JSFiddle - React, Tailwind, and code Playground

HTML

<div class="um">
    <div class="dois">
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
        asdf<br />
    </div>
</div>

CSS

.um {
    max-height: 300px;
    display: block;
}

.um .dois {
    border: 1px solid #000;
    overflow: scroll;
    max-height: inherit;
}