JSFiddle - React, Tailwind, and code Playground

HTML

<div id="content">
    <div id="head">
        <div id="header">
            <ul>
                <li>First</li>
                <li>Second</li>
            </ul>
        </div>
    </div>
</div>

CSS

* {
    margin: 0;
    padding: 0;
}

div#content {
    width: 100%;
    background-color: red;
}

div#head {   
    height: 20%;
}

div#header {
    width: 100%;
    height: 17%;
    color: #dedede;
    background-color: #444;
}

div#header ul li {
    display: inline;
	font-size-adjust: none;
	-webkit-text-size-adjust: none;
}