JSFiddle - React, Tailwind, and code Playground

HTML

<footer>
    <button class="btn-primary">Reply</button>
</footer>

CSS

footer {
    display: block;
    height: 50px;
    line-height: 50px;
    border: 1px solid red;
    padding: 0 20px;
    text-align: center;
    margin-top: 20px;
}

em {
    display: inline-block;
    height: 50px;
    width: 50px;
    border: 1px solid blue;
    box-sizing: border-box;
    float:left;
}