JSFiddle - React, Tailwind, and code Playground

HTML

<ul>
    <li>
        <ul>
            <li>A</li>
            <li>B</li>
        </ul>
    </li>
    <li>
        <ul>
            <li>C</li>
            <li>D</li>
        </ul>
    </li>
</ul>

CSS

ul {
    list-style:none;
    padding:0;
}
ul li ul li {
    display:block;
    float:left;
}
ul li ul { clear:both; }