var curImg = 1;
function showImage(i,n) {
	for(j=1;j<=n;j++) {
		if(j==i) {
			document.getElementById('gallery-layer-'+j).style.visibility = 'visible';
			document.getElementById('navi-item-'+j).style.borderBottom = '1px solid white';
			curImg = i;
		} else {
			document.getElementById('gallery-layer-'+j).style.visibility = 'hidden';
			document.getElementById('navi-item-'+j).style.borderBottom = 'none';
		}
	}
}
function forWard(n) {
	i = (curImg+1) % n;
	if(i==0) i=n;
	curImg = i;
	showImage(i,n);
}
function backWard(n) {
	i = (curImg-1) % n;
	if(i==0) i=n;
	curImg = i;
	showImage(i,n);
}