JSFiddle - React, Tailwind, and code Playground

HTML

<div style="width:100%; height:50px;" id="div1"></div>
<div style="width:100%;" id="div2"></div>

CSS

#div1 {background-color:#ddd;}
#div2 {background-color:red; position:absolute; bottom:0px;top:50px}

body{padding:0px}