   </li>
    <li class="common">   <p>Second A</p>   </li>
    <li class="common">   <p>Third A</p> </li>
    <li class="common">   <p><b>SELECT ME</b></p>   </li>
    <li class="common custom">   <p>First B</p>   </li>
    <li class="common custom">   <p>Second B</p>   </li>
    <li class="common custom">   <p>...</p>   </li>
</ul>

JavaScript

$('li.common.custom').first().prev('.common').css('background','yellow');