JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrapper">
    <div class="float left">left</div>
    <div class="float right">right</div>
</div>

CSS

#wrapper {width:500px; height:300px; position:relative;}
.float {background-color:black; height:300px; margin:0; padding:0; color:white;}
.left {background-color:blue; position:fixed; width:400px;}
.right {float:right; width:100px;}