# Safari Technology Preview 203 Release Notes Learn about the latest web technology updates in Safari Technology Preview: Accessibility, Canvas, CSS, Editing, JavaScript, Media, Networking, Rendering, SVG, Web API, Web Apps, Web Assembly, Web Extensions, and Web Inspector. ## Overview [Safari Technology Preview](https://webkit.org/blog/6017/introducing-safari-technology-preview/) Release 203 is now [available for download](https://developer.apple.com/safari/resources/) for macOS Sequoia beta and macOS Sonoma. 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: [282390@main…283042@main](https://github.com/WebKit/WebKit/compare/01bcff3058440abda06beecdd2df3b7e3c3930f1...da72e62564fb6cd84c716a04605ac5f11c26bb45). ### Accessibility #### Resolved Issues - Fixed `display: contents` on `tbody` elements preventing table rows from being properly exposed in the accessibility tree. ([282413@main](https://commits.webkit.org/282413@main)) (129131780) - Fixed the handling of `ElementInternals.ariaValueNow` null values so the right value is exposed to assistive technologies. ([282422@main](https://commits.webkit.org/282422@main)) (129218234) - Fixed updating the accessibility tree when text underneath an `aria-describedby` element changes. ([282430@main](https://commits.webkit.org/282430@main)) (131877635) ### Canvas #### Resolved Issues - Fixed CanvasRenderingContext2D `globalAlpha` property getting ignored for some values of `globalCompositeOperation`. ([282995@main](https://commits.webkit.org/282995@main)) (134840885) ### CSS #### New Features - Added support for `scrollbar-gutter`. ([282662@main](https://commits.webkit.org/282662@main)) (111918434) - Added support for `cursor` in `::marker`. ([282642@main](https://commits.webkit.org/282642@main)) (133256523) - Added support for `ruby-overhang`. ([283012@main](https://commits.webkit.org/283012@main)) (135058411) #### Resolved Issues - Fixed `text-underline-offset` to support percentages. ([282611@main](https://commits.webkit.org/282611@main)) (117246233) - Fixed: Updated `calc()` to the most recent web standard, including support for dividing by numbers with additional units. ([282580@main](https://commits.webkit.org/282580@main)) (134446246) ### Editing #### Resolved Issues - Fixed aligning with the standardized version of the `autocorrect` attribute, which does not support Email, URL, and Password fields and does not treat the empty string value in a special way. ([282792@main](https://commits.webkit.org/282792@main)) (101036922) - Fixed inserting text before a `` element inserting the text after the element instead. ([282825@main](https://commits.webkit.org/282825@main)) (134378236) ### JavaScript #### New Features - Added support for `Iterator.prototype.constructor` and `Iterator.prototype[@@toStringTag]`. ([282687@main](https://commits.webkit.org/282687@main)) (134598491) - Added support for `Iterator.from` from Iterator Helpers Proposal. ([283016@main](https://commits.webkit.org/283016@main)) (135065388) #### Resolved Issues - Fixed: Disallow `yield` and `await` expressions in class field initializers. ([282819@main](https://commits.webkit.org/282819@main)) (132338331) - Fixed `Object.keys(global)` including non-enumerable properties unless deleted first. ([282554@main](https://commits.webkit.org/282554@main)) (134121649) - Fixed the error message of `Temporal.Instant.fromEpochMilliseconds`. ([282587@main](https://commits.webkit.org/282587@main)) (134454596) - Fixed duration format’s nanoseconds calculation ordering. ([282690@main](https://commits.webkit.org/282690@main)) (134526619) - Fixed TimeZoneAnnotation to disallow sub-minute. ([282710@main](https://commits.webkit.org/282710@main)) (134541964) - Fixed: `Temporal.Instant.prototype.epochMilliseconds` to return a floored value. ([282718@main](https://commits.webkit.org/282718@main)) (134666158) #### Deprecations - Remove obsoleted `Temporal.Instant` API. ([282400@main](https://commits.webkit.org/282400@main)) (134195010) ### Media #### New Features - Added support for allowing websites to override the system-default accessibility caption styling. ([282568@main](https://commits.webkit.org/282568@main)) (134265139) #### Resolved Issues - Fixed a bug in WebCodecs where audio and video codecs with pending work could be prematurely garbage collected. ([282657@main](https://commits.webkit.org/282657@main)) (134297589) ### Networking #### Resolved Issues - Fixed a bug where `Cross-Origin-Opener-Policy` header fields in the response of iframes were not ignored, resulting in `window.opener` being null after multiple cross-origin navigations of the main frame. ([282482@main](https://commits.webkit.org/282482@main)) (132840366) ### Rendering #### Resolved Issues - Fixed items that span multiple tracks with optimizations. ([282464@main](https://commits.webkit.org/282464@main)) (132435056) - Fixed rendering tick marks of the range input type when the page zoom is less than 1. ([282451@main](https://commits.webkit.org/282451@main)) (134282707) ### SVG #### Resolved Issues - Fixed an issue for `getPointAtLength` to throw an exception when `path` is empty. ([282665@main](https://commits.webkit.org/282665@main)) (122574451) ### Web API #### Resolved Issues - Fixed: Changed `click`, `auxclick`, `contextmenu`, and `click()` to use PointerEvent. ([282524@main](https://commits.webkit.org/282524@main)) (71202646) - Fixed: Aligned `oncuechange` event handler handling with other event handlers. ([282977@main](https://commits.webkit.org/282977@main)) (98254058) - Fixed `popovertarget` to work on buttons in a form. ([282801@main](https://commits.webkit.org/282801@main)) (131042177) - Fixed `XMLSerializer.serializeToString()` not serializing the children of `` and also not closing the `` if it has children. ([282725@main](https://commits.webkit.org/282725@main)) (133404338) - Fixed: Moved `onbeforeinput` to `GlobalEventHandlers`. ([282912@main](https://commits.webkit.org/282912@main)) (134943272) ### Web Apps #### New Features - Parse `dir` member of Web Application Manifest. ([282761@main](https://commits.webkit.org/282761@main)) (131900106) #### Resolved Issues - Fixed Web Application Manifest parsing to trim all ASCII whitespace. ([282544@main](https://commits.webkit.org/282544@main)) (134336817) ### Web Assembly #### New Features - Added support for `return_call_ref`. ([282853@main](https://commits.webkit.org/282853@main)) (134442713) ### Web Extensions #### Resolved Issues - Fixed Safari Web Extension ports to receive messages in content scripts when sent from the `onConnect` event listener. ([283006@main](https://commits.webkit.org/283006@main)) (133501214) (FB14721836) ### Web Inspector #### New Features - Added support for sourcemaps to be blackboxed. ([282740@main](https://commits.webkit.org/282740@main)) (133731737) - Added support for showing `boundThis` for arrow functions in the console. ([282553@main](https://commits.webkit.org/282553@main)) (134268331) --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)