JSFiddle - React, Tailwind, and code Playground

HTML

<nav class="nav nav-fixed">
    <a href="#">Home</a>
    <a href="#">Something</a>
    <a href="#">Contact</a>
</nav>

<section class="long-scrollable"></section>

CSS

.long-scrollable {
    border: 2px dotted #999;
    height: 2000px;
}

.nav {
    background-color: #000;
    color: #fff;
    width: 100%;
    height: 40px;
}

.nav-fixed {
    position: fixed;
}