JSFiddle - React, Tailwind, and code Playground

HTML

<section id="main">
        <div id="video"></div>
        <nav>
            <ul>
                Video list
            </ul>
        </nav>
        <div id="comments"></div>
    </section>

CSS

section#main{
    width: 960px;
    margin: 7% auto 0;
    background: #000;
    opacity: 0.86;
    -webkit-border-radius: 5px;
    -moz-border-radius: 5px;
    border-radius: 5px;
    padding: 5px;
}

div#video{
    border: 1px solid red;
    width: 640px;
    height: 360px;
    margin: 10px;
    display: inline-block; 
    vertical-align:top;
}

nav{
    margin: 10px;
    border: 1px solid yellow;
    display: inline-block;
    vertical-align:top;
    height: 360px;
    width: 270px;
}