JSFiddle - React, Tailwind, and code Playground

HTML

<div id="sidebar">
    links and whatnot go here
</div><table id="sizer">
    <tr>
        <td width="205"></td>
        <td valign="top" style="background-color:red;">
            this is the container (but its top is not aligned with the sidebar as I would like)
        </td>
    </tr>
</table>

CSS

#sidebar {
    width:190px;
    height:571px;
    top:50%;
    margin-top:-300px;
    position:fixed;
    padding:5px 15px 30px 0;
    font-size:12px;
    background-color:#575D60;
    border-top-right-radius:8px;
    border-bottom-right-radius:8px;
}

html {
    height:100%;
}

body {
    height:100%;
}

#sizer {
    width:100%;
    height:100%;
}