<style> was previously in FORBID_TAGS and stripped entirely. It's now
allowed, but its CSS is rewritten by a new hand-rolled scoper
(src/utils/scope-css.ts) so a customer's rules only match inside their own
block's wrapper -- never leak out and restyle the rest of the page. The
wrapper div (class="whp-html-<hash>") is only emitted when a block actually
has surviving <style> content, so blocks that don't use it stay
byte-identical to before this change.
Key findings, both covered by tests:
- DOMPurify's body-only serialization silently drops a <style> tag that
appears before any other content in a block (the HTML5 parser implicitly
places it in <head>, which DOMPurify never looks at). Fixed with
FORCE_BODY: true.
- DOMPurify does not sanitize CSS declaration values at all (expression(),
behavior:, url() to any host all pass through verbatim) -- @import is
stripped explicitly by scopeCss() since it's the one CSS-level
exfiltration/fetch vector in scope here.
Scope identifier reuses the existing djb2 stableHash() from utils/escape.ts
(already used for this exact class of problem) over the block's own `code`
string -- deterministic, no node id, no Math.random/Date.now.
1141/1141 tests passing (was 1077), tsc clean.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
shadowdaoandClaude Opus 5
32f4092156