JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.3.1/css/bootstrap-combined.min.css">
<header>
    <div class="navbar">
        <div class="navbar-inner"> <a class="brand" href="#">My Inbox</a>

            <ul class="nav">
                <li class="active"><a href="#">Home</a>
                </li>
                <li><a href="#">Link</a>
                </li>
                <li><a href="#">Link</a>
                </li>
            </ul>
        </div>
    </div>
</header>
<div id="side">
    <nav>
        <ul>
            <li><a href="#nowhere" title="Lorum ipsum dolor sit amet">Lorem</a>
            </li>
            <li><a href="#nowhere" title="Aliquam tincidunt mauris eu risus">Aliquam</a>
            </li>
            <li><a href="#nowhere" title="Morbi in sem quis dui placerat ornare">Morbi</a>
            </li>
            <li><a href="#nowhere" title="Praesent dapibus, neque id cursus faucibus">Praesent</a>
            </li>
            <li><a href="#nowhere" title="Pellentesque fermentum dolor">Pellentesque</a>
            </li>
        </ul>
    </nav>
    <p>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur molestie pharetra lacus, a tincidunt elit fermentum ac. Praesent ac mauris nisl. Cras aliquet imperdiet nunc, vestibulum faucibus urna laoreet eu. Aliquam pharetra leo ut mauris tempus dignissim. Aenean mollis dui sed orci hendrerit vitae hendrerit nisi convallis. Ut id libero a metus ullamcorper consectetur. Suspendisse sed risus erat. In pharetra velit condimentum nisl interdum sed iaculis mi consectetur. Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Maecenas vulputate consectetur urna, a dignissim odio vestibulum a.</p>
    <p>Aliquam pharetra, nunc a tempor sodales, orci sem pretium orci, quis pretium tellus purus ac nunc. Morbi dignissim urna eget sapien laoreet volutpat. Sed lacus lorem, vulputate eu aliquet non, egestas vel augue. Fusce...

CSS

HTML {
    height: 100%;
}
BODY {
    position: relative;
    height: 100%;
}
HEADER {
    position: absolute;
    top: 0;
    left: 0;
    right: 0;
    height: 64px;
    padding: 8px;
    background-color: #ddd;
}
#side {
    position: absolute;
    top: 80px;
    left: 0;
    bottom: 0;
    width: 20%;
    background-color: #eee;
    overflow: auto;
}
#content {
    position: absolute;
    top: 80px;
    left: 20%;
    bottom: 0;
    right: 0;
    overflow: auto;
}