I’m happy to look into it and help. Do you have a demo of it I can access and inspect?

I think I see what you’re after, and I think you’re right. There isn’t a wholesale way to stabilize all `random()` calls in a document. Might be worth raising an issue to the CSS WG with the the theoretical “testing” use-case and maybe a concrete example to go along with it.

random() - CSS | MDN he random() CSS function generates a random value within a specified range, optionally limiting the possible values to step size intervals between those limits.

Yes, this is possible! The syntax you're looking for is: random(fixed 0.5, 1em, 40vw)

The first optional argument can be specified to set a fixed "seed": fixed <number>

For more, we helped in getting the MDN web docs page for `random()` landed recently: developer.mozilla.org/en-US/docs/W...

📝 Algorithmic hover states with contrast-color() - Taking some cool new features for a spin.

daverupert.com/2026/01/algo...

Interop 2025 graph shows Safari jumping from 64 to 98 in one fell swoop, this week. The blue line goes almost straight up, jumping ahead of all the other browsers. And the interop score line goes right with it. Overall scores: Chrome 95, Edge 96, Firefox 90, Safari 98.

More holiday cheer. For those of you asking about Safari’s “stable” Interop 2025 score…

Online Identity Verification with the Digital Credentials API The rise of e-commerce in the past decade changed the way customers interact with businesses online, leading to new innovations and improved user experiences.

The Digital Credentials API is transforming online identity verification. Instead of uploading photos of IDs, users can now securely share verified credentials directly from their digital wallet.

You can read up on the API and security best practices here:
webkit.org/blog/17431/o...

Rolling the Dice with CSS random() Random functions in programming languages are amazing.

The WebKit team published "Rolling the Dice with CSS random()". CSS random() is a new function to generate random values for CSS properties opening up a huge range of possibilities for procedurally generated layouts. Learn more on the WebKit blog:

webkit.org/blog/17285/r...

The best way I can recommend is to look for the fix to show up in Safari release notes. Beta release notes can give you the earliest indication of what release of Safari the fix will be included in, though it's not a guarantee.

A gentle introduction to anchor positioning Anchor positioning allows you to place an element on the page based on where another element is.

New WebKit post! “A gentle introduction to anchor positioning” webkit.org/blog/17240/a...

A guide to Scroll-driven Animations with just CSS CSS animations have come a long way since Apple first introduced them to the web in 2007.

Now that my blog post got the thumbs up from @zeldman.bsky.social, I can die a happy evangelist 🥰

Check out my intro to scroll-driven animations, hope you like it too ❤️ webkit.org/blog/17101/a...

State of CSS 2025 Take the State of CSS survey

Still a week left to take the State of CSS survey!

The survey hasn't got as many responses as last year, so any help sharing will be much appreciated :)

survey.devographics.com/en-US/survey...

Requesting a lab appointment is available to members of the Apple Developer Program — if you're already a member, this is one of the best perks of your subscription!

Sessions & Labs - WWDC25 - Apple Developer Learn about WWDC25 sessions, group labs, and one-on-one labs.

Want to chat 1-on-1 with Safari and WebKit engineers during #WWDC25? Our teams are hosting labs this week — it’s your chance to ask questions, share feedback, and connect directly with the folks behind the browser.

developer.apple.com/wwdc25/sessi...

Hope to see you there!

News from WWDC25: WebKit in Safari 26 beta Welcome to WWDC25!

Safari 26 beta!

webkit.org/blog/16993/n...

Safari 26.0 Beta Release Notes | Apple Developer Documentation Released June 9, 2025 — 26.0 beta (20622.1.14)

Looks like you got your wish: developer.apple.com/documentatio...

How to have the browser pick a contrasting color in CSS Have you ever wished you could write simple CSS to declare a color, and then have the browser figure out whether black or white should be paired with that color?

Have you ever tried using color contrast tools backed by the WCAG 2 contrast algorithm (probably didn’t realize) — and then wonder “WHY IN THE WORLD DOES BLACK ON MEDIUM BLUE PASS WHILE WHITE ON MEDIUM BLUE FAILS?”

You aren’t the only one.

Learn what’s going on:
webkit.org/blog/16929/c...

How to have the browser pick a contrasting color in CSS Have you ever wished you could write simple CSS to declare a color, and then have the browser figure out whether black or white should be paired with that color?

Have you ever wished the browser would look at a background color and pick black or white for the text — whichever one provides more contrast?

Now, the `constrast-color()` function in CSS does just that.

webkit.org/blog/16929/c...

Polishing your typography with line height units See how to use line-height units when setting paragraph margins, and create vertical rhythm in your text.

If you use `lh` units in your CSS, you can start to establish vertical rhythm in your web designs. Learn how in this short & easy tutorial.

webkit.org/blog/16831/l...

The CSS shape() function Shapes are an important aspect of graphic design.

Say hello to responsive, adaptable shapes in CSS with the new shape() function!

Instead of static SVG paths in clip-path, shape() allows you to define scalable, flexible shapes with familiar CSS units, variables, and even calc().

Learn more on the WebKit blog post.
webkit.org/blog/16794/t...

Better typography with text-wrap pretty Support for text-wrap: pretty just shipped in Safari Technology Preview, bringing an unprecedented level of polish to typography on the web.

I’m super excited about `text-wrap: pretty`. It does a lot more to improve typography than you might expect — at least in Safari Technology Preview 216.

It improves all lines of text, not just the last 4. It enhances hyphenation & rag, not just avoiding short last lines.

webkit.org/blog/16547/b...

Item Flow – Part 1: A new unified concept for layout CSS Grid and Flexbox brought incredible layout tools to the web, but they don’t yet do everything a designer might want.

Are you excited for masonry layouts in CSS? Wondering what’s happening?

Well, a third option is emerging. One that unifies the `flex-flow` and `grid-auto-flow` properties into a whole new mechanism — Item Flow.

Learn what it is, and what it means for Flexbox and Grid in webkit.org/blog/16587/i...

Meet Declarative Web Push Web Push notifications are a powerful and important part of the web platform.

Web Push is exciting. But it requires service workers and a bunch of custom code that can be different from project to project.

How about instead we standardize on using JSON & leave JavaScript out of it!

Meet Declarative Web Push. Available in iOS and iPadOS 18.4 beta.

webkit.org/blog/16535/m...

Safari Technology Preview app icon on macOS Sequoia featuring a red and white compass needle over a purple background with white radial marks.

The release notes for Safari Technology Preview 210 are available covering updates to CSS, DOM, JavaScript, Rendering, Web Animations, Web API, Web Extensions, and Web Inspector.

www.webkit.org/blog/16406/r...

Got it. I'll share it with the team.

Can you be more specific about the kind of interest would you like to be able to signal?

You are correct that WebKit Bugzilla bugs are, for the most part, public (security bugs are not). Feedback Assistant reports are also a good way of reporting sensitive information to Apple directly, such as when you need to include a sysdiagnose, for example.

The most basic way to think about it is that any web content (e.g. web page rendering, JavaScript execution) are a WebKit Bugzilla report. Feedback Assistant reports are the right place for browser issues (e.g. user-interface and browser features like Reader, bookmarks, tabs, profiles, etc.)

Side by side comparison of a layout with and without text-box. With text-box, a headline lines up with the top of the image it's next to.

Safari 18.2 is here! For web developers, it’s the biggest release of new features this year. Highlights include cross-document View Transitions, text-box, spatial videos in visionOS, ruby improvements, WASM garbage collection, HTTPS by default, Genmoji, and more.

webkit.org/blog/16301/w...

Safari Technology Preview app icon on macOS Sequoia featuring a red and white compass needle over a purple background with white radial marks.

Release notes are available for Safari Technology Preview 209 with updates to the Browser, CSS, Rendering, Scrolling, SVG, Text, Web API, Web Extensions, and Web Inspector.

www.webkit.org/blog/16296/r...

Improvements are ongoing, as Bugzilla is a deeply tentacled application, but I'm pleased we were able to bring this to the WebKit and broader web community.