body{background:#191919;color:#fff;font-family:sans-serif}html,body{height:100%;overflow:hidden}body,section{display:grid;justify-content:center;align-items:center;gap:2ch}button{background:#000;border:none;color:#fff;font-size:1.5em;padding:.25em}div.error{border:1px solid red;background:pink;padding:1em;color:red}