Release Notes for Safari Technology Preview 103

Safari Technology Preview Release 103 is now available for download for macOS Catalina and macOS Mojave. If you already have Safari Technology Preview installed, you can update in the Software Update pane of System Preferences on macOS.

This release covers WebKit revisions 257162-258409.

Web Inspector

  • Merged the toolbar and tab bar to save vertical space (r257759, r257765, r257810)
  • Redesigned resource and action identifier icons (r257753, r257757, r257791, r258039)
  • Allowed the use of dark mode theme independently from the system-wide theme (r257620, r257801, r257833)
  • Annotated tabs so that they are properly recognized as such (r257965)
  • Changed to not re-cycle through items in the Styles or Computed details sidebar panel when pressing tab (r257959)
  • Fixed clicking a button navigation item to focus it, allowing for subsequent keyboard navigation (r257411)
  • Supported expanding and collapsing details sections with the spacebar or “enter” key (r258058)
  • Supported cycling through scope bar items by pressing tab (r258057)


  • Aligned garbage collection for XMLHttpRequest objects with the specification (r258159)
  • Aligned Fetch ‘request Origin header’ behavior with the specification (r258194)
  • Changed the case of an activating service worker getting terminated to go to an activated state (r257929)
  • Changed to load async scripts with a low priority (r257566)
  • Changed to accept a Document as an explicit root (r257976)
  • Implemented wildcard behavior for Cross-Origin-Expose-Headers (r258330)


  • Made the style invalidation accurate for user-action pseudo classes (r258321)
  • Changed to avoid full style resolution on Element::focus() (r257839, r257846)

Page loading

  • Changed fixed sized SVG content to be taken into account when computing visually not empty status (r257952)
  • Changed layers going from visually empty to non-empty to immediately trigger layer unfreezing (r257840)

Back-Forward Cache

  • Added quirk to disable to back-forward cache on (r257714)


  • Updated custom element caching to be aware of different worlds (r257414)

Bug Fixes

  • Fixed leaking DocumentTimeline and CSSTransition objects on (r257417)
  • Fixed notes text in titles and headings is distorted (r258282)
  • Fixed not loading properly with screen flickering when zooming (r257716)