JSFiddle - React, Tailwind, and code Playground

HTML

<html>
<head>
    <meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
</head>
<body>
    <div id="wid">fixed</div>
    <div id="wrapper">
        <div style="height: 1000px;"></div>
    </div>
</body>
</html>

CSS

html, body {
    overflow: hidden;
    width: 100%;
    height: 100%;
    padding: 0;
    margin: 0;
}
#wid {
    height: 40px;
    background: red;
    z-index: 10;
    width: 100%;
}
#wrapper {
    height: 100%;
    overflow: auto;
    position:relative;
    width: 100%;
}