// JavaScript Document
var i=0; // ID van Eerste div.
var c1 = 'Column13'; // Classname van eerste kolom.
var c2 = 'Column23'; // Classname van tweede kolom.
var c3 = 'Column33'; // Classname van derde kolom.


function scrollNext() {
	if (t-3==i) {
		return;
	}

	var n1 = document.getElementById('n'+i);
	var n2 = document.getElementById('n'+(i+1));
	var n3 = document.getElementById('n'+(i+2));
	var n4 = document.getElementById('n'+(i+3));
	
	n1.className='';
	n2.className=c1;
	n3.className=c2;
	n4.className=c3;
	
	n1.style.display='none';
	n4.style.display='block';
	
	i++;
	checkLinks();
}

function scrollPrev() {
	if (i==0) {
		return;
	}

	var n1 = document.getElementById('n'+(i-1));
	var n2 = document.getElementById('n'+(i));
	var n3 = document.getElementById('n'+(i+1));
	var n4 = document.getElementById('n'+(i+2));
	
	n1.className=c1;
	n2.className=c2;
	n3.className=c3;
	n4.className='';
	
	n1.style.display='block';
	n4.style.display='none';
	
	i--;
	checkLinks();
}

function checkLinks() {
	if (t-3==i) {
		document.getElementById('nextLink').style.display='none';
	} else {
		document.getElementById('nextLink').style.display='block';
	}
	
	if (i==0) {
		document.getElementById('prevLink').style.display='none';
	} else {
		document.getElementById('prevLink').style.display='block';
	}
}