diff --git a/fog.js b/fog.js
index d8728ea..9b17a96 100644
--- a/fog.js
+++ b/fog.js
@@ -19,13 +19,26 @@
     // ===============================
     const canvas = document.createElement("canvas");
     const ctx = canvas.getContext("2d");
+
     canvas.style.position = "absolute";
-    canvas.style.top = 0;
-    canvas.style.left = 0;
+    canvas.style.top = "0";
+    canvas.style.left = "0";
     canvas.style.pointerEvents = "none";
 
     const revealedPoints = [];
 
+    // -------------------------------
+    // Utility
+    // -------------------------------
+    function metersToPixels(m, lat) {
+      return (
+        m / 40075017 *
+        256 *
+        Math.pow(2, map.getZoom()) /
+        Math.cos(lat * Math.PI / 180)
+      );
+    }
+
     function resizeCanvas() {
       const size = map.getSize();
       canvas.width = size.x;
@@ -33,47 +46,55 @@
       redrawFog();
     }
 
+    // -------------------------------
+    // Fog redraw (最重要)
+    // -------------------------------
     function redrawFog() {
-      ctx.clearRect(0, 0, canvas.width, canvas.height);
+      if (!canvas.width || !canvas.height) return;
 
-      // 霧
+      // ★ 毎回状態を完全リセット（超重要）
+      ctx.setTransform(1, 0, 0, 1, 0, 0);
+      ctx.globalCompositeOperation = "source-over";
+      ctx.shadowBlur = 0;
+
+      // 霧を描画
+      ctx.clearRect(0, 0, canvas.width, canvas.height);
       ctx.fillStyle = "rgba(0,0,0,0.85)";
       ctx.fillRect(0, 0, canvas.width, canvas.height);
 
+      // 穴あけ
+      ctx.save();
       ctx.globalCompositeOperation = "destination-out";
       ctx.shadowColor = "rgba(0,0,0,1)";
       ctx.shadowBlur = 20;
 
-      revealedPoints.forEach(latlng => {
+      for (const latlng of revealedPoints) {
         const p = map.latLngToContainerPoint(latlng);
         const r = metersToPixels(REVEAL_RADIUS, latlng.lat);
 
         ctx.beginPath();
         ctx.arc(p.x, p.y, r, 0, Math.PI * 2);
         ctx.fill();
-      });
+      }
 
-      ctx.globalCompositeOperation = "source-over";
+      ctx.restore();
     }
 
-    function metersToPixels(m, lat) {
-      return m / 40075017 * 256 * Math.pow(2, map.getZoom()) / Math.cos(lat * Math.PI / 180);
-    }
-
-    // ===============================
+    // -------------------------------
     // Map Init
-    // ===============================
+    // -------------------------------
     function initMap() {
       map = L.map("locationmap").setView(START_POS, 16);
 
-      L.tileLayer("https://{s}.tile.osm.org/{z}/{x}/{y}.png", {
+      L.tileLayer("https://{s}.tile.openstreetmap.org/{z}/{x}/{y}.png", {
         attribution: '© OpenStreetMap contributors'
       }).addTo(map);
 
       map.getPanes().overlayPane.appendChild(canvas);
 
       resizeCanvas();
-      map.on("resize move zoom", redrawFog);
+      map.on("resize", resizeCanvas);
+      map.on("move zoom", redrawFog);
 
       playerMarker = L.marker(map.getCenter()).addTo(map);
       playerMarker.bindPopup("STARTで探索開始").openPopup();
@@ -81,9 +102,9 @@
       map.on("click", e => updateLocation(e.latlng));
     }
 
-    // ===============================
+    // -------------------------------
     // Game Logic
-    // ===============================
+    // -------------------------------
     function reveal(latlng) {
       revealedPoints.push(latlng);
       redrawFog();
@@ -97,10 +118,9 @@
     }
 
     function onSuccess(pos) {
-      updateLocation(L.latLng(
-        pos.coords.latitude,
-        pos.coords.longitude
-      ));
+      updateLocation(
+        L.latLng(pos.coords.latitude, pos.coords.longitude)
+      );
     }
 
     function startWatch() {
@@ -120,6 +140,9 @@
       titleEl.textContent = "STOP";
     }
 
+    // -------------------------------
+    // Events
+    // -------------------------------
     startBtn.addEventListener("click", startWatch);
     stopBtn.addEventListener("click", stopWatch);