JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <p>Testing paragraph</p>
    <p>Testing paragraph</p>
</div>
<div>
    <p>Testing paragraph</p>
    <p>Testing paragraph</p>
</div>

CSS

div {
    background-color: green;
}

p {
    background-color: yellow;
}

.hovered,
.hovered * {
    cursor: pointer;
    color: black;
    background-color: red;
}

JavaScript

var last,
    bgc;
document.onmouseover = function(e) {
    var elem = e.target;

    if (last != elem) {
        if (last != null) {
            last.classList.remove("hovered");
        }

        last = elem;
        elem.classList.add("hovered");
    }
}