Fancier homepage and a bit of performance improvement through aggressive caching.

js/collapsible.js

@@ -3,12 +3,34 @@ var i;
 
 for (i = 0; i < coll.length; i++) {
   coll[i].addEventListener("click", function() {
-    this.classList.toggle("active");
     var content = this.nextElementSibling;
-    if (content.style.display === "block") {
+    var isCurrentlyOpen = content.style.display === "block" || content.style.display === "grid";
+
+    // If this collapsible has a parent with book-grid class, close all siblings in that grid
+    var parentGrid = this.closest('.book-grid');
+    if (parentGrid) {
+      var siblings = parentGrid.querySelectorAll('.collapsible');
+      for (var j = 0; j < siblings.length; j++) {
+        if (siblings[j] !== this) {
+          siblings[j].classList.remove("active");
+          var siblingContent = siblings[j].nextElementSibling;
+          if (siblingContent) {
+            siblingContent.style.display = "none";
+          }
+        }
+      }
+    }
+
+    // Toggle current element
+    this.classList.toggle("active");
+    if (isCurrentlyOpen) {
       content.style.display = "none";
     } else {
-      content.style.display = "block";
+      if (content.classList.contains('chapter-grid')) {
+        content.style.display = "grid";
+      } else {
+        content.style.display = "block";
+      }
     }
   });
 }