Published pages/Preview ship a head reset (*{margin:0;padding:0}, img block,
a inherit, body line-height 1.6 / #1f2937 / 16px); the editor canvas had none,
so h1-h6/p margins, line-height and inherited size/colour differed.
- editor.css: one commented block scoping the reset to .canvas-device-frame,
every selector zero-specificity (:where) so inline styles / class rules win
exactly as when published; editor chrome untouched (snapshot identical).
- tokens.ts: canvas heading/link token rules made zero-specificity too.
- utils/css-reset.ts: single source for the reset declarations (html-export
imports it; test asserts byte-identity with the backend head and that the
editor.css block carries the same declarations).
- scripts/e2e-canvas-parity.mjs (npm run test:browser:canvas): real editor vs
published HTML in Firefox + Chromium, boxes within 1px + computed styles.
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
