JSFiddle - React, Tailwind, and code Playground

HTML

<div id="parent">
    <div id="child">
</div>

CSS

#parent {
    width: 300px;
    height: 100px;
    background-color: black;
    border: 1px solid grey;
    position: relative;
}
#child {
    position: absolute;
    height: 100px;
    width: 20px;
    left: 50%;
    top: 50%;
    -webkit-transform: translateX(-50%) translatey(-50%);
    background-color:red;
}