diff --git a/A00_Common/main.ts b/A00_Common/main.ts
index c1dca79fd..2d94e6e8b 100644
--- a/A00_Common/main.ts
+++ b/A00_Common/main.ts
@@ -59,6 +59,10 @@ function bootstrap(): void {
   let shown = "";
   let shownHash = "";
   const renderAll = (): void => {
+    document.documentElement.classList.toggle(
+      "is-bm-route",
+      NATIVE_MENU_ROUTE.test(currentRoute()),
+    ); // 전역 글 선택 막음(81-1)
     const within = showWithinPage(currentRoute()); // B05 ↔ B06 — 보기만 바꿈(24-3a)
     shown = currentRoute();
     shownHash = window.location.hash;
diff --git a/ui_template/ui_template_theme.css b/ui_template/ui_template_theme.css
index 036d2a651..4685e1666 100644
--- a/ui_template/ui_template_theme.css
+++ b/ui_template/ui_template_theme.css
@@ -510,3 +510,20 @@ a:hover {
   outline: 2px solid var(--color-focus-ring);
   outline-offset: 2px;
 }
+
+/* ─── B · M 화면 전역 글 선택 막음(81-1) ───────────────────────────────────
+   `html.is-bm-route` 는 main.ts 가 라우트마다 토글(A 영역은 안 붙음).
+   허용 = input · textarea · select · [contenteditable] · 원문 본문(m01lab-src__body). */
+html.is-bm-route {
+  user-select: none;
+  -webkit-user-select: none;
+}
+html.is-bm-route input,
+html.is-bm-route textarea,
+html.is-bm-route select,
+html.is-bm-route [contenteditable],
+html.is-bm-route .m01lab-src__body,
+html.is-bm-route .m01lab-src__body * {
+  user-select: text;
+  -webkit-user-select: text;
+}