JSFiddle - React, Tailwind, and code Playground

HTML

<div class="main">
    <div class="left"></div>
    <div class="right"></div>
</div>

CSS

.main {
    margin: 40px;    
    border: 1px solid #ccc;
}

.left {
    width: 300px;
    height: 500px;
    
    float: left;    
    background: #fbfbfb;
}

.right {
    height: 500px;
    margin-left: 300px;
    
    border-left: 1px solid #ccc;
    background: #f2f2f2;
}