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Apple Releases Safari Technology Preview 178 – Brings Bug Fixes and Performance Improvements

Apple Releases Safari Technology Preview 178 – Brings Bug Fixes and Performance Improvements

Apple has released Safari Technology Preview 178, 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.

Safari Technology Preview‌ 178 includes fixes and updates for Web Inspector, CSS, CSS Container Queries, JavaScript, SVG, Accessibility, Media, IntersectionObserver, Web API, and WebGL.


Safari Technology Preview Release 178 is now available for download for macOS Sonoma beta and macOS Ventura. 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: 266624@main…267312@main.

Web Inspector

  • Added color palette with CSS variables in color picker (266794@main)
  • Moved the details sidebar to the bottom when Web Inspector is too narrow (266784@main)


  • Implemented counter-set property (267137@main)
  • Fixed counter values to prevent them from overflowing or underflowing (266817@main)
  • Fixed <resolution> to not accept negative resolutions for @property (267134@main)
  • Fixed currentcolor to correctly inherit computed :visited style (267139@main)
  • Fixed color-mix() to respect :visited style to resolve “currentcolor” (267271@main)
  • Fixed baseline aligned flex items to also be aligned using their fallback alignment (267026@main)
  • Fixed border-image to fall back to the border property if the image is invalid (266749@main)
  • Fixed the scripting media query to never match initial-only (267198@main)
  • Fixed font-size-adjust toggling font sizes for system-ui font (266771@main)
  • Fixed :user-invalid and :user-valid interactions with form reset and submission (266702@main)
  • Added the support for mixed percentage and length/number arguments in CSS step functions (267072@main)

CSS Container Queries

  • Fixed container unit resolution to check if the selected container is eligible (267192@main)
  • Fixed container-name to use scoped names (267163@main)
  • Fixed container selection for container units in pseudo-elements (267197@main)
  • Fixed container query with font units to invalidate when the font changes (267258@main)


  • Enabled import attributes (266957@main)
  • Added support for Intl.NumberFormat’s FormatApproximately operation (266645@main)
  • Changed Intl.DurationFormat digital’s default from narrow to short (266891@main)
  • Fixed a positive look-behind RegExp with alternatives of different minimum lengths (266912@main)
  • Increased minimumFractionDigits and maximumFractionDigits limit from 20 to 100 (266879@main)
  • Updated Intl.DateTimeFormat’s to obtain options only once, matching spec changes (266868@main)
  • Updated Intl.NumberFormat and Intl.PluralRules roundingIncrement handling (267123@main)


  • Added the missing default value translate for animateTransform (266758@main)
  • Fixed paint-order property to inherit (267002@main)
  • Fixed SVG filters to prevent them from leaking visited hyperlinks (266683@main)


  • Fixed an issue where innerHTML and innerText changes to labels did not update their corresponding input element’s accessibility title (266919@main)


  • Added support for negative timestamps of TextTrackCue (267042@main)
  • Fixed vertical multiline WebVTT captions getting cut off (267162@main)



  • Enabled Fetch Priority by default (267196@main)
  • Enabled requestIdleCallback (267023@main266750@main)
  • Made event loop to execute idle callbacks at the end of each task (266877@main)
  • Enabled responsive images in <link rel=preload> (266787@main)
  • Added the change event for the Cookie Store API (266850@main)
  • Added more restrictions for top-frame navigations by a third-party iframe (266666@main)
  • Added support for from-image to ImageBitmapOptions (266893@main)
  • Changed navigable target names to _blank if they have dangling markup (267154@main)
  • Fixed ServiceWorkerRegistration data deletion (266882@main)
  • Fixed details element to use ToggleEvent for toggle events (267076@main)
  • Fixed SpeechSynthesisUtterance to not get GC’ed if there is a pending event (267161@main)
  • Added the support for key pair checks for Ed25519 in WebCrypto (267184@main)
  • Added basic support for SVGImageElement in createImageBitmap (267218@main)
  • Fixed <a> and <area> origin getters to return an empty string for non-parsable URLs (267222@main)
  • Fixed <a> and <area> protocol setters for non-parsable URLs (267265@main)


  • Fixed WebGL to not send a non-standard webglcontextchanged event (266861@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.