Nicolas Chevobbe

A graphic with the All Day Hey! logo at the top left, and conference information on the top right, reading: "Thursday 7th May 2026 09:00 – 17:00 BST Everyman Cinema Leeds UK" Below shows a Firefox logo which displays a swirl pattern alongside the word Firefox. Below that reads "Without our sponsors, there would be no conference. All Day Hey! is made possible by Firefox."

The mighty @webdevs.firefox.com are supporting All Day Hey! 2026. Without them, there would be no conference. @jakearchibald.com will be around on the day if you want to talk all things Mozilla!

Tickets and more information:
heypresents.com/conferences/...

CSS shape() landed in Firefox 148. It's similar to path(), but allows the full expressiveness of CSS…

You can throw away innerHTML and replace it with the new setHTML(), which has a built-in sanitizer. Here's how it works:

Igalia Coding Experience | Igalia - Open Source Consultancy and Development Igalia is an open source consulting firm specialised in the development of innovative projects and solutions. Our engineers have expertise in a wide range of technological areas, including browsers an...

If you're a student or early in your software/CS career, I encourage you to apply to the Igalia Coding Experience program. The deadline to apply is April 3.

People from underrepresented groups are encouraged to apply!

www.igalia.com/coding-exper...

Gecko: Intent to ship: ariaNotify

Hello Ana, thanks for the report
We filed bugzilla.mozilla.org/show_bug.cgi... for this

HTML might be getting a new type of tag, which… hasn't happened this millennium. Here's the new syntax, and how it works:

To celebrate my first merged PR into Firefox core, I wrote a too-long article on Contextual Design for (Opinionated) Component Libraries.

frehner.me/blog/context...

And it concludes with my reasons for submitting patches to Firefox and WebKit.

Lots of thanks to everyone who helped out, or

Who should I speak to to get this t-shirt Jake?

This was actually some of my first contributions to the area of web browsers, just finding and fixing errors in the support data. Normally just ones I stumbled across as a web developer too, rather than anything deliberate.

A straight, orange and yellow old building with front covered with bricks. It has a lot of small windows that each are near each other in a stair pattern. A lot of different yet satisfying shapes next to each other near the top of the building. The front is half-covered with a warm afternoon winter light.

Saw this building in Paris, last year. Super nice shapes #reference #environmentart

One more custom <select> demo, with a bunch of CSS transforms and animations.
I can't get enough of this. So cool.

View Transition Types are newly baseline! These make it easier to build transitions that are specific to particular situations.

Also, we have some new View Transition DevTools in Firefox 147…

Do not give up your brain It's tempting to just let tools think for you, but you still need to be able to think for yourself and stay sharp.

"Once men turned their thinking over to machines in the hope that this would set them free. But that only permitted other men with machines to enslave them."

― Frank Herbert, Dune

cassidoo.co/post/good-br...

The Navigation API is newly baseline! The web now has sensible, low-level routing for navigations.

CSS anchor positioning is newly baseline! This opens the door for lots of new creative CSS.

It's a huge feature, but here are the basics.

fqueze - Overview fqueze has 35 repositories available. Follow their code on GitHub.

I only reviewed the patch, github.com/fqueze wrote the feature 🙂

a soft hill with a ray of golden light shining on it there's a small house and a tree at its foot

Golden light study

I still haven't found who is the photographer that took the ref picture :/

Ah yeah, that's this one, I mixed it up

That's exactly what's planned, do the same thing as WebMidi
There was an intent to prototype sent last week 🙂

Neither is herpes, but I’ll keep doing my work without either.

and surprisingly not super easy to get right! There's so much that you have to think of when you do this, I should write a small blog post about it

In Firefox 146 DevTools, long lists of unused CSS custom properties collapse, decluttering the UI, and improving performance

Firefox 146 release notes for developers (Stable) - Mozilla | MDN This article provides information about the changes in Firefox 146 that affect developers. Firefox 146 was released on December 9, 2025.

A bunch of web platform features and bug fixes landed in Firefox 146. There'll be more videos about the highlights soon, but in the meantime, here's a summary: https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/146

Me smiling at the camera, sit on a red office chair, with my young cat wrapped around my neck, also looking at the camera

It's been 10 years since my first patch landed on the #Firefox repo: hg-edge.mozilla.org/mozilla-cent... 🎂

Here's a picture of me at that time, with my beloved assistant

CSS @​scope has landed in Firefox 146, making it a new baseline feature. Here's how it works:

New blog post: Why the Sanitizer API is just `setHTML()` - https://frederikbraun.de/why-sethtml.html

thanks a lot for the link
There are a few surprising things, I'll investigate
But I'm also pretty confident this will be faster in 146 :)

Next week Firefox 146 will be out, and this will have bugzilla.mozilla.org/show_bug.cgi... , which does have a pretty nice impact on performance.
I'll check the page though to see if there's anything we could to do make performance even better