diff --git a/src/BookReader.js b/src/BookReader.js
index a7e6dea1b..b4f5250aa 100644
--- a/src/BookReader.js
+++ b/src/BookReader.js
@@ -788,6 +788,24 @@ BookReader.prototype.unbind = function(name, callback) {
   return this.off(name, callback);
 };
 
+/**
+ * Resolves `this.el` to a DOM Element, whether it was provided as an
+ * Element reference or a CSS selector string.
+ *
+ * This is needed because some consumers (e.g. apps using shadow DOM)
+ * must pass a DOM element directly — `document.querySelector` cannot
+ * cross shadow boundaries. jQuery's `$()` already handles both forms,
+ * but code that calls `document.querySelector(br.el)` will fail when
+ * `el` is an Element or when the target is inside a shadow root.
+ *
+ * @returns {Element|null}
+ */
+BookReader.prototype.resolveEl = function() {
+  if (this.el instanceof Element) return this.el;
+  if (typeof this.el === 'string') return document.querySelector(this.el);
+  return null;
+};
+
 /**
  * Resizes based on the container width and height
  */
diff --git a/src/ia-bookreader/ia-bookreader.js b/src/ia-bookreader/ia-bookreader.js
index 728645ea5..4937775cd 100644
--- a/src/ia-bookreader/ia-bookreader.js
+++ b/src/ia-bookreader/ia-bookreader.js
@@ -337,7 +337,7 @@ export class IaBookReader extends LitElement {
 
   /** gets element that houses the bookreader in light dom */
   get mainBRContainer() {
-    return document.querySelector(this.bookreader?.el);
+    return this.bookreader?.resolveEl?.() ?? document.querySelector(this.bookreader?.el);
   }
 
   get baseProviderConfig() {
diff --git a/src/plugins/search/view.js b/src/plugins/search/view.js
index fdf3be7a5..50df2e184 100644
--- a/src/plugins/search/view.js
+++ b/src/plugins/search/view.js
@@ -331,7 +331,8 @@ class SearchView {
     const modal = document.createElement('div');
     modal.classList.add('BRprogresspopup', 'search_modal');
     modal.innerHTML = messageHTML;
-    document.querySelector(this.br.el).append(modal);
+    const container = this.br.resolveEl?.() ?? document.querySelector(this.br.el);
+    container?.append(modal);
   }
 
   /**