The window follows OneNote's layout in light and dark themes that track
the system appearance: title bar with the app icon and notebook name, two
compact toolbar rows after the Home ribbon, section tabs that lean at 45°
and rise when opened, a section-coloured frame shading down the window,
and page tabs whose open tab joins the page. Sections keep their stored
hue at per-theme saturation and lightness; --ui-font sets the interface
typeface without bundling one.

In the dark theme the paper darkens and automatic text turns light,
resolved at paint time. The 71 background pictures of OneNote 2010's page
templates are recognised by hash and painted from authored SVG
recreations in light and dark, rasterized off the frame thread at the
current zoom.

Large pages stay within a 165 Hz frame: painting skips paragraphs and
highlights outside the view, accessibility updates only what changed and
moves the page by one transform on scroll, keystrokes validate and lay
out only what they touch, scrolling no longer saves, and hover no longer
animates boxes that don't show it.

draw gains filled, stroked and blurred SVG paths, gradients and tinted
icons, and draw::edit holds the text editing the page and ui share; the
renderer sits behind draw's default render feature.

Assisted-by: claude-opus-5.5
Assisted-by: claude-opus-5