JSFiddle - React, Tailwind, and code Playground

HTML

<div class='l'></div><div class='r'></div>
    
<br />
should look like:
<br />

<div style='display:inline-block;background:green;height:20px;width:10%;'></div><div style='display:inline-block;background:red;width:90%;height:20px;'></div>

CSS

.l {
    display:inline-block;
    background:green;
    width:100px;
    height:20px;
}

.r {
    background:red;
    height:20px;
}