JSFiddle - React, Tailwind, and code Playground

HTML

<div class="out">
    <div class="in">
    </div>
</div>

CSS

.out {
    position: relative;
    height: 0;
    padding-bottom: 100%;
}
.in {
    position: absolute;
    top: 0;
    bottom: 0;
    width: 100%;
    background-color: red;
}