function image_swap(id, state){
	document.getElementById(id).src = 'img/' +id+state+'.png';	
}

function top_nav_roll(a, page){
	id = 'top_nav_'+page;
	switch(a){		
		case 'index':
			document.getElementById(id).style.backgroundPosition = '0px 0px';
		break;
		
		case 'about_us':
			document.getElementById(id).style.backgroundPosition = '0px -42px';
		break;
		
		case 'current_projects':
			document.getElementById(id).style.backgroundPosition = '0px -84px';
		break;
		
		case 'past_projects':
			document.getElementById(id).style.backgroundPosition = '0px -126px';
		break;
	
		case 'submissions':
			document.getElementById(id).style.backgroundPosition = '0px -168px';
		break;
		
		case 'donate':
			document.getElementById(id).style.backgroundPosition = '0px -210px';
		break;
		
		case 'contact_us':
			document.getElementById(id).style.backgroundPosition = '0px -252px';
		break;
	}
}