v2.0.0-rc.7 — Theming Fixes, Simpler Tailwind Setup, and Clearer Customization Guidance

v2.0.0-rc.7 is a cleanup release aimed at styling correctness and clearer implementation guidance rather than new surface area. The main focus is fixing the theming regressions that showed up in rc.6, tightening the contract around how c15t styles interact with Tailwind, clarifying the customization ladder across the docs, and improving the manual review workflow for cross-environment CSS behavior before the final 2.0 release.

Highlights

• Fixed slot theming regressions in the React prebuilt UI
• Simplified the Tailwind setup contract to match the actual shipped @layer components behavior
• Clarified the recommended customization ladder across the AI agent docs plus the React and Next.js component guides
• Added a manual CSS matrix harness to compare Tailwind 3, Tailwind 4, and plain CSS side by side
• Strengthened regression coverage for slot styling, switch tokens, and packaging/tooling edge cases

Fixed Theming Regressions

The biggest user-facing fixes in rc.7 are around per-slot theming.

Slot noStyle no longer leaks to the DOM

Resolved slot metadata is now sanitized before it reaches rendered DOM elements, so internal flags such as noStyle are consumed by c15t instead of being forwarded as invalid HTML attributes.

Slot style now applies on the documented surfaces

Inline styles provided through slot objects now apply correctly on the rendered elements, including the consentWidgetAccordion path that was previously documented but not fully wired.

Switch track tokens now win correctly

switchTrack and switchTrackActive theme tokens now resolve from the rendered component subtree instead of losing to the shared module defaults. This makes provider-level and scoped theme overrides behave predictably without requiring !important.

Shared adapter guardrail in @c15t/ui

@c15t/ui now exports a small DOM prop sanitizing helper so future framework adapters can safely bind resolved slot styles without reintroducing these same issues.

Tailwind Setup Is Simpler

This RC also removes the stale idea that c15t needs its own dedicated Tailwind layer contract.

The shipped component CSS already lands in Tailwind's components layer, so the docs and templates now reflect that reality:

• Tailwind 4: import Tailwind normally, with no extra c15t layer declaration
• Tailwind 3: keep the wrapped @tailwind base pattern, but standardize on @layer base, components, utilities;

This cleanup affects the public setup guidance in the React and Next.js docs as well as the CLI Tailwind CSS template helper used during setup.

Clearer Customization Guidance

rc.7 also tightens the guidance around how teams should customize the shipped UI.

The docs, AI-agent guidance, and React compound-component examples now push the same escalation path:

• start with the stock component and provider options
• use theme tokens and slots for styling changes
• reach for compound components only when markup really needs to change
• use noStyle or headless mode only when the stock structure is no longer the right fit

This matters because the rc.6 theming regressions showed that users were hitting advanced escape hatches too early. rc.7 fixes the broken slot behavior and also makes the recommended path much harder to misread.

Better CSS Review Before Release

To make styling regressions easier to catch, the repo now includes a manual CSS matrix harness under benchmarks/.

It renders the same consent scenarios across:

• Tailwind 3
• Tailwind 4
• plain CSS

The preview shell shows those environments side by side so complex styling cases can be checked visually before release work lands. This is intentionally a manual review tool for now, not a CI gate.

Improvements

• The demo theme showcase now includes regression-focused previews for the fixed theming contract
• Added browser/render-path regression tests for slot props and switch token styling
• Added CLI coverage for the new Tailwind CSS template contract
• Refreshed the bundled guidance for agents and the React/Next.js docs so customization advice matches the shipped component model
• Fixed CI issues around preview workflow outputs, benchmark config typing, and CSS test path resolution

Learn more

• #697 — fix RC theming regressions, clean up Tailwind setup guidance, and add the CSS matrix harness
• #699 — clarify the customization ladder across AI agent docs, React/Next.js guides, and component examples

Notes

• There are no planned breaking changes in v2.0.0-rc.7
• This release is scheduled for April 8, 2026