JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrapper">
    <div id="wrap">
    Some relative item placed item
    <div id="fixed"></div>
    </div>
</div>

CSS

body{ height:20000px }
#wrapper {
   padding: 0%;
   
}
#wrap{ 
    float: left;
    position: relative;
    margin: 10%;
    width: 40%; 
    background:gray; 
}
#fixed{ 
    position:fixed;
    width:inherit;
    padding:0px; 
    height:10px;
    background-color: orange;    
}