body {
	background: lightgrey;
	display: flex;
	font-family: sans-serif;
	font-size: 20px;
	justify-content: center;
	margin: 0;
}

input[type=button] {
	font-size: 30px;
	padding: 10px;
	width: 100%;
}

.content {
	max-width: 640px;
	text-align: center;
	width: 640px;
}

.selected {
	background: #ff7;
}

.element {
	padding: 15px;
}

.pianoKey.selected {
	--fill-color: #ff7;
}

.pianoKey.correct {
	--fill-color: #7f7;
}

.pianoKey.incorrect {
	--fill-color: #f77;
}

.hidden {
	display: none;
}