a.css

td
{
	background-color: #C38147;
	width: 12vmin;
	height: 12vmin;
}
td.one
{
	background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 10 10'><circle cx='5' cy='5' r='3.8' stroke='black' fill='black'/></svg>");
}
td.two
{
	background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 10 10'><circle cx='5' cy='5' r='3.8' stroke='white' fill='white'/></svg>");
}
td.possible
{
	background-image: url("data:image/svg+xml;utf8,<svg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 10 10'><line x1='1' y1='1' x2='9' y2='9' stroke='red'/><line x1='1' y1='9' x2='9' y2='1' stroke='red'/></svg>");
	background-size: 25%;
	background-repeat: no-repeat;
	background-position: center;
}
tr:nth-child(odd) td:nth-child(even),
tr:nth-child(even) td:nth-child(odd)
{
	background-color: #FDCEA0;
}
body
{
	margin: 0;
	padding: 0;
}
.hidden
{
	display: none;
}