header .logo img {
	visibility: hidden;
}
header .logo span {
	position: absolute;
	top: 50%;
	left: 50%;
	width: 100px;
	height: 100px;
	transform: translate(-50%, -50%);
	background-size: 100%;
}
header .logo span.fussball {
	background-image: url('https://www.tsvbrunsbrock.de/File/brunsbrock-fussball.png');
}
header .logo span.tennis {
	background-image: url('https://www.tsvbrunsbrock.de/File/brunsbrock-tennis.png');
	opacity: 0;
	transition: 0.5s linear;
}
header .logo.show-tennis span.tennis {
	opacity: 1;
}