JSFiddle - React, Tailwind, and code Playground

HTML

<div class="main">
    <div class="center"></div>
</div>

CSS

.main {
    width: 500px;
    height: 500px;
    position: relative;
    background: #eee;
}
.center {
    width: 100px;
    height: 100px;
    background: #000;
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%, -50%);
    -webkit-transform: translate(-50%, -50%);
}