JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="inner"></div>
</div>

CSS

.container {
    background-color: red;
    width: 100%;
    height: 100vh;  
    display: -webkit-box;
    display: -moz-box;
    display: -ms-flexbox;
    display: -webkit-flex;
    display: flex;
    -ms-flex-direction: column;
    -webkit-flex-direction: column;
    flex-direction: column;
}

.inner {
    -ms-flex: 1;
    -webkit-flex: 1;
    -webkit-box-flex: 1.0;
    flex: 1;
    background-color: blue;
}