Apple’s Safari Technology Preview 249 adds new CSS tools and fixes dozens of bugs

Apple just pushed out Safari Technology Preview 249, and this one is a bigger deal than the last few. Where recent builds mostly cleaned up bugs, this release actually hands developers a pile of new tools to play with, on top of a long list of fixes.

If you’re new to this, Safari Technology Preview is the testing version Apple uses to try out browser changes before they land in the Safari on your Mac. It runs next to your normal Safari, and you don’t need a developer account to grab it. This build works on macOS Tahoe and the upcoming macOS Golden Gate (currently in beta).

The main addition that we spotted is a bunch of new functions, including ‎’attr()’, ‎’if()’, ‎’calc-mix()’, and custom ‎’@function’ rules. In plain terms, these give the people building websites more ways to style pages without leaning on extra code. There’s also a new ‎’outline-offset: inset’ option and dark mode finally showing up in the XML document viewer.

JavaScript gets something folks have wanted for years. As Apple puts it, the release “Added support for the Temporal object.” That’s a new and much cleaner way to handle dates and times in code, and it has been a long time coming.

Now, coming to the bug fixes. VoiceOver, the screen reader, no longer goes silent while moving through text inside certain embedded frames. A ‎’box-shadow’ bug that broke when you zoomed a page is gone. There are also a bunch of CSS Grid layout fixes and a security fix tied to how Digital Credentials requests get checked.

Web Inspector, the tool developers use to poke at pages, got some love too. One fix stops it from mislabeling the color ‎’crimson’ with the wrong value.

Of course, none of this is stuff most people will notice day to day, but it’s the groundwork for features you’ll eventually use in regular Safari.

If you already have the browser, just open Software Update in System Settings to pull it in. Otherwise, you can download it fresh from Apple’s site. The full changelog is on Apple’s developer pages if you want to read through every line.

For more on what came before, check out our coverage of Safari Technology Preview 248.

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