JSFiddle - React, Tailwind, and code Playground

HTML

<div id="box">
    <div id="test">
        hello
    </div>
</div>

CSS

body {
    width:100%;
    height: 100%;
    margin: 0;
    padding: 0;
}
#box {
    width:100%;
    height: 500px;
    background: lightblue
}
#test {
    width: 300px;
    height: 300px;
    border: 1px solid red;
    margin: 0 auto
}