JSFiddle - React, Tailwind, and code Playground

HTML

<div id="main">

 <div id="sidebar">
     <ul>
         <li>abc</li>
         <li>def</li>
     </ul>
 </div>

 <div id="content">
defsdfasdfasd fjasd;lf jasdl;fkjasd; lfjas; lfkjadsfl;sdajfs dlfjsdlfksjflaskfjsdaljfasdl asdfsad sfljsf sadfjsldfj sakfj;alsdfj dfsjsadfl;j asdlfjl;asdfj 
defsdfasdfasd fjasd;lf jasdl;fkjasd; lfjas; lfkjadsfl;sdajfs dlfjsdlfksjflaskfjsdaljfasdl asdfsad sfljsf sadfjsldfj sakfj;alsdfj dfsjsadfl;j asdlfjl;asdfj 
 </div>

 <div id="main-footer">
 </div>

</div>

CSS

#main {
   border: solid green 2px;
}

#sidebar {
    background-color: red;
    width: 20%;
    overflow: auto;
    float: left;
    height: 100%;
}

#content {
    background-color: orange;
    width: 80%;
    overflow: auto;
    float: left;
    height: 100%;
}

#main-footer {
    clear: both;
}