Mehrere Stylesheets nutzen / wechseln

Um mehrere externe Stylesheets zu benutzen, bin man zuerst die verschiedenen CSS-Dateien im -Bereich der Seite ein:

<link rel="stylesheet" type="text/css" href="style/ff.css" title="small" />
<link rel="alternate stylesheet" type="text/css" href="style/big.css" title="big" />

Nun bindet man folgendes Javascript in die Seite ein.

function set_active_sheet(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;
    }
  }
}

function get_active_sheet() {
  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 get_preferred_sheet() {
  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 create_cookie(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 read_cookie(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 = read_cookie("style");
  var title = cookie ? cookie : get_preferred_sheet();
  set_active_sheet(title);
}

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

var cookie = read_cookie("style");
var title = cookie ? cookie : get_preferred_sheet();
set_active_sheet(title);

Als nächstes muss man noch Links definieren, die den Swicht des Stylesheets auslösen:

Schriftgröße rauf
Schriftgröße runter