Added itb_scroll

tools/itb/bin/itb_screenshot

@@ -13,9 +13,19 @@ class ScreenshotGenerator:
     def get_page_content(self) -> dict:
         script = """
         function processElement(element) {
-            if (!element.offsetParent && element !== document.body) return null;
-            
+            // Check if element is actually visible in viewport
             const rect = element.getBoundingClientRect();
+            if (!element.offsetParent && element !== document.body) return null;
+            if (rect.width === 0 || rect.height === 0) return null;
+            
+            // Check if element is within viewport bounds
+            const viewportWidth = window.innerWidth;
+            const viewportHeight = window.innerHeight;
+            if (rect.bottom < 0 || rect.top > viewportHeight || 
+                rect.right < 0 || rect.left > viewportWidth) {
+                return null;
+            }
+            
             const styles = window.getComputedStyle(element);
             
             const text = Array.from(element.childNodes)