JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://raw.github.com/LeaVerou/prefixfree/gh-pages/prefixfree.min.js"></script>
<header>The header</header>
<ul>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
    <li>Scroll to your heart's content</li>
</ul>

CSS

header {
    background: #ACDAAC;
    padding: 20px;
    position: fixed;
    top: 0; left:0; right: 0;
}















body {
    font-size: 30px;
    padding: 20px;
    padding-top: 120px;
    background: linear-gradient(#E4FDFB, #D4A1E7);
}
header {
    box-shadow: 0 3px 10px #053305;
}