fix scrolling to position.

frontend/src/app/stories/[id]/page.tsx

@@ -140,10 +140,14 @@ export default function StoryReadingPage() {
     // Calculate target scroll position
     const targetScroll = contentTop + (ratio * contentHeight) - (windowHeight * 0.3);
 
-    // Smooth scroll to position
+    // Use smooth scrolling only for shorter stories (< 15 000 words).
+    // For longer stories the saved position can be 50 000+ px from the top;
+    // browsers animate smooth-scroll at ~1 000–1 500 px/s, so the animation
+    // would take tens of seconds and often stalls or cancels before finishing.
+    const scrollBehavior = (story.wordCount ?? 0) < 15000 ? 'smooth' : 'instant';
     window.scrollTo({
       top: Math.max(0, targetScroll),
-      behavior: 'smooth'
+      behavior: scrollBehavior
     });
 
     setHasScrolledToPosition(true);

frontend/src/components/collections/CollectionReadingView.tsx

@@ -70,10 +70,14 @@ export default function CollectionReadingView({
     // Calculate target scroll position
     const targetScroll = contentTop + (ratio * contentHeight) - (windowHeight * 0.3);
 
-    // Smooth scroll to position
+    // Use smooth scrolling only for shorter stories (< 15 000 words).
+    // For longer stories the saved position can be 50 000+ px from the top;
+    // browsers animate smooth-scroll at ~1 000–1 500 px/s, so the animation
+    // would take tens of seconds and often stalls or cancels before finishing.
+    const scrollBehavior = (story.wordCount ?? 0) < 15000 ? 'smooth' : 'instant';
     window.scrollTo({
       top: Math.max(0, targetScroll),
-      behavior: 'smooth'
+      behavior: scrollBehavior
     });
 
     setHasScrolledToPosition(true);