function changeTab(id) {
	document.getElementById('tab-content').className = document.getElementById('tab-content').className.replace(' active', '');
	document.getElementById('issue-content').style.display = 'none';
	
	if(document.getElementById('tab-lesercd')) {
		document.getElementById('tab-lesercd').className = document.getElementById('tab-lesercd').className.replace(' active', '');
		document.getElementById('issue-lesercd').style.display = 'none';
	}
	
	if(document.getElementById('tab-proficd')) {
		document.getElementById('tab-proficd').className = document.getElementById('tab-proficd').className.replace(' active', '');
		document.getElementById('issue-proficd').style.display = 'none';
	}
	if(document.getElementById('tab-kreuz_loesung')) {
		document.getElementById('tab-kreuz_loesung').className = document.getElementById('tab-kreuz_loesung').className.replace(' active', '');
		document.getElementById('issue-kreuz_loesung').style.display = 'none';
	}
	
	document.getElementById('tab-sources').className = document.getElementById('tab-sources').className.replace(' active', '');
	document.getElementById('issue-sources').style.display = 'none';
	
	document.getElementById('tab-' + id).className += ' active';
	document.getElementById('issue-' + id).style.display = 'block';
}