Mastodawn

I can finally quickly test adaptive layouts in Firefox’s new Split View mode. For more advanced testing, there’s https://polypane.app, of course. But there are many other simpler side-by-side use cases. Yay!

https://blog.mozilla.org/en/firefox/split-view/

Vadim Makeev 4h ago

W3C Advisory Board 17h ago

Are LLMs useful or problematic for the standards process? We gave it some thought and listed benefits, risks, and best practices in a position paper that we published today: https://www.w3.org/TR/llms-standards/

Use of Large Language Models in Standards Work

As Large Language Models (LLMs) become increasingly synonymous with “AI”, and are used by people within our community, we want to highlight considerations around different ways in which LLMs can be useful or problematic when it comes to leveraging them in standards work at W3C.

Vadim Makeev 20h ago

Firefox for Web Developers 21h ago

Firefox 149 is out now, and adds bunch of new web platform features, such as:

🎉 The CloseWatcher API
🎉 popover=hint (although I'm concerned about the spec'd behaviour)
🎉 hasUAVisualTransition on PopStateEvent
🎉 font-family: math
🎉 The CSP reporting API

And more!

https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/149

Firefox 149 release notes for developers (Stable) - Mozilla | MDN

This article provides information about the changes in Firefox 149 that affect developers. Firefox 149 was released on March 24, 2026.

MDN Web Docs

Vadim Makeev 1d ago

Web Standards 1d ago

Firefox 149 release notes for developers. The release adds the popover="hint" value, CloseWatcher for custom closeable components, shape-outside support for xywh(), vertical-align as a shorthand property, optional @container query conditions, HTMLSelectElement.showPicker() for <datalist> elements, and HTMLMediaElement.captureStream(). #firefox #browser

https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/149

Vadim Makeev 1d ago

Firefox for Web Developers 1d ago

There are many browsers, but only three widely-used engines. We maintain one of those engines - Gecko. Here's why we feel that browser engine diversity is essential for the future of the web https://blog.mozilla.org/netpolicy/2026/03/23/competition-innovation-and-the-future-of-the-web/

Competition, Innovation, and the Future of the Web – Why Independent Browser Engines Matter – Open Policy & Advocacy

Gecko matters because it ensures there’s an independent voice shaping how the internet evolves. Without Gecko, the landscape would be dominated by Apple and Google alone. Is that really the ...

Open Policy & Advocacy

Vadim Makeev 2d ago

Brecht 2d ago

🚀 A little while ago, I released an article on my blog redesign as a progressive enhancement. A few people DM'd me after that, asking for more info on the architecture. Well, it sure isn't perfect, and I'll surely tinker more on it, but I wrote about how I did the new CSS Architecture 🤓
https://utilitybend.com/blog/under-the-hood-a-closer-look-at-the-css-architecture-behind-the-redesign

Under the hood: a closer look at the CSS architecture behind the redesign | utilitybend

A deep dive into the CSS architecture behind utilitybend.com: cascade layers, a three-tier design token system, light-dark() for dark mode, a modern reset, container queries, logical properties, and progressive enhancement as a structural principle.

Vadim Makeev 2d ago

Web Standards 2d ago

CSSkit, a high-performance CSS toolchain written in Rust. @keithamus’s project combines CSS parsing, minification, linting, formatting, transpilation, bundling, and analysis into one tool with zero configuration. It also includes LSP integration for IDE support. The project is inspired by oxc and is currently in alpha. #css #tools

https://csskit.rs

Vadim Makeev 5d ago

Bramus 6d ago

CSS `light-dark()` is about to support images!

https://www.bram.us/2026/03/19/more-easy-light-dark-mode-switching-light-dark-is-about-to-support-images/

Shipping in Firefox 150. Starting tomorrow, available behind a flag in Chromium 148.

More Easy Light-Dark Mode Switching: light-dark() is about to support images!

CSS light-dark() is being extended to support images.

Bram.us

Vadim Makeev 6d ago

Web Standards 6d ago

Abusing customizable selects. @patrickbrosset builds three creative demos with the new <select>: a curved folder stack, a fanned card deck with anchor positioning, and a radial emoji picker with CSS trigonometric functions. #css #html

https://css-tricks.com/abusing-customizable-selects/

Vadim Makeev Mar 17

CSS Day Mar 17

Also, we announce new speakers today. @kevinpowell @leaverou @matuzo and @html5test will join us on 11th and 12th of June.

No flamethrowers will be used. Probably.

https://cssday.nl/

CSS Day 2026, 11th & 12th of June, Amsterdam

CSS Day is the conference for CSS designers, developers, spec writers, and browser vendors.

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