JSFiddle - React, Tailwind, and code Playground

HTML

<div id='game'>
        <div id='container'>
            <div id='board'>
                <div class='emptyTile' ></div>
                <div class='emptyTile' ></div>
                <div class='emptyTile' ></div>
                <div class='emptyTile' ></div>
                <div class='emptyTile' ></div>
                <div class='emptyTile'></div>
                <div class='emptyTile' ></div>
                <div class='emptyTile'></div>
                <div class='emptyTile'></div>
            </div>
        </div>

    </div>

CSS

div#board div.cross,
div#board div.nought,
div#board div.emptyTile { border: 1px solid black; width: 20px; height: 20px; }
div#board div.nought { background-color: blue; }
div#board div.cross { background-color: red; }

JavaScript

$('.emptyTile').click(function () {
   $(div).addClass('nought');
    }});