.tuerchen {
	font-size: 2em;
	width: 120px;
	height: 120px;
	border: 4px solid green;
	margin: 2px;
	background-color: brown;
	color: white;
	float: left;
	display: flex;
	align-items: center;
	justify-content: center;
}

.offen {
	background-color: gold;
}