JSFiddle - React, Tailwind, and code Playground

HTML

<div id="app_pane">
    <div id="sidebar">
        <div id="logo">
        </div>
        <div id="list">
            <ul>
                <li>One</li>
                <li>Two</li>
                <li>Three</li>
                <li>Four</li>
                <li>Five</li>
                <li>Six</li>
                <li>Seven</li>
                <li>Eight</li>
                <li>Nine</li>
                <li>Ten</li>
                <li>One</li>
                <li>Two</li>
                <li>Three</li>
                <li>Four</li>
                <li>Five</li>
                <li>Six</li>
                <li>Seven</li>
                <li>Eight</li>
                <li>Nine</li>
                <li>Ten</li>
                <li>One</li>
                <li>Two</li>
                <li>Three</li>
                <li>Four</li>
                <li>Five</li>
                <li>Six</li>
                <li>Seven</li>
                <li>Eight</li>
                <li>Nine</li>
                <li>Ten</li>
            </ul>
        </div>
    </div>
</div>

CSS

#app_pane,
#sidebar,
#logo {
    padding: 5px;
}

#app_pane {
    position: absolute;
    width: 100%;
    height: 100%;
    -webkit-box-sizing: border-box;
    -mox-box-sizing: border-box;
    box-sizing: border-box;
    background: #000;
}

#sidebar {
    display: -webkit-box;
    display: -moz-box;
    -webkit-box-orient: vertical;
    -moz-box-orient: vertical;
    width: 200px;
    height: 100%;
    -webkit-box-sizing: border-box;
    -moz-box-sizing: border-box;
    box-sizing: border-box;
    background: #666;
}

#logo {
    height: 50px;
    margin-bottom: 5px;
    background: #999;
}

#list {
    overflow-y: scroll;
    -webkit-box-flex: 1;
    -moz-box-flex: 1;
    background: #999;
}