2025.3 Release
This release includes support for declarative shadow roots, improved CSS support, plus the latest changes to the W3 HTML and CSS validators.
New Features
- Cascade support for nested CSS rules
- Support for declarative shadow roots (shadowrootmode)
- Validation of CSS in HTML style attributes
Rule Changes
- Updated browser compatibility checks to Chrome/Edge 142, FF 144, Opera 122, Safari 26
- Updated to October 2025 HTML 5 Validator
- Updated to October 2025 CSS Validator
- Updated to August 2025 URL Standard
- See full list of changed rules in engine 6.58
Fixes
- Various stability fixes and performance improvements