JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div id="content">
        Content
    </div>
    <div id="sidebar">
        SidebarSidebarSidebarSidebarSidebarSidebarSidebarSidebarSidebarSidebarSidebar
    </div>
</div

CSS

#container {
    display: table;
    width: 70%;
    margin: 0 auto;
}

#content, #sidebar {
    display: table-cell;
}

#content {
    max-width: 70%;
    border: 1px solid blue;
}

#sidebar {
    width: 254px;
    border: 1px solid red;
}