JSFiddle - React, Tailwind, and code Playground

HTML

<div id="content">
<div id="menu">
<ul>
    
    <li> haha</li>
    </ul>
</div>
<p style="clear:both"></p>
</div>

CSS

#menu li{
 width :200px;   
}
#menu{
    float:left;
    background-color:red;
    height:200px;
}
#content{
    background-color:yellow
}