JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wrap">
    <div class="fleft"></div>
    <div class="fright"></div>
    
</div>

CSS

.wrap {
width: 100%;
overflow:auo;
}

.fleft {
    float:left; 
    width: 80%;
background:blue;
    height: 400px;
}

.fright {
float: right;
    background:pink;
    height: 400px;
    width: 20%;
}