Safari Technology Preview 243: Key Changes and Fixes Explained
Welcome to our detailed Q&A on Safari Technology Preview Release 243, now available for download on macOS Tahoe and macOS Sequoia. If you already have the preview installed, you can update it via System Settings under General > Software Update. This release incorporates WebKit changes from revision 310600 to 312007, bringing a host of improvements across accessibility, animations, and CSS. Below, we answer the most pressing questions about what’s new and what’s been fixed.
How can I download or update to Safari Technology Preview 243?
You can download Safari Technology Preview 243 directly from Apple’s developer website for macOS Tahoe and macOS Sequoia. If you already have a previous version installed, updating is straightforward: open System Settings, navigate to General, then Software Update, and follow the prompts. This release includes all WebKit changes from revision 310600 to 312007, so it’s packed with the latest enhancements and fixes. Make sure your system meets the requirements for either macOS version to ensure a smooth installation and update process.
What accessibility issues have been fixed in this release?
Several important accessibility bugs have been resolved. First, the contextmenu event now fires correctly for elements inside iframes when triggered by keyboard or assistive technology actions like VoiceOver’s VO+Shift+M. VoiceOver users can also activate color picker inputs with the press action, which was previously broken. Additionally, the invalidation of aria-hidden="true" when focus lands inside the hidden subtree has been fixed, ensuring assistive tools accurately respect hidden elements. Finally, VoiceOver support for base <select> elements has been improved: the popover now closes upon selection, and accessibility path positioning works correctly even when CSS transforms are present. These changes make Safari Technology Preview more inclusive and easier to use for everyone.
What animation glitches were resolved?
Two key animation issues were fixed. First, !important declarations now correctly override CSS animation values when CSS transitions are also running on the same property. Previously, the !important rule could be ignored in such mixed scenarios. Second, identity matrix decomposition no longer generates invalid quaternions, which was causing incorrect transform animations. This fix ensures that transform-based animations behave as intended, particularly when dealing with complex 3D transformations. These improvements enhance the reliability of CSS animations and transitions in your web projects.
What new CSS features were added?
Two notable CSS features made their debut. First, support for contain: style now applies to CSS quote counters, as specified in CSS Containment Level 2. This allows developers to limit the scope of style containment more effectively, improving performance and predictability. Second, the insert keyword for the text-autospace property has been added. This keyword enables automatic insertion of spacing between certain character combinations, enhancing typography control. Both features expand the power of CSS in Safari Technology Preview, giving web developers more tools for precise styling.
What are the most important CSS layout fixes?
Several layout bugs have been squashed. Flex layout now uses the used flex-basis instead of the specified value for definiteness evaluation, leading to more accurate sizing. Element positioning is correct 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 fit-content now gets the correct height. Percentage size resolution in flex items under quirks mode has been fixed. clip-path: inset() border-radius values render correctly at different sizes. -webkit-box flexbox emulation sizes children correctly inside <fieldset>. Performance improved on pages using :where and :is selectors. Elements with display: table and borders now lay out properly. Finally, elements with border, position: absolute, and aspect-ratio: 1 render as squares again. These fixes make CSS more reliable for complex layouts.
What does this release mean for developers?
For developers, Safari Technology Preview 243 represents a significant step forward in stability and feature support. The accessibility fixes ensure that web content is more usable with assistive technologies, while the animation and CSS improvements reduce cross-browser inconsistencies. The addition of contain: style for quotes and the text-autospace property gives developers finer control over styling. Performance enhancements with :where and :is selectors also benefit large stylesheets. Overall, this release encourages testing your web applications with the latest WebKit changes to catch any regressions early.