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Safari Technology Preview 103 Offers The Usual Bug Fixes and Performance Improvements

Safari Technology Preview 103 Offers The Usual Bug Fixes and Performance Improvements

Apple on Thursday released Safari Technology Preview 103, 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.

Release 103

Web Inspector

  • Merged the toolbar and tab bar to save vertical space
  • Redesigned resource and action identifier icons
  • Allowed the use of dark mode theme independently from the system-wide theme
  • Annotated tabs so that they are properly recognized as such
  • Changed to not re-cycle through items in the Styles or Computed details sidebar panel when pressing tab
  • Fixed clicking a button navigation item to focus it, allowing for subsequent keyboard navigation
  • Supported expanding and collapsing details sections with the spacebar or “enter” key
  • Supported cycling through scope bar items by pressing tab


  • Aligned garbage collection for XMLHttpRequest objects with the specification
  • Aligned Fetch ‘request Origin header’ behavior with the specification
  • Changed the case of an activating service worker getting terminated to go to an activated state
  • Changed to load async scripts with a low priority
  • Changed to accept a Document as an explicit root
  • Implemented wildcard behavior for Cross-Origin-Expose-Headers


  • Made the style invalidation accurate for user-action pseudo classes
  • Changed to avoid full style resolution on Element::focus()

Page loading

  • Changed fixed sized SVG content to be taken into account when computing visually not empty status
  • Changed layers going from visually empty to non-empty to immediately trigger layer unfreezing

Back-Forward Cache


  • Updated custom element caching to be aware of different worlds

Bug Fixes

  • Fixed leaking DocumentTimeline and CSSTransition objects on CNN.com
  • Fixed icloud.com notes text in titles and headings is distorted
  • Fixed maps.google.com not loading properly with screen flickering when zooming

The update can be downloaded from the Safari Technology Preview website, or if the browser is already installed, it can be updated via the “Update” tab in the Mac App Store. Full release notes for the update are also available on the Safari Technology Preview website.

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.