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# Safari Technology Preview 136 Release Notes

Preview the latest web technology updates including: CSS, GPU Process, JavaScript, Web API, Media, Web Animations, WebAuthn, Private Click Measurement, Web Extensions, and other bugs.

## Overview

[Safari Technology Preview](https://webkit.org/blog/6017/introducing-safari-technology-preview/) Release 136 is now [available for download](https://webkit.org/downloads/) for macOS Big Sur and macOS Monterey. 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 [285101-285788](https://trac.webkit.org/log?stop_rev=285101&rev=285788&limit=687).

**Note:** Tab Groups do not sync in this release.

### CSS

- Added support for `contain: paint` ([r285583](https://trac.webkit.org/changeset/285583/webkit/))
- Added support for the `revert-layer` value ([r285624](https://trac.webkit.org/changeset/285624/webkit/))
- Added `flex-basis: content` support ([r285709](https://trac.webkit.org/changeset/285709/webkit/))
- Fixed `::slotted` element style to invalidate correctly in nested case ([r285211](https://trac.webkit.org/changeset/285211/webkit/))
- Fixed `::slotted` to not match an active `<slot>` ([r285209](https://trac.webkit.org/changeset/285209/webkit/))
- Fixed `:host::part(foo)` selector to select elements inside shadow roots ([r285262](https://trac.webkit.org/changeset/285262/webkit/))
- Fixed a mask or isolation to set `transform-style` to `flat` ([r285482](https://trac.webkit.org/changeset/285482/webkit/))
- Fixed `border-radius` inline style to serialize with valid syntax ([r285235](https://trac.webkit.org/changeset/285235/webkit/))
- Fixed `font-synthesis` inline and computed style to be in canonical order ([r285383](https://trac.webkit.org/changeset/285383/webkit/), [r285384](https://trac.webkit.org/changeset/285384/webkit/))
- Fixed rendering bug with `height: min-content`, `position: absolute`, and `box-sizing: border-box` ([r285495](https://trac.webkit.org/changeset/285495/webkit/))
- Fixed the default computed value for `content` to be `none` for `::before` and `::after` ([r285621](https://trac.webkit.org/changeset/285621/webkit/))
- Implemented parsing and animation support for `offset-path` ([r285343](https://trac.webkit.org/changeset/285343/webkit/))
- Implemented Scroll To Text Fragment directive parsing ([r285528](https://trac.webkit.org/changeset/285528/webkit/))
- Implemented `transform: perspective(none)` ([r285255](https://trac.webkit.org/changeset/285255/webkit/))
- Removed non-standard `-webkit-border-fit` CSS property ([r285615](https://trac.webkit.org/changeset/285615/webkit/))
- Updated the `content-size` grid width before laying out a grid item with block constraints and `aspect-ratio` ([r285497](https://trac.webkit.org/changeset/285497/webkit/))

### GPU Process

- Fixed enabling “media source inline painting” by default to work when using GPU Process for media ([r285410](https://trac.webkit.org/changeset/285410/webkit/))

### JavaScript

- Implemented IntlNumberFormat v3 (`formatRangeToParts` is not implemented yet) ([r285418](https://trac.webkit.org/changeset/285418/webkit/))
- Implemented `Temporal.Instant` ([r285178](https://trac.webkit.org/changeset/285178/webkit/))

### Web API

- Implemented custom element definition’s *disable shadow* flag ([r285740](https://trac.webkit.org/changeset/285740/webkit/))
- Fixed the `cssText` property for a computed style to return an empty string ([r285604](https://trac.webkit.org/changeset/285604/webkit/))

### Media

- Fixed showing languages and subtitles tracks button and menu for `<audio>` ([r285216](https://trac.webkit.org/changeset/285216/webkit/))

### Web Animations

- Added support for composite operations for software animations ([r285397](https://trac.webkit.org/changeset/285397/webkit/))
- Fixed accelerated animations with a single keyframe not accounting for prior forward-filling animations ([r285728](https://trac.webkit.org/changeset/285728/webkit/))
- Fixed discrete animation of `content` property not working ([r285423](https://trac.webkit.org/changeset/285423/webkit/))
- Improved additivity support when animating the transform property ([r285631](https://trac.webkit.org/changeset/285631/webkit/))

### WebAuthn

- Implemented `add_virtual_authenticator` and `remove_virtual_authenticator` for WebDriver ([r285267](https://trac.webkit.org/changeset/285267/webkit/))

### Private Click Measurement

- Fixed occasionally dropped attribution reports for Private Click Measurement ([r285170](https://trac.webkit.org/changeset/285170/webkit/))

### Web Extensions

- Added support for `manifest_version` 3 and `service_worker` background scripts, while also supporting the option of using non-persistent background pages
- Added support for script and style injection via the `browser.scripting` APIs
- Added support for dynamic and session rules via the `browser.declarativeNetRequest` APIs
- Fixed an issue with new tab pages not being remembered when switching from Favorites
- Fixed an issue with long extension descriptions causing the title to be cut-off in Preferences
- Enforces limits on the size and number of items in extension sync storage

### Other Bugs

- Fixed opening local HTML files when the Develop menu was enabled ([r285130](https://trac.webkit.org/changeset/285130/webkit/))
- Stopped using a timer to dispatch the source element’s error event asynchronously ([r285413](https://trac.webkit.org/changeset/285413/webkit/))

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