function sidebarHeight(){
	contentHeight = document.getElementById('mainContent').offsetHeight;
	topicsHeight = document.getElementById('mainTopics').offsetHeight;
	if (contentHeight > topicsHeight)
		document.getElementById('mainTopics').style.height = contentHeight - 2 + 'px';
	else if (topicsHeight > contentHeight)
		document.getElementById('mainContent').style.height = topicsHeight - 10 + 'px';
}