Release Notes for Safari Technology Preview 123

Safari Technology Preview Release 123 is now available for download for macOS Big Sur and macOS Catalina. 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 273903-274002.

Web Inspector

  • Make the border color of the grid badge match to the corresponding outline (r273992)
  • Save and restore user-defined CSS Grid overlay colors (r273912)


  • Changed to consider intrinsic sizes as automatic whenever the block axis of the flex item is the flexible box main size (r273955)
  • Fixed orthogonal items with percentage sizes in Flexbox (r273958)
  • Fixed position: sticky behavior in a table with dir=RTL (r273982)


  • Removed the Origin header if the navigation request goes from POST to GET (r273905)