JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent">
    <div class="a"></div>
    <div class="b"></div>
</div>

CSS

.parent {
    width: 100%;
    height: 100%;
    border: 1px solid green;
    text-align: center;
}

.parent > div {
    display: inline-block;
}

.a {
    width: 100px;
    height: 100px;
    background: red;
}

.b {
    width: 200px;
    height: 100px;
    background: blue;
}