fix(core): keep portal sheets' :root token defaults from overriding host tokens by JpMaxMan · Pull Request #1 · fntechgit/widgets

JpMaxMan · 2026-09-13T02:37:21Z

Problem

createWidgetShadow injects a manifest's portalSheets into document.head so markup a widget portals out of its shadow root (my-orders-tickets' datepicker) is styled.

my-orders-tickets-widget's CSS (from src/components/Filters/styles.module.scss) ships design-token defaults on :root:

:root {
  --color_primary: #000000;
  --color_primary_contrast: #ffffff;
  --color_secondary: #00a2ff;
  /* … */
}

Inside a shadow root :root never matches, so these are harmless in vendorSheets. In document.head they match the host's <html>. The portal sheet is appended after the host's own server-rendered token block, and the specificity is equal, so the widget's defaults win and repaint the whole site.

Seen in practice. In a host using the web-component build (Astro starter for the 2026 OCP Global Summit), /a/my-tickets rendered:

a black navbar instead of the show's color_primary #8DC63F
blue (#00a2ff) accents inside the widget instead of the brand colours

Any page that mounts my-tickets is affected.

Fix

Before injecting, injectPortalSheet rewrites :root selectors to :where(:root) (new exported helper demoteRootSelectors).

:where() has zero specificity, so any host :root { … } token declaration wins regardless of stylesheet order.
Hosts that declare no tokens still get the widget's defaults for portaled markup, so behaviour is unchanged there.
Only selector preludes are rewritten. A small scanner skips declaration values, strings, comments, url() and escapes (.\:root) at any nesting depth (added after CodeRabbit review).
vendorSheets (shadow-adopted) and fontFaces are untouched.

Tests

packages/widgets/src/core/__tests__/widget-shadow.test.ts:

Behavioural regression test: host tokens are declared, a portal sheet with :root defaults is mounted, and the computed --color_primary on <html> must still be the host's. Without the fix this fails with expected '#000000' to be '#8dc63f'.
Unit tests for demoteRootSelectors: selector lists, compounds, @media, CSS nesting and idempotence. Also checks that strings, comments, url(), escaped selectors and custom-property values are left alone.
Real sheet check (not committed): run against myTicketsSheets, every :root is wrapped and the text is otherwise byte-identical.

pnpm test passes: 95 vitest tests, the web-components tests and typecheck.

Follow-ups (not in this PR)

The token defaults arguably belong in the widget's own theme rather than on :root in my-orders-tickets-widget.
Hosts currently can't pass base styles into a widget's shadow root. In production these widgets render in the light DOM and inherit the site's Bootstrap 3 heading styles and the 10px root font size; in shadow DOM they lose them. A host-styles slot in the mount contract would let hosts restore that; the Astro starter works around it today by adding a stylesheet to widget shadow roots itself.

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https://claude.ai/code/session_01H91jC95F3EjBfzk5DVqRVb

Summary by CodeRabbit

Bug Fixes
- Host-defined design tokens now correctly override default widget tokens in portal sheets.
- Widget styles continue to provide defaults when no host token is declared.

…ost tokens Portal sheets are injected into document.head so portaled widget markup (e.g. my-orders-tickets' datepicker) is styled. my-orders-tickets-widget's CSS carries design-token defaults on :root (`--color_primary: #000000; --color_secondary: #00a2ff; ...`). Inside a shadow root :root never matches, but in document.head it matches the host's <html>, and because the sheet is appended after the host's own token block, equal specificity lets the widget repaint the whole site: black navbar, blue accents on every page that mounts my-tickets. Rewrite :root selectors in portal sheets to :where(:root) before injection. Zero specificity means any host :root declaration wins regardless of order, while the defaults still apply to portaled markup on hosts that declare none. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01H91jC95F3EjBfzk5DVqRVb

coderabbitai · 2026-09-13T02:37:35Z

📝 Walkthrough

Walkthrough

Portal stylesheet injection now converts standalone :root selectors to :where(:root). Tests cover selector conversion and confirm that host-declared tokens remain effective when portal defaults are injected.

Changes

Root selector demotion

Layer / File(s)	Summary
Portal CSS selector demotion `packages/widgets/src/core/widget-shadow.ts`	Adds `demoteRootSelectors` and applies it before portal CSS is injected into `document.head`.
Selector and token precedence validation `packages/widgets/src/core/__tests__/widget-shadow.test.ts`	Tests selector conversion, idempotency, unrelated text, and host token precedence.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Bug fix

Suggested reviewers: gcutrini

Merge Risk: 🔵 Low · up to ea75a

Custom portal styles containing literal or escaped :root text can be altered during injection, causing localized styling changes. Scope the rewrite to selectors before merging.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 2 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: preventing portal sheet :root token defaults from overriding host tokens.

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Inline comments:
In `@packages/widgets/src/core/widget-shadow.ts`:
- Line 85: Update demoteRootSelectors as used by createWidgetShadow so :root is
replaced only within CSS selector preludes, not declaration values, strings, or
escaped selectors. Keep this correction scoped to the portalSheets processing
path and preserve rewriting of ordinary :root selectors.

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ℹ️ Review info

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Configuration used: defaults

Review profile: CHILL

Plan: Advanced

Run ID: 6a183bdf-1c98-4f0e-8333-b5033393053a

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Reviewing files that changed from the base of the PR and between f4604db and ea75afd.

📒 Files selected for processing (2)

packages/widgets/src/core/__tests__/widget-shadow.test.ts
packages/widgets/src/core/widget-shadow.ts

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Review feedback (CodeRabbit): the regex rewrote any `:root` text, so a portal sheet with `content: ":root"` or an escaped `.\:root` selector would be altered. Replace it with a small scanner that rewrites only selector preludes (the text a `{` closes), skipping strings, comments, url() and escapes, at any nesting depth. Verified against the real my-tickets sheet: every :root is wrapped and the text is otherwise byte-identical. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_01H91jC95F3EjBfzk5DVqRVb

coderabbitai Bot reviewed Sep 13, 2026

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Comment thread packages/widgets/src/core/widget-shadow.ts Outdated

JpMaxMan requested a review from gcutrini September 13, 2026 02:44

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fix(core): keep portal sheets' :root token defaults from overriding host tokens - #1

fix(core): keep portal sheets' :root token defaults from overriding host tokens#1
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fix/portal-sheet-root-token-defaults

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JpMaxMan commented Sep 13, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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JpMaxMan commented Sep 13, 2026 •

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