# Safari Technology Preview 223 Release Notes Learn about the latest web technology updates in Safari Technology Preview: CSS, JavaScript, Rendering, SVG, Text, Web API, Web Extensions, and Web Inspector. ## Overview [Safari Technology Preview](https://webkit.org/blog/6017/introducing-safari-technology-preview/) Release 223 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: [295968@main…296486@main](https://github.com/WebKit/WebKit/compare/f62be7241507b5c2953d46569c35a12418d4c4e5...4203492397b80e376ff463ddbb8074bdc7f0b855). ### CSS #### New Features - Added support for allowing declarations directly inside `@scope` rule without a style rule ancestor. ([296262@main](https://commits.webkit.org/296262@main)) (145101643) #### Resolved Issues - Fixed: Apply space from align-content when grid container and rows have definite sizes during column sizing ([296300@main](https://commits.webkit.org/296300@main)) (85252183) - Fixed `` and `` to always be in-flow and non-floating. ([296236@main](https://commits.webkit.org/296236@main)) (102670652) - Fixed style container query on `:host` CSS pseudo-class to be correctly applied to slotted elements. ([296080@main](https://commits.webkit.org/296080@main)) (147684247) - Fixed `space-around` and `space-evenly` to fallback to `safe center` for `align-content`. ([296239@main](https://commits.webkit.org/296239@main)) (153403381) - Fixed the serialization of `` custom properties to provide the used value. ([296337@main](https://commits.webkit.org/296337@main)) (153675017) - Fixed clamping the result of `progress()` between 0 and 1. ([296440@main](https://commits.webkit.org/296440@main)) (153895964) ### JavaScript #### New Features - Added support for `Intl.Locale.prototype.variants` getter. ([296467@main](https://commits.webkit.org/296467@main)) (153939662) #### Resolved Issues - Fixed `RegExp#[Symbol.search]` to throw `TypeError` when `lastIndex` isn’t writable. ([296443@main](https://commits.webkit.org/296443@main)) (146488846) - Fixed DateTime string parsing for ISO8601 inputs. ([296339@main](https://commits.webkit.org/296339@main)) (153679940) - Fixed `toIntegerOrInfinity` to truncate negative fractional values to `+0.0`. ([296468@main](https://commits.webkit.org/296468@main)) (153939418) ### Rendering #### Resolved Issues - Fixed a `list-style-position: inside` list item marker to be rendered as the first child of the list item. ([296451@main](https://commits.webkit.org/296451@main)) (79587134) - Fixed using `setDragImage` with a fixed-position element, so that the drag preview bitmap includes the correct content. ([296117@main](https://commits.webkit.org/296117@main)) (90120656) - Fixed integrating popovers with anchor positioning. ([295995@main](https://commits.webkit.org/295995@main)) (141094328) - Fixed `box-shadow` with spread on a border-radius box to scale the radii correctly. ([296481@main](https://commits.webkit.org/296481@main)) (149490613) - Fixed SVG transform `translate(X)` not equal to `translate(X,0)`. ([296008@main](https://commits.webkit.org/296008@main)) (151643419) - Fixed `border-image` repaint code is broken in some writing modes. ([296016@main](https://commits.webkit.org/296016@main)) (152396671) - Fixed `box-shadow` to repaint correctly in `vertical-rl` and `horizontal-bt` writing modes. ([295977@main](https://commits.webkit.org/295977@main)) (152803240) - Fixed `border` to no longer be adjusted in computed style for elements with native appearance ([296129@main](https://commits.webkit.org/296129@main)) (153152167) - Fixed `margin-trim` to not trim inline margins on block-level boxes, regardless of their position. ([296212@main](https://commits.webkit.org/296212@main)) (153240895) - Fixed `text-wrap-style` to not constrain single line content. ([296471@main](https://commits.webkit.org/296471@main)) (153755326) ### SVG #### Resolved Issues - Fixed handling of `auto` for `rx` and `ry` on ``. ([296195@main](https://commits.webkit.org/296195@main)) (153274593) ### Text #### Resolved Issues - Fixed Korean counter styles to be aligned with manual Korean numbering in lists. ([296203@main](https://commits.webkit.org/296203@main)) (152969810) ### Web API #### Resolved Issues - Fixed the `mousemove` event to be fired when the mouse stays in the document but there is no element. ([296341@main](https://commits.webkit.org/296341@main)) (120551245) - Fixed IntersectionObvserver to notify observers asynchronously. ([296279@main](https://commits.webkit.org/296279@main)) (152684301) ### Web Extensions #### New Features - Added support for `dom.openOrClosedShadowRoot()` and `element.openOrClosedShadowRoot`. ([296168@main](https://commits.webkit.org/296168@main)) (153118095) #### Resolved Issues - Fixed high priority redirects to supercede low priority blocks for declarativeNetRequest. ([296000@main](https://commits.webkit.org/296000@main)) (145241581) - Fixed CSS `display: none` matching everything still getting applied even after an `ignore-following-rules` action was matched. ([296149@main](https://commits.webkit.org/296149@main)) (152996225) - Fixed calling `scripting.registerContentScripts()` sometimes returning the error: “Error: Invalid call to scripting.registerContentScripts(). Failed to add content script.” ([296093@main](https://commits.webkit.org/296093@main)) (153001967) ### Web Inspector #### Resolved Issues - Fixed clicking on the “+” button in the Sources tab sidebar doing nothing when Web Inspector is undocked. ([296458@main](https://commits.webkit.org/296458@main)) (153193833) --- 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)