JSFiddle - React, Tailwind, and code Playground

HTML

<div class="demo">
    <button>Span 1</button>
    <button>Span 2</button>
    <button>Span 3</button>
</div>

CSS

div.demo {
    display:table;
    width:100%;
}
div.demo button {
    display:table-cell;
    text-align:center;
}