@import url('https://fonts.googleapis.com/css2?family=Source+Sans+3:wght@700&display=swap');
body{font-family:'Source Sans 3',sans-serif;background:#0c121a;color:#eef4ff;padding:22px}
.cell{display:inline-block;width:38px;height:38px;margin:4px;border:1px solid #3a4f66;border-radius:6px;line-height:38px;text-align:center}
.on{background:#3b82f6}