JSFiddle - React, Tailwind, and code Playground

HTML

<div id="header"></div>
<div id="body"></div>
<div id="footer"></div>

CSS

html, body {
    height: 100%;
    margin: 0;
}
#header {
    background: #f0f;
    height: 20px;
}
#footer {
    background: #f0f;
    height: 20px;
}
#body {
    background: #0f0;
    min-height: calc(100% - 40px);
}