JSFiddle - React, Tailwind, and code Playground

HTML

<h2>This header should be RED to match the h2 element selector</h2>
<div class="myClass">
    <h1>This header should be GREEN to match the class selector</h1>
    <h2>This header should be BLUE to match the element.class selector</h2>
</div>

CSS

h2 {
    color: red;
}

.myClass {
    color: green;
}

.myClass h2 {
    color: blue;
}