Heads up that this feature has been scoped down due to feedback from working groups around <style type="module>. As of the original announcement, it included both <style type="module> and <template shadowrootadoptedstylesheets>, and it now only includes <template shadowrootadoptedstylesheets>. As such, the feature has been renamed (from "Declarative CSS module scripts" to "Declarative Shadow DOM shadowrootadoptedstylesheets") in Chromestatus and all relevant sections have been updated for accuracy.
These changes will impact the running OT. The explainer has been updated with this information as well as a workaround while I redesign <style type=module>, accounting for input from the working groups. ________________________________ From: Rick Byers <[email protected]> Sent: Wednesday, April 1, 2026 8:11 AM To: Chromestatus <[email protected]> Cc: [email protected] <[email protected]>; Kurt Catti-Schmidt (SCHMIDT) <[email protected]> Subject: [EXTERNAL] Re: [blink-dev] Intent to Experiment: Declarative CSS module scripts LGTM to experiment On Mon, Mar 30, 2026 at 4:33 PM Chromestatus <[email protected]<mailto:[email protected]>> wrote: Contact emails [email protected]<mailto:[email protected]> Explainer https://github.com/MicrosoftEdge/MSEdgeExplainers/blob/main/ShadowDOM/explainer.md Specification https://github.com/whatwg/html/pull/11687 Design docs https://github.com/MicrosoftEdge/MSEdgeExplainers/blob/main/ShadowDOM/explainer.md Summary Declarative CSS Modules Scripts are an extension of the existing script-based CSS Module Scripts. They allow for developers to share declarative stylesheets with shadow roots, including declarative shadow roots. Developers can define inline style modules with <style type="module" specifier="foo"> and apply a declarative module to a declarative shadow DOM by referencing specifier or a URL, such as <template shadowrootmode="open" shadowrootadoptedstylesheets="foo">. Blink component Blink>HTML<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EHTML%22> Web Feature ID Missing feature TAG review https://github.com/w3ctag/design-reviews/issues/1000. A second issue was brought up to the TAG and has been addressed by the current design: https://github.com/w3ctag/design-reviews/issues/1195 TAG review status Issues addressed Goals for experimentation We would like feedback on the API shape from developers, as well as real-life performance benefits from using this API. Risks Interoperability and Compatibility No information provided Gecko: No signal (https://github.com/mozilla/standards-positions/issues/1081) WebKit: No signal (https://github.com/WebKit/standards-positions/issues/407) Web developers: Positive (https://github.com/WICG/webcomponents/issues/939) "Styling and Customization" is listed as the #1 pain point for Web Components in https://2023.stateofhtml.com/en-US/features/web_components/#using_web_components_pain_points, which this proposal addresses. Other signals: WebView application risks Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications? No information provided Ongoing technical constraints None Debuggability Applied styles are reflected in developer tools. Adopted stylesheets are reflected in the DOM. Error conditions are logged to the console. Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)? Yes Is this feature fully tested by web-platform-tests<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>? Yes https://wpt.fyi/results/shadow-dom/declarative/tentative/shadowrootadoptedstylesheets https://wpt.fyi/results/html/semantics/document-metadata/the-style-element/tentative Flag name on about://flags None yet Finch feature name DeclarativeCSSModules Requires code in //chrome? False Tracking bug https://issues.chromium.org/issues/448174611 Estimated milestones Origin trial desktop first 148 Origin trial desktop last 153 Origin trial Android first 148 Origin trial Android last 153 Origin trial WebView first 148 Origin trial WebView last 153 Link to entry on the Chrome Platform Status https://chromestatus.com/feature/4790543041298432?gate=5195795808780288 Links to previous Intent discussions Intent to Prototype: https://groups.google.com/a/chromium.org/d/msgid/blink-dev/68dab832.050a0220.1ba43a.01ee.GAE%40google.com This intent message was generated by Chrome Platform Status<https://chromestatus.com/>. -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]<mailto:[email protected]>. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/69caddf0.050a0220.219f27.0666.GAE%40google.com<https://groups.google.com/a/chromium.org/d/msgid/blink-dev/69caddf0.050a0220.219f27.0666.GAE%40google.com?utm_medium=email&utm_source=footer>. -- You received this message because you are subscribed to the Google Groups "blink-dev" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/DM4PR00MB255569886416B7DB1635CE4ED61A2%40DM4PR00MB2555.namprd00.prod.outlook.com.
