JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
<div class="item"></div>
</div>

CSS

.container{
    position: relative;
    width: 300px;
    height: 300px;
    background-color: red;
    margin:auto;
}

.item{
    position: absolute;
    width: 100px;
    height: 100px;
    background-color: blue;
    left:50%;
    top:50%;
    margin-left:-50px;
    margin-top:-50px;
}