JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div id="main"></div>
</div>

CSS

html, body {
    width: 100%;
    height: 100%;
    margin: 0;
    padding: 0;
}
#container {
    width: 100%;
    height: 100%;
}
#main {
    position: absolute;
    height: auto;
    bottom: 0;
    top: 0;
    left: 0;
    right: 0;
    margin: 10px;
    background-color: green;
}