Safari Technology Preview 242: What's New and Fixed?

Welcome to the release notes for Safari Technology Preview 242. This latest build is available for macOS Tahoe and macOS Sequoia, and it includes significant WebKit enhancements from revisions 310187 to 310599. Whether you're a web developer testing cutting-edge features or an early adopter seeking improved accessibility, this update has something for you. Below, we've answered the most common questions about installation, new capabilities, and resolved issues. Use the anchor links to jump to sections that interest you most: installation details, accessibility improvements, new CSS features, CSS bug fixes, form enhancements, HTML and dialog updates, and image fixes.

How do I install or update to Safari Technology Preview 242?

Safari Technology Preview 242 is now available for download on macOS Tahoe and macOS Sequoia. If you already have a previous version installed, you can update directly through System Settings. Navigate to General → Software Update, and the new release should appear as an available update. For a fresh installation, visit the official Safari Technology Preview download page and follow the instructions. This build encompasses WebKit changes ranging from revision 310187 to 310599, bringing a wealth of improvements and fixes.

What accessibility issues were resolved in this release?

Two key accessibility fixes are included. First, VoiceOver no longer reads text within images that have role="presentation"; this ensures that decorative images are properly ignored by screen readers. Second, macOS accessibility support has been enhanced for customizable <select> elements that use the appearance: base-select property. These changes improve the browsing experience for users relying on assistive technologies, making custom form controls more predictable and usable.

What new CSS features does Safari Technology Preview 242 add?

Two notable CSS additions are introduced. The first is support for the attr() function from CSS Values Level 5. This allows developers to retrieve attribute values directly from HTML elements and use them in style rules, offering more dynamic styling options. The second is the oblique-only value for the font-synthesis-style property, as defined in CSS Fonts Level 4. This value restricts font synthesis to only oblique (slanted) styles, giving finer control over how fonts are rendered when a specific style variant is missing.

What CSS rendering bugs were squashed?

This release addresses several CSS issues. Key fixes include: @media (prefers-color-scheme: dark) inside an iframe now matches when the iframe’s color-scheme is set to dark; position-try-order correctly interprets logical axis values using the containing block’s writing mode; and percent‑height replaced elements no longer compute stale preferred widths in shrink‑to‑fit containers. Additionally, the table cell nowrap minimum width calculation quirk is no longer applied outside quirks mode, checkbox outlines are correctly aligned, anchor‑positioned elements anchored to children of sticky‑positioned boxes stick properly, pseudo‑elements sort correctly by tree order, ligatures no longer cause non‑zero layout width for font-size: 0, the :in-range and :out-of-range pseudo‑classes update when the readonly attribute changes, and view-timeline-inset serialization now coalesces identical values correctly.

What changes were made to form elements?

A specific issue with <select multiple> has been resolved: the element now consistently fires the onchange event when the mouse button is released far outside the element. This ensures that multi‑select controls behave as expected even when users click away from the dropdown. The fix improves the reliability of form interactions, particularly in complex user interfaces.

What HTML improvements and dialog updates are included?

The HTML parser fast path received three bug fixes: it now correctly processes escaped attribute values longer than one character, properly detects nested <li> elements, and uses the adjusted current node for MathML and SVG integration point checks. Additionally, the <dialog> element now supports the closedby attribute. This attribute, when set, allows the dialog to close when the user clicks outside or presses the escape key, enhancing native modal behavior without JavaScript.

Were any image‑related issues fixed?

Yes, a problem with images using the srcset attribute has been corrected. Previously, inserting an image with srcset into certain contexts could cause rendering errors or unexpected behavior. This fix ensures that responsive images behave reliably, maintaining proper display across different viewports and device pixel ratios.