Exploring Safari Technology Preview 242: New Features and Fixes

Welcome to the latest developer preview from Apple! Safari Technology Preview 242 is now available for download on macOS Tahoe and macOS Sequoia. If you already have it installed, you can quickly update via System Settings > General > Software Update. This release bundles WebKit changes from revision 310187 to 310599, bringing a mix of new capabilities and important bug fixes. Below, we dive into the key updates across Accessibility, CSS, Forms & HTML, and Images.

What improvements does Safari Technology Preview 242 bring for accessibility?

This release tackles two specific accessibility issues. First, VoiceOver no longer reads text inside images that carry a role="presentation" attribute. This ensures that purely decorative images do not distract screen reader users, keeping the browsing experience clean and focused. Second, macOS accessibility support has been improved for customizable <select> elements that use the appearance: base-select CSS property. Developers can now create custom-styled dropdowns that remain fully accessible via VoiceOver and other assistive technologies. These fixes reflect WebKit’s ongoing commitment to making web content usable for everyone.

What new CSS features are included in this release?

Two notable CSS additions debut in Safari Technology Preview 242. First is support for the attr() function as defined in CSS Values Level 5. This function allows you to retrieve the value of an HTML attribute directly from within CSS—for example, using attr(data-tooltip) to generate a tooltip’s content. It opens up new possibilities for dynamic styling without JavaScript. Second, the oblique-only value for font-synthesis-style is now supported per CSS Fonts Level 4. This gives authors finer control over font style synthesis, ensuring that only oblique (slanted) styles are synthesized when a true italic is unavailable. These features expand the expressive power of CSS while maintaining backward compatibility.

What key CSS bugs were resolved in this update?

Several longstanding CSS issues have been fixed. One important fix concerns @media (prefers-color-scheme: dark) inside iframes — previously, the media query did not match when the iframe’s own color-scheme was set to dark. Now it correctly inherits the preferred color scheme. Another fix addresses position-try-order, which now interprets logical axis values using the containing block’s writing mode rather than the element’s own mode. Additionally, percent-height replaced elements no longer compute stale preferred widths in shrink-to-fit containers. Other corrections include: checkbox outlines appearing misaligned, anchor-positioned elements not sticking correctly when anchored to children of sticky boxes, and pseudo-elements sorted incorrectly when ordering anchor elements by tree order. Ligatures no longer cause non-zero layout width with font-size: 0, and the :in-range / :out-of-range pseudo-classes now update properly when the readonly attribute changes. Finally, serialization of view-timeline-inset now coalesces identical values correctly.

What changes were made to Forms and HTML?

In the Forms area, a fix ensures that <select multiple> elements fire the onchange event reliably when the mouse button is released far outside the element. This improves interaction for multi-select lists. On the HTML side, a new feature adds support for the closedby attribute on <dialog> elements, giving developers more control over how users dismiss modals. Several parser fixes also land: the fast path now correctly processes escaped attribute values longer than one character, accurately detects nested <li> elements, and uses the adjusted current node for MathML and SVG integration point checks. These under-the-hood improvements enhance performance and standards compliance.

What image‑related issue was resolved in Safari Technology Preview 242?

The release fixes a problem where inserting an image with a srcset attribute into certain contexts could cause unexpected behavior. While the original release notes did not detail the exact scenario, this correction ensures that responsive images using srcset are handled correctly during dynamic insertion. Developers relying on art‑directed or resolution‑switching images should see more predictable results. This fix, combined with the broader set of improvements, makes Safari Technology Preview 242 a solid update for web developers testing emerging standards.