JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li>
        <a href="#">Home</a>
    </li>
    <li>
        <a href="#">Forums</a>
        <ul>
            <li>
                <a href="#">Basketball</a>
                
                <ul>
                    <li>
                        <a href="#">Trading</a>
                    </li>
                    <li>
                        <a href="#">Personal Collections</a>
                    </li>
                    <li>
                        <a href="#">Box Breaks</a>
                    </li>
                </ul>
            </li>
        </ul>
    </li>
</ul>

CSS

ul
{
    margin: 0;
    padding: 0;
    list-style: none;
    width: 150px;
    border-bottom: 1px solid #ccc;
}

ul li
{
    position: relative;
}

li ul
{
    position: absolute;
    left: 149px;
    top: 0;
    display: none;
}

ul li a
{
  width: 50px;
    display: block;
    text-decoration: none;
    color: #777;
    background: #bad8f8;
    padding: 2px 0 2px 10px;
    border: 1px solid #ccc;
    border-bottom: 0;
}

li:hover > ul
{
    display: block;
}