Safari Technology Preview 243: Key Questions and Answers

What are the major accessibility fixes in this release?

Safari Technology Preview 243 resolves several critical accessibility issues. The contextmenu event now correctly fires for elements inside iframes when triggered by keyboard or assistive technology (e.g., VoiceOver’s VO+Shift+M). Color picker inputs can be activated using VoiceOver’s press action, improving form usability. The invalidation of aria-hidden="true" when focus lands inside the hidden subtree has been fixed, ensuring proper accessibility tree updates. Additionally, VoiceOver support for base <select> elements is enhanced: the popover now closes upon selection, and accessibility path positioning is corrected when CSS transforms are applied.

How does this update fix animation problems?

Two animation-related issues are addressed. First, !important declarations now correctly override CSS animation values when CSS transitions are also running on the same property, ensuring expected styling behavior. Second, identity matrix decomposition previously generated invalid quaternions, leading to incorrect transform animations. This bug is fixed, so developers can rely on accurate and smooth transform animations.

What new CSS features are introduced?

This release adds support for two CSS capabilities. Containment Level 2 is extended: the contain: style now applies to CSS quote counters, giving developers more precise control over rendering isolation. Additionally, the insert keyword for the text-autospace property is supported, allowing finer-grained control over automatic spacing around inserted content in text layouts.

What important CSS layout and rendering bug fixes are included?

Numerous CSS issues have been resolved. Flex layout now uses the used flex-basis instead of the specified value for definiteness evaluation, improving dynamic sizing accuracy. Element positioning is corrected when the containing block is an anonymous block. Box-shadow now works on display: table-row elements. Text-indent with calc() containing percentages correctly treats percentage components as zero for intrinsic size contributions. Out-of-flow content with height: fit-content now calculates the correct height. Percentage size resolution in flex items under quirks mode is fixed. Clip-path with inset() and border-radius values renders correctly at various sizes. Additionally, -webkit-box flexbox emulation properly sizes children inside <fieldset> elements.

How does this release improve performance?

Performance is enhanced for pages using :where and :is selectors. These pseudo-classes are now optimized, reducing style recalculation overhead. This is especially beneficial for large stylesheets or complex selectors, resulting in smoother scrolling and faster page rendering.

What other CSS rendering issues were addressed?

Several minor but impactful bugs were fixed. Elements with display: table no longer have incorrect layout when borders are present. Elements with border, position: absolute, and aspect-ratio: 1 now render as squares correctly. These fixes ensure more predictable and consistent visual output across different CSS properties.