Release Notes for Safari Technology Preview 174

Safari Technology Preview Release 174 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: 265305@main…265693@main.


  • Added support for contain-intrinsic-size: auto none property syntax (265617@main)
  • Fixed text-overflow: ellipsis so it works with overflow: clip (265445@main)
  • Fixed cjk-earthly-branch and cjk-heavenly-stem counter styles to fallback to cjk-decimal (265474@main)
  • Fixed inline-flex and inline-grid boxes to stop propagating underlines to align with other browsers (265471@main)
  • Fixed CSS accelerated animation handling with multiple effects on the stack (265498@main)
  • Fixed cursor style to respect explicitly set cursor type over system default (265597@main)

CSS Container Queries

  • Fixed container units in a container query to evaluate against the ancestor container (265583@main)
  • Fixed container units to consider writing mode for unit resolution (265654@main)

Fixed how text decorations propagate into tables to align with other browsers (265488@main)


  • Fixed list alignment when a list item has a flex container (265464@main)
  • Fixed font size to allow use of fractional pixel values (265657@main)
  • Fixed bordercolor attribute on table elements to not create a visible border (265670@main)


  • Renamed .groupByToMap() on Array to .groupBy() on Object and Map in order to align with latest TC-39 proposal (265632@main)


  • Added support for WebCodecs temporal scalabilityMode for software codecs, including parsing and error handling (265561@main)
  • Added support for WebM files with no track ID (265425@main)
  • Updated VTTCue to match latest W3C specification, including support for CSS updated default CSS properties, as well as support for vh, vw, cqh, and cqw units. (265596@main)


  • Fixed togglePopover() to always throw an exception if it’s disconnected or not a popover (265589@main)


  • Improved accessibility for tables and table components with display: flex, grid, block, inline-block, and contents (265486@main)
  • Prioritized HTML required attribute over aria-required when both are present (265552@main)


  • Fixed dominant-baseline CSS property to be inherited (265525@main)
  • Fixed references for SVG fragments in shadow DOM trees (265565@main)


  • Fixed constructing a SharedWorker in a detached document so it throws an exception (265483@main)
  • Removed artificial memory limit for canvas context, given it the same memory restrictions as other Web features (265628@main)