diff --git a/userscript/manga-bookmark.user.js b/userscript/manga-bookmark.user.js
index fc46fec..7255d1c 100644
--- a/userscript/manga-bookmark.user.js
+++ b/userscript/manga-bookmark.user.js
@@ -511,9 +511,6 @@
     refresh().then(() => maybeAutoUpdate()); // sync, then auto-record this page
   }
 
-  if (document.body) init();
-  else document.addEventListener("DOMContentLoaded", init);
-
   // ============================================================
   // Markup + styles (kept at bottom for readability)
   // ============================================================
@@ -598,4 +595,13 @@
     .toast.show { opacity: 1; transform: translateY(0); }
     .toast.err { background: #7f1d1d; }
   `;
+
+  // ============================================================
+  // Boot — MUST run last: init() -> buildUI() reads TEMPLATE/CSS,
+  // which are const (TDZ) and only initialized above. At
+  // @run-at document-idle document.body already exists, so init()
+  // fires synchronously here, after the consts are set.
+  // ============================================================
+  if (document.body) init();
+  else document.addEventListener("DOMContentLoaded", init);
 })();