JSFiddle - React, Tailwind, and code Playground

HTML

<div id="content">
  
  <div id="main"><div id="sidebar">some sidebar content</div>some main content</div>
</div>

CSS

#content{
    width: 100%;
}
#sidebar, #main{
    float: left;
    display: block;
}
#sidebar{
    width: 100px;
    background-color: orange;
    margin-left: -100px;
}
#main{
    padding-left: 100px;
    background-color: green;
    width: 100%;
}