JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">

  <h2>Title 1</h2>

  <p>Someone someone someone someone</p>
  <p>Someone someone someone someone</p>
  <p>Not yellow : /</p>

  <h2>Title 2</h2>

  <p>Someone someone someone someone</p>
  <p>Someone someone someone someone</p>
  <p>Someone someone someone someone</p>

  <div class="narrow">

    <h2>Title 2</h2>

    <p>Someone someone someone someone</p>
    <p>Someone someone someone someone</p>
    <p>Someone someone someone someone</p>

  </div>  

</div>

CSS

p:last-of-type {
  background: yellow;
}