JSFiddle - React, Tailwind, and code Playground

HTML

<table>
    <tr>
        <td>
            <textarea>
            </textarea>
            <div class="b">button</div>
        </td>
    </tr>
</table>

CSS

td {
    position:relative;
}

textarea {
    height:300px;
    width:300px;
}

.b {
    position:absolute;
    top:0;
    right:0;
    z-index:20;
    padding:5px;
    background-color:#eee;
}