The app sets canvas.height = Math.ceil(viewport.height) per page and stacks pages by those
heights; the backend page_top used the raw float, so it fell ~1px/page short, compounding to a
visible upward shape shift on later pages (~36px over 40 pages). Ceil rendered_h to match exactly.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
6c73174829