10 Essential Updates in Safari Technology Preview 241 You Should Know

Apple continues to refine the web browsing experience with the latest Safari Technology Preview release. Build 241 is now available for macOS Tahoe and Sequoia (download or update via System Settings > General > Software Update). This version packs a host of WebKit improvements—from accessibility fixes to CSS enhancements—that make your browsing smoother, more compliant, and more powerful. Here are ten key changes you need to know about.

1. Smoother Speech and Better MathML Accessibility

Accessibility gets a solid boost in this release. A previously nagging issue with speechSynthesis.cancel() has been resolved: it no longer removes utterances queued by subsequent speechSynthesis.speak() calls, ensuring voice output works as intended. MathML also receives attention—bounding boxes for table rows and cells are now computed accurately, improving screen reader navigation for mathematical content. Additionally, comboboxes now correctly forward focus to their aria-activedescendant, allowing assistive technologies to interact with list items. And the aria-owns attribute is finally respected when computing accessible names from element content, eliminating another barrier for users relying on accessibility tools.

2. Animation Fill-Mode Fix for Viewport Resizing

Web animations using animation-fill-mode can behave unexpectedly when the viewport is resized, especially when using viewport-based units like vw or vh. This release fixes that inconsistency, ensuring that the fill mode correctly applies its styling after a resize. Developers working on responsive designs with CSS animations will find this a welcome change—no more jarring jumps or incorrect final states when users switch between devices or rotate their screens.

3. New Box Sizing Options and Stable Scroll Anchoring

Two notable CSS additions arrive. First, the stretch keyword is now supported in box sizing properties (box-sizing: stretch), giving developers finer control over how elements fill their containers. Second, CSS scroll anchoring gains stable support—this feature prevents abrupt page jumps when content above the viewport loads (e.g., images or ads), keeping the user’s scroll position steady. Both additions align Safari more closely with modern web standards.

4. Line Separator Rendering and Outline-Offset Fix

Two rendering issues have been corrected. The U+2028 LINE SEPARATOR character now renders as a forced line break per the CSS specification, which matters for pre-formatted text and certain international content. Additionally, the outline-offset property was incorrectly inflated when outline: auto was used on macOS; this has been fixed, ensuring outlines appear exactly where intended—no more mysterious extra spacing around focused elements.

5. Font-Family Serialization and Unicode-Range Optimization

Two font-related fixes improve both accuracy and performance. When serializing the font-family property, quotes around family names that match CSS-wide keywords (like initial) or generic families (like serif) are now preserved, preventing font fallback errors. Also, WebKit no longer downloads a font if no characters in the document fall within its unicode-range, saving bandwidth and speeding up page loads for sites that define multiple custom fonts.

6. Flex Items and Percentage-Height Images

A tricky layout bug has been squashed: when a flex item contained an image with a percentage height, the item did not shrink correctly around the image, often causing overflow or misalignment. This release fixes that behavior, so flex items now respect the intrinsic size constraints of their percentage-height children. Layouts using flexbox with responsive images will render as expected, without unexpected gaps or clipping.

7. View Transition Color Accuracy and Contain Performance

Two improvements target rendering and performance. View Transition snapshots were previously stored in sRGB even when the source content used a wider color space, leading to washed-out colors. This has been corrected, preserving the original color gamut. On the performance front, using contain: layout on an element could cause significantly slower forced layouts when all its siblings also created their own formatting context. The fix dramatically reduces layout cost, making complex UI containers more efficient.

8. Underline Splitting, Ruby Text, and Color-Scheme Repaint

Three subtle fixes polish the browsing experience. Underlines are no longer split when a ruby base is expanded due to long ruby text, ensuring consistent styling in East Asian typography. Changing the color-scheme CSS property now correctly repaints the background of composited iframes—previously, dark mode toggles could leave iframes stuck in the wrong background color. Additionally, color: initial now resolves to the correct color in dark appearance mode, fixing a contrast issue.

9. Popover Nested Children and Anchor-Scope Fix

Two issues related to positioning and anchoring have been resolved. Nested children of a popover element using position: absolute failed to render—they would simply disappear outside the popover’s coordinate system. That is now fixed. Also, an element with display: contents did not establish an anchor scope when anchor-scope was used, breaking CSS anchor positioning. The fix ensures that anchor-scope works correctly even on logically empty containers.

10. Media Queries Regression Resolved and More

The release also fixes a regression where media queries could fail to resolve correctly in certain circumstances (exact details were cut off in the original notes, but the fix ensures reliable responsive design breakpoints). Combined with all the above changes, Safari Technology Preview 241 represents a significant step forward in stability, standards compliance, and user experience. Developers should update and test their sites thoroughly.

These ten updates only scratch the surface—Safari Technology Preview 241 includes many more under-the-hood improvements. Whether you're building accessible web apps, crafting animations, or fine-tuning CSS layouts, this release has something for you. Download it today and see the difference for yourself.