JSFiddle - React, Tailwind, and code Playground

HTML

<div id='top'>
    <div id='other'>
        This is 1 <br />
        THis is 2 <br />
        This is 3 <br />
        
    </div>
    <div id='this-bottom'>
        This should be bottom
    </div>
</div>

CSS

#top{
    width:300px;
    position:relative;
    padding:20px;
    border:1px solid #222;
    height:200px;
}
#this-bottom{
    position:absolute;
    width:100%;
    bottom:0;
    border:1px solid #333;
}
#other{
    width:100%;
    border:1px solid #333;
}