function bodysize(grote)
{
    var cookiewaarde = xgetCookie('grote');
    if (cookiewaarde == '' || cookiewaarde == null ) {
        cookiewaarde = 10/10;
    }

    switch(grote) {
        case "=" :
            cookiewaarde = parseFloat(cookiewaarde);
        break;
        case "-" :
            cookiewaarde = parseFloat(cookiewaarde) - parseFloat(stap);
        break;
        case "+" :
            cookiewaarde = parseFloat(cookiewaarde) + parseFloat(stap);
        break;
	default :
            cookiewaarde = parseFloat(grote);
    }
    fontsizeof(document.body,cookiewaarde);
    xsetCookie('grote',cookiewaarde);
}

function fontsizeof(oObject,grote) {
    if (oObject) {
        oObject.style.fontSize = grote  + 'em';
    }
}

function xsetCookie(name,value) {
    //document.cookie = name + "=" + value + ";";
   document.cookie = name + '=' + value + '; expires=Thu, 2 Aug 2020 20:47:11 UTC; path=/'
}

function xgetCookie(name) {
    //Haal de waardes van een specieke cookie op
    var dc = document.cookie;
    var prefix = name + "=";
    var begin = dc.indexOf("; " + prefix);
    if (begin == -1) {
        begin = dc.indexOf(prefix);
        if (begin != 0) return null;
    }
    else {
        begin += 2;
    }
    var end = document.cookie.indexOf(";", begin);
    if (end == -1) end = dc.length;

    return unescape(dc.substring(begin + prefix.length, end));
}










function setActiveStyleSheet(title) {
  var i, a, main;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title")) {
      a.disabled = true;
      if(a.getAttribute("title") == title) a.disabled = false;
    }
  }
   fixswitchknoppen(title);
}

function getActiveStyleSheet() {
  var i, a;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1 && a.getAttribute("title") && !a.disabled) return a.getAttribute("title");
  }
  return null;
}

function getPreferredStyleSheet() {
  var i, a;
  for(i=0; (a = document.getElementsByTagName("link")[i]); i++) {
    if(a.getAttribute("rel").indexOf("style") != -1
       && a.getAttribute("rel").indexOf("alt") == -1
       && a.getAttribute("title")
       ) return a.getAttribute("title");
  }
  return null;
}

function createCookie(name,value,days) {
  if (days) {
    var date = new Date();
    date.setTime(date.getTime()+(days*24*60*60*1000));
    var expires = "; expires="+date.toGMTString();
  }
  else expires = "";
  document.cookie = name+"="+value+expires+"; path=/";
}

function readCookie(name) {
  var nameEQ = name + "=";
  var ca = document.cookie.split(';');
  for(var i=0;i < ca.length;i++) {
    var c = ca[i];
    while (c.charAt(0)==' ') c = c.substring(1,c.length);
    if (c.indexOf(nameEQ) == 0) return c.substring(nameEQ.length,c.length);
  }
  return null;
}

window.onload = function(e) {
  var cookie = readCookie("style");
  var title = cookie ? cookie : getPreferredStyleSheet();
  setActiveStyleSheet(title);
  fixswitchknoppen(title);
}

window.onunload = function(e) {
  var title = getActiveStyleSheet();
  createCookie("style", title, 365);
}

var cookie = readCookie("style");
var title = cookie ? cookie : getPreferredStyleSheet();
setActiveStyleSheet(title);



function fixswitchknoppen(title) {
  if(title == "Zwart Wit") {
	if(document.getElementById('zwartwit')) document.getElementById('zwartwit').style.display = "none";
	if(document.getElementById('kleuren'))  document.getElementById('kleuren').style.display  = "inline";

  }
  else {
	if(document.getElementById('kleuren'))	document.getElementById('kleuren').style.display  = "none";
	if(document.getElementById('zwartwit')) document.getElementById('zwartwit').style.display = "inline";
  }
	fixnaartopknop();
}

function fixnaartopknop() {
 var title = getActiveStyleSheet()

 if(document.getElementById('naartop')) 
 {
	if(title == "Zwart Wit") {
		document.getElementById('naartop').src = "images/button_naartop_bw.gif"
	}
	else {
		document.getElementById('naartop').src = "images/button_naartop.gif"
	}
 }
}