JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://code.jquery.com/jquery-3.7.1.js"></script>
<h1 style="text-align: center;">JavaScript 系列四：第4課 ── jQuery 套件 (運用jQ)</h1>

<h1 class="title">
  Make me green
</h1>

<p class="para">
  Make me red
</p>
<p class="para">
  Me red too
</p>
<p class="para">
  Also me
</p>

JavaScript

$("h1.title").css("color", "green");
$("p.para").css("color", "red");