JSFiddle - React, Tailwind, and code Playground

HTML

<div class="square-grid">
    <div class="sg-3">
        <div>
            <div class="sg-3">
                <div>
                    <div class="sg-3"><div>1</div></div>
                    <div class="sg-3"><div>2</div></div>
                    <div class="sg-3"><div>3</div></div>
                    <div class="sg-3"><div>4</div></div>
                    <div class="sg-3"><div>5</div></div>
                    <div class="sg-3"><div>6</div></div>
                    <div class="sg-3"><div>7</div></div>
                    <div class="sg-3"><div>8</div></div>
                    <div class="sg-3"><div>9</div></div>
                </div>
            </div>
            <div class="sg-3">
                <div>
                    <div class="sg-3"><div>1</div></div>
                    <div class="sg-3"><div>2</div></div>
                    <div class="sg-3"><div>3</div></div>
                    <div class="sg-3"><div>4</div></div>
                    <div class="sg-3"><div>5</div></div>
                    <div class="sg-3"><div>6</div></div>
                    <div class="sg-3"><div>7</div></div>
                    <div class="sg-3"><div>8</div></div>
                    <div class="sg-3"><div>9</div></div>
                </div>
            </div>
            <div class="sg-3">
                <div>
                    <div class="sg-3"><div>1</div></div>
                    <div class="sg-3"><div>2</div></div>
                    <div class="sg-3"><div>3</div></div>
                    <div class="sg-3"><div>4</div></div>
                    <div class="sg-3"><div>5</div></div>
                    <div class="sg-3"><div>6</div></div>
                    <div class="sg-3"><div>7</div></div>
                    <div class="sg-3"><div>8</div></div>
                    <div class="sg-3"><div>9</div></div>
                </div>
            </div>
            <div class="sg-3">
                <div>
                    <div class="sg-3"><div>1</div></div>
...

CSS

body {
    text-align: center;
}
.square-grid {
    position: relative;
}
.sg-3 {
    float: left;
    width: 33.3333%;
    position: relative;
    height: 0;
    padding-top: 33%;
    position: relative;
    outline: 1px solid black;
}
.sg-3 > div {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
}