function showSection(id) {
  var divs = document.getElementsByTagName("div");
  for (var i=0; i<divs.length; i++ ) {
    if (divs[i].className.indexOf("section") == -1) continue;
    if (divs[i].getAttribute("id") != id) {
      divs[i].style.display = "none";
    } else {
      divs[i].style.display = "block";
    }
  }
}


function prepareInternalnav() {
  if (!document.getElementsByTagName) return false;
  if (!document.getElementById) return false;
  if (!document.getElementById("internalnav")) return false;
  var nav = document.getElementById("internalnav");
  var links = nav.getElementsByTagName("a");
/*  var showFirst = document.getElementById("ensimmainen");*/
  

  for (var i=0; i<links.length; i++ ) {
	/*Alustus*/
	var first = links[0].getAttribute("href").split("#")[1]; 
	document.getElementById(first).style.display = "block";
	links[0].parentNode.className = "current";
	/*---------*/
    var sectionId = links[i].getAttribute("href").split("#")[1];
    if (!document.getElementById(sectionId)) continue;
    document.getElementById(sectionId).style.display = "none";
    links[i].destination = sectionId;
    links[i].onclick = function() {
		for (var i=0; i<links.length; i++ ) {
			links[i].parentNode.className = null;
		}
		this.parentNode.className = "current";
      showSection(this.destination); 
      return false;
    }
  }
	
}

addLoadEvent(prepareInternalnav);