JSFiddle - React, Tailwind, and code Playground

HTML

<header><div id="mydiv"></div></header>
    <div id="content"><p>hello</p></div>

CSS

header {padding:0.001em;background-color:#CCCCCC; width:960px; height:430px;}
#mydiv {width:960px; height:320px; margin:80px 0px 0px 0px; background-color:#CC0000; }