diff --git a/index.html b/index.html
index 39424db..79bb3e3 100644
--- a/index.html
+++ b/index.html
@@ -7,10 +7,10 @@
     TABLE { width: 100%; }
     HR { height:5px; border: 0px;}
     TD { vertical-align: top; width: 10%; }
-    LI { 
-        text-indent:-1.3em; 
+    LI {
+        text-indent:-1.3em;
          padding-left:1.4em;
-         list-style-type:none; 
+         list-style-type:none;
          overflow: hidden;
          margin-bottom: 0.2em;
          }
@@ -31,7 +31,7 @@
     A:focus { text-decoration: underline; }
     #filter { width: 100%; }
     #search { width: 100%; display: table; }
-    .search_span { display: table-cell; text-align: center; vertical-align: middle; 
+    .search_span { display: table-cell; text-align: center; vertical-align: middle;
                    padding-left: 0.1em; padding-right: 0.1em; }
     .head { font-size: 16px; text-align:left; padding-top: 0.2em; margin-bottom: -0.5em; }
     #menu { font-size: 12px; width: 3em; }
@@ -49,7 +49,7 @@
 </STYLE>
 <script language="javascript">
 function init() {
-    var head = document.head; 
+    var head = document.head;
     if (config.style!=null) {
       var link = document.createElement('link');
       link.type = 'text/css';
@@ -70,8 +70,8 @@ function init() {
     if (!config.search) {
       document.getElementById('search').style.display='none';
     }
-    if (config.columns==1 || narrow_window()) { 
-      make_menu(); 
+    if (config.columns==1 || narrow_window()) {
+      make_menu();
     }
     document.getElementById("open_blank_arrow").innerHTML=config.arrows[0];
     document.getElementById("filter").focus();
@@ -90,7 +90,7 @@ String.prototype.capitalizeFirstLetter = function() {
 
 function make_link(md) {
     var match=linkReg.exec(md);
-    if (match != null) { 
+    if (match != null) {
         return "<li>"+match[1]+"<a href=\""+match[3]+"\">"+match[2]+"</a>"+match[4];
     }
     match=linkPlain.exec(md);
@@ -104,7 +104,7 @@ function make_head(c,index="") {
     var name=c.substring(1).trim();
     var head=c.replace(/ /g,"&nbsp;");
     var id=name.replace(/ /g,"")+"_"+index;
-    return '<a name="'+name+'" id="anchor_'+id+'" onclick="fold_content(\''+id+'\')">'+
+    return '<a name="'+name+'" id="anchor_'+id+'" onclick="fold_toggle(\''+id+'\')">'+
         '<div class=head align=center id="head_'+id+'">'+head+'</div></a>'+
         '<hr WIDTH="100%" SIZE=3 NOSHADE>';
 }
@@ -148,7 +148,7 @@ function filter(ev) {
         if (c>1) {
             document.getElementById('filter').focus();
         }
-    }   
+    }
 }
 function no_filter(){}
 
@@ -172,13 +172,13 @@ function search_hits(needle) {
       }
     }
     var match=linkReg.exec(linkList[l].toLowerCase());
-    if (match != null ) { 
+    if (match != null ) {
       /* matches to markdown link */
-        if ( match[2].indexOf(needle)>-1 ) { hitList.push(l); } 
+        if ( match[2].indexOf(needle)>-1 ) { hitList.push(l); }
         continue
     }
     match=linkPlain.exec(linkList[l].toLowerCase());
-    if (match != null ) { 
+    if (match != null ) {
       /* matches to plain link */
         if ( match[2].indexOf(needle)>-1 ) { hitList.push(l); }
         continue
@@ -248,7 +248,7 @@ function reload_source() {
     location.href=config.source
 }
 function get_URL(s) {
-    if (window.XMLHttpRequest) { xmlhttp=new XMLHttpRequest(); } 
+    if (window.XMLHttpRequest) { xmlhttp=new XMLHttpRequest(); }
     else { xmlhttp=new ActiveXObject("Microsoft.XMLHTTP"); }
     xmlhttp.onreadystatechange=function()
             { if (xmlhttp.readyState==4 && xmlhttp.status==200)
@@ -258,8 +258,8 @@ function get_URL(s) {
     xmlhttp.send();
 }
 
-function read_links() { 
-  get_URL(config.source); 
+function read_links() {
+  get_URL(config.source);
 }
 
 function parse_links(s) {
@@ -271,15 +271,15 @@ function parse_links(s) {
     }
   }
   linkList=links.slice(0);
-  init();  
+  init();
 }
 function keyboard_entry(ev) {
-  var kC=ev.keyCode; 
-  var k=String.fromCharCode(ev.keyCode); 
+  var kC=ev.keyCode;
+  var k=String.fromCharCode(ev.keyCode);
   if ( document.activeElement === document.getElementById("filter")) {
     return
   }
-  if (/S/.test(k)) { 
+  if (/S/.test(k)) {
     document.getElementById("filter").focus();
   }
   if (/N/.test(k)) {
@@ -287,8 +287,8 @@ function keyboard_entry(ev) {
   }
 }
 function keyboard_control(ev) {
-  var kC=ev.keyCode; 
-  var k=String.fromCharCode(ev.keyCode); 
+  var kC=ev.keyCode;
+  var k=String.fromCharCode(ev.keyCode);
   if (ev.ctrlKey) {
     if (k=='C') {
       document.getElementById("filter").value='';
@@ -305,7 +305,7 @@ function toggle_blank() {
       span.attributes['data']="false";
     } else {
       span.attributes['data']="true";
-    }  
+    }
   } else {
     span.attributes['data']="true"
   }
@@ -354,33 +354,83 @@ function filter_cookies(cookies,name) {
       }
     }
   }
-  return null
+  return null;
 }
-function fold_content(name) {
+function fold_toggle(name,save_state = true) {
   if (!narrow_window()) { return }
   if (!config.foldCategories) { return }
   var title = document.getElementById("head_"+name);
   var el = document.getElementById("content_"+name);
   el.hidden = ! el.hidden;
   title.classList.toggle("fold_plus");
+  if (save_state) {
+    set_cookie("fold",fold_get_state());
+  }
+}
+function fold_set(name,value) {
+  if (!narrow_window()) { return }
+  if (!config.foldCategories) { return }
+  var title = document.getElementById("head_"+name);
+  var el = document.getElementById("content_"+name);
+  el.hidden = value;
+  if (value) {
+    title.classList.add("fold_plus");
+  } else {
+    title.classList.remove("fold_plus");
+  }
 }
 function fold_initial() {
   if (!narrow_window()) { return }
   if (!config.foldCategories) { return }
+  var state = get_cookie("fold");
+  if (state !== null) {
+    fold_set_state(state);
+    return;
+  }
   var slides = document.getElementsByClassName("head");
   for(var i = 0; i < slides.length; i++) {
     var el = slides.item(i);
     var rect = el.getBoundingClientRect();
     if (window.innerHeight*1.5 < rect.top) {
       var name = el.id.replace("head_","");
-      fold_content(name);
+      fold_toggle(name);
     }
   }
 }
+function fold_get_state() {
+  var slides = document.getElementsByClassName("head");
+  var state = "";
+  for(var i = 0; i < slides.length; i++) {
+    var title = slides.item(i);
+    var name = title.id.replace("head_","");
+    var el = document.getElementById("content_"+name);
+    if (el.hidden) {
+      state += '-';
+    } else {
+      state += '+';
+    }
+  }
+  return state;
+}
+function fold_set_state(state) {
+  var slides = document.getElementsByClassName("head");
+  for(var i = 0; i < slides.length; i++) {
+    var title = slides.item(i);
+    var name = title.id.replace("head_","");
+    if (state[i] == '-') {
+      fold_set(name, true);
+    }
+    if (state[i] == '+') {
+      fold_set(name, false);
+    }
+  }
+  return;
+}
+
 function set_cookie(name,value) {
   // Save cookies for 2 hours
   document.cookie = name + "=" + value.toString() + "&" + window.location.pathname +
-   ";path=" + window.location.pathname + ";max-age="+ (60*60*2).toString() + ";"; 
+   ";path=" + window.location.pathname + ";max-age="+ (60*60*2).toString() + ";";
 }
 document.onkeyup=keyboard_entry;
 document.onkeydown=keyboard_control;