Update Frame resizing logic.

layouts/scripts/frame-index.js

@@ -8,7 +8,7 @@ function setupResizeListener() {
   const RESIZE_CODE = 'resize:';
 
   const resizeObserver = new ResizeObserver(entries => {
-    const height = document.body.offsetHeight;
+    const height = document.body.scrollHeight;
     window.parent.postMessage(RESIZE_CODE + JSON.stringify({height}), '*');
   })