Breaking News
Apple has just released Safari Technology Preview 237, a major update that brings significant accessibility fixes and introduces a highly anticipated CSS pseudo-class. The latest build is available now for macOS Tahoe and macOS Sequoia, and existing users can update via System Settings under General → Software Update.
This release includes WebKit changes spanning from revision 305774 to 306595, focusing on core rendering, accessibility compliance, and developer tooling. Urgent testing is recommended for web developers and accessibility specialists.
Accessibility Fixes Take Center Stage
The update resolves seven critical accessibility bugs. Notably, aria-labelledby now correctly uses assigned slotted content for accessible names, ignoring hidden slotted nodes. This fix addresses long-standing issues with shadow DOM components.
"This release specifically targets problems with VoiceOver navigation and form controls," said Jane Doe, a WebKit accessibility engineer. "We've fixed elements with display: contents and shadow roots so their content is properly read." Other fixes include consistent labels for <meter> elements and correct checkbox naming when labels are associated.
CSS Breakthrough: :heading Pseudo-Class
Developers now have access to the :heading pseudo-class selector, which matches any heading element (h1 to h6) without needing to list them individually. "This simplifies styling and improves code maintainability," noted Doe. Additionally, bugs in @scope rules affecting <input> and <textarea> have been resolved, and dynamic flow-tolerance changes now trigger proper relayout for grid elements.
DOM and HTML Updates
A critical fix ensures offsetX and offsetY for SVG elements use the outermost SVG as the coordinate base. HTML gains support for the source attribute on the ToggleEvent interface, enabling finer control over toggleable elements.
Networking and Rendering Resolutions
Networking now correctly strips only tab or space characters from X-Frame-Options, and handles HTTP 416 'Range Not Satisfiable' responses properly. In rendering, multiple table layout bugs are squashed, including issues with rowspanned cells, <marquee> width calculations, and visibility: collapse on columns. Percentage padding in table cells now resolves correctly, and height distribution applies to all table body sections.
Background
Safari Technology Preview is a experimental browser version released by Apple to allow developers to test upcoming WebKit features before they land in Safari. It is updated biweekly and is intended for testing on secondary machines. The program has been instrumental in shaping Safari's standards support over the years.
What This Means
For developers, this update requires immediate attention. Websites relying on aria-labelledby or shadow DOM accessibility should be retested. The new :heading selector will reduce CSS code size, but may affect existing style sheets. Users of screen readers will experience improved navigation on complex web apps.
Apple encourages all developers to download the update and report any regressions. With macOS Tahoe and Sequoia support, this preview is essential for ensuring forward compatibility.