JSFiddle - React, Tailwind, and code Playground

HTML

<section>
    <header>a</header>
    <article>b</article>
</section>

CSS

section {display: table;border-spacing: 5px;width: 400px;height: 500px;background: #A7E14B;}
header {background: #C64747;}
article {display: table-row;height: 100%;background: #477AC6;}