diff --git a/src/app/dashboard/plant/map/map-view.tsx b/src/app/dashboard/plant/map/map-view.tsx
index e00318a..0cf617d 100644
--- a/src/app/dashboard/plant/map/map-view.tsx
+++ b/src/app/dashboard/plant/map/map-view.tsx
@@ -122,8 +122,18 @@ export function MapView({ vehicles, sites }: { vehicles: MapVehicle[]; sites: Ma
   // for the Topbar (~4rem) plus ~5rem of vertical breathing room
   // (margin + the bottom-of-page gap). On phones the margin tightens
   // so the map still gets most of the screen.
+  //
+  // `isolate` (= `isolation: isolate`) traps Leaflet's internal
+  // z-index ladder (tile=200, overlay=400, marker=600, popup=700,
+  // controls=1000) inside the wrapper. Without it those values leak
+  // up to the dashboard layout and bury the Topbar's "All Sites"
+  // dropdown (z-50) when it opens over the map area. With it, the
+  // dropdown stays above because it competes with the wrapper as a
+  // single atomic unit. Nothing inside the wrapper needs to change —
+  // the legend / layer switcher are already at `z-[400]`, which is
+  // well above the tile pane but well below the marker controls.
   return (
-    <div className="relative mx-3 my-4 h-[calc(100dvh-9rem)] sm:mx-5 sm:my-5 lg:mx-6 lg:my-6">
+    <div className="isolate relative mx-3 my-4 h-[calc(100dvh-9rem)] sm:mx-5 sm:my-5 lg:mx-6 lg:my-6">
       <LeafletMap vehicles={vehicles} sites={sites} baseLayer={baseLayer} />
 
       {vehicles.length === 0 && (