Safari Technology Preview Release 229 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: 299669@main…300290@main.

Accessibility

Resolved Issues

• Fixed an issue where <label> elements targeted by aria-labelledby lost their LabelFor relationships after content changes. (300029@main) (158906980)

CSS

New Features

• Added support for text-decoration-line values spelling-error and grammar-error. (299919@main) (160494378)

Resolved Issues

• Fixed offsetParent to correctly return the fixed-position element’s containing block when it is not the viewport, such as a transformed element. (300097@main) (63739636)
• Fixed propagation of the body element’s writing-mode to the document element to match the CSS Writing Modes Level 4 specification. (300278@main) (149475070)
• Fixed @position-try so that revert-layer correctly only reverts the position-try origin instead of affecting other cascade origins. (299900@main) (154355428)
• Fixed the calculation of anchor() positions in right-to-left or vertical-rl containers to correctly account for left-side scrollbars. (300018@main) (155852237)
• Fixed baseline alignment for grid items by adding correct first baseline and last baseline row axis handling and properly accounting for baseline offsets. (299933@main). (155967278)
• Fixed issues with anchor() positioning during overscroll by clamping scroll positions, preventing unnecessary scroll recaptures, and ensuring anchor resolution stays in sync with layout changes. (300061@main) (159356009)
• Fixed an issue where anchor-positioned elements failed to update their position when the default anchor changed. (300142@main) (159899182)
• Fixed an issue where collapsed table rows subtracted border-spacing twice. (300023@main) (160542118)
• Fixed ::view-transition pseudo-element to use position: absolute instead of fixed to align with the updated specification. (300008@main) (160622000)
• Fixed container queries to allow container-name matching across the full flat tree, making container names tree-scoped in line with the CSS Conditional 5 specification. (300033@main) (160696378)
• Fixed handling of ::first-letter pseudo-elements to always force inline display unless floated.(300073@main) (160710650)
• Fixed the behavior of the nesting selector & directly inside @scope to correctly act like :where(:scope) for proper specificity handling. (300153@main) (160769736)

Events

Resolved Issues

• Fixed boundary pointer and mouse events not firing when the hit test target changed under a stationary pointer. (300277@main) (160147423)
• Fixed scroll event handling by consolidating scroll and scrollend into a single queue. (300239@main) (160936070)

Forms

Resolved Issues

• Fixed input fields with field-sizing: content so that larger placeholder text now correctly expands the height of the field by including the placeholder’s computed height. (299672@main) (123125836)
• Fixed painting for <input type="range"> sliders in right-to-left vertical block writing modes. (299690@main) (158567821)

JavaScript

Resolved Issues

• Fixed TypeError messages to be clearer in for-of loops. (300154@main) (159814766)

Networking

Resolved Issues

• Fixed the frozen iOS user agent string to report version 18_7 for iOS 26.1. (299818@main) (159902747)

SVG

New Features

• Added support for the onbegin event in the SVGAnimationElement IDL interface to align with the SVG animations specification. (299724@main) (130609424)
• Added support for the async attribute in SVGScriptElement to align behavior with HTMLScriptElement and other browsers. (299735@main) (151561361)
• Added support for the hreflang IDL attribute on SVGAElement to improve SVG link handling. (299704@main) (160133102)
• Added support for type attribute on SVG <a> element. (299770@main) (160222206)

Resolved Issues

• Fixed absolutely positioned SVG elements to correctly account for the containing block’s padding. (300054@main) (127608838)

Storage

Resolved Issues

• Fixed an issue where dedicated workers could inherit storage access from their parent document, preventing them from sending cross-site requests with cookies. (300120@main) (158814068)

Web API

New Features

• Added preview support for Event Timing API (Interaction to Next Paint) (300205@main) (160880698)

Resolved Issues

• Fixed window.opener being incorrectly set to null when a site-isolated iframe navigated to a new site, ensuring opener relationships persist across frame migrations. (299924@main) (117269418)
• Fixed scroll and scrollend events so they correctly fire on <input type="text"> elements instead of their inner elements. (300260@main) (157880733)
• Fixed the order of pointerup and boundary events so that pointerout and pointerover fire before pointerup when a child element is attached under the cursor. (https://commits.webkit.org/300273@main) (160913756)
• Fixed element.scrollTo and element.scrollBy so they correctly scroll text input fields by forwarding scroll operations to the inner text element. (300274@main) (160963921)

Deprecations

• Removed support for the non-standard “overflow” event. (281672@main) (71129110)

Web Inspector

Resolved Issues

• Fixed an issue where the Console truncated long string outputs. (300077@main) (124629101)

WebDriver

New Features

• Added support for new endpoints for setting storage access permission state and granting storage access to embedded frames for specific origins. (158263193)

Resolved Issues

• Fixed the navigate endpoint in WebDriver to properly validate URLs against the current browsing context and set the default readiness state to Interactive to align with the specification. (299780@main) (157031091)

WebGPU

New Features

• Added support for using GPUTexture objects as depth-stencil and resolve attachments in WebGPU render passes to match the specification. (299708@main) (159952306)