JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div id="sidebar">
        <p>This is a sidebar</p>
    </div>
    <div id="content">
        <p>Lorem ipsum dolor sit amet</p>
    </div>
</div>

CSS

#container {
    overflow: hidden;
}
#sidebar, #content {
    float: left;
}
#sidebar {
    background-color: #f0f000;
    width: 100px;
}
#content {
    background-color: #00f0f0;
    width: calc(100% - 100px);
}