JSFiddle - React, Tailwind, and code Playground

CSS

.target {
    background:#000000 !important;
    // etc.
}
.target::-webkit-scrollbar {
    width: 22px;
}
.target::-webkit-scrollbar-track {
    -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,0.3); 
    -webkit-border-radius: 10px;
    border-radius: 10px;
}

JavaScript

var bottomChild = document.createElement('div');
bottomChild.id = 'bottomChildId';
bottomChild.style.width = '100px';
bottomChild.style.position = 'relative';
bottomChild.style.overflowY = 'scroll';
bottomChild.style.background = 'red';
bottomChild.style.top = '0px';
bottomChild.style.borderLeft = '0px solid #E4E7EA';
bottomChild.style.height = '200px';
bottomChild.className = 'target';
document.body.appendChild(bottomChild);