JSFiddle - React, Tailwind, and code Playground

HTML

<div class="blackwrap">
    <header class="blackbar">
        <h2>Before he knew it, he couldn't see a thing.</h2>
        <h4>He fumbled around for the <a id="flash">flashlight</a> on his phone.</h4>
    </header>
</div> <!-- .blackwrap-->

CSS

.blackbar {
    background: black;
    color: white;
}
.blackbar.lit {
    background:yellow;
    color:black;
}

JavaScript

$("#flash").on("mouseover", function(){
    $(".blackbar").addClass("lit");
}).on("mouseout", function(){
    $(".blackbar").removeClass("lit");
});