JSFiddle - React, Tailwind, and code Playground

HTML

<button>Example</button>

CSS

BODY {padding: 20px; }

BUTTON {
    background: #ccc;
    border: 1px solid #000;
    padding: 10px;
}

BUTTON::-moz-focus-inner {
    border: 0;
    padding: 0;
}