Release Notes for Safari Technology Preview 125

Safari Technology Preview Release 125 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 275811-277448.

Web Inspector

  • Remote Inspection
    • Fixed an issue that prevented remotely inspecting iOS and iPadOS devices
  • Sources Tab
    • Added support for panning and zooming image resources (r277279)
  • Audit Tab
    • Fixed edits not saving if the text input was still focused when leaving Edit mode (r276616)
    • Fixed default and new test cases showing minified source (r276680, r277212)


  • Added parsing for @counter-style descriptors (r276488)
  • Added support for CSS display 2-value syntax (e.g. display: inline flex ) (r276293)
  • Added support for inline-{start/end} values to float & clear CSS properties (r276216)
  • Changed to not use margins when computing aspect ratio cross sizes (r277371)
  • Changed invalid media query keyword values to not be parsable (r277039)
  • Fixed treating border and padding correctly for box-sizing: border-box with aspect-ratio (r276745)
  • Fixed flex item construction to not affect sibling flex item height computation (r277222, r277435)
  • Fixed percent children to resolve against the flex basis on a fully inflexible item with fixed flex-basis (r276634)
  • Fixed table layout disregarding the overriding width in CSS Flexbox (r276572)
  • Fixed logical shorthands with var() (r276837)
  • Fixed using a modifier key on an element causing it stop matching :focus-visible (r276698)
  • Fixed CSS custom properties on pseudo-elements background gradients that caused infinite layout and high CPU load (r277112)
  • Fixed position for orthogonally positioned element with writing-mode: vertical-rl (r277391)
  • Improved parsing and computed style of the rotate CSS property (r276554)
  • Shared style resolvers between author shadow trees with identical style (r276882)

Web Animations

  • Added discrete animation support for border-image-repeat (r276465)
  • Fixed interpolation of stroke-dasharray in the discrete case (r276643)
  • Fixed interpolation of page-break- ** properties (r276638). Fixed animation of the visibility CSS property between hidden and collapse (r276639)
  • Fixed interpolation of the clip CSS property (r276552)
  • Fixed interpolation of the rotate CSS property (r276231)
  • Support interpolation of the background-repeat shorthand (r276553)


  • Added call_ref instruction (r276896)


  • Improved local storage size estimation for quota limitation (r276689)


  • Fixed picture element to ignore any img descendant that is not a direct child (r276679)
  • Fixed blob contentType being ignored when it contained a charset (r276986)
  • Implemented <form>.requestSubmit() (r277257)
  • Implemented FontFace in Workers for OffscreenCanvas (r276450)
  • Implemented ShadowRoot.prototype.delegatesFocus attribute (r276585)
  • Avoided error for a fetch body stream when its request or response is stopped (r277028)
  • Changed to not compute image aspect ratios from width and height attributes for lazy loaded images (r276521)
  • Fixed Notification.requestPermission() to return a Promise (r277420)


  • Fixed computed style for the translate CSS property to use px for the z value (r276551)
  • Fixed will-change CSS property to create a containing block when the one of the specified properties may create one (r276627)
  • Fixed sizing of CSS backgrounds affected by background-size and EXIF orientation (r276984)


  • Fixed color gamut in WebRTC when using VPx software decoder (r276478)
  • Set audio transceiver nMax to 1 (r276717)