Store progress in localStorage, not sessionStorage

quiz.js

@@ -7,7 +7,7 @@
  * http://creativecommons.org/publicdomain/zero/1.0/. */
 
 "use strict";
-const version = "$Id: quiz.js,v 1.27 2024/01/21 19:34:22 oj14ozun Exp oj14ozun $";
+const version = "$Id: quiz.js,v 1.28 2024/01/21 19:44:14 oj14ozun Exp oj14ozun $";
 
 const js_version  = document.getElementById("js-version");
 js_version.innerText = version;
@@ -69,6 +69,7 @@ function update_stats(q) {
     wrong.innerText = data.wrong;
     seen.innerText = (Object.keys(progress).length || 0) +
         (progress.hasOwnProperty(q.id) ? 0 : 1);
+    
 }
 
 function remember(q, ok) {
@@ -80,8 +81,9 @@ function remember(q, ok) {
         data["wrong"]++;
     }
 
+    // store in local storage
     progress[q.id] = data;
-    window.sessionStorage.setItem("progress", progress);
+    window.localStorage.setItem("progress", JSON.stringify(progress));
 }
 
 function pick() {