// utility functions
function ShowHide(elementId, visible) 
{
    var obj = document.getElementById(elementId);
    obj.style.display = visible ? "block" : "none";
}

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

function getActiveStyleSheet()
{
  var i, a;
  var linkTags = document.getElementsByTagName("link");
  for (i = 0; a = linkTags[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;
  var linkTags = document.getElementsByTagName("link");
  for (i = 0; a = linkTags[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);
}

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

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