JSFiddle - React, Tailwind, and code Playground

HTML

<div id="content">
content content content content content content content content content content content content content content content content
</div>
<div id="footer">
    abc
</div>

CSS

* { box-sizing: border-box } 
html,body { height: 100%; padding: 0; margin: 0 }
#content { min-height: 90%; outline: 1px solid blue } 
#footer { background: gray; height: 10%; }