# Safari Technology Preview 238 Release Notes Learn about the latest web technology updates in Safari Technology Preview: Animations, CSS, Editing, Forms, Networking, Rendering, SVG, Scrolling, Web API, Web Inspector, WebAssembly, and WebRTC. ## Overview [Safari Technology Preview](https://webkit.org/blog/6017/introducing-safari-technology-preview/) Release 238 is now [available for download](https://developer.apple.com/safari/resources/) 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: [306596@main…307618@main](https://github.com/WebKit/WebKit/compare/a908742cd775de5fa23dbf408618449db7f5fefb...b73f15088293cec470e0c2ceddd58bcd0b8480e5). ### Animations #### New Features - Enabled threaded time-based animation resolution, synchronizing accelerated time-based animations with scroll-driven animations while preserving enhanced performance by running animations off the main thread. This also allows CSS Motion Path animations to be accelerated. ([307252@main](https://commits.webkit.org/307252@main)) (170131323) ### CSS #### New Features - Added support for the CSS `:open` pseudo-class, which matches form elements and other elements in an open state. ([307295@main](https://commits.webkit.org/307295@main)) (170108337) #### Resolved Issues - Fixed scrollable overflow computation for block containers to account for `padding-inline-end`, aligning with the CSS Overflow specification. ([307212@main](https://commits.webkit.org/307212@main)) (144312078) - Fixed rendering of linear gradients when all color stops are at the same position. ([306823@main](https://commits.webkit.org/306823@main)) (169063497) ### Editing #### New Features - Added menu items to convert editable text between Simplified and Traditional Chinese characters in the “Transformations” submenu. ([306761@main](https://commits.webkit.org/306761@main)) (156354464) ### Forms #### New Features - Enabled the customizable `` element, allowing custom styling and content in `` dropdowns using `appearance: base-select`. ([307548@main](https://commits.webkit.org/307548@main)) (170328089) ### Networking #### Resolved Issues - Fixed an issue where Safari’s address bar could display an internationalized domain name (IDN) homograph as a visually identical legitimate Latin domain, enabling potential phishing attacks. ([307005@main](https://commits.webkit.org/307005@main)) (166796168) - Fixed incorrect URL query percent-encoding when using non-UTF-8 character encodings such as `iso-8859-2`, `windows-1250`, and `gbk`. ([306768@main](https://commits.webkit.org/306768@main)) (169566553) ### Rendering #### Resolved Issues - Fixed a performance issue causing a hang when rendering tables with a large number of `rowspan="0"` cells. ([306891@main](https://commits.webkit.org/306891@main)) (146056348) ### SVG #### Resolved Issues - Fixed: Updated the default values of `fx` and `fy` attributes on `SVGRadialGradientElement` to `50%` to align with the SVG2 specification. ([306811@main](https://commits.webkit.org/306811@main)) (169645572) - Fixed `SVGAnimatedRect.baseVal` to ignore invalid values set on the `viewBox` attribute, such as negative width or height, aligning with Firefox and Chrome. ([307463@main](https://commits.webkit.org/307463@main)) (170214971) - Fixed SVG length attributes to reset to their default values when removed, rather than retaining previously set values. ([307585@main](https://commits.webkit.org/307585@main)) (170360351) ### Scrolling #### New Features - Enabled scroll anchoring, which prevents visible jumps in scroll position when content is inserted or removed above the viewport. ([307475@main](https://commits.webkit.org/307475@main)) (170279026) ### Web API #### New Features - Added support for `ReadableStream.from()` to create a `ReadableStream` from an async iterable or iterable. ([306786@main](https://commits.webkit.org/306786@main)) (169605740) - Added support for transferring `ReadableStream` objects via `postMessage()`. ([307068@main](https://commits.webkit.org/307068@main)) (169950592) #### Resolved Issues - Fixed an issue where Speculation Rules did not trigger prefetches for anchor elements that were not themselves visible but had visible descendants. ([306730@main](https://commits.webkit.org/306730@main)) (169561588) - Fixed `NavigateEvent.canIntercept` to correctly return `false` when navigating to a URL with a different port, aligning with the Navigation API specification. ([307316@main](https://commits.webkit.org/307316@main)) (169845691) ### Web Inspector #### New Features - Improved discoverability of color formats and gamuts in the color picker by adding explicit format and gamut toggle controls. ([306691@main](https://commits.webkit.org/306691@main)) (168216591) #### Resolved Issues - Fixed an issue where the text filter in the Sources tab did not apply to Local Overrides and Console Snippets sections. ([306647@main](https://commits.webkit.org/306647@main)) (169443917) - Fixed an issue where tree outlines in Web Inspector would intermittently show blank content while scrolling when a filter was active. ([306680@main](https://commits.webkit.org/306680@main)) (169502061) - Fixed an issue in the Timelines tab where rows containing object previews were sometimes not visible in the heap snapshot data grid. ([307358@main](https://commits.webkit.org/307358@main)) (170164522) - Fixed context menu items in the Elements tab to only display relevant options when multiple DOM nodes are selected. ([307485@main](https://commits.webkit.org/307485@main)) (170307979) ### WebAssembly #### New Features - Added support for JavaScript Promise Integration (JSPI) for WebAssembly, enabling WebAssembly code to suspend and resume execution while waiting for JavaScript promises. ([307404@main](https://commits.webkit.org/307404@main)) (170260385) ### WebRTC #### Resolved Issues - Fixed `RTCRtpSynchronizationSource.timestamp` to use the correct time base, aligning with the WebRTC specification. ([307063@main](https://commits.webkit.org/307063@main)) (169679084) - Fixed `RTCIceCandidate.toJSON()` to include the `usernameFragment` field in the serialized output. ([306845@main](https://commits.webkit.org/306845@main)) (169679947) - Fixed `RTCRtpTransceiver.setCodecPreferences()` to accept codec entries regardless of the `mimeType` case, aligning with Firefox and the specification. ([307062@main](https://commits.webkit.org/307062@main)) (169789074) - Fixed `RTCRtpSender` to allow a `maxFramerate` encoding parameter value of `0`, aligning with the specification and other browsers. ([307034@main](https://commits.webkit.org/307034@main)) (169863687) --- Copyright © 2026 Apple Inc. 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