diff --git a/assets/overlay.js b/assets/overlay.js
index a972c50..e9de619 100644
--- a/assets/overlay.js
+++ b/assets/overlay.js
@@ -4,10 +4,10 @@
 // low-level focus/Escape/bfcache patterns from modal.js rather than that
 // component's panel chrome.
 //
-// openOverlay(node, opts) MOVES `node` (an existing rail <aside>) into the
-// overlay body and restores it to its original DOM position on close, so the
-// rail keeps its state (expanded tree folders, rendered TOC). Only one overlay
-// is open at a time.
+// openOverlay(node) MOVES `node` (an existing rail <aside>) into the overlay
+// body and restores it to its original DOM position on close, so the rail keeps
+// its state (expanded tree folders, rendered TOC). Only one overlay is open at
+// a time.
 (function () {
     var overlay = null;
     var bodyEl = null;
@@ -16,7 +16,6 @@
     var placeholder = null; // marks where to restore it
     var prevFocus = null;
     var onKeydown = null;
-    var onCloseCb = null;   // opts.onClose of the currently hosted node
 
     function build() {
         overlay = document.createElement('div');
@@ -51,13 +50,11 @@
         overlay.appendChild(bodyEl);
     }
 
-    function open(node, opts) {
+    function open(node) {
         if (overlay && overlay.parentNode) close();
         if (!overlay) build();
-        opts = opts || {};
 
         prevFocus = document.activeElement;
-        onCloseCb = typeof opts.onClose === 'function' ? opts.onClose : null;
         hosted = node;
         placeholder = document.createComment('overlay-slot');
         node.parentNode.insertBefore(placeholder, node);
@@ -72,9 +69,6 @@
         document.addEventListener('keydown', onKeydown);
 
         setTimeout(function () { closeBtn.focus(); }, 0);
-
-        if (typeof opts.onOpen === 'function') opts.onOpen();
-        return { close: close };
     }
 
     function close() {
@@ -98,12 +92,6 @@
         if (toRestore && toRestore.focus) {
             try { toRestore.focus(); } catch (e) {}
         }
-
-        // Fires after the node is back in its original spot, so the callback
-        // sees the final DOM.
-        var cb = onCloseCb;
-        onCloseCb = null;
-        if (cb) cb();
     }
 
     // Belt-and-suspenders bfcache guard: force the overlay closed (restoring