<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>