diff --git a/addon/chrome/content/preferences.xhtml b/addon/chrome/content/preferences.xhtml
index af67264..c9b5207 100644
--- a/addon/chrome/content/preferences.xhtml
+++ b/addon/chrome/content/preferences.xhtml
@@ -1,33 +1,30 @@
 <linkset>
   <html:link rel="localization" href="__addonRef__-preferences.ftl" />
 </linkset>
-<vbox
-  id="zotero-prefpane-__addonRef__"
-  onload="Zotero.__addonInstance__.hooks.onPrefsEvent('load', {window})"
+<groupbox
+  onload="Zotero.__addonInstance__.hooks.onPrefsEvent('load', { window });"
 >
-  <groupbox>
-    <label><html:h2 data-l10n-id="pref-title"></html:h2></label>
-    <checkbox
-      id="zotero-prefpane-__addonRef__-enable"
-      preference="extensions.zotero.__addonRef__.enable"
-      data-l10n-id="pref-enable"
-    />
-    <hbox>
-      <html:label
-        for="zotero-prefpane-__addonRef__-input"
-        data-l10n-id="pref-input"
-      ></html:label>
-      <html:input
-        type="text"
-        id="zotero-prefpane-__addonRef__-input"
-        preference="extensions.zotero.__addonRef__.input"
-      ></html:input>
-    </hbox>
-    <hbox class="virtualized-table-container" flex="1" height="300px">
-      <html:div id="__addonRef__-table-container" />
-    </hbox>
-  </groupbox>
-</vbox>
+  <label><html:h2 data-l10n-id="pref-title"></html:h2></label>
+  <checkbox
+    id="zotero-prefpane-__addonRef__-enable"
+    preference="extensions.zotero.__addonRef__.enable"
+    data-l10n-id="pref-enable"
+  />
+  <hbox>
+    <html:label
+      for="zotero-prefpane-__addonRef__-input"
+      data-l10n-id="pref-input"
+    ></html:label>
+    <html:input
+      type="text"
+      id="zotero-prefpane-__addonRef__-input"
+      preference="extensions.zotero.__addonRef__.input"
+    ></html:input>
+  </hbox>
+  <hbox class="virtualized-table-container" flex="1" height="300px">
+    <html:div id="__addonRef__-table-container" />
+  </hbox>
+</groupbox>
 <vbox>
   <html:label
     data-l10n-id="pref-help"