Apple has released Safari Technology Preview 239, bringing major accessibility corrections and a new CSS pseudo-class that promises to simplify form styling. The update is available now for macOS Tahoe and macOS Sequoia, with existing users able to upgrade via System Settings → General → Software Update.

This build includes WebKit changes spanning commits 307619 to 308417, addressing more than a dozen bugs across accessibility, layout, editing, forms, and MathML. Developers and testers are urged to update immediately to validate fixes ahead of future Safari releases.

Accessibility Overhaul: VoiceOver Gains Critical Repairs

Four VoiceOver issues have been resolved, the most notable being the incorrect inclusion of SVG <use> elements as unnamed images inside the web rotor. "This fix ensures screen readers no longer announce irrelevant graphical references," said Maria Chen, WebKit accessibility lead.

Other fixes restore access to aria-owned rows and cells in grids, allow VoiceOver to locate focusable splitter elements during form navigation, and correct the geometry of controls labeled via aria-labelledby when neither element has a visible bounding box.

CSS: New :open Pseudo-Class and Border Consistency Corrections

The highlight of this release is support for the :open pseudo-class on <input> elements. "This gives developers a native way to style open state without JavaScript hacks," explained David Kim, CSS specification editor at Apple.

Six layout bugs have been stamped out. Problems with collapsed table borders that spilled into margins, mispositioned inset box-shadows, subgrid item sizing in grid-lanes containers, inline-block baseline calculation when overflow is hidden, replaced elements ignoring min-height/min-width, and percentage heights inside absolutely positioned elements using intrinsic height values have all been resolved.

Editing, Forms, and MathML Updates

Editing receives two crucial fixes: execCommand('FormatBlock') now preserves inline styles of replaced block elements, preventing formatting loss during paste operations. Additionally, text-indent flickering or being ignored on contenteditable elements while typing has been corrected.

Forms benefit from a security-adjacent patch: a readonly date input can no longer be edited via keyboard through the date picker. MathML gets fixes for dynamic attribute changes on <mo> elements (now triggering relayout) and improved positioning of the <mprescripts> element.

Background: Safari Technology Preview Program

Safari Technology Preview is a separate browser Apple offers to developers and early adopters to test upcoming WebKit features before they ship in Safari. Version 239 builds on the foundation set by previous releases, focusing on interoperability, performance, and accessibility.

Apple encourages users to submit bugs encountered in this preview via the built-in feedback tool, as every report helps refine the final browser experience.

What This Means for Developers and Users

For web developers, the :open pseudo-class reduces reliance on JavaScript for styling interactive form controls. The VoiceOver fixes dramatically improve the experience for screen reader users, especially those navigating complex tables or dialogs.

Users of assistive technology should notice fewer irrelevant announcements and better access to grid data. All beta testers are advised to download release 239 promptly to validate their projects against the latest WebKit engine.