<script type='text/javascript'>  
function Switchable(classname) {  
function getElementsByClassName(imgclass) {  
   if ( document.getElementsByClassName ) {  
    return document.getElementsByClassName(imgclass);  
   } else {  
    var nodes = document.getElementsByTagName('*'),  
    tmp = [];  
    for ( var i = 0; i < nodes.length; i++ ) {  
     if ( new RegExp('\\b' + imgclass + '\\b').test(nodes[i].className) ) {  
      tmp.push(nodes[i]);  
     }  
    }  
    return tmp;  
   }  
}  

function Next(element) {  
   var next = element;  
   while (next = next.nextSibling)  
    if ("innerHTML" in next)  
     return next;  
   return element;  
}  

function getCookie(a){var b=document.cookie.match(new RegExp("(?:^|; )"+a.replace(/([\.$?*|{}\(\)\[\]\\\/\+^])/g,"\\$1")+"=([^;]*)"));return b?decodeURIComponent(b[1]):undefined}function setCookie(b,f,c){c=c||{};var i=c.expires;if(typeof i=="number"&&i){var h=new Date();h.setTime(h.getTime()+i*1000);i=c.expires=h}if(i&&i.toUTCString){c.expires=i.toUTCString()}f=encodeURIComponent(f);var a=b+"="+f;for(var e in c){a+="; "+e;var g=c[e];if(g!==true){a+="="+g}}document.cookie=a}  
   var nodes = getElementsByClassName(classname);  
   for (var i = 0; i < nodes.length; i++) {  
    var toggler = document.createElement("A");  
    toggler.href = "javascript://";  
    toggler.id = "toggler" + i;  
    toggler.innerHTML = getCookie("toggler" + i) == "hide" ? "+" : "-";  
    toggler.onclick = function () {  
     Next(this.parentNode).style.display = getCookie(this.id) == "hide" ? "" : "none";  
     setCookie(this.id, getCookie(this.id) == "hide" ? "show" : "hide", {  
      expires: new Date("01 Jan 2020")  
     });  
     this.innerHTML = getCookie(this.id) == "hide" ? "+" : "-";  
    };  
    Next(nodes[i]).style.display = getCookie("toggler" + i) == "hide" ? "none" : "";  
    nodes[i].appendChild(toggler);  
   }  
}  

Switchable("header");  
</script>

<div class='header'>  
Заголовок  
</div>  
<div>  
Содержимое  
</div>