diff --git a/dist/index.html b/dist/index.html
index d03278a..1e38d81 100644
--- a/dist/index.html
+++ b/dist/index.html
@@ -5,7 +5,7 @@
     <link rel="icon" type="image/svg+xml" href="/favicon.svg" />
     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
     <title>furniture-app</title>
-    <script type="module" crossorigin src="/assets/index-z6fd8Sn7.js"></script>
+    <script type="module" crossorigin src="/assets/index-BIL7D6zM.js"></script>
     <link rel="stylesheet" crossorigin href="/assets/index-9k24Ci9h.css">
   </head>
   <body>
diff --git a/src/components/ControlPanel.tsx b/src/components/ControlPanel.tsx
index c031499..565131c 100644
--- a/src/components/ControlPanel.tsx
+++ b/src/components/ControlPanel.tsx
@@ -308,11 +308,23 @@ export function ControlPanel({
               <div className="grid-2">
                 <label className="field">
                   <span>Width</span>
-                  <NumberField value={state.room.width} min={100} width="100%" onChange={(v) => setRoom({ width: v })} />
+                  <NumberField
+                    value={state.room.width}
+                    min={100}
+                    max={5000}
+                    width="100%"
+                    onChange={(v) => setRoom({ width: v })}
+                  />
                 </label>
                 <label className="field">
                   <span>Height</span>
-                  <NumberField value={state.room.height} min={100} width="100%" onChange={(v) => setRoom({ height: v })} />
+                  <NumberField
+                    value={state.room.height}
+                    min={100}
+                    max={5000}
+                    width="100%"
+                    onChange={(v) => setRoom({ height: v })}
+                  />
                 </label>
               </div>
             </div>
diff --git a/src/components/RoomCanvas.tsx b/src/components/RoomCanvas.tsx
index 75986ad..f0eeb4a 100644
--- a/src/components/RoomCanvas.tsx
+++ b/src/components/RoomCanvas.tsx
@@ -33,6 +33,38 @@ export function RoomCanvas({ state, onStateChange, mode, selectedId, onSelect, s
     return () => clearInterval(t);
   }, [showPaths]);
 
+  const [viewport, setViewport] = useState({ width: 1200, height: 800 });
+  const containerRef = useRef<HTMLDivElement>(null);
+
+  useEffect(() => {
+    const resize = () => {
+      if (containerRef.current) {
+        setViewport({
+          width: Math.floor(containerRef.current.clientWidth),
+          height: Math.floor(containerRef.current.clientHeight),
+        });
+      }
+    };
+    resize();
+    window.addEventListener('resize', resize);
+    return () => window.removeEventListener('resize', resize);
+  }, []);
+
+  useEffect(() => {
+    const canvas = canvasRef.current;
+    if (!canvas) return;
+    const dpr = Math.max(1, window.devicePixelRatio || 1);
+    const baseW = Math.min(state.room.width, viewport.width || state.room.width);
+    const baseH = Math.min(state.room.height, viewport.height || state.room.height);
+    canvas.style.width = `${baseW}px`;
+    canvas.style.height = `${baseH}px`;
+    canvas.width = baseW * dpr;
+    canvas.height = baseH * dpr;
+    const ctx = canvas.getContext('2d');
+    if (ctx) ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
+    draw();
+  }, [state.room.width, state.room.height, zoom, viewport]);
+
   useEffect(() => {
     draw();
   }, [state, selectedId, mode, zoom, showPaths, phase]);
@@ -42,9 +74,14 @@ export function RoomCanvas({ state, onStateChange, mode, selectedId, onSelect, s
     if (!canvas) return;
     const ctx = canvas.getContext('2d');
     if (!ctx) return;
-    ctx.clearRect(0, 0, canvas.width, canvas.height);
+    const dpr = Math.max(1, window.devicePixelRatio || 1);
+    ctx.setTransform(dpr, 0, 0, dpr, 0, 0);
+    ctx.clearRect(0, 0, canvas.width / dpr, canvas.height / dpr);
     ctx.save();
-    ctx.scale(zoom, zoom);
+    const scaleX = (canvas.width / dpr) / state.room.width;
+    const scaleY = (canvas.height / dpr) / state.room.height;
+    const s = Math.min(scaleX, scaleY);
+    ctx.scale(s, s);
 
     ctx.fillStyle = '#12151b';
     ctx.fillRect(0, 0, state.room.width, state.room.height);
@@ -308,17 +345,19 @@ export function RoomCanvas({ state, onStateChange, mode, selectedId, onSelect, s
   };
 
   return (
-    <canvas
-      ref={canvasRef}
-      width={Math.max(state.room.width, 400)}
-      height={Math.max(state.room.height, 300)}
-      style={{ maxWidth: '100%', height: 'auto' }}
-      onMouseDown={handleMouseDown}
-      onMouseMove={handleMouseMove}
-      onMouseUp={handleMouseUp}
-      onDragOver={handleDragOver}
-      onDrop={handleDrop}
-    />
+    <div ref={containerRef} style={{ width: '100%', height: '100%' }}>
+      <canvas
+        ref={canvasRef}
+        width={Math.min(state.room.width, 2000)}
+        height={Math.min(state.room.height, 2000)}
+        style={{ maxWidth: '100%', maxHeight: '100%', width: '100%', height: '100%', objectFit: 'contain' }}
+        onMouseDown={handleMouseDown}
+        onMouseMove={handleMouseMove}
+        onMouseUp={handleMouseUp}
+        onDragOver={handleDragOver}
+        onDrop={handleDrop}
+      />
+    </div>
   );
 }