var lastPage = 'home';

function showContent(contentId){

	// change main content
	document.getElementById('mainR_content').style.display = 'none';	// clear content
	document.getElementById('mainR_content').style.backgroundImage = 'url(img/mainR_'+contentId+'.png)';	// change bg image
	document.getElementById('mainR_content').innerHTML = document.getElementById('mainR_'+contentId).innerHTML;	// change content
	Effect.Appear('mainR_content');	// fade-in content
	
	// add permanent 'glow' to new content and remove from previous
	document.getElementById(lastPage).style.backgroundImage = 'url(img/nav/'+lastPage+'.png)';
	document.getElementById(contentId).style.backgroundImage = 'url(img/nav/'+contentId+'_r.png)';
	lastPage = contentId;

}