JSFiddle - React, Tailwind, and code Playground

HTML

<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<div id="menu">
    <div class="menutext">
        <ul>
            <li><a href="#">home</a>
            </li>
            <li><a href="#">about</a>
            </li>
            <li><a href="#">product</a>
            </li>
        </ul>
    </div>

    
    <p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
 <p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p><p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p><p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p><p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p><p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p><p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p><p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p><p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p><p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p><p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p><p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p><p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p><p> cekekekkkkkkkkkkkkkkkkkkkkkkkkkk</p>
<p>...

CSS

.menutext {
     float: left;
     border-bottom:1px solid #d2d6d5;
     width: 100%;
     background:gray;
 }
 .menutext ul {
     margin: 0 0 0 10%;
 }
 .menutext ul li {
     float: left;
     position: relative;
     border-left: none;
     list-style: none;
 }
 .menutext li a {
     text-decoration: none;
     color: #444;
     display: inline-block;
     font-size: 14px;
     font-family: MuseoSans, serif;
     text-transform: uppercase;
     padding:10px;
     border-right: 1px solid #d2d6d5;
     text-align: center;
 }
 .menutext ul li :hover {
     color:#919191;
     background-color: #f4f4f4;
 }

JavaScript

$(document).ready(function() {
	// Menentukan elemen yang dijadikan normal yaitu .normal
	var normalNavTop = $('.menutext').offset().top; 
	var normalNav = function(){
		var scrollTop = $(window).scrollTop();  
		// Kondisi jika discroll maka .nav ditambahkan class normal dan sebaliknya		
		if (scrollTop < normalNavTop) { 
            $('.menutext').css({ 'position': 'fixed', 'top':0, 'left':0, 'z-index':9999 });
		} else {
			$('.menutext').css({ 'position': 'relative' });
		}
	};

	// Jalankan fungsi
	normalNav();
	$(window).scroll(function() {
		normalNav();
	});
});