JSFiddle - React, Tailwind, and code Playground

HTML

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

<div class="footer">
</div>

CSS

.header {
background:red;
width:500px;
height:100px;
}

.container {
background:yellow;
width:500px;
height:100%;
}

.footer {
background:green;
width:500px;
height:100px;
    margin-top:-100px;
}
html,body{
    height:100%;
}