td {
border: 1px solid #bbb;
text-align: center;
line-height: 20px;
width: 20px;
height: 20px;
background: #888;
}
td.opened { background: white; }
td.flag { background: red; }
td.question { background: orange; }
</style>
</head>
<body>
<table id="table">
<tbody></tbody>
</table>
<div id="result"></div>
<script>
const $tbody = document.querySelector('#table tbody');
const $result = document.querySelector('#result');
</script>
</body>
</html>