Release Notes for Safari Technology Preview 150

Safari Technology Preview Release 150 is now available for download for macOS Monterey 12.3 or later and macOS Ventura beta. If you already have Safari Technology Preview installed, you can update in the Software Update pane of System Preferences on macOS Monterey, or System Settings under General → Software Update on macOS Ventura.

This release includes WebKit changes between:

Note: Shared Tab Groups and syncing for Tab Groups, Website Settings, and Web Extensions are not enabled in this release.

Web Inspector

  • Elements Tab
    • Changed CSS autocomplete so that the most commonly used property accounts for fuzzy-matching (252194@main)
    • Fixed property usage counts to ignore variables in CSS autocomplete (252195@main)
    • Make popover for resolved CSS variable values consistent with other popovers (252133@main)
    • Automatically hide the CSS documentation popover when navigating away (252175@main)
  • Sources Tab
    • Provided an option for controlling whether local overrides entirely replace or have some passthrough (251884@main)
  • Network Tab
  • Timelines Tab
    • Fixed Screenshots timeline overview records to adjust their position when zooming in or zooming out (252148@main)
  • Layers Tab
    • Fixed reasons for compositing for an element with clip-path and composited descendants (252354@main)
  • Search Tab
    • Improved search performance for short queries on many sites (252279@main)
  • Device Settings and Develop menu
    • Updated user-agent overrides to match options in Safari 16 (251881@main)


Shadow DOM

  • Fixed :focus pseudo-class failing to repaint on a shadow host when the focus moves from outside the page to inside a shadow tree (252261@main)
  • Fixed :focus-within pseudo-class not getting updated when the frame loses or gains focus (252324@main)
  • Fixed :lang pseudo-class to work across shadow boundaries (252099@main)
  • Fixed the :host() function pseudo-class to only accept a single compound-selector (252110@main)
  • Fixed vw units to get updated inside shadow trees as the frame is resized (252149@main)


  • Adjusted ArrayBuffer size tracking only when full garbage collection happens (252368@main)
  • Adopted Intl.NumberFormat v3 spec change for useGrouping option (252013@main)
  • Fixed interpretation of the fractional part of an ISO8601 Duration string (251809@main)

Web Animations

  • Added support for custom properties in Animation.commitStyles() (251858@main)
  • Added support for custom properties in JavaScript-originated animations (251856@main)

Web Share


  • Added getPublicKey and getPublicKeyAlgorithm methods to AuthenticatorAttestationResponse (251844@main)
  • User handles that are too long or too short are now rejected (251938@main)
  • Empty RP ids are now rejected (252142@main)
  • Added support for authenticators over CCID (252425@main)
  • Fixed passing CBOR-encoded extensions along during assertions (252626@main)


  • Designed an intentional way to invalidate platform font caches (251845@main)
  • Fixed PushManager in private browsing (251831@main)
  • Fixed IntersectionObserver stopping tracking when ⌘+ (Command-plus) is used to zoom in (251829@main)
  • Fixed ⇧⇥ (Shift-Tab) when focused in the middle of a contenteditable element (252029@main)
  • Fixed an issue where SameSite=Lax cookies were sometimes not sent on link navigations (252341@main)
  • Fixed SVGs loading an external file via <use> ignoring the ServiceWorker when offline (252132@main)
  • Fixed video.currentSrc to not be reset when a new load errors (251899@main)
  • Fixed an issue where inserting an iframe erroneously performs a micro-task checkpoint. (252015@main)


  • Fixed padding on a flex-based horizontal scroller preventing the last item from being fully viewable (251770@main)
  • Fixed clipping of absolutely positioned descendants of a transformed element with overflow: hidden (252387@main)
  • Implemented aspect-ratio mapping for the canvas element (252001@main)
  • Reduced memory use for for non-animated compositing layers with zero opacity (251965@main)
  • Fixed re-inserting <object> that previously rendered fallback content (251903@main)


  • Fixed WebSpeech to correctly allow the use of selected voices (252346@main)