JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrapper">
  <div id="sidebar">Sidebar</div>
  <div id="content">Content</div>
</div>

CSS

#wrapper {
    width:400px;
    overflow:hidden;
    padding:10px;
}
#sidebar {
    float:left;
    width:100px;
}
#content {
    width:100%;
    float:right;
}
div {
    border:1px solid #333;
}