JSFiddle - React, Tailwind, and code Playground

HTML

<body style="min-height:2000px;min-width:2000px;">

<div class="fixed">
    <ul>
        <li>Test1</li>
        <li>Test1</li>
        <li>Test1</li>
        <li>Test1</li>
    </ul>
</div>

</body>

CSS

.fixed {
    padding:20px;
    border:1px solid #ccc;
    position:absolute;
    top:0;
    left:0;
}

JavaScript

$(document).ready(function() {
   
    $(window).scroll(function() {
       $(".fixed").css("top", $(window).scrollTop() + "px"); 
    });
    
});