Release Notes for Safari Technology Preview 223

Jul 9, 2025

by Jon Davis

Safari Technology Preview Release 223 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: 295968@main…296486@main.

CSS

New Features

  • Added support for allowing declarations directly inside @scope rule without a style rule ancestor. (296262@main) (145101643)

Resolved Issues

  • Fixed: Apply space from align-content when grid container and rows have definite sizes during column sizing (296300@main) (85252183)
  • Fixed <frame> and <frameset> to always be in-flow and non-floating. (296236@main) (102670652)
  • Fixed style container query on :host CSS pseudo-class to be correctly applied to slotted elements. (296080@main) (147684247)
  • Fixed space-around and space-evenly to fallback to safe center for align-content. (296239@main) (153403381)
  • Fixed the serialization of <color> custom properties to provide the used value. (296337@main) (153675017)
  • Fixed clamping the result of progress() between 0 and 1. (296440@main) (153895964)

JavaScript

New Features

  • Added support for Intl.Locale.prototype.variants getter. (296467@main) (153939662)

Resolved Issues

  • Fixed RegExp#[Symbol.search] to throw TypeError when lastIndex isn’t writable. (296443@main) (146488846)
  • Fixed DateTime string parsing for ISO8601 inputs. (296339@main) (153679940)
  • Fixed toIntegerOrInfinity to truncate negative fractional values to +0.0. (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) (79587134)
  • Fixed using setDragImage with a fixed-position element, so that the drag preview bitmap includes the correct content. (296117@main) (90120656)
  • Fixed integrating popovers with anchor positioning. (295995@main) (141094328)
  • Fixed box-shadow with spread on a border-radius box to scale the radii correctly. (296481@main) (149490613)
  • Fixed SVG transform translate(X) not equal to translate(X,0). (296008@main) (151643419)
  • Fixed border-image repaint code is broken in some writing modes. (296016@main) (152396671)
  • Fixed box-shadow to repaint correctly in vertical-rl and horizontal-bt writing modes. (295977@main) (152803240)
  • Fixed border to no longer be adjusted in computed style for elements with native appearance (296129@main) (153152167)
  • Fixed margin-trim to not trim inline margins on block-level boxes, regardless of their position. (296212@main) (153240895)
  • Fixed text-wrap-style to not constrain single line content. (296471@main) (153755326)

SVG

Resolved Issues

  • Fixed handling of auto for rx and ry on <ellipse>. (296195@main) (153274593)

Text

Resolved Issues

  • Fixed Korean counter styles to be aligned with manual Korean numbering in lists. (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) (120551245)
  • Fixed IntersectionObvserver to notify observers asynchronously. (296279@main) (152684301)

Web Extensions

New Features

  • Added support for dom.openOrClosedShadowRoot() and element.openOrClosedShadowRoot. (296168@main) (153118095)

Resolved Issues

  • Fixed high priority redirects to supercede low priority blocks for declarativeNetRequest. (296000@main) (145241581)
  • Fixed CSS display: none matching everything still getting applied even after an ignore-following-rules action was matched. (296149@main) (152996225)
  • Fixed calling scripting.registerContentScripts() sometimes returning the error: “Error: Invalid call to scripting.registerContentScripts(). Failed to add content script.” (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) (153193833)