diff --git a/src/islands/maps/GeoViewer.tsx b/src/islands/maps/GeoViewer.tsx
index 48b536e..ee1fbef 100644
--- a/src/islands/maps/GeoViewer.tsx
+++ b/src/islands/maps/GeoViewer.tsx
@@ -19,6 +19,7 @@ export default function GeoViewer() {
   const mapRef = useRef<MlMap | null>(null);
   const mlRef = useRef<typeof import('maplibre-gl') | null>(null);
   const fcRef = useRef<FeatureCollection>(EMPTY);
+  const roRef = useRef<ResizeObserver | null>(null);
 
   const [style, setStyle] = useState<StyleChoice>('auto');
   const [count, setCount] = useState(0);
@@ -56,9 +57,13 @@ export default function GeoViewer() {
         const feats = map.queryRenderedFeatures(e.point, { layers: ['geo-fill', 'geo-line', 'geo-point'] });
         setSelected(feats[0]?.properties ?? null);
       });
+      map.on('load', () => map.resize());
+      const ro = new ResizeObserver(() => map.resize());
+      if (containerRef.current) ro.observe(containerRef.current);
+      roRef.current = ro;
       mapRef.current = map;
     })();
-    return () => { cancelled = true; mapRef.current?.remove(); mapRef.current = null; };
+    return () => { cancelled = true; roRef.current?.disconnect(); mapRef.current?.remove(); mapRef.current = null; };
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, []);
 
diff --git a/src/islands/maps/MapExplorer.tsx b/src/islands/maps/MapExplorer.tsx
index 0d90717..5aa8d14 100644
--- a/src/islands/maps/MapExplorer.tsx
+++ b/src/islands/maps/MapExplorer.tsx
@@ -21,6 +21,7 @@ export default function MapExplorer() {
   const measureMarkersRef = useRef<MlMarker[]>([]);
   const measureRef = useRef<LatLng[]>([]);
   const measuringRef = useRef(false);
+  const roRef = useRef<ResizeObserver | null>(null);
 
   const [style, setStyle] = useState<StyleChoice>('auto');
   const [pin, setPin] = useState<LatLng | null>(null);
@@ -86,9 +87,16 @@ export default function MapExplorer() {
       map.addControl(new ml.GeolocateControl({ positionOptions: { enableHighAccuracy: true }, trackUserLocation: false }), 'top-right');
       map.on('click', e => handleClick(e.lngLat.lat, e.lngLat.lng));
       map.on('style.load', () => { ensureMeasureLayer(); refreshMeasureLine(); });
+      map.on('load', () => map.resize());
+      // The container is mounted via a dynamically-imported island, so it can be
+      // laid out after the map is created — resize once it (or its size) settles,
+      // otherwise the map renders blank at 0×0.
+      const ro = new ResizeObserver(() => map.resize());
+      if (containerRef.current) ro.observe(containerRef.current);
+      roRef.current = ro;
       mapRef.current = map;
     })();
-    return () => { cancelled = true; mapRef.current?.remove(); mapRef.current = null; };
+    return () => { cancelled = true; roRef.current?.disconnect(); mapRef.current?.remove(); mapRef.current = null; };
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, []);
 
diff --git a/src/islands/maps/StaticMap.tsx b/src/islands/maps/StaticMap.tsx
index ea4bd2c..293dbc6 100644
--- a/src/islands/maps/StaticMap.tsx
+++ b/src/islands/maps/StaticMap.tsx
@@ -17,6 +17,7 @@ export default function StaticMap() {
   const mapRef = useRef<MlMap | null>(null);
   const mlRef = useRef<typeof import('maplibre-gl') | null>(null);
   const markerRef = useRef<MlMarker | null>(null);
+  const roRef = useRef<ResizeObserver | null>(null);
 
   const [style, setStyle] = useState<StyleChoice>('auto');
   const [pinCenter, setPinCenter] = useState(false);
@@ -40,9 +41,13 @@ export default function StaticMap() {
         preserveDrawingBuffer: true, // required to read the canvas for PNG export
       });
       map.addControl(new ml.NavigationControl(), 'top-right');
+      map.on('load', () => map.resize());
+      const ro = new ResizeObserver(() => map.resize());
+      if (containerRef.current) ro.observe(containerRef.current);
+      roRef.current = ro;
       mapRef.current = map;
     })();
-    return () => { cancelled = true; mapRef.current?.remove(); mapRef.current = null; };
+    return () => { cancelled = true; roRef.current?.disconnect(); mapRef.current?.remove(); mapRef.current = null; };
     // eslint-disable-next-line react-hooks/exhaustive-deps
   }, []);