diff --git a/frontend/src/components/Runtime/RuntimeControls.tsx b/frontend/src/components/Runtime/RuntimeControls.tsx
index 82f9736..5bba22c 100644
--- a/frontend/src/components/Runtime/RuntimeControls.tsx
+++ b/frontend/src/components/Runtime/RuntimeControls.tsx
@@ -34,6 +34,10 @@ interface RuntimeControlsProps {
   pages?: PreloadPage[];
   isFullscreen: boolean;
   toggleFullscreen: () => void;
+  /** Canvas width in pixels (for positioning relative to canvas) */
+  canvasWidth?: number;
+  /** Canvas height in pixels (for positioning relative to canvas) */
+  canvasHeight?: number;
 }
 
 /**
@@ -381,12 +385,31 @@ function useCounterZoom() {
   return scale;
 }
 
+/**
+ * Hook to get viewport dimensions
+ */
+function useViewportSize() {
+  const [size, setSize] = useState({ width: 0, height: 0 });
+
+  useEffect(() => {
+    const update = () => {
+      setSize({ width: window.innerWidth, height: window.innerHeight });
+    };
+    update();
+    window.addEventListener('resize', update);
+    return () => window.removeEventListener('resize', update);
+  }, []);
+
+  return size;
+}
+
 /**
  * RuntimeControls - Main component for presentation controls
  *
  * Renders offline toggle and fullscreen button using fixed pixel values
  * to maintain usable size regardless of canvas scaling.
  * Uses visualViewport API to counter pinch-zoom scaling on mobile.
+ * Positions controls relative to the canvas area (not viewport edges).
  */
 export default function RuntimeControls({
   projectId,
@@ -395,14 +418,28 @@ export default function RuntimeControls({
   pages,
   isFullscreen,
   toggleFullscreen,
+  canvasWidth = 0,
+  canvasHeight = 0,
 }: RuntimeControlsProps) {
   // Counter-scale to resist pinch-zoom
   const counterScale = useCounterZoom();
+  const viewport = useViewportSize();
+
+  // Calculate position relative to centered canvas
+  // Canvas is centered with: left: 50%, top: 50%, transform: translate(-50%, -50%)
+  // So we offset from viewport edge by (viewport - canvas) / 2 + padding
+  const padding = 16;
+  const rightOffset = canvasWidth > 0 && viewport.width > 0
+    ? (viewport.width - canvasWidth) / 2 + padding
+    : padding;
+  const topOffset = canvasHeight > 0 && viewport.height > 0
+    ? (viewport.height - canvasHeight) / 2 + padding
+    : padding;
 
   const containerStyle: CSSProperties = {
     position: 'fixed',
-    top: 16,
-    right: 16,
+    top: topOffset,
+    right: rightOffset,
     display: 'flex',
     alignItems: 'center',
     gap: 8,
diff --git a/frontend/src/components/RuntimePresentation.tsx b/frontend/src/components/RuntimePresentation.tsx
index f2b2ba1..14d4d48 100644
--- a/frontend/src/components/RuntimePresentation.tsx
+++ b/frontend/src/components/RuntimePresentation.tsx
@@ -92,7 +92,7 @@ export default function RuntimePresentation({
 
   // Canvas scale for responsive UI elements and letterbox mode
   // Uses page's design dimensions (saved at constructor save time) for presentation isolation
-  const { cssVars, letterboxStyles, isPortrait, showRotatePrompt } =
+  const { cssVars, letterboxStyles, isPortrait, showRotatePrompt, canvasWidth, canvasHeight } =
     useCanvasScale({
       designWidth: currentPage?.design_width ?? undefined,
       designHeight: currentPage?.design_height ?? undefined,
@@ -774,6 +774,8 @@ export default function RuntimePresentation({
           pages={pages}
           isFullscreen={isFullscreen}
           toggleFullscreen={toggleFullscreen}
+          canvasWidth={canvasWidth}
+          canvasHeight={canvasHeight}
         />
 
         {/* Toast notifications for offline download status */}