JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/base/jquery-ui.css">
<h3>Pick a number on the SIDE MENU and drag t inside the iframe. Then make a fast drag (in order the mouse goes out the number div area)</h3>

<div class="container">
    <div class="side-menu">
        SIDE MENU
        <ul id="draggable">
          <li class="ui-state-default">1</li>
          <li class="ui-state-default">2</li>
          <li class="ui-state-default">3</li>
          <li class="ui-state-default">4</li>
          <li class="ui-state-default">5</li>
        </ul>
    </div>
    <div class="content">
        
        <iframe src="http://www.w3schools.com"></iframe>
        
    </div>
    
</div>

CSS

.container{
    overflow: hidden;
}

.side-menu{
    width: 20%;
    float: left;
    background: gray;
}

.content{
    width: 80%;
    height: 400px;
    float: left;
}

.content iframe{
    min-width: 400px;
    height: 400px;
}


ul { 
    list-style-type: none; 
}

li { 
    margin: 1px; 
    padding: 1px; 
    width: 10px; 
}

JavaScript

$(function() {
      $( "#draggable li" ).draggable({
          revert: true
      });
  });