Release Notes for Safari Technology Preview 148

Safari Technology Preview Release 148 is now available for download for macOS Monterey 12.3 or later and macOS Ventura beta. Updates to Safari Technology Preview are no longer available for macOS Big Sur. 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 in WebKit-7614.1.17.2.

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

Web Inspector

  • Added “Copy as fetch” in a contextual menu for resources (251226@main)
  • Updated Open Resource dialog to support matching file paths (251155@main)
  • Elements Tab
    • Added eyedropper to the color picker to allow picking a color from anywhere on the screen (251236@main)
    • Improved CSS autocompletion to suggest the most commonly used property, not the alphabetically first one (250994@main, 251171@main)
    • Layout
      • Fixed overlay color swatches to not allow format changes via context menu (251194@main)
      • Fixed overlay color swatches not updating the color of an overlay until the popover is dismissed (251248@main)
  • Sources Tab
    • Blackbox breakpoint evaluations in the debugger by default (251170@main)
    • Fixed newly added header not appearing when adding it to a request local override (250821@main)
    • Fixed the cursor not being automatically placed where it was before when creating a local override while viewing a resource (251279@main)
    • Fixed popover not resizing when wrapping to a new line while editing a breakpoint action (251072@main)
  • Network Tab
    • Added EventSource resource type (250672@main)
    • Fixed activity not getting marked as a previous session when the Network Tab is not selected (250902@main)
  • Timelines Tab
  • Audit Tab
    • Allowed audits to simulate a user gesture (251241@main)
    • Replaced the “Export Audit” and “Export Result” buttons with a single button that has a picker (251295@main)

:has() pseudo-class

  • Added support for invalidating :target pseudo-class (250483@main)
  • Added partial support for invalidating :in-range and :out-of-range (250839@main)
  • Fixed invalidation with scope breaking :is() or :not() (251130@main)

CSS Container Queries

  • Fixed a bug in style caching with container units (251268@main)
  • Changed to update query container layout unconditionally when an ancestor style changes (251310@main)


  • Added support for each-line keyword in text-indent (250978@main)
  • Changed to not allow unit-less values for CSS unprefixed perspective property (250582@main)
  • Fixed handling of text-align: match-parent on root element (251211@main)
  • Implemented :modal pseudo-class (250424@main)
  • Implemented ray() shape in offset-path (250437@main, 250776@main)
  • Implemented contain flag for ray() in offset-path (250776@main)
  • Updated logical *vi (inline) and *vb (block) viewport units to be based on the current element’s writing-mode (250835@main)


  • Made appearance: textfield behave like auto for most cases (250605@main)
  • Changed input.showPicker() to throw when the input element is readonly or disabled (250532@main)
  • Made input placeholder line-height user agent declaration !important (250414@main)
  • Made sure :active state is removed on keyup for radio button inputs (250734@main)
  • Removed the following values from the appearance property (250538@main, 250889@main, 250865@main, 250584@main, 250871@main)
    • caret
    • continuous-capacity-level-indicator
    • default-button
    • discrete-capacity-level-indicator
    • inner-spin-button
    • listitem
    • media-controls-dark-bar-background
    • media-controls-light-bar-background
    • progress-bar-value
    • rating-level-indicator
    • relevancy-level-indicator
    • sliderthumb-horizontal
    • sliderthumb-vertical


  • Changed to dynamically toggle acceleration of offset animations depending on the ability of animations in the effect stack to be accelerated (250737@main)
  • Ensured that animations using offset properties correctly run on a composited layer (250687@main)

inert attribute

  • Fixed the inert attribute to ignore display: contents elements with assistive technologies (251185@main)
  • Fixed the inert attribute to affect pseudo-elements (250446@main)


  • Changed Temporal round and total methods to accept a string parameter (Temporal is behind the --useTemporal runtime flag) (250433@main)
  • Fixed Temporal.Duration#toString to never ignore fractionalSecondDigits (Temporal is behind the --useTemporal runtime flag) (250388@main)
  • Updated Temporal and Date to reject expanded year -000000 (Temporal is behind the --useTemporal runtime flag) (250432@main)


  • Fixed perspective to not be affected by transform-origin (250841@main)
  • Stopped assuming that an absolute positioned block box’s height is always resolvable (251215@main)


  • Allowed Service Workers to run for a little longer in the case of functional events (250635@main)
  • Fixed fetch event handling delays caused by other JavaScript work on the main thread (251183@main)
  • Made sure calling showNotification will extend the service worker lifetime (250583@main)


  • Fixed sequential WebVTT cues with the same contents getting dropped (250988@main)
  • Fixed audio playback rate speeding up for few seconds when using createMediaElementSource (250579@main)
  • Fixed capturing a canvas that is not in the DOM leading to erratic frame rates or no frame emission at all (250996@main)
  • Changed to trigger element fullscreen video extraction after the seeked event (251090@main)


  • Added support for Link nonces (250972@main)
  • Aligned Intelligent Tracking Prevention client side cookie cap with other script-writable storage (251397@main)
  • Fixed script-src-elem Content Security Policies in workers (250386@main)


  • Fixed loading a very large image as an image document (251253@main)


  • Fixed automated mouse movement to correctly fire mouse events (251457@main)
  • Fixed rapid session creation and deletion leading to a timeout in session creation