body{max-width:70em}#board{margin-top:1em;display:flex;flex-wrap:wrap;gap:1px;justify-content:center}#board .card{user-select:none;color:#fff;font-size:2em;border:1px solid #fff;width:3em;height:3em;display:flex;justify-content:center;align-items:center;cursor:pointer}#board .card:hover,#board .card.solved{background-color:#fff;color:#000}