JSFiddle - React, Tailwind, and code Playground

HTML

<div id="fixedBox">Меню</div>
<br />
                <script>
                    for (i=1; i<101; i++) document.write('<br />');
                </script>

CSS

#fixedBox{
    width:100%;
    position:fixed;
    margin-top:120px;
    min-height:1600px;
}

JavaScript

jQuery(document).ready(function(){
        function getScrollTop() {
                   var scrOfY = 0;
                   if( typeof( window.pageYOffset ) == "number" ) {
                           scrOfY = window.pageYOffset;
                   } else if( document.body
                   && ( document.body.scrollLeft
                   || document.body.scrollTop ) ) {
                           scrOfY = document.body.scrollTop;
                   } else if( document.documentElement
                   && ( document.documentElement.scrollLeft
                    || document.documentElement.scrollTop ) ) {
                           scrOfY = document.documentElement.scrollTop;
                   }
                   return scrOfY;
        }
        jQuery(window).scroll(function() {
            fixPaneRefresh();
        });
         
        function fixPaneRefresh(){
            if (jQuery("#fixedBox").length) {
                var top  = getScrollTop();
                if (top < 120) jQuery("#fixedBox").css("margin-top",120-top+"px");
                else jQuery("#fixedBox").css("margin-top","0");
            }
        }
     
    });