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Apple Releases Safari Technology Preview 158 – Brings Bug Fixes and Performance Improvements

Apple Releases Safari Technology Preview 158 – Brings Bug Fixes and Performance Improvements

Apple has released Safari Technology Preview 158, the latest version of their developer preview web browser. The preview version of Apple’s popular browser offers developers and other interested users the ability to try out features that may or may not, debut in future public release versions of Safari.

‌The current ‌Safari Technology Preview‌ release is built on the Safari 16 update and it includes features coming in macOS Ventura. It adds support for Live Text in videos and images, new web technologies, web push Passkeys, improved Safari Web Extensions, and more.

The preview is available for both macOS Monterey and macOS Ventura. It is no longer available for macOS Big Sur.

Release 158

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

Web Inspector

  • Added support for editing @-rules in the Styles sidebar of the Elements tab (256043@main)


  • Implemented CSS font-size-adjust property (255927@main)
  • Implemented font-variant-alternates functions, along with matching @font-feature-values at-rule (256002@main255677@main)
  • Implemented CSS property contain-intrinsic-size behind a flag (255971@main)
  • Changed to allow calc() with combined percentages and lengths for line-height (256095@main)
  • Changed to always use percentages for computed values of font-stretch, never keywords (256094@main)
  • Fixed font shorthand to not reject values that happen to have CSS-wide keywords as non-first identifiers in a font family name (255894@main)
  • Fixed font-style descriptor for @font-face to accept angle ranges in reverse order (255893@main)
  • Fixed font-style: oblique with calc() to allow out-of-range angles and clamp them for computed style (255925@main)
  • Fixed computed value CSS gradients to serialize colors in their computed form (256073@main)
  • Fixed text-shadow positioning on text with text-combine-upright (255892@main)
  • Fixed line-height to allow calc() with combined percentages and lengths (256095@main)


  • Changed to check for overflow content after trimming trailing content (256045@main)
  • Fixed a table cell overflowing its contents when it has inline children that change the writing-mode (255919@main)
  • Fixed elements with negative margins to not avoid floats when appropriate (256132@main)


  • Enabled AVIF image decoding for macOS Monterey and macOS Big Sur (255984@main)
  • Fixed “A MediaStreamTrack ended due to a capture failure” when selecting bluetooth headphones as audio input device (256091@main)


  • Accelerated Array.prototype.slice on DirectArguments (256027@main)
  • Accelerated Array.prototype.concat when applied to the self array (256040@main)


  • Enabled WebCodecs by default (256060@main)
  • Added WebCodecsVideoFrame initial support for serialisation and transfer (255949@main)
  • Changed to schedule dequeue event when the encoder queue size decreases (255962@main)
  • Changed to set VPx decoder frame type based on given parameter (255963@main)
  • Changed to prevent garbage collecting an encoder or decoder with content being processed (256007@main)
  • Exposed decoded video frames colorSpace (256068@main)
  • Exposed encoder color space in decoder config (256052@main)
  • Flushed before reconfiguring the encoder (255957@main)
  • Implemented pixel buffer conversion for video frames produced by libwebrtc VPX decoders (255958@main)


  • Aligned fetch header handling with fetch specification (256003@main)
  • Changed calling CSSStyleValue.parseAll() on a list-valued CSS property to split its value list (256070@main)
  • Changed CSSStyleValue.parse() to throw when passed an empty string as custom property value (256011@main)
  • Changed creating a shared worker connection to retry without providing a specific webprocess (255968@main)
  • Implemented input validation for CSSRGB constructor and setters (256024@main)
  • Optimized postMessage between two MessageChannel ports living in the same process (255948@main)

While the preview is intended for use by developers and advanced users, in order to provide Apple with feedback on the development of the Safari browser, it can be run side-by-side with the release version of Safari. The app doesn’t require a developer account to download and install. For more information, visit the Safari Technology Preview website.