Mailbox display and Settings → Appearance get an interface-size picker,
stored per device in localStorage and applied as CSS zoom on <html>.
Viewport-height layouts divide by --ui-zoom, and code that turns mouse
coordinates or bounding rects into CSS lengths (resizers, compose dock,
emoji picker, editor popups and image handles, swipe-to-delete) divides
by the zoom factor.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>