JSFiddle - React, Tailwind, and code Playground

HTML

<div id="all">
    <div id="content">
        Content<br/><br/><br/><br/><br/><br/><br/><br/><br/><br/>
    </div>
    
    <div id="menu">
        Menu<br/>Menu<br/>Menu<br/>Menu<br/>Menu<br/>Menu<br/>
    </div>
    
    <div id="footer">
        Footer
    </div>
</div>

CSS

#all{
    background: gray;
    width:400px;
}

#content{
    background:yellow;
    width:300px;
    float: left;
}

#menu{
    background:red; 
    width:100px;
    float: right;
}

#footer{
    background:green;
    clear: both;
}