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

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

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

function creaCookie(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 leggiCookie(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 = leggiCookie("style");
  var title = cookie ? cookie : stilePreferito();
  impostaStile(title);
}

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

var cookie = leggiCookie("style");
var title = cookie ? cookie : stilePreferito();
impostaStile(title);