JSFiddle - React, Tailwind, and code Playground

HTML

<div id="container">
    <div> some content</div>
</div>

CSS

div#container::-webkit-scrollbar {
    background: yellow;
    width: 12px;
}
::-webkit-scrollbar-track {
    -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,0.3);
    border-radius: 10px;
}
::-webkit-scrollbar-thumb {
    border-radius: 10px;
    -webkit-box-shadow: inset 0 0 6px rgba(0,0,0,0.5);
}
div#container {
    height: 300px;
    border: 1px solid gray;
    overflow: scroll;
}
div#container:hover::-webkit-scrollbar {
    background: lightyellow;
}
div#container > div {
    height: 1000px;
}