diff --git a/containers/libreportal/frontend/css/topbar.css b/containers/libreportal/frontend/css/topbar.css
index 71f07f7..12812e4 100644
--- a/containers/libreportal/frontend/css/topbar.css
+++ b/containers/libreportal/frontend/css/topbar.css
@@ -2,17 +2,21 @@
 
 /* Topbar layout, nav pills, donate/logout buttons. Extracted from style.css. Theme via var(--*) tokens. */
 
-/* Developer-mode strip — sits flush under the fixed topbar when CFG_DEV_MODE
-   is on. Neutral glass so it reads as "system bar" not "warning"; only the
-   icon picks up the theme accent. Body gets .has-dev-banner to bump
-   padding-top by the strip's height; dismissal is local and remembered in
+/* Developer-mode strip — sits flush at the very top of the viewport above
+   the topbar when CFG_DEV_MODE is on. Above-chrome is the standard env-
+   banner placement (Stripe test-mode, GitHub staff-mode); pushing the
+   topbar down 36px is a deliberate signal that the environment is non-
+   standard. Neutral glass so it reads as "system bar" not "warning"; only
+   the icon picks up the theme accent. Body gets .has-dev-banner to bump
+   padding-top + shift every other fixed-positioned chrome element down
+   by the strip's height. Dismissal is local and remembered in
    localStorage until dev mode is toggled off + on again. */
 .dev-banner {
   position: fixed;
-  top: 60px;
+  top: 0;
   left: 0;
   right: 0;
-  z-index: 999;
+  z-index: 1001;
   height: 36px;
   display: flex;
   align-items: center;
@@ -63,6 +67,13 @@
 }
 
 body.has-dev-banner { padding-top: 96px; }
+/* Shift every other fixed-positioned chrome element down by the banner
+   height when it's on. Topbar slides from top:0 → 36 (under the banner);
+   anything that was at top:60 (the topbar's bottom edge — sidebar, apps
+   layout, mobile-drawer) slides to 96 to clear the now-pushed-down topbar. */
+body.has-dev-banner .topbar       { top: 36px; }
+body.has-dev-banner .sidebar      { top: 96px; }
+body.has-dev-banner .apps-layout  { top: 96px; }
 
 @media (max-width: 768px) {
   .dev-banner { padding: 0 48px 0 12px; font-size: 0.8rem; }