Safari Technology Preview Release 231 is now available for download for macOS Tahoe and macOS Sequoia. If you already have Safari Technology Preview installed, you can update it in System Settings under General → Software Update.

This release includes WebKit changes between: 300987@main…301765@main.

CSS

New Features

• Added support for the safe keyword with anchor-center in CSS Anchor Positioning. (301301@main) (155767796)
• Added support for flip-x and flip-y options in position-try-fallback for CSS Anchor Positioning. (302057@main) (163282036)

Resolved Issues

• Fixed handling of padding and margins for flex and grid layouts across all writing modes. (301814@main) (71046552)
• Fixed position-visibility: no-overflow to respond correctly to scrolling. (301211@main) (162173481)
• Fixed: Renamed position-area keywords from x-self-start, x-self-end, y-self-start, and y-self-end to self-x-start, self-x-end, self-y-start, and self-y-end respectively to align with updated CSSWG specifications.(301226@main) (162214793)
• Fixed <iframe> elements so their content correctly respects the page’s usedZoom(). (302097@main) (162314059)
• Fixed auto margins by converting them to zero when position-area or anchor-center is applied in CSS Anchor Positioning. (301662@main) (162809291)

JavaScript

Resolved Issues

• Fixed TypeError messages when calling class or function constructors without new to include the constructor name. (301023@main) (161152354)

Media

Resolved Issues

• Fixed an issue where custom WebVTT caption text size settings did not propagate to cue child elements by moving the font-size definition into the cue’s shared <style> block. (301681@main) (162547969)

Rendering

New Features

• Added support for text shaping across inline boxes. (301354@main) (162430932)

Resolved Issues

• Fixed an issue where selecting table cells could cause overlapping selections in flex and grid layouts. (294464@main) (160805174)
• Fixed a performance issue on layouts with long pre blocks and word-break: break-all by including whitespace in overflow width calculations. (301657@main) (162695099)
• Fixed Largest Contentful Paint to optimize text paints by performing an early area comparison when an element has only one text box. (301895@main) (163067611)
• Fixed Largest Contentful Paint to skip tracking loadTime for data URI images. (301988@main) (163213487)
• Fixed how Largest Contentful Paint performs area checks for text nodes, optimizing calculations when all rects are collected and ancestor transforms are absent. (302072@main) (163285757)

Web API

Resolved Issues

• Fixed Navigation API WPT tests failing due to a WebDriver error. (161199777)
• Fixed PerformanceEventTiming so that keydown and pointerdown entries no longer wait for their corresponding keyup or pointerup events before assigning a duration, preventing durations from appearing too long. (302107@main) (161911473)
• Fixed attachShadow() to use the global custom element registry by default when customElementRegistry is null, aligning with the WHATWG DOM specification (300996@main). (161949493)
• Fixed navigate() with { history: "replace" } to correctly update the current History item instead of adding a new one during same-document navigations. (302130@main) (163323288)

Web Inspector

Resolved Issues

• Fixed an issue where the Sources tab won’t show contents of a script that contains a for statement with optional chaining in the test condition. (301197@main) (160617913)

WebDriver

Resolved Issues

• Fixed an issue where element references nested inside Array or Object arguments were not properly extracted when executing scripts. (301445@main) (162571946)