JSFiddle - React, Tailwind, and code Playground

HTML

<div id="header">Header</div>
<div id="content">
    my content
    sdgfgdsfg
    gsdfgsdf
    sdgfgsdf
    
</div>

CSS

#header{
    width:100%;
    position:fixed;
    top:0;
    height:40px;
    background-color:gray;
}

#content{
    height:800px;
}

body{
    margin:0;
}