JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li>A</li>
    <li>B</li>
</ul>

CSS

ul {
    list-style: none;
    padding: 0;
    width: 45px;
    text-align: center;
    position: relative;
}
li {
    background: silver;
    margin: 0 0 5px;
}
li:after {
    content:"\25be";
    font-size: 2em;
    position: absolute;
    left: 10px;
    top: 35px;
}
li:hover:after {
    z-index: 1;
}
li:nth-child(1):hover:after {
    color: red;
}
li:nth-child(2):hover:after {
    color: blue;
}