JSFiddle - React, Tailwind, and code Playground

HTML

<div class="parent">
    parent
    
    <div class="child">child</div>
    
 </div>

CSS

body {
    width: 100%;
    height: 100%;
    padding: 0;
    margin: 0;
}

.parent {
    border: solid red;
    width: 200px;
    height: 200px;
    transform: translate3d(20px,20px,20px);
}


.child {
    position: fixed;
    top: 0;
    left: 0;
    border: solid green;
    width: 100px;
    height: 100px;
}