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# Safari Technology Preview 166 Release Notes

Learn about the latest web technology updates in Safari Technology Preview: Web Inspector, CSS, JavaScript, Popover, Media, MSE, Web API, and Accessibility.

## Overview

[Safari Technology Preview](https://webkit.org/blog/6017/introducing-safari-technology-preview/) Release 166 is now [available for download](https://webkit.org/downloads/) for macOS Monterey 12.3 or later and macOS Ventura. If you already have Safari Technology Preview installed, you can update it in the Software Update pane of System Preferences on macOS Monterey, or System Settings under General → Software Update on macOS Ventura.

This release includes WebKit changes between: [260849@main…261247@main](https://github.com/WebKit/WebKit/compare/e0b27b7e1c9b741347a581acc2007229791fed86...5f740dd938f6c31db68977b08ffe94d1a986324e).

### Web Inspector

- Added input fields for editing variation axes values in Fonts sidebar panel ([261162@main](https://commits.webkit.org/261162@main))

### CSS

- Enabled `@counter-style` by default ([261182@main](https://commits.webkit.org/261182@main), [260912@main](https://commits.webkit.org/260912@main), [261135@main](https://commits.webkit.org/261135@main))
- Enabled CSS `contain-intrinsic-size` by default ([261185@main](https://commits.webkit.org/261185@main))
- Fixed serialization of `image-set()` to use authored order ([261015@main](https://commits.webkit.org/261015@main))
- Implemented `@supports` with the `&` nesting operator ([261004@main](https://commits.webkit.org/261004@main))
- Implemented `text-transform: full-width` ([261211@main](https://commits.webkit.org/261211@main))
- Fixed floats trimmed margins to not contribute to the containing block’s intrinsic sizing ([260906@main](https://commits.webkit.org/260906@main))

### JavaScript

- Implemented RegExp `v` flag with set notation and properties of strings ([261188@main](https://commits.webkit.org/261188@main))
- Enabled new WASM baseline JIT (BBQ) for increased performance ([261153@main](https://commits.webkit.org/261153@main))
- Inlined Proxy [[Set]] trap in DFG / FTL ([261058@main](https://commits.webkit.org/261058@main))
- Made C++ to JS calls faster ([260858@main](https://commits.webkit.org/260858@main))

### Popover

- Enabled the `popover` attribute ([261193@main](https://commits.webkit.org/261193@main))
- Implemented `[popover=auto]` and light dismiss behavior ([261093@main](https://commits.webkit.org/261093@main))

### Media

- Fixed picture-in-picture video snapping to incorrect size ([261383@main](https://commits.webkit.org/261383@main))

### MSE

- Changed to only fire `durationchange` after parsing the media buffer ([261029@main](https://commits.webkit.org/261029@main))

### Web API

- Added support for `preconnect` via HTTP early hints ([261079@main](https://commits.webkit.org/261079@main))
- Added Cancel, Unknown, and Clear keycodes ([261008@main](https://commits.webkit.org/261008@main))
- Added selection API that works across shadow boundaries ([261021@main](https://commits.webkit.org/261021@main))
- Added support for `largeBlob` extension for the local authenticator ([260958@main](https://commits.webkit.org/260958@main))
- Adjusted text input `scrollWidth` and `scrollHeight` to include padding and any whitespace added by decorations ([261121@main](https://commits.webkit.org/261121@main))
- Fixed translation for shadow DOM content ([261096@main](https://commits.webkit.org/261096@main))
- Fixed translation to treat a floating list item as its own paragraph ([261114@main](https://commits.webkit.org/261114@main))
- Fixed Speech Recognition API terminating after one utterance or a short time ([260886@main](https://commits.webkit.org/260886@main))
- Fixed `window.onload` getting repeatedly re-executed when changing the URL fragment during `onload` ([260860@main](https://commits.webkit.org/260860@main))
- Improved support for prioritized HTTPS navigations ([261022@main](https://commits.webkit.org/261022@main))
- Stripped tab and newline from Location, URL, `<a>`, and `<area>`’s protocol setter ([261017@main](https://commits.webkit.org/261017@main))

### Accessibility

- Fixed `input[type=date]` individual fields getting announced as “group” ([261123@main](https://commits.webkit.org/261123@main))
- Fixed the wrong role displayed for `input` in Web Inspector ([260868@main](https://commits.webkit.org/260868@main))

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