JSFiddle - React, Tailwind, and code Playground

HTML

<div class="square">square</div>
<div class="bar">square</div>

CSS

.square, .bar {
    position:relative;
    margin-left:auto;
    margin-right:auto
}
.square {
    background-color:blue;
    width: 100px;
    height: 100px;
}
.bar {
    background-color:green;
    top: -70px;
    width: 400px;
    height: 40px;
}